Gorgeous amp. I had a silverface Pro Reverb that was incredible. Unfortunately it was stolen and never recovered. I miss it. Great video Doug. I enjoy your expertise and narrations.
Love your videos. I'm a retired USAF radar repairman, and long time guitarist. I started down the repair/mod road years ago, but use your videos as topical refreshers. And your sidekicks are awesome.. Tell Rusty he's loved in NC.
I have this same model Pro Reverb. I replaced the the grill cloth, but kept the original. I couldn't stand the tear. It just didn't go with the almost new looking cabinet. Always heard it referred to as the Baby Twin. It is a great amp. Thanks for your videos and tips!
You're welcome, Joe. I understand your desire to make the grill cloth match the quality of the rest of the amp. Since you kept the old torn cloth, if you ever sell the amp to a real purist, I guess they could re-install it :)
Hi Uncle Doug. Thought I had seen all of your videos but this one slipped by until recently. I have been focused on building my first amp (the 5F2A) and had not searched your channel for a BF-PR until recently, and your post really caught my attention because I have a 65 BF Pro Reverb that I bought in a pawn shop many years ago. The previous owner had installed a mystery set of 8Ω and 16Ω speakers. I seldom used it because I was concerned about the impedance mismatch and also because it popped and wheezed even while sitting idle, but with the help of your videos I discovered the fix could be an easy one and it was. I replaced the old filter caps and the rectifier tube, which had no markings but looked like a light bulb, with a new GZ34. The rest of the tubes were replaced with vintage NOS. Lastly, I replaced the speakers and the dead reverb tank and it sounds fantastic. I wouldn't part with the old girl for anything. Tremolo is a little shallow and trails off if set below 3 so I'll be looking at the ceramic caps as your video suggests. Not long ago I would have never attempted this repair of my first build, but with the help of your videos and excellent instruction I found the job very rewarding and fairly easy. I cannot claim to thoroughly understand everything that I did but the information you have made available for people like myself has proved invaluable. My guess is that you have a deep background in engineering or instruction or both, but whatever the case may be your presentation is very effective. I'm starting to get the feeling that if I keep searching through your video collection I may find something else to build or fix! :) Thanks again for another great video.
+Slugg0matic Wow....thanks for the very nice comments, Sluggo. Rusty and I are glad our videos are helpful and wish you the best of luck with all your projects :)
Blessings to you Good Friend and our Lil Hero..your service and knowledge is second to none,...I've learned from you and so has so many,many others please keep in there Later!1
The "72" in "Patented 72" as you note is not the date. My best information is it is the silkscreen # for that panel. When you look on the back panel between the Ext Speaker jack and the Trem footswitch jack, you will see "73". You will also notice if you look in those spots on every different Fender model that you will see different numbers. For example, my '63 Deluxe has "Design & Circuits Patented A7" under the pilot light, while some earlier brownface Deluxes have a "007" instead of "A7". Flip over to the back panel, and it is marked near the middle with "008".
Wow, balanced is right! The low end is perfect. You can tell even through a camera microphone. It's present and full, but not boomy without any mud. Thanks for the vid.
Hi again Uncle Doug, it's that pesky Tim bringing up things long forgotten by you I'm sure. I just love this stuff and I'm glued to the screen when I'm watching you. I believe I've watched this video 2 or 3 times now as I have been refurbishing my own SF 67 Pro Reverb. I believe you are correct about it being a transitional Pro. Besides the knobs, when you scroll by the PT on the inside of the chassis it looks to me like someone re stenciled the last 7 over what I'm guessing was a 6. I know this amp is probably long gone, but just wanted to chime in.
I had that exact year pro reverb, purchased in 1969, stolen in mid 80's (along with my early 70's Gibson SG Standard :( I recognized every square inch of your close-up look, thanks for the memories!
If it is working, it would be wise to simply use it until it needs repair, Steven, simply because between two-way shipping, labor, and parts, the total cost will be around $450, which is a lot of money to spend on a working amp.
Hi Uncle Doug - really been enjoying your videos - I'd be really interested to see you spruce up some British amps - maybe a vintage Marshall or a Vox. Keep up the good work - and good to see Rusty has a chum!
I agree, Pod, but there are virtually none in my area....only Fenders, Gibsons, Valcos, and an Alamo or two. I have studied British amp schematics and am ready for action if given the opportunity. Hopefully one will show up in the near future. Thanks so much for your input :)
the reverb on this amp is amazing !!!!love it ,I have a fender harvard reverb amp thats pretty close to this its not a tube amp but is a powerhouse of a amp
Amen, Alva. It's the first Pro Reverb I ever worked on and it was quite impressive in all respects. I would love to find one for myself some day. Thanks for your nice comments.
I have seen all of your videos now. I feel like a cheat taking all this collaborated knowledge that's gold. Your videos are great and very entertaining. I have put much of you teachings to work for myself and I wanted to thank you. I put a bias pot on my fender blues deville (us made one) and just scratch built a small single ended amp (breadboard style) to play through. Oh and I think Rusty could use a dam good belly rub to lol. Thanks.
allaird1 Greetings, A1, and thanks for the kind words. Rusty and I are quite pleased that you have put the information in our videos to such good use. You are exactly the type of viewer we are doing this for. We send you our best regards and wish you the best of luck with your projects.
nice to see Rusty’s pal, We have 2 tricolor collies in our family, as well as a mahagony sable collie and a blonde english shepherd. My Vibrolux Reverb is probably same year, only 2 10” instead of 2 12”. Lovely amps.. Fenders finest.. everything was just right in these.
Excellent video Uncle Doug. I do take issue with the way the new filter caps are installed. It is so easy to straighten the leads and put a nice bend in them when they are installed. Also I would replace the dropping resistors with 2 watt MO's. But that is just my borderline OCD. lol I noticed that you did not replace the bias filter cap. It looks original and I just wondered if you did it and left it out of the video. Keep those vids coming and I will eventually get around to watching them all.
Robert Hurless Thanks, Robert. I share your compulsion for straight, neatly bent leads. The filter caps in the video had already been installed by a previous (non-OCD) tech. I don't recall on the bias cap.....if it tested OK, I probably left it alone. Please keep watching :)
say.. thanks again for listening. rev issue was bad 820ohm/cap (resistor actually) in the recovery stage. tested a little high @850ohms..go figure.... love your vids!
I have one of these but mine is a '65. I picked it up at a garage sale. It came from Webb Music out in Calif. but the amp wound up in west Texas, where I found it.
Hi Doug, for what it's worth, the Pro Reverb was the last blackface amp design to come out of Fender. Since they were introduced in 1965, there are NO pre-CBS Pro Reverbs. These are very nice amps, and these days go for a nice premium price... two 12" speakers, a more reasonable 40 watt output (which translates to smaller transformers than on a Twin Reverb, and lighter weight. Frankly, I think a 40 watt amp needs two (or four in the case of a Super Reverb) speakers to get the sound out... maybe someday I'll manage to get one.
Speaking of pre-vs post-CBS amps, the blackface series was introduced in mid 1964, and CBS took over Fender in February of 1965, most blackface amps are post-CBS, but they weren't changed until 1968 (after Leo Fender left Fender).
It seems like they still produced good amps for several years after the CBS takeover, but by the mid to late 1970's the higher-wattage circuits got pretty strange.
By 1968, Leo had left Fender and the crazies took over... ever see those weird solid-state amps they made in 1968? I don't think you'll find one today... they had a very high failure rate.
I'm really glad I found you Uncle Doug. I have been interested in tube amps all of my life and have considered building one. It appears I have found the holy grail of tube amp information. I am impressed with the thoroughness of your inspection on " just in for a bias check" . The two fried resistors that you found would have made for very poor performance had you just biased the amp and sent it out the door. Well done!
Tad Barnaby Thanks, Tad. Yes, you have to give "the patient" a thorough physical exam and follow up on any symptoms or visible problems. Roasted screen grid resistors are a common source of cracking, rustling noises in vintage tube amps.
Hello Doug your knowledge is fantastic.I have a pre CBS Fender Princeton Reverb has OF on the tube sticker is that March of 1965?????I had the amp since the mid 1970S and still works great only changed some tubes and speaker once everything works great.Glenn in N.Y.
Thanks so much, GP. I really appreciate it :) Since F is the sixth letter of the alphabet, the month would be June of 1965. It's a great amp......you made a wise choice back in the 70's :)
Great Video Uncle Doug! I actually have a 5e3 clone I'm replacing the JJ 6v6's with a pair of Tung Sol's and also changing the JJ 5y3 to an NOS Tung Sol 5y3. I'm wondering if it will be fine? To my knowledge the JJ 6v6's are able to withstand higher plate voltages than most 6v6's. I think everything will be ok but would like to hear you're opinion on it. Thanks!
+Tyler Jones Thanks, Tyler. It's impossible for me to provide an accurate answer since I'm not able to personally test the amp, but if your plate voltages and dissipation are within normal limits then you should have no problems. Good luck.
Previous benchwork guy did a recap of all electrolytics except the 50uf 50v by the diode, and he left a new 100uf 100vdc with the parts, im sure this was for an upgrade that never occured. the 50uf read 75uf on the heathkit IT11 but the leakdown was surprisingly good at 50volts < 10ua. Ill already found a Bad 6V6 socket with a repair job, and a very large 470K on just one socket but not both. on that socket the tube does not sit in flush which points towards a botched repair or heat damage so I need to get a new Octal. Also I found the 10K PS resistors in Excess of 14K so thats gotta go too. This is only one night of testing so far, movie will follow soon.
Great videos Uncle Doug! I am trying to find more information about some of your vibrato fixes. Checking the values on the capacitors will be the first thing I do. I just picked up a '74 super six reverb and the vibrato is not very intense. I did see where you stacked some resistor in another one of your videos. What should I try first? Your videos are the most informative on the web, and I thank you for that!
Greetings, Thomas. I have no experience with the Fender Super Six model, but understand that it is simply a Fender Super Reverb with six speakers. They incorrectly call the tremolo "vibrato". Since it modulates the volume of the signal rather than the pitch, it really is a tremolo. You need a shorted plug or a footswitch to activate the tremolo, or it will not function. For specific hints on how to improve the circuit, I highly recommend this site: fenderguru.com/amps/super-reverb Good luck !!!
Thanks Buddy! I have checked out the Fender Guru site and found a lot of great information for modding this 98lb beast. It seem all mentions of the trem circuit revolve around better pre amp gain on the vibrato channel. I did connect the foot switch. I have tremolo, but the intensity is not to my liking. I have to turn it all the way to 10, and even then it's not enough. Yes, I am one of those trem guys. HA! I have changed the tube to a new EH 12AX7, but the intensity stayed the same. I was hoping to find out wether the caps or resistance could help my to increase the intensity of the effect or if I should replace the optocoupler. Thanks again for your great instruction!
As a fellow trem-hound I can sympathize with your need for more intensity. There are three capacitors (.01, .01, .02uf) between the grid and plate of the trem 12AX7 that have to be exact in value. Replacing them with new, high-quality caps may help. Be sure the opto-bug is shaded when the chassis is out and you are testing (lay a piece of thick, black paper over it.....any light affects its function). Finally, some people report that having the output tubes biased too hot can reduce the trem effect, so be sure your 6L6GC's are at 21W of PD or a little less (70% of max). Good luck !!
I’m gassing for one of these, which would be my first vintage amp. I’ve owned tons of “boutique” amps but really feel like I should own a real blackface. Can one of these pro reverbs get the Mayer/SRV tones?
The two 350V caps in series are placed before the standby switch, and will charge gently as the rectifier warms up, and will remain charged during standby, protecting the rectifier from high current surges when switching out of standby. I noticed that the other three filter caps are rated at 350V, but, according to the schematic, they are expected to work at 440V, 430V and 390V.
@@UncleDoug The most humble of apologies! My face is lighting up the room with a crimson glow! I'll try to put my brain in gear before hitting the keyboard in future! (BTW, after 30 years in the live music business, I've already got hearing aids and I guess my two year old varifocals need an update.)
I really nice series of Fender models were the late 70's/ early 80's Rivera models (like the Princeton Reverb II, Deluxe Reverb II, Concert Reverb II etc...) They were the last point to point wired amps Fender ever made. Lots of gems out there cheap with great tones available and great for mods.
The bias pot inside the chassis....BRILLIANT...lol I guess Fender wanted an eye on the components when changing tubes..I am not collector so I am after a later model Pro reverb 70's 80's Any reason to stray away from them?
The best, affordable Pro Reverbs were made from 1968 to 1972 (Silverface). You would be better off with one of these, from both a collector and player standpoint.
Thanks, F. Actually, the shop guitar is an old 1980 Matsumoku Vantage V-695 with MMK-45 humbucker pickups. Rescued from a pawn shop and spruced up many years ago :)
Uncle Doug! I can't list all the superlatives I wish to send your way. I might be a potential "stalker" , and it will look bad in court. Just know I spend almost all my (non pole dancer vid viewing) spare time watching your excellent vids. I love your humor! I loved the PA conversion vid, where you had to take your vallum several times due to your excitement. REQUEST: An Uncle Doug greatest hits / instructional vid. Please teach us the songs you consistently play and ramble on for an hour or so, with great 'snarcasm'(coined). Since I have NO ADULT SUPERVISION, I really do just sit with my ,(muahahahaha) pile of amps and while fondling them, watch and relearn from your vids.1 month into retirement and loving it! Bamboo Bob, seriously deranged Uncle Doug fan!!!
+Bob Davidson Thanks for the nice comments, Bob. Rusty and I are glad you enjoy our videos. The little riffs I play from time to time are dredged up from foggy recollections of my misspent youth and are not meant to resemble any known tunes.....living or dead. I concur with your assessment of retirement, it is indeed wonderful to have the freedom to pursue your projects without any petty interruptions from an employer who selfishly expects you to actually "work" :)
Hi Uncle Doug, thanks, great video Question for you: if the bands are burned off the resistors on the tubes, how do you find out what the values should be? Can you actually get schematics for these old amps? Thanks!
Hey Uncle Doug, was thinking yea I know dangerous but here we go...could you be so kind as to taking a picture of our lil Hero Rusty next to a phonograph,stereo,PA System,etc. I think (here we go again) it would be a perfect keepsake as by how I heard you say a kind word or gesture and his response with the ball as a chew toy just seemed natural being he just has a way of being a technological companion and you two are humorous as well, thanks! .The Lady Friend in my life thought it by her words your comradery is adorable and my idea of a picture captures the devotion of your commitment to the ways of your hard dedicated work and sharing it along with man's best friend and the perfect Mascot for the technology and skills in Rusty ''The Wonder Dawg'' !! I Agree you're great at what teach us all!! Thanks !!
Thanks so much, Nelson. I'm deeply touched at your awareness of the special place Rusty occupies in my life. He has been my companion for over 15 years, and is a true friend. I included him in one of my early videos as a little comic break, and secretly worried that viewers might think it was silly or a waste of time....but before long, people actually began to complain if Rusty didn't make at least one appearance in every video. He remains the loyal friend who is always glad to see me in the morning and who looks so sad and lonely when I go inside at night. Never did I realize, when I stopped to look at a bunch of puppies for sale in the back of a pickup truck many years ago, that the one I picked would someday be known by thousands of people all over the world.....as Rusty the Wonder Dog :) ^. .^
Hey Uncle Doug. I see that amp has the ic capacitors installed. What is your thoughts on that brand ? I have run into a few guys that recommend not using them. Not due to vintage blah blah but, due too reliability. Have you jad any issues with them ?
No problems at all, Bryan. I have installed hundreds of them, without a single issue of any sort. Beware of people who badmouth products without offering actual data or proof of their assertions.
Hi there from France Uncle Doug. I really am hoping that you may have an idea as to the problem I'm having with my 65' Fender Pro Reverb. As I'm an Englishman living over here, I've not found it easy to find a guy who I trust with my beloved amp! It works fine for 15 minutes or so, but then loses it's output almost completely. I don't really know where to start looking! Any help would be most welcome. Keep up the good work!!!
Greetings, Peter. I'm going to make a wild guess that your coupling capacitors are failing when they get warm and allowing the B+ from a previous stage to get to the grid(s) of the next stage and, in effect, biasing them "off". I saw this frequently in 1950's Seeburg Jukebox amplifiers. That's the first place I'd look. Good luck.
As usual your gathering of ''Wish I Had That'' brings us this sample of great tone machines! I'm really a lover of amps that make Teles and Strats perform their magic. I taking a guess here but if the tonestack consisted of a 220k and the NFB were comparable I'd think this is also a form of a Super Reverb 4x10'' but in this format. At times Fender which are great ( BlackFace Era) at using speaker circuit adjustments say from the 4x10'' to 2x12'' they would implement a cap and or a resistor to compensate for compression and tone of the speaker's range(s) the ''Pro Reverb'' was known as lil Twin in it's day and even though the ''Super was preferred over the ''Pro'', when it switched over to the ''Silver Face'' the ''Pro was preferred over the ''Super. Oddly enough production numbers also were less and eventually went through more changes and the ''Twin and ''Super were for it's wattage needs the go tos for stage and recording which is why when the statement was ever made that the Deluxe Reverb (2x6V6s) the tones of a 6L6 over a 6V6 were upgraded circuits and the most modded amp to it's prior glory the Pros were upgraded back to the 'BlackFace Era, not so with the Twins or Super. It may be the reason you only see like the one here so rare in it's numbers! Alot of the SF Pros were restored to the BF circuits I'm sure there are other models that also were restored to other preferences but I saw this topic quite a number of times in the last 10-15 years! BTW I noticed on the original schematics they show a 5U4B but they actually use ''OUR'' favorite 5AR4/GZ34. I had a agree to disagree with a Mesa Boogie Co. repairman from Bethesda, Md. saying the 5U4 was the ''Superior'' and I had to replace the 3 5U4s on my customer's Triple Rectifier according to the warranty, I did a strong looksee from the Groove Tube Schematics and the tube breakdowns, they were very close which I was kinda stunned figuring they'd be a bigger margin but I still feel and know in my own mind the 5AR4 is what I'd use if left up to me!
Greetings, Nelson. I am always astounded by your experience with vintage amps, and definitely agree with your high esteem for the GZ34. I have no idea what the Mesa tech was thinking.....the GZ34 is better in every way. Thanks for your input :)
I noticed the same...I always wondered why some Fender amps have that amazing 3D sounding lush reverb and why some just sound kind of thin. Is there a way to actually adjust (or mod) the amount of dwell, etc on these combos??
I think they all started out sounding great, Peter, and then, over time, some of the components drifted out of spec or got weak, and the reverb deteriorated. It's mainly a matter of locating and replacing those worn out electrical components.....particularly the driver and recovery tubes.
I love Pro Reverbs! Surprisingly, Fender didn't sell as many of them as they did Vibrolux Reverbs, Super Reverbs, Pro Reverbs and even the piggy-back amps like the Bandmaster and the Showman. But the Pro had a slightly larger output transformer than its counterpart, the Vibrolux Reverb, and generally they were only rated 5 watts different in wattage (Blackface Vibrolux 35 watts, Pro Reverb 40 watts. Silverface Vibrolux 40 watts, Pro Reverb 45 watts). The Pro was a much better amp (than the Vibrolux) for Gibson players with humbucker pickups, because the headroom kept the amps from squishing out at medium-high levels. The Pro Reverb is one of the few classic Fender combo amps that has not been reissued. Crazy....that should have been the first one reissued!
What The Heck...... not much effort into this one Doug. I think i will have to ask for my money back 🙂 I have always had a soft spot for the Pro Rev. Not sure why...... maybe they seemed powerful enough and "light" enough to gig with on a routine basis. As for "Original" speakers or any other part. It has never meant anything to me. If you like a different speaker(s) then change them. Certainly this owner was smart to save the Jensen's, but he may prefer these Eminence Much More Thanks for another good one Uncle D 😎
anything to worry about with the PT considering the evidence of overheating? I have just received a used amp that shows similar issue on the PT. what would be the prudent thing in this situation? thanks Unk.
Severely overheating a PT probably shortens its life, but as long as it's still working, I think it makes sense to continue using it. The PT in the video is still working just fine.
I have recently come across your videos while searching for an adjustable bias mod for a princeton amp I acquired in April. Your tutorial was great and I installed one - works like a charm! Thanks Uncle Doug and Rusty! I just subscribed to your channel - gonna go back and watch lots of past ones! Now I have purchased a '66 pro reverb, and was so happy to find this video while I await its arrival! I intend to do a cap job on it (I have done several before). I saw that the pro reverb in the video has 100uf@350v caps in series as opposed to 70uf@350v as the schematic calls for. Wondering what your thoughts are on whether to go with what the schematic calls for (70uf), or should I bump it to 100uf? With my bandmaster and dual showman (both solid state rectification), I was advised on the fender forum to go with 100uf@350v to replace the two 70uf@350v caps that are in series. So that is what I did. However, the pro has a GZ34 rectifier, so wondering what the benefits and/or detriments are to going with 100uf vs 70uf for the two filter caps in series in a pro reverb? And...which would you go with?
Greetings, TC. It's great to hear that your adjustable bias modification worked so well. Increasing the capacitance of electrolytics is a two-edged sword: on one hand you may reduce ripple (hum) and (slightly) increase bass response but on the other, you tax your rectifier by flowing much higher current at start-up. This is of particular concern if you have a tube rectifier, and you may be shortening it's life in return for no audible improvement in tone. In my opinion, with a tube rectifier, increasing capacitance is only advisable if it's actually necessary to improve hum reduction and/or bass response. If your Pro Reverb is reasonably quiet and sounds good, I would leave the series capacitance values alone (i.e. 70uf each). On the other hand, increasing the voltage rating of electrolytics is never a bad idea. Since wall outlet voltages are about 10% higher now than when the amp was made, voltage surges and spikes within the circuit may be higher than the voltage capability of the original electrolytics......especially the first (series) pair. Bottom line: 70uf at 350V is probably just fine, but if you really want to change the values of the series capacitors, I would stick with 70uf, but go up to 450V rather than 350V (= 900V rating). It's just my (conservative) opinion, but you would be gaining a safety margin, with no added stress to any component (except your wallet, since 450V caps cost a little more :). Good luck.
Uncle Doug Thanks so much - your explanations are so clear and concise. Really helpful! I think I will likely not go up to 100uf then. Sprague atoms come in an 80uf@450V value. If I go with those, I will be at 40uf (dividing by two in series as you explained) which is within 15% of the original 35uf value, but increasing the voltage to 900V as you suggest. Is that a decent compromise? I am assuming going up in capacitance less than 15% is not a big deal. What do you think?
I've a question about screen grid resistors. I see a lot of vintage amps that don't have them in. Sometimes I hear a difference in feel and characteristics if they put in screen resistors afterwards. They loose character if you understand what I mean. Somebody was telling me that in the earlier years they made power tubes that could handle more plate voltages and where a better built quality so they didn't need those resistors. The mass production tubes from now require these resistors.... Would you suggest that it is always better to put them in?
+Marco Hermans Greetings, Marco. Screen grid resistors are normally seen in amps that have a filter choke in the power supply. Amps that simply have resistors between nodes generally don't have (or need) them. The Fender Deluxe Reverb has a filter choke and screen resistors. The Fender Princeton Reverb has resistors (no filter choke) and does not have screen resistors. It really doesn't have to do with the quality of tubes, it's just a matter of whether the circuit has a filter choke or not.
Hey Uncle Doug, Where are you located? First of all, thank you for all of the great information! It is much appreciated. I have a 1967 Blackface Fender Super Reverb that is really beat, but thanks in large part to your videos I am planning on doing an overhaul. Hopefully it has a variable bias circuit (pretty sure it would) I did get some really sweet sounds out of it so hopefully it isn't totally shot, but even with a smoked transformer and some burnt resistors - it can be brought back. Be well, and thank you again for putting this stuff out. Best regards, Lloyd
You're quite welcome, Lloyd. I'm in West Texas. I checked the schematic, and your SR does indeed have an adjustable bias control, much like the Deluxe Reverb. If the power transformer is roasted, you can get a nice replacement at Triode Electronics, but be sure you correct the cause of the PT and resistor failure before you install a new one. The BF SR is a great amp....definitely worth the time, effort, and expense to restore. Best of luck.
No, Sir, it was not. The '64 PRO amp came right after the brownface Pro, and kept the 15" but did not yet have reverb. In '65, it changed to 2X12 with added reverb. Would be VERY cool to have each version, if you were playing out and needed some TONEFUL amps that really cooked. Amp switching between the two, would be quite Heavenly! I think the two schematics were also different ... Actually, Weber Speakers makes an Alnico speaker, a 15" version of their Blue Dog, which is quite incredible. Check this URL, then go under "FEATURES" and listen to John Bohlenger using one in his Vibroverb, I think it is ... tedweber.com/blue15a/
@@Tonetwisters happily the old jensen is still ticking along nicely, and may very well outlast myself! There was a brownface pro for sale nearby me that I was tempted to go for a tyrekick recently before the covid hit. I sometimes run mine into a 2 x 12 for a more focussed top and bottom end, but always end up preferring the glorious full fidelity a 15 has on tap. I'm pretty sure you're right, the added reverb channel makes for a very different sounding circuit
1967....last year for the PR black face im thinking....ive a 68/69 that im about to send off to be black faced....great job.... ps any suggestions before it goes?
+Mark C My only suggestion would be to check out this site for an excellent overview of tone improvement for the Pro Reverb: fenderguru.com/amps/pro-reverb Best of luck with the modifications.
Maybe the greatest black panel Fender of all time. If you haven’t played one at full song it will make you weak in the knees. It’s essentially identical to the more famous Vibrolux Reverb but with a bit more B+ and 12’s instead of 10’s.
i have a question, do you have or have you ever had a 70749 power trasnformer adn if so could you tell me what the wires are and what the outputs of them are? i have no means to test and the local electrical places were not sure how to test it ( even after watching youtube vids LOL
+lordraptor11 Greetings, LR. The advice that Enzo gave you on the DIY Audio forum was about the best you will get. I have no personal experience with or knowledge of this particular transformer. My suggestion would be to buy an inexpensive multimeter, plug the two black (probably primary) wires into a current limiter, and then measure the output from the pairs and trios of wires. Your best bet is to perform voltage measurements or find a schematic for the circuit that the transformer came from, with color coding. Good luck.
Makes sense to me... Fender already called the vibrato mechanism on their guitars a tremolo. Stands to reason they should call the tremolo mechanism on their amplifiers a vibrato.
i was talking with someone a few days ago regarding Sprague caps, and after doing some research...wow is it a complicated history! the Orange Drops were initially manufactured by Sprague Electric (obviously), which became SBE. they sold the OD cap division to Vishay (in the 90's i believe), who marketed them as "Vishay-Sprague". at least for awhile, they were still being made in the original SBE factory, which Vishay had either purchased or leased from SBE (i can't remember which.) more recently Vishay sold the Orange Drop line to Cornell-Dublier (who also currently manufactures the Mallory 150 line, since Mallory doesn't actually exist anymore.) the American factory was part of the deal, but CDE (Cornell-Dublier) has said that they're going to close the US factory at some point, after which OD's will most likely be made overseas somewhere. nobody's sure when this will happen, or if it already has, but apparently the quality control has really slipped over the past couple of years (the CDE buyout was in 2011, if i remember correctly.) similarly, the Sprague Atom caps are/were made by United Chemicon (not sure if they still make them), but most come from Taiwan these days. a lot of people have cut open the Atoms only to find a much smaller (usually unbranded) electrolytic inside. there doesn't seem to be any consensus on whether they're coming from the legitimate factory that way, or of counterfeiters have gotten out huge batches, but they _are_ coming from official distributors so i'm assuming they're coming from the actual factory. Sprague is another one of those kinda sad stories where the parts we like in our amps and guitars really only exist as branding devices. along with things like the "reissue" tube brands (that all mostly come out of the same couple of Russian factories owned by New Sensor aka Mike Matthews of Electro-Harmonix fame), these days a Sprague is only a Sprague in name only. it kind of bothers me when i see younger players specifying these parts for their projects, not realising they're not the same thing as the classic components were. i can understand using names like "Orange Drop", but when a totally different factory uses the _actual_ old brand name despite no connection to it, it seems a little disingenuous and sleazy to me. ...then again, i don't think i have a low enough ethical standard to work in marketing department for some of these companies, so what do i know?
From what I understand, this amp hasn't been worked on for many years, so the Orange Drop caps are probably legit. I have heard a very similar story about the "Bumblebee" caps that are being remade for use in guitars, like Gibsons, and are sold for very high prices. Apparently, someone dissected one of them and found a cheap, no-name capacitor enclosed within the hard, cast "Bumblebee" shell. As in your example, perhaps it was just an unauthorized imitation.....or not. My approach to this is to order and use good quality, reasonably priced capacitors and buy NOS vintage ones whenever I can. Thanks for your informative post, Cat.
Uncle Doug eep, yeah i've seen the photos of those Luxe Bumblebees (and a couple other "premium" caps that really aren't.) i can't understand why _anyone_ would pay $50-$100 for a couple of _new_ guitar caps, especially when they're not going to work any better than a $1 Xicon or something. i think there are way too many scams in the guitar electronics world that have bled over from the audiophile thing, and it's a major pet peeve of mine. people will completely ignore the science of how these things work and instead waste a ton of money simply because someone else claims it's "better" (without ever providing any verifiable evidence of this, of course.) capacitors are not magical things: science knows exactly what they do and how they work, and they're very simple devices. you can even make them yourself with mineral oil, aluminum foil, kraft paper and bus wire if you're the tinkering type (really messy though!) i can understand buying vintage/NOS caps for the sake of restorations or repair, or even "just because". at least it makes a little more sense to me from the standpoint of why they're more expensive and for keeping something as close to original as possible. buying a new PiO or Bumblebee for ridiculous prices, on the other hand, just seems like a waste of cash when there's zero evidence of them _actually_ being "premium" (aside from clever marketing, which doesn't count.) i'd just as soon spend $1.50 for a couple of poly caps from RadioShack.
I agree completely. I'll bet that if you blindfolded someone and had them listen to a guitar with the $150 bumblebees and one with $1.50 Xicons, they couldn't tell the difference. IMHO, there is no scientific merit to the idea that different capacitors sound completely different. I have a bunch of vintage bumblebees (harvested from organ amps at very little cost) and occasionally use them in guitar amp tone circuits, mostly for fun, since people go nuts when they see them. Just between you and me, I honestly hear no difference between them and any other capacitor.
Uncle Doug Same here. There's no reason one cap should sound different from another given the same values. Either you've got the stated amount of farads or you don't. It's not like electricity itself has a sound.
I concur, St. H, particularly when the capacitor simply provides a pathway to ground for certain frequencies. To me, the overall amp design, speaker(s) used, and type of speaker housing would have an infinitely greater effect on tone.
Not usually, Philo, since it's not the way I use them, but, it's my experience that an amp that sounds great without effects generally sounds great with them.....and I guess I'm just a retro kind of guy :))
hi. is it possible to convert a solid state amp to a tube? if so, r some amps easier than others to do so? if not, is there anything i can do to make one more tube-like. i have a johnson jm150. it has a tube preamp. the rest is solid state. thanx for any info.
Greetings, MJT. I guess anything is possible, but it would be a huge and expensive task to convert a solid state amp into a tube amp......and I don't think the final result would be worth it. I had a JM-120 and was really impressed by the effects it had. It was really "ahead of its time", but I understand your desire for the tone of a tube amp. I really think you would be better off simply buying a tube amp, rather than attempting a conversion. Good luck !!!
You mentioned you lived in the desert. I recently moved to the High Desert in CA. Where are you located? I have two old Fenders, one that needs work (1965 Twin Reverb) My 1961 Showman is recently refurbished. If you're near me, I will need a new amp tech to work on the Twin after the first of the year. Thanks.
+Jakexx01 I'm afraid that I'm quite a distance from you, Jake......in West Texas. Also, I have retired from doing outside work, particularly when it involves shipping. It sounds like you have a couple really nice amps. I hope you can find a good, reliable repair person in your area. Good luck :)
If you need a tube amp repair guy go to Steve Beaver at Guitar Center in Palmdale. He does amps and great luthier work as well. There is also a guy in canyon country who does old radio repair and he does amps as well, I think it's Jerrys Antique radio or something like that.
Im slowly working my way to Uncle Doug status. I got a good iron a few weeks ago and became confident in guitars, now Im thinking about building a Blackface Princeton Reverb (:
It sounds like a great plan, Wes, and judging from your icon, you have a good partner to assist you (just like Rusty assists me). Now all you need is to download some schematics, make up a parts list, order your supplies, and get started. Two challenges will be the metal chassis and wooden cabinet, which are available on the Internet if you don't have the facilities to build them yourself. Study all the safety rules.....and be careful. Good luck !!!
This amp seems to be similar to a Deluxe Reverb. Only difference is wattage and 2 speakers.. So DR is 22 Watts with 1 x12 and Pro Reverb is 40 Watts in 2 x12... Same bassman config in the normal channel, with Reverb and Trem in the second channel.Just noticed the Pro Reverb is 6L6, as Deluxe is 6V6
+ContraBand Joe It may be the amp many would have preferred over a Twin, if the twin was not such a popular go to, must have amp, in their eyes. This having less weight, less tubes, tube rectification, and more usable breakup with being super crazy loud.
Doug, as usual a great video. I have a 1968 Pro reverb... with the drip edge and black lines. It’s a road worn beast and shows its mileage... lol. I’ve always been curious if the sf circuitry is any different from the bf. This was a cool video to compare bf to my sf amp. Unfortunately it seems someone has been inside of mine... And appears that the power transformer was changed. Mine has a 606 code which is a Schumacher I believe. Which is a correct manufacturer for Fender. But many of the wires are cut and taped off from the pt... Which would make it an incorrect pt for my amp. Curious 🤔 Also I was wondering if you change the bias capacitor in this bf amp??? I wished you had videos your bias process of this wonderful amplifier. Thank you for your wonderful videos.👍
The circuit differences between the BF and SF versions are quite minimal, especially in the '68 models, since CBS had not started screwing things up. Check the Fender Guru's site for suggestions on how to improve tone. In your amp, overall bias voltage is altered by replacing the 15K resistor (not capacitor) from the bias pot wiper to ground. The bias voltage to the tubes is then fine tuned with the pot. The higher the resistance, the lower the tube bias. Since the circuit is grid biased, there is no "bias capacitor". You may have an export model with extra primary voltage inputs that are taped off. Otherwise, there are no extra wires from a normal PT to be taped off.
Doug, The capacitor I referred to is seen at 8:52 of the video. I thought this cap regulated the negative voltage to the bias. I am far from an amp tech or expert so forgive me if I’m wrong. I often see this capacitor changed routinely in most amps... I was wondering if you changed that old Mallory? Thank you again.👍
It's actually a filter cap to smooth the ripple in the rectified negative DC used in the bias circuit. Yes, it definitely should be replaced. Most people also replace the diode that does the rectification (next to the cap).
Thank you for the replies. I love old tube amps... and love watching knowledgeable people work on them. Enjoy all of your videos. Keep up the great work.👍
You're welcome, Josef. Sadly, I rarely encounter Vox amps in my area, so my experience with them is virtually nil. If I ever get the chance to work on one, I will definitely make a video about it.
Hey Doug, I want to start off by saying I love your videos! I also find myself consistently humbled by Rusty's aptitude with electrical components. ;) Anyway, I recently purchased a silverface Fender Pro Reverb, 1976 model year from Guitar Center and did the usual speaker change/tube replacement job. When I plugged it in and turned it on i noticed a horrible ground hum even with both channel volumes on 1. it has a three prong switch that seems to be wired correctly and everything. furthermore I was messing with the ground switch on the back and experienced a brief shock when it was in the right hand position (if viewing from the back) and even felt it in the footswitch. I'm sure it's a ground issue but i'm having trouble deciphering it. Any insights?
Addendum: So I went ahead and checked the wall plug i was using and it wasn't properly grounded. No shocks from properly grounded plugs. It still has a bad hum when it's on 2.5 and up. It's probably filter caps but i'm not sure.
You need to determine the frequency of the hum, Ted. Bad filter caps are associated with 120Hz hum.......not 60Hz. See my video on the subject for more help.
i watched that one and determined that the filtercaps probably aren't the case (definite 60hz hum) but the hum still gets louder when i turn the vibrato channel volume up; the normal channel doesn't do that. mind you i dont have any instrument cables plugged in when i'm experiencing this
If the volume of the hum is affected by the VC, then its source is BEFORE the VC in the circuit......which would narrow it down to the first triode of the Vibrato channel 7025, or the tone controls. See if switching tubes helps. Also, see if any of the tone controls affect the hum. This will help narrow it down further.
I sometimes shoot from the hip and that's how I read it...I'd never try to define anyone else's role for them since I'd rather not be the subject of limitation myself!
You guys are a great team--I mean that sincerely. The subject of electricity is intense to a non-professional and the comedy that works so well in between sessions is rather genius and would not work the same without Rusty! Stay well !
Credit where it's due I say...I appreciate talent and you guys have tons of it! It's great to see the depth of creativity so evident in your work. The interface of the technical and artistic world is fascinating and there is a wealth of it all right here...to paraphrase, "it's like a string of Christmas lights, for those of you who observe Christmas", if that makes any sense to you...;) Peace to ya, and no need to reply!!
No kidding, TF. I remember a music store I used to go to way back in the 1960's. They were Fender dealers, and the place was full of brand new guitars and amps; which I, being a penniless punk kid, would drool over. If only I had the resources at the time, I would have bought them out, stored everything, and been a rich man today......instead of just an old codger who missed the boat :))
Uncle Doug Ditto for me as well, Doug. I did the exact same thing as you, drooling and all. Unfortunately I only had the resources to buy 2nd hand back in the 60's. The most sought after Fender equipment today are the ones made before the CBS takeover.
It's very confusing, Snorky. Apparently, the number "72" references a patent or group of patents that protect this amplifier circuit (and Fender) from duplication. It is definitely not a date or year. I have yet to see or hear a clear explanation of what the number specifically means. Perhaps a viewer can provide one.
google tells us "All blackface Fenders have "patented" followed by a number under the pilot light. I was told it had to do with the order in which the amps were patented, not the year. A BFVC says 66, BF Bassman 64, BF Princeton 70, BF Bandmaster 50 etc. "
It's rather mysterious, and since no one really understands what it means, it makes me wonder why they do it.....unless it's some sort of legal requirement.
Hello, I hope you can help me. I have a blackface pro reverb, that makes a terrible sound when turning on. So I want to disassemble it to try to find the source of that. I already reemoved the panel with the speakers, but have no clue how to get the upper part out of the chassis. Do you have any hint for me, how to disassemble that beast? ANy help would be hioghly appreciated.
Yes, I hope I get that fixed. In my amp, the label shows Production #1 and the Letters OE, so must be 1965/5, if I am right. Serial No. is A00252. And it is in far better optical condition than that in the video.
The Amp is optical in a good shape, but unfortunately it does not work. It makes a horrible noise, when turned on. I already replaced all the big capacitors, but nothin gchanged. Would be great, if youcould give me any hint that could help to get the Amp working again. I uploaded a short video, that show the noise when switching the standby switch to on. ruclips.net/video/rY47sdQAZk4/видео.html
Pretty much more interesting since I caught a guy at place in San Francisco guy was tearing it up on a pro Reverb blackface can't remember the name of the place but it was called something like the Queens jazz club or something like that little bit South of San Francisco and it was right around of the place that you can only smoke cigarettes at a place that had like all of the movie actors pictures on the walls and they didn't care if you smoke cigarettes it was only one of the places you can actually do this but back to the main issue this cat was tearing up a pro Reverb amp because when I heard it I was amazed and then I said what is that a m p you're playing through I can see it's a fender of some sort I'm a little ways away and when I got up close at what's up Fender Pro Reverb and he was just nailing it through a Gibson 335 anyway just thought I'd throw this tidbit of information towards you
I would in the future like you to restore one of my fender vintage amps. How can I contact you for the purpose of explaining what I have and want done as well as how to ship you the amp plus your cost for your services?
Honestly, I like that 1940's amp you built, better. With reverb it would sound even better. Just my opinion... I really like that amp you built. Not saying this isn't a great amp but....... Thanks for the great vids... keep em comin' :-D
O.k. that took about 33 seconds. "J C Clean" refers to the "Roland Jazz Chorus" amp, which apparently is a thing and happens to be my favorite setting on its little 5-watt sibling. Still sounds like a blackface to me.
Gorgeous amp. I had a silverface Pro Reverb that was incredible. Unfortunately it was stolen and never recovered. I miss it. Great video Doug. I enjoy your expertise and narrations.
God bless you. SO sorry for your loss.
Thanks for the video Doug. I really appreciate the time and effort you put into making these extremely informative videos.
You're welcome, CC :)
Love your videos. I'm a retired USAF radar repairman, and long time guitarist. I started down the repair/mod road years ago, but use your videos as topical refreshers. And your sidekicks are awesome.. Tell Rusty he's loved in NC.
+Ben “Slick51” Holbrook Thanks so much, Ben. Rusty and I are glad the videos are helpful, and he sends his regards to all his groupies in NC :)
Doug is a rare breed, we must protect him
Thanks, Jay :)
I do repair videos myself....but Uncle Doug is the best!...So educational and so well done. Thank you!
You're welcome, Pierre. Thanks for the nice comment :)
I have this same model Pro Reverb. I replaced the the grill cloth, but kept the original. I couldn't stand the tear. It just didn't go with the almost new looking cabinet. Always heard it referred to as the Baby Twin. It is a great amp. Thanks for your videos and tips!
You're welcome, Joe. I understand your desire to make the grill cloth match the quality of the rest of the amp. Since you kept the old torn cloth, if you ever sell the amp to a real purist, I guess they could re-install it :)
Hi Uncle Doug. Thought I had seen all of your videos but this one slipped by until recently. I have been focused on building my first amp (the 5F2A) and had not searched your channel for a BF-PR until recently, and your post really caught my attention because I have a 65 BF Pro Reverb that I bought in a pawn shop many years ago. The previous owner had installed a mystery set of 8Ω and 16Ω speakers.
I seldom used it because I was concerned about the impedance mismatch and also because it popped and wheezed even while sitting idle, but with the help of your videos I discovered the fix could be an easy one and it was. I replaced the old filter caps and the rectifier tube, which had no markings but looked like a light bulb, with a new GZ34. The rest of the tubes were replaced with vintage NOS. Lastly, I replaced the speakers and the dead reverb tank and it sounds fantastic. I wouldn't part with the old girl for anything. Tremolo is a little shallow and trails off if set below 3 so I'll be looking at the ceramic caps as your video suggests.
Not long ago I would have never attempted this repair of my first build, but with the help of your videos and excellent instruction I found the job very rewarding and fairly easy. I cannot claim to thoroughly understand everything that I did but the information you have made available for people like myself has proved invaluable.
My guess is that you have a deep background in engineering or instruction or both, but whatever the case may be your presentation is very effective.
I'm starting to get the feeling that if I keep searching through your video collection I may find something else to build or fix! :)
Thanks again for another great video.
+Slugg0matic Wow....thanks for the very nice comments, Sluggo. Rusty and I are glad our videos are helpful and wish you the best of luck with all your projects :)
love the doggy breaks thanks for the info
You're welcome, Jesse :)
Especially Max, the anteater! ☺
Blessings to you Good Friend and our Lil Hero..your service and knowledge is second to none,...I've learned from you and so has so many,many others please keep in there Later!1
Thank you so much for pointing out the difference between vibrato and tremolo. Even Fender seems to use the terms interchangeably!
They do indeed, Bill, and it's very frustrating. You're welcome :)
Thanks Doug for covering this classic blackface fender. Let us all keep these amps up and jammi'n for another 50 years!
You're welcome, Fred. I'm not sure if I can handle another 50 years......but, hopefully, the amps will :)
The "72" in "Patented 72" as you note is not the date. My best information is it is the silkscreen # for that panel. When you look on the back panel between the Ext Speaker jack and the Trem footswitch jack, you will see "73".
You will also notice if you look in those spots on every different Fender model that you will see different numbers.
For example, my '63 Deluxe has "Design & Circuits Patented A7" under the pilot light, while some earlier brownface Deluxes have a "007" instead of "A7". Flip over to the back panel, and it is marked near the middle with "008".
Very interesting, Brian. Thanks for your input.
Blast the neighbors with impunity. That meaningful phrase has become part of my vocabulary. Thanks, Uncle Doug. I love your work.
Most neighbors have it coming, GT. Show no mercy ;()
I own the 66’ blackface version of this.. bad ass combo, great for pedals, but pretty loud if you want it to breath some fire on its own🔥
I have the opportunity to buy one at a good price; but I just don't need the volume anymore ...
Tonetwisters yes.. I’ve realized this..
I much prefer my brown deluxe . It’s my favorite in my small collection
This is a blackface.
Another great video Uncle Doug, thank you!
Thanks, Jerry.
Wow, balanced is right! The low end is perfect. You can tell even through a camera microphone. It's present and full, but not boomy without any mud. Thanks for the vid.
+Elsif You're welcome.....glad you like the amp and the video :)
Sorry about all the comments :) in case you can't tell, I'm kind of tearing through your videos right now.
No problem. I'm glad you like them enough to leave comments. Thanks for watching :)
Great video, awesome narration, valuable information!
Thanks, Hugo :)
Hi again Uncle Doug, it's that pesky Tim bringing up things long forgotten by you I'm sure. I just love this stuff and I'm glued to the screen when I'm watching you. I believe I've watched this video 2 or 3 times now as I have been refurbishing my own SF 67 Pro Reverb. I believe you are correct about it being a transitional Pro. Besides the knobs, when you scroll by the PT on the inside of the chassis it looks to me like someone re stenciled the last 7 over what I'm guessing was a 6. I know this amp is probably long gone, but just wanted to chime in.
Thanks for your input, Tim. It's always welcome :)
I had that exact year pro reverb, purchased in 1969, stolen in mid 80's (along with my early 70's Gibson SG Standard :( I recognized every square inch of your close-up look, thanks for the memories!
I hope the memories were pleasant ones, Jeff. Glad you enjoyed the video :)
I actually have a Pro Reverb that I picked up a few years ago. It’s been checked, but I need to have it brought up to date.
If it is working, it would be wise to simply use it until it needs repair, Steven, simply because between two-way shipping, labor, and parts, the total cost will be around $450, which is a lot of money to spend on a working amp.
Thanks for another great story Uncle Doug.
I swear I could smell my old Super Reverb whilst watching this!
You're welcome, Vinny :)
Hi Uncle Doug - really been enjoying your videos - I'd be really interested to see you spruce up some British amps - maybe a vintage Marshall or a Vox.
Keep up the good work - and good to see Rusty has a chum!
I agree, Pod, but there are virtually none in my area....only Fenders, Gibsons, Valcos, and an Alamo or two. I have studied British amp schematics and am ready for action if given the opportunity. Hopefully one will show up in the near future. Thanks so much for your input :)
Beautiful piece... too bad I got rid of my Fender amps. It was fun in the time.
Why did you get rid of them?
the reverb on this amp is amazing !!!!love it ,I have a fender harvard reverb amp thats pretty close to this its not a tube amp but is a powerhouse of a amp
Thanks, Joe.
A superb old amp, despite the transformer woes. And I love the old surf licks!
Amen, Alva. It's the first Pro Reverb I ever worked on and it was quite impressive in all respects. I would love to find one for myself some day. Thanks for your nice comments.
I have seen all of your videos now. I feel like a cheat taking all this collaborated knowledge that's gold. Your videos are great and very entertaining. I have put much of you teachings to work for myself and I wanted to thank you. I put a bias pot on my fender blues deville (us made one) and just scratch built a small single ended amp (breadboard style) to play through. Oh and I think Rusty could use a dam good belly rub to lol. Thanks.
allaird1 Greetings, A1, and thanks for the kind words. Rusty and I are quite pleased that you have put the information in our videos to such good use. You are exactly the type of viewer we are doing this for. We send you our best regards and wish you the best of luck with your projects.
One of those all time great amps ... I had a '66 that was near basket case condition ... I would love to find another someday
So would I, Martin.
nice to see Rusty’s pal, We have 2 tricolor collies in our family, as well as a mahagony sable collie and a blonde english shepherd. My Vibrolux Reverb is probably same year, only 2 10” instead of 2 12”. Lovely amps.. Fenders finest.. everything was just right in these.
Glad you enjoyed the video, JW. We share your enthusiasm for collies and vintage Fender amps :)
Everything you do "seems interesting to you" or well, me. Thanks again Uncle Doug.
You're welcome, F86. I'm glad we share the same interests :))
Excellent video Uncle Doug. I do take issue with the way the new filter caps are installed. It is so easy to straighten the leads and put a nice bend in them when they are installed. Also I would replace the dropping resistors with 2 watt MO's. But that is just my borderline OCD. lol I noticed that you did not replace the bias filter cap. It looks original and I just wondered if you did it and left it out of the video. Keep those vids coming and I will eventually get around to watching them all.
Robert Hurless Thanks, Robert. I share your compulsion for straight, neatly bent leads. The filter caps in the video had already been installed by a previous (non-OCD) tech. I don't recall on the bias cap.....if it tested OK, I probably left it alone. Please keep watching :)
say.. thanks again for listening. rev issue was bad 820ohm/cap (resistor actually) in the recovery stage. tested a little high @850ohms..go figure.... love your vids!
+Don Molenda You're welcome, Don. We're glad you solved the problem.
I have one of these but mine is a '65. I picked it up at a garage sale. It came from Webb Music out in Calif. but the amp wound up in west Texas, where I found it.
You're a lucky guy, BB. These are wonderful amps. Congratulations on a great acquisition.
Oh, the vintage Fender sound.
We had tears in our eyes during the audio demo, C :)
i'm loving that reverb sound,,,, i want one.
I don't blame you, Paul. That sound has sold a bunch of amps :)
Very much admire your knowledge base and presentation - a pleasure to watch and learn.
Thanks, John. I'm glad you enjoy the videos :))
Hi Doug, for what it's worth, the Pro Reverb was the last blackface amp design to come out of Fender. Since they were introduced in 1965, there are NO pre-CBS Pro Reverbs. These are very nice amps, and these days go for a nice premium price... two 12" speakers, a more reasonable 40 watt output (which translates to smaller transformers than on a Twin Reverb, and lighter weight. Frankly, I think a 40 watt amp needs two (or four in the case of a Super Reverb) speakers to get the sound out... maybe someday I'll manage to get one.
+Bill Daniels Thanks for the info, Bill. I was not aware that there were no pre-CBS Pro Reverbs. They are indeed excellent amps.
Speaking of pre-vs post-CBS amps, the blackface series was introduced in mid 1964, and CBS took over Fender in February of 1965, most blackface amps are post-CBS, but they weren't changed until 1968 (after Leo Fender left Fender).
It seems like they still produced good amps for several years after the CBS takeover, but by the mid to late 1970's the higher-wattage circuits got pretty strange.
By 1968, Leo had left Fender and the crazies took over... ever see those weird solid-state amps they made in 1968? I don't think you'll find one today... they had a very high failure rate.
This sounds like another good reason to stick with tube circuitry :)
Felt relaxed watching this fine video. Thanks
Larry Walton You're welcome, Larry. Glad you liked it :)
These are great amps! IIRC, the only 2X12, 40 watt, handwired amp that Fender ever made.
Glad you liked it, TT :)
I'm really glad I found you Uncle Doug. I have been interested in tube amps all of my life and have considered building one. It appears I have found the holy grail of tube amp information. I am impressed with the thoroughness of your inspection on " just in for a bias check" . The two fried resistors that you found would have made for very poor performance had you just biased the amp and sent it out the door. Well done!
Tad Barnaby Thanks, Tad. Yes, you have to give "the patient" a thorough physical exam and follow up on any symptoms or visible problems. Roasted screen grid resistors are a common source of cracking, rustling noises in vintage tube amps.
Your guitar playing was very tasty and nicely done. Great tone! I continue to watch and learn.
Thanks, JG :)
Hello Doug your knowledge is fantastic.I have a pre CBS Fender Princeton Reverb has OF on the tube sticker is that March of 1965?????I had the amp since the mid 1970S and still works great only changed some tubes and speaker once everything works great.Glenn in N.Y.
Thanks so much, GP. I really appreciate it :) Since F is the sixth letter of the alphabet, the month would be June of 1965. It's a great amp......you made a wise choice back in the 70's :)
hi Max, glad to meet you, are you still on this side?
Yes, he is :)
Great Video Uncle Doug! I actually have a 5e3 clone I'm replacing the JJ 6v6's with a pair of Tung Sol's and also changing the JJ 5y3 to an NOS Tung Sol 5y3. I'm wondering if it will be fine? To my knowledge the JJ 6v6's are able to withstand higher plate voltages than most 6v6's. I think everything will be ok but would like to hear you're opinion on it. Thanks!
+Tyler Jones Thanks, Tyler. It's impossible for me to provide an accurate answer since I'm not able to personally test the amp, but if your plate voltages and dissipation are within normal limits then you should have no problems. Good luck.
Previous benchwork guy did a recap of all electrolytics except the 50uf 50v by the diode, and he left a new 100uf 100vdc with the parts, im sure this was for an upgrade that never occured. the 50uf read 75uf on the heathkit IT11 but the leakdown was surprisingly good at 50volts < 10ua. Ill already found a Bad 6V6 socket with a repair job, and a very large 470K on just one socket but not both. on that socket the tube does not sit in flush which points towards a botched repair or heat damage so I need to get a new Octal. Also I found the 10K PS resistors in Excess of 14K so thats gotta go too. This is only one night of testing so far, movie will follow soon.
It sounds like you are making good progress, Jordan. Much of any vintage amp repair generally involves undoing some of the botched previous repairs.
I watched the video and commented, Jordan. Thanks for the link.
Great videos Uncle Doug! I am trying to find more information about some of your vibrato fixes. Checking the values on the capacitors will be the first thing I do. I just picked up a '74 super six reverb and the vibrato is not very intense. I did see where you stacked some resistor in another one of your videos. What should I try first? Your videos are the most informative on the web, and I thank you for that!
Greetings, Thomas. I have no experience with the Fender Super Six model, but understand that it is simply a Fender Super Reverb with six speakers. They incorrectly call the tremolo "vibrato". Since it modulates the volume of the signal rather than the pitch, it really is a tremolo. You need a shorted plug or a footswitch to activate the tremolo, or it will not function. For specific hints on how to improve the circuit, I highly recommend this site: fenderguru.com/amps/super-reverb Good luck !!!
Thanks Buddy! I have checked out the Fender Guru site and found a lot of great information for modding this 98lb beast. It seem all mentions of the trem circuit revolve around better pre amp gain on the vibrato channel. I did connect the foot switch. I have tremolo, but the intensity is not to my liking. I have to turn it all the way to 10, and even then it's not enough. Yes, I am one of those trem guys. HA! I have changed the tube to a new EH 12AX7, but the intensity stayed the same. I was hoping to find out wether the caps or resistance could help my to increase the intensity of the effect or if I should replace the optocoupler. Thanks again for your great instruction!
As a fellow trem-hound I can sympathize with your need for more intensity. There are three capacitors (.01, .01, .02uf) between the grid and plate of the trem 12AX7 that have to be exact in value. Replacing them with new, high-quality caps may help. Be sure the opto-bug is shaded when the chassis is out and you are testing (lay a piece of thick, black paper over it.....any light affects its function). Finally, some people report that having the output tubes biased too hot can reduce the trem effect, so be sure your 6L6GC's are at 21W of PD or a little less (70% of max). Good luck !!
I’m gassing for one of these, which would be my first vintage amp. I’ve owned tons of “boutique” amps but really feel like I should own a real blackface. Can one of these pro reverbs get the Mayer/SRV tones?
If you can create those tones, the amp can convey them quite well, Mike.
The two 350V caps in series are placed before the standby switch, and will charge gently as the rectifier warms up, and will remain charged during standby, protecting the rectifier from high current surges when switching out of standby. I noticed that the other three filter caps are rated at 350V, but, according to the schematic, they are expected to work at 440V, 430V and 390V.
Time for some new bifocals and possibly a hearing aid, Silas. The three filter caps are all rated at 500V.
@@UncleDoug The most humble of apologies! My face is lighting up the room with a crimson glow! I'll try to put my brain in gear before hitting the keyboard in future! (BTW, after 30 years in the live music business, I've already got hearing aids and I guess my two year old varifocals need an update.)
I really nice series of Fender models were the late 70's/ early 80's Rivera models (like the Princeton Reverb II, Deluxe Reverb II, Concert Reverb II etc...) They were the last point to point wired amps Fender ever made. Lots of gems out there cheap with great tones available and great for mods.
Thanks for your input, Joe.
The bias pot inside the chassis....BRILLIANT...lol I guess Fender wanted an eye on the components when changing tubes..I am not collector so I am after a later model Pro reverb 70's 80's Any reason to stray away from them?
The best, affordable Pro Reverbs were made from 1968 to 1972 (Silverface). You would be better off with one of these, from both a collector and player standpoint.
Another excellent video Doug. You are a fine and very knowledgable instructor. Would love to know what model guitar was used to test this amp...Tele?
Thanks, F. Actually, the shop guitar is an old 1980 Matsumoku Vantage V-695 with MMK-45 humbucker pickups. Rescued from a pawn shop and spruced up many years ago :)
Uncle Doug! I can't list all the superlatives I wish to send your way. I might be a potential "stalker" , and it will look bad in court.
Just know I spend almost all my (non pole dancer vid viewing) spare time watching your excellent vids. I love your humor! I loved the PA conversion vid, where you had to take your vallum several times due to your excitement. REQUEST: An Uncle Doug greatest hits / instructional vid. Please teach us the songs you consistently play and ramble on for an hour or so, with great 'snarcasm'(coined). Since I have NO ADULT SUPERVISION, I really do just sit with my ,(muahahahaha) pile of amps and while fondling them, watch and relearn from your vids.1 month into retirement and loving it! Bamboo Bob, seriously deranged Uncle Doug fan!!!
+Bob Davidson Thanks for the nice comments, Bob. Rusty and I are glad you enjoy our videos. The little riffs I play from time to time are dredged up from foggy recollections of my misspent youth and are not meant to resemble any known tunes.....living or dead. I concur with your assessment of retirement, it is indeed wonderful to have the freedom to pursue your projects without any petty interruptions from an employer who selfishly expects you to actually "work" :)
So, Doug, when resistors show damage, do we replace with Higher Wattage?
I tend to do this, but first you need to verify there was no reason for excess current to flow through the original-spec resistor.
Another interesting video ! Thanks ! Enjoyed it !
You bet, Kal. Thanks for watching !!
Hi Uncle Doug, thanks, great video Question for you: if the bands are burned off the resistors on the tubes, how do you find out what the values should be? Can you actually get schematics for these old amps? Thanks!
Yes, schematics for virtually all vintage amps are available on the Internet. Try a Google search.
Hey Uncle Doug, was thinking yea I know dangerous but here we go...could you be so kind as to taking a picture of our lil Hero Rusty next to a phonograph,stereo,PA System,etc. I think (here we go again) it would be a perfect keepsake as by how I heard you say a kind word or gesture and his response with the ball as a chew toy just seemed natural being he just has a way of being a technological companion and you two are humorous as well, thanks! .The Lady Friend in my life thought it by her words your comradery is adorable and my idea of a picture captures the devotion of your commitment to the ways of your hard dedicated work and sharing it along with man's best friend and the perfect Mascot for the technology and skills in Rusty ''The Wonder Dawg'' !! I Agree you're great at what teach us all!! Thanks !!
Thanks so much, Nelson. I'm deeply touched at your awareness of the special place Rusty occupies in my life. He has been my companion for over 15 years, and is a true friend. I included him in one of my early videos as a little comic break, and secretly worried that viewers might think it was silly or a waste of time....but before long, people actually began to complain if Rusty didn't make at least one appearance in every video. He remains the loyal friend who is always glad to see me in the morning and who looks so sad and lonely when I go inside at night. Never did I realize, when I stopped to look at a bunch of puppies for sale in the back of a pickup truck many years ago, that the one I picked would someday be known by thousands of people all over the world.....as Rusty the Wonder Dog :) ^. .^
I've been hearing about 'Black Face' a lot in the news recently - Are Fender producing these amps again? XD
They make and sell reissues, PW, and virtually all have the black control panel on the front.
One just landed on my bench this week
I think you'll enjoy working on it, Jordan. They are really nice amps.
Hey Uncle Doug. I see that amp has the ic capacitors installed. What is your thoughts on that brand ? I have run into a few guys that recommend not using them. Not due to vintage blah blah but, due too reliability. Have you jad any issues with them ?
No problems at all, Bryan. I have installed hundreds of them, without a single issue of any sort. Beware of people who badmouth products without offering actual data or proof of their assertions.
Hi there from France Uncle Doug. I really am hoping that you may have an idea as to the problem I'm having with my 65' Fender Pro Reverb. As I'm an Englishman living over here, I've not found it easy to find a guy who I trust with my beloved amp! It works fine for 15 minutes or so, but then loses it's output almost completely. I don't really know where to start looking! Any help would be most welcome. Keep up the good work!!!
Greetings, Peter. I'm going to make a wild guess that your coupling capacitors are failing when they get warm and allowing the B+ from a previous stage to get to the grid(s) of the next stage and, in effect, biasing them "off". I saw this frequently in 1950's Seeburg Jukebox amplifiers. That's the first place I'd look. Good luck.
As usual your gathering of ''Wish I Had That'' brings us this sample of great tone machines! I'm really a lover of amps that make Teles and Strats perform their magic. I taking a guess here but if the tonestack consisted of a 220k and the NFB were comparable I'd think this is also a form of a Super Reverb 4x10'' but in this format. At times Fender which are great ( BlackFace Era) at using speaker circuit adjustments say from the 4x10'' to 2x12'' they would implement a cap and or a resistor to compensate for compression and tone of the speaker's range(s) the ''Pro Reverb'' was known as lil Twin in it's day and even though the ''Super was preferred over the ''Pro'', when it switched over to the ''Silver Face'' the ''Pro was preferred over the ''Super. Oddly enough production numbers also were less and eventually went through more changes and the ''Twin and ''Super were for it's wattage needs the go tos for stage and recording which is why when the statement was ever made that the Deluxe Reverb (2x6V6s) the tones of a 6L6 over a 6V6 were upgraded circuits and the most modded amp to it's prior glory the Pros were upgraded back to the 'BlackFace Era, not so with the Twins or Super. It may be the reason you only see like the one here so rare in it's numbers! Alot of the SF Pros were restored to the BF circuits I'm sure there are other models that also were restored to other preferences but I saw this topic quite a number of times in the last 10-15 years! BTW I noticed on the original schematics they show a 5U4B but they actually use ''OUR'' favorite 5AR4/GZ34. I had a agree to disagree with a Mesa Boogie Co. repairman from Bethesda, Md. saying the 5U4 was the ''Superior'' and I had to replace the 3 5U4s on my customer's Triple Rectifier according to the warranty, I did a strong looksee from the Groove Tube Schematics and the tube breakdowns, they were very close which I was kinda stunned figuring they'd be a bigger margin but I still feel and know in my own mind the 5AR4 is what I'd use if left up to me!
Greetings, Nelson. I am always astounded by your experience with vintage amps, and definitely agree with your high esteem for the GZ34. I have no idea what the Mesa tech was thinking.....the GZ34 is better in every way. Thanks for your input :)
from my homestate!! wonderful amp
Thanks, JZ. I'm glad you liked it.
LOVE the pro reverb
We do too, Neale. It's a dandy amp :)
that reverb is awesome on this amp. I thought for a second you were playing A RECORDING .
Bob Barcus Thanks so much, Bob. High praise indeed :) The reverb was exceptional.
I noticed the same...I always wondered why some Fender amps have that amazing 3D sounding lush reverb and why some just sound kind of thin. Is there a way to actually adjust (or mod) the amount of dwell, etc on these combos??
I think they all started out sounding great, Peter, and then, over time, some of the components drifted out of spec or got weak, and the reverb deteriorated. It's mainly a matter of locating and replacing those worn out electrical components.....particularly the driver and recovery tubes.
Thanks. nice demo.
You're welcome, Jason :)
I love Pro Reverbs! Surprisingly, Fender didn't sell as many of them as they did Vibrolux Reverbs, Super Reverbs, Pro Reverbs and even the piggy-back amps like the Bandmaster and the Showman. But the Pro had a slightly larger output transformer than its counterpart, the Vibrolux Reverb, and generally they were only rated 5 watts different in wattage (Blackface Vibrolux 35 watts, Pro Reverb 40 watts. Silverface Vibrolux 40 watts, Pro Reverb 45 watts). The Pro was a much better amp (than the Vibrolux) for Gibson players with humbucker pickups, because the headroom kept the amps from squishing out at medium-high levels. The Pro Reverb is one of the few classic Fender combo amps that has not been reissued. Crazy....that should have been the first one reissued!
Thanks for your excellent analysis, Eric. I'm sure many Fender fans agree with you.
Now he can blast the neighbors with impunity. Hahaha that’s hilarious!
Glad you liked it, DM :)
What The Heck...... not much effort into this one Doug.
I think i will have to ask for my money back 🙂
I have always had a soft spot for the Pro Rev. Not sure why...... maybe they seemed powerful enough and "light" enough to gig with on a routine basis.
As for "Original" speakers or any other part. It has never meant anything to me. If you like a different speaker(s) then change them. Certainly this owner was smart to save the Jensen's, but he may prefer these Eminence Much More
Thanks for another good one Uncle D 😎
Glad you enjoyed it, M.
anything to worry about with the PT considering the evidence of overheating? I have just received a used amp that shows similar issue on the PT. what would be the prudent thing in this situation? thanks Unk.
Severely overheating a PT probably shortens its life, but as long as it's still working, I think it makes sense to continue using it. The PT in the video is still working just fine.
I have recently come across your videos while searching for an adjustable bias mod for a princeton amp I acquired in April. Your tutorial was great and I installed one - works like a charm!
Thanks Uncle Doug and Rusty! I just subscribed to your channel - gonna go back and watch lots of past ones!
Now I have purchased a '66 pro reverb, and was so happy to find this video while I await its arrival! I intend to do a cap job on it (I have done several before). I saw that the pro reverb in the video has 100uf@350v caps in series as opposed to 70uf@350v as the schematic calls for. Wondering what your thoughts are on whether to go with what the schematic calls for (70uf), or should I bump it to 100uf? With my bandmaster and dual showman (both solid state rectification), I was advised on the fender forum to go with 100uf@350v to replace the two 70uf@350v caps that are in series. So that is what I did. However, the pro has a GZ34 rectifier, so wondering what the benefits and/or detriments are to going with 100uf vs 70uf for the two filter caps in series in a pro reverb? And...which would you go with?
Greetings, TC. It's great to hear that your adjustable bias modification worked so well.
Increasing the capacitance of electrolytics is a two-edged sword: on one hand you may reduce ripple (hum) and (slightly) increase bass response but on the other, you tax your rectifier by flowing much higher current at start-up. This is of particular concern if you have a tube rectifier, and you may be shortening it's life in return for no audible improvement in tone.
In my opinion, with a tube rectifier, increasing capacitance is only advisable if it's actually necessary to improve hum reduction and/or bass response. If your Pro Reverb is reasonably quiet and sounds good, I would leave the series capacitance values alone (i.e. 70uf each).
On the other hand, increasing the voltage rating of electrolytics is never a bad idea. Since wall outlet voltages are about 10% higher now than when the amp was made, voltage surges and spikes within the circuit may be higher than the voltage capability of the original electrolytics......especially the first (series) pair. Bottom line: 70uf at 350V is probably just fine, but if you really want to change the values of the series capacitors, I would stick with 70uf, but go up to 450V rather than 350V (= 900V rating). It's just my (conservative) opinion, but you would be gaining a safety margin, with no added stress to any component (except your wallet, since 450V caps cost a little more :). Good luck.
Uncle Doug Thanks so much - your explanations are so clear and concise. Really helpful! I think I will likely not go up to 100uf then. Sprague atoms come in an 80uf@450V value. If I go with those, I will be at 40uf (dividing by two in series as you explained) which is within 15% of the original 35uf value, but increasing the voltage to 900V as you suggest. Is that a decent compromise? I am assuming going up in capacitance less than 15% is not a big deal. What do you think?
That sounds like an excellent compromise, TC. Please let me know how it turns out.
Uncle Doug Will do - thanks!
I've a question about screen grid resistors. I see a lot of vintage amps that don't have them in. Sometimes I hear a difference in feel and characteristics if they put in screen resistors afterwards. They loose character if you understand what I mean. Somebody was telling me that in the earlier years they made power tubes that could handle more plate voltages and where a better built quality so they didn't need those resistors. The mass production tubes from now require these resistors.... Would you suggest that it is always better to put them in?
+Marco Hermans Greetings, Marco. Screen grid resistors are normally seen in amps that have a filter choke in the power supply. Amps that simply have resistors between nodes generally don't have (or need) them. The Fender Deluxe Reverb has a filter choke and screen resistors. The Fender Princeton Reverb has resistors (no filter choke) and does not have screen resistors. It really doesn't have to do with the quality of tubes, it's just a matter of whether the circuit has a filter choke or not.
Hey Uncle Doug, Where are you located? First of all, thank you for all of the great information! It is much appreciated. I have a 1967 Blackface Fender Super Reverb that is really beat, but thanks in large part to your videos I am planning on doing an overhaul.
Hopefully it has a variable bias circuit (pretty sure it would) I did get some really sweet sounds out of it so hopefully it isn't totally shot, but even with a smoked transformer and some burnt resistors - it can be brought back.
Be well, and thank you again for putting this stuff out.
Best regards,
Lloyd
You're quite welcome, Lloyd. I'm in West Texas. I checked the schematic, and your SR does indeed have an adjustable bias control, much like the Deluxe Reverb. If the power transformer is roasted, you can get a nice replacement at Triode Electronics, but be sure you correct the cause of the PT and resistor failure before you install a new one. The BF SR is a great amp....definitely worth the time, effort, and expense to restore. Best of luck.
Inspired to restore (aka De-Boogie) my 64 Pro after hearing that. I assumed the Pro Reverb was a single 15 like mine but perhaps not.
Good luck with your project, Tony.
No, Sir, it was not. The '64 PRO amp came right after the brownface Pro, and kept the 15" but did not yet have reverb. In '65, it changed to 2X12 with added reverb. Would be VERY cool to have each version, if you were playing out and needed some TONEFUL amps that really cooked. Amp switching between the two, would be quite Heavenly! I think the two schematics were also different ...
Actually, Weber Speakers makes an Alnico speaker, a 15" version of their Blue Dog, which is quite incredible. Check this URL, then go under "FEATURES" and listen to John Bohlenger using one in his Vibroverb, I think it is ...
tedweber.com/blue15a/
@@Tonetwisters happily the old jensen is still ticking along nicely, and may very well outlast myself! There was a brownface pro for sale nearby me that I was tempted to go for a tyrekick recently before the covid hit. I sometimes run mine into a 2 x 12 for a more focussed top and bottom end, but always end up preferring the glorious full fidelity a 15 has on tap. I'm pretty sure you're right, the added reverb channel makes for a very different sounding circuit
The 15" Pros are the most underrated Fender amps of all. I love Bassmen, but Pros might even be better.
Walk don't run to that glorious Fender Reverb. One thing about the most Fender's, seem to have, a nice full bass response.
They do indeed, Clarence, and that quality endears them to me :)
My 66 pro is not too bass heavy in fact, au contraire .
1967....last year for the PR black face im thinking....ive a 68/69 that im about to send off to be black faced....great job.... ps any suggestions before it goes?
+Mark C My only suggestion would be to check out this site for an excellent overview of tone improvement for the Pro Reverb: fenderguru.com/amps/pro-reverb Best of luck with the modifications.
Maybe the greatest black panel Fender of all time. If you haven’t played one at full song it will make you weak in the knees. It’s essentially identical to the more famous Vibrolux Reverb but with a bit more B+ and 12’s instead of 10’s.
It's definitely one of my favorites, Jerry.
i have a question, do you have or have you ever had a 70749 power trasnformer adn if so could you tell me what the wires are and what the outputs of them are? i have no means to test and the local electrical places were not sure how to test it ( even after watching youtube vids LOL
+lordraptor11 Greetings, LR. The advice that Enzo gave you on the DIY Audio forum was about the best you will get. I have no personal experience with or knowledge of this particular transformer. My suggestion would be to buy an inexpensive multimeter, plug the two black (probably primary) wires into a current limiter, and then measure the output from the pairs and trios of wires. Your best bet is to perform voltage measurements or find a schematic for the circuit that the transformer came from, with color coding. Good luck.
Makes sense to me... Fender already called the vibrato mechanism on their guitars a tremolo. Stands to reason they should call the tremolo mechanism on their amplifiers a vibrato.
Well said, Professor :)
i was talking with someone a few days ago regarding Sprague caps, and after doing some research...wow is it a complicated history! the Orange Drops were initially manufactured by Sprague Electric (obviously), which became SBE. they sold the OD cap division to Vishay (in the 90's i believe), who marketed them as "Vishay-Sprague". at least for awhile, they were still being made in the original SBE factory, which Vishay had either purchased or leased from SBE (i can't remember which.) more recently Vishay sold the Orange Drop line to Cornell-Dublier (who also currently manufactures the Mallory 150 line, since Mallory doesn't actually exist anymore.) the American factory was part of the deal, but CDE (Cornell-Dublier) has said that they're going to close the US factory at some point, after which OD's will most likely be made overseas somewhere. nobody's sure when this will happen, or if it already has, but apparently the quality control has really slipped over the past couple of years (the CDE buyout was in 2011, if i remember correctly.)
similarly, the Sprague Atom caps are/were made by United Chemicon (not sure if they still make them), but most come from Taiwan these days. a lot of people have cut open the Atoms only to find a much smaller (usually unbranded) electrolytic inside. there doesn't seem to be any consensus on whether they're coming from the legitimate factory that way, or of counterfeiters have gotten out huge batches, but they _are_ coming from official distributors so i'm assuming they're coming from the actual factory.
Sprague is another one of those kinda sad stories where the parts we like in our amps and guitars really only exist as branding devices. along with things like the "reissue" tube brands (that all mostly come out of the same couple of Russian factories owned by New Sensor aka Mike Matthews of Electro-Harmonix fame), these days a Sprague is only a Sprague in name only. it kind of bothers me when i see younger players specifying these parts for their projects, not realising they're not the same thing as the classic components were. i can understand using names like "Orange Drop", but when a totally different factory uses the _actual_ old brand name despite no connection to it, it seems a little disingenuous and sleazy to me.
...then again, i don't think i have a low enough ethical standard to work in marketing department for some of these companies, so what do i know?
From what I understand, this amp hasn't been worked on for many years, so the Orange Drop caps are probably legit. I have heard a very similar story about the "Bumblebee" caps that are being remade for use in guitars, like Gibsons, and are sold for very high prices. Apparently, someone dissected one of them and found a cheap, no-name capacitor enclosed within the hard, cast "Bumblebee" shell. As in your example, perhaps it was just an unauthorized imitation.....or not. My approach to this is to order and use good quality, reasonably priced capacitors and buy NOS vintage ones whenever I can. Thanks for your informative post, Cat.
Uncle Doug eep, yeah i've seen the photos of those Luxe Bumblebees (and a couple other "premium" caps that really aren't.) i can't understand why _anyone_ would pay $50-$100 for a couple of _new_ guitar caps, especially when they're not going to work any better than a $1 Xicon or something. i think there are way too many scams in the guitar electronics world that have bled over from the audiophile thing, and it's a major pet peeve of mine. people will completely ignore the science of how these things work and instead waste a ton of money simply because someone else claims it's "better" (without ever providing any verifiable evidence of this, of course.) capacitors are not magical things: science knows exactly what they do and how they work, and they're very simple devices. you can even make them yourself with mineral oil, aluminum foil, kraft paper and bus wire if you're the tinkering type (really messy though!)
i can understand buying vintage/NOS caps for the sake of restorations or repair, or even "just because". at least it makes a little more sense to me from the standpoint of why they're more expensive and for keeping something as close to original as possible. buying a new PiO or Bumblebee for ridiculous prices, on the other hand, just seems like a waste of cash when there's zero evidence of them _actually_ being "premium" (aside from clever marketing, which doesn't count.) i'd just as soon spend $1.50 for a couple of poly caps from RadioShack.
I agree completely. I'll bet that if you blindfolded someone and had them listen to a guitar with the $150 bumblebees and one with $1.50 Xicons, they couldn't tell the difference. IMHO, there is no scientific merit to the idea that different capacitors sound completely different. I have a bunch of vintage bumblebees (harvested from organ amps at very little cost) and occasionally use them in guitar amp tone circuits, mostly for fun, since people go nuts when they see them. Just between you and me, I honestly hear no difference between them and any other capacitor.
Uncle Doug Same here. There's no reason one cap should sound different from another given the same values. Either you've got the stated amount of farads or you don't. It's not like electricity itself has a sound.
I concur, St. H, particularly when the capacitor simply provides a pathway to ground for certain frequencies. To me, the overall amp design, speaker(s) used, and type of speaker housing would have an infinitely greater effect on tone.
I realize you put this back together a long time ago, but do you recall approximately the dimensions of the electrolytic capacitor board ?
Thanks
No. I never measured it and would probably not recall the dimensions if I had.
Thank you.
Australian Cattle Dog supervising?
Yes, Rusty was a Queensland Blue Heeler, I believe.
my OCD wants to see you fix/replace the noisy transformer ! - happy new year Doug
I understand, Mitch :) Happy New Year to you all.
You always play that retro stuff.I do like The Ventures Walk Dont Run.Do you ever test the amps with overdrive or distortion?
Not usually, Philo, since it's not the way I use them, but, it's my experience that an amp that sounds great without effects generally sounds great with them.....and I guess I'm just a retro kind of guy :))
hi. is it possible to convert a solid state amp to a tube? if so, r some amps easier than others to do so? if not, is there anything i can do to make one more tube-like. i have a johnson jm150. it has a tube preamp. the rest is solid state. thanx for any info.
Greetings, MJT. I guess anything is possible, but it would be a huge and expensive task to convert a solid state amp into a tube amp......and I don't think the final result would be worth it. I had a JM-120 and was really impressed by the effects it had. It was really "ahead of its time", but I understand your desire for the tone of a tube amp. I really think you would be better off simply buying a tube amp, rather than attempting a conversion. Good luck !!!
You mentioned you lived in the desert. I recently moved to the High Desert in CA. Where are you located? I have two old Fenders, one that needs work (1965 Twin Reverb) My 1961 Showman is recently refurbished. If you're near me, I will need a new amp tech to work on the Twin after the first of the year. Thanks.
+Jakexx01 I'm afraid that I'm quite a distance from you, Jake......in West Texas. Also, I have retired from doing outside work, particularly when it involves shipping. It sounds like you have a couple really nice amps. I hope you can find a good, reliable repair person in your area. Good luck :)
+Uncle Doug Thanks for responding. Enjoy your retirement.
If you need a tube amp repair guy go to Steve Beaver at Guitar Center in Palmdale. He does amps and great luthier work as well. There is also a guy in canyon country who does old radio repair and he does amps as well, I think it's Jerrys Antique radio or something like that.
+Rail Rider Records Thanks.
Could the 73 on the back panel be 7 for 67 and 3 for 3rd month and the numbers on the front for the panel that was made a month earlier?
I don't recall the numbers, CC, but I guess it's possible.
Im slowly working my way to Uncle Doug status. I got a good iron a few weeks ago and became confident in guitars, now Im thinking about building a Blackface Princeton Reverb (:
It sounds like a great plan, Wes, and judging from your icon, you have a good partner to assist you (just like Rusty assists me). Now all you need is to download some schematics, make up a parts list, order your supplies, and get started. Two challenges will be the metal chassis and wooden cabinet, which are available on the Internet if you don't have the facilities to build them yourself. Study all the safety rules.....and be careful. Good luck !!!
Uncle Doug Im not as good with words as you, but it wouldnt be right to not acknowledge how awesome the time you put into your channel is! (:
Thanks so much, Wesley. Hearing such nice comments as yours makes it all worthwhile :)
This amp seems to be similar to a Deluxe Reverb. Only difference is wattage and 2 speakers.. So DR is 22 Watts with 1 x12 and Pro Reverb is 40 Watts in 2 x12... Same bassman config in the normal channel, with Reverb and Trem in the second channel.Just noticed the Pro Reverb is 6L6, as Deluxe is 6V6
+ContraBand Joe I think most of the medium and high wattage Fender amps share a lot of circuit similarities, Joe. Thanks for your input.
+ContraBand Joe It may be the amp many would have preferred over a Twin, if the twin was not such a popular go to, must have amp, in their eyes. This having less weight, less tubes, tube rectification, and more usable breakup with being super crazy loud.
Doug, as usual a great video.
I have a 1968 Pro reverb... with the drip edge and black lines.
It’s a road worn beast and shows its mileage... lol.
I’ve always been curious if the sf circuitry is any different from the bf.
This was a cool video to compare bf to my sf amp.
Unfortunately it seems someone has been inside of mine...
And appears that the power transformer was changed.
Mine has a 606 code which is a Schumacher I believe.
Which is a correct manufacturer for Fender.
But many of the wires are cut and taped off from the pt...
Which would make it an incorrect pt for my amp.
Curious 🤔
Also I was wondering if you change the bias capacitor in this bf amp???
I wished you had videos your bias process of this wonderful amplifier.
Thank you for your wonderful videos.👍
The circuit differences between the BF and SF versions are quite minimal, especially in the '68 models, since CBS had not started screwing things up. Check the Fender Guru's site for suggestions on how to improve tone. In your amp, overall bias voltage is altered by replacing the 15K resistor (not capacitor) from the bias pot wiper to ground. The bias voltage to the tubes is then fine tuned with the pot. The higher the resistance, the lower the tube bias. Since the circuit is grid biased, there is no "bias capacitor". You may have an export model with extra primary voltage inputs that are taped off. Otherwise, there are no extra wires from a normal PT to be taped off.
Doug, The capacitor I referred to is seen at 8:52 of the video.
I thought this cap regulated the negative voltage to the bias.
I am far from an amp tech or expert so forgive me if I’m wrong.
I often see this capacitor changed routinely in most amps...
I was wondering if you changed that old Mallory?
Thank you again.👍
It's actually a filter cap to smooth the ripple in the rectified negative DC used in the bias circuit. Yes, it definitely should be replaced. Most people also replace the diode that does the rectification (next to the cap).
Thank you for the replies.
I love old tube amps... and love watching knowledgeable people work on them.
Enjoy all of your videos.
Keep up the great work.👍
Amazing channel!! Do you have Vox Ac30 videos? Thank you Uncle Doug!
You're welcome, Josef. Sadly, I rarely encounter Vox amps in my area, so my experience with them is virtually nil. If I ever get the chance to work on one, I will definitely make a video about it.
Hey Doug, I want to start off by saying I love your videos! I also find myself consistently humbled by Rusty's aptitude with electrical components. ;) Anyway, I recently purchased a silverface Fender Pro Reverb, 1976 model year from Guitar Center and did the usual speaker change/tube replacement job. When I plugged it in and turned it on i noticed a horrible ground hum even with both channel volumes on 1. it has a three prong switch that seems to be wired correctly and everything. furthermore I was messing with the ground switch on the back and experienced a brief shock when it was in the right hand position (if viewing from the back) and even felt it in the footswitch. I'm sure it's a ground issue but i'm having trouble deciphering it. Any insights?
Addendum: So I went ahead and checked the wall plug i was using and it wasn't properly grounded. No shocks from properly grounded plugs. It still has a bad hum when it's on 2.5 and up. It's probably filter caps but i'm not sure.
You need to determine the frequency of the hum, Ted. Bad filter caps are associated with 120Hz hum.......not 60Hz. See my video on the subject for more help.
i watched that one and determined that the filtercaps probably aren't the case (definite 60hz hum) but the hum still gets louder when i turn the vibrato channel volume up; the normal channel doesn't do that. mind you i dont have any instrument cables plugged in when i'm experiencing this
If the volume of the hum is affected by the VC, then its source is BEFORE the VC in the circuit......which would narrow it down to the first triode of the Vibrato channel 7025, or the tone controls. See if switching tubes helps. Also, see if any of the tone controls affect the hum. This will help narrow it down further.
thank you so much. if i can figure this out without taking it to a tech i will be so happy
I think Rusty is one of the best 'straight men' in the world of comedy. Pure magic!
Thanks, WTD. Sometimes I'm not sure if he's the straight man.....or I am ;)
I sometimes shoot from the hip and that's how I read it...I'd never try to define anyone else's role for them since I'd rather not be the subject of limitation myself!
You guys are a great team--I mean that sincerely. The subject of electricity is intense to a non-professional and the comedy that works so well in between sessions is rather genius and would not work the same without Rusty! Stay well !
Thanks again for your very nice comments, WTD. Rusty and I really appreciate them :)
Credit where it's due I say...I appreciate talent and you guys have tons of it! It's great to see the depth of creativity so evident in your work. The interface of the technical and artistic world is fascinating and there is a wealth of it all right here...to paraphrase, "it's like a string of Christmas lights, for those of you who observe Christmas", if that makes any sense to you...;)
Peace to ya, and no need to reply!!
I wished I had bought a truck load of these back in the day.
No kidding, TF. I remember a music store I used to go to way back in the 1960's. They were Fender dealers, and the place was full of brand new guitars and amps; which I, being a penniless punk kid, would drool over. If only I had the resources at the time, I would have bought them out, stored everything, and been a rich man today......instead of just an old codger who missed the boat :))
Uncle Doug
Ditto for me as well, Doug. I did the exact same thing as you, drooling and all. Unfortunately I only had the resources to buy 2nd hand back in the 60's. The most sought after Fender equipment today are the ones made before the CBS takeover.
My drooling was in the early 60's, so the guitars and instruments were all pre-CBS, which makes me feel even worse :(
does the "72"relate to the number of designs and patents????
It's very confusing, Snorky. Apparently, the number "72" references a patent or group of patents that protect this amplifier circuit (and Fender) from duplication. It is definitely not a date or year. I have yet to see or hear a clear explanation of what the number specifically means. Perhaps a viewer can provide one.
it was the wording "designs and patents 72" kind of indicates"number of designs and patents = 72" .....maybe
google tells us "All blackface Fenders have "patented" followed by a number under the pilot light. I was told it had to do with the order in which the amps were patented, not the year. A BFVC says 66, BF Bassman 64, BF Princeton 70, BF Bandmaster 50 etc. "
It's rather mysterious, and since no one really understands what it means, it makes me wonder why they do it.....unless it's some sort of legal requirement.
Hello, I hope you can help me. I have a blackface pro reverb, that makes a terrible sound when turning on. So I want to disassemble it to try to find the source of that. I already reemoved the panel with the speakers, but have no clue how to get the upper part out of the chassis. Do you have any hint for me, how to disassemble that beast? ANy help would be hioghly appreciated.
Got it. Just had to remove thze 4 screws that go from the top through the chassis. Now hoping to find someone, who could help me fix that thing.
We're glad you were able to solve the problem and hope you can find a qualified tech to repair the circuit.
Yes, I hope I get that fixed. In my amp, the label shows Production #1 and the Letters OE, so must be 1965/5, if I am right. Serial No. is A00252. And it is in far better optical condition than that in the video.
Probably May of 1965. It must be a really exceptional amp.
The Amp is optical in a good shape, but unfortunately it does not work. It makes a horrible noise, when turned on. I already replaced all the big capacitors, but nothin gchanged. Would be great, if youcould give me any hint that could help to get the Amp working again. I uploaded a short video, that show the noise when switching the standby switch to on.
ruclips.net/video/rY47sdQAZk4/видео.html
Pretty much more interesting since I caught a guy at place in San Francisco guy was tearing it up on a pro Reverb blackface can't remember the name of the place but it was called something like the Queens jazz club or something like that little bit South of San Francisco and it was right around of the place that you can only smoke cigarettes at a place that had like all of the movie actors pictures on the walls and they didn't care if you smoke cigarettes it was only one of the places you can actually do this but back to the main issue this cat was tearing up a pro Reverb amp because when I heard it I was amazed and then I said what is that a m p you're playing through I can see it's a fender of some sort I'm a little ways away and when I got up close at what's up Fender Pro Reverb and he was just nailing it through a Gibson 335 anyway just thought I'd throw this tidbit of information towards you
Thanks for sharing, William.
Why didn't you do the bias on camera
I have demonstrated bias procedure several times in other videos, Chris. I felt no need to include it in this video, to keep its length reasonable.
thanks uncle doug
You're welcome, Franky. Thanks for watching.
I would in the future like you to restore one of my fender vintage amps. How can I contact you for the purpose of explaining what I have and want done as well as how to ship you the amp plus your cost for your services?
Rusty and I have retired, GG, but occasionally take on interesting outside projects. Please contact us by private message so we can discuss it.
Honestly, I like that 1940's amp you built, better. With reverb it would sound even better. Just my opinion... I really like that amp you built. Not saying this isn't a great amp but....... Thanks for the great vids... keep em comin' :-D
Thanks again, Otter.....high praise indeed. I never thought of adding a reverb to the '47 Deluxe circuit. It would be a really nice addition :)
Uncle Doug Oh maaaaan.... If you ever decide to do it, please make a video! I'd love to hear it. Talk about ear candy!!! :-D
O.k. that took about 33 seconds. "J C Clean" refers to the "Roland Jazz Chorus" amp, which apparently is a thing and happens to be my favorite setting on its little 5-watt sibling. Still sounds like a blackface to me.
The one I ran into that looks like a black face had 112 in Jensen speaker I see this one has the 212?
Yes, it does.