2:03 First look at the amp 4:32 Dog house filter caps 11:36 First look at the circuit 15:12 350 volts of fun 15:47 Removal of 2nd power transformer center tap 19:13 Grid stoppers 20:04 Current limiter and biasing 4 output tubes 22:11 Finding plate voltages for 6L6B tubes 24:57 *Uncle Doug’s video on biasing double/quad ended amps 25:06 New (plate current) matched tubes 26:20 Amp biasing with only a multimeter 26:40 Identifying output tube pairs in a quad ended amp 37:55 Signal generator (400HZ tone) 41:26 Slowing the trem 42:45 Capacitor inventory 43:35 Alligator clipping capacitors into the trem circuit 44:10 Reverb tank and circuit evaluation 45:34 Negative feedback switch / Rewiring power cord 49:40 NFB loop - audio demonstration 50:55 P-90 pickup - audio demonstration 56:42 Single coil - audio demonstratio 1:00:21 Humbucker - audio demonstration 1:03:05 Humbucker + reverb - audio demonstration 1:06:33 Final thoughts 1:08:40 Texas drone blues
Uncle Doug, I recently bought a 68 silver drip face at a great price. When I got it home and after reading how to tell the difference I discovered the reason for the great price was it had the AC 568 circuit even though labeled AB 763. Made week 34 on 1968 I would like to get it back the the best of the AB 763. I see several mentions of this up/down grade on the interwebs but wanted to know if you have anything on this. I don't mind spending money on it because of love the twin reverb sound. After watching most of your videos and subscribing, I think I would like to tackle the job myself to feed my true geek desire.. Any thoughts on that as well? I would like to also implement some of the audio improvement you did in this video. Thanks for your videos on this stuff. I find myself watching them for hours and learning much.. Dave
Greetings, Dave. If you feel qualified to perform the modifications, by all means do so. Some will probably yield little or no improvement in tone, but that's for you to discover. Good luck.
Another lovely long video from Uncle Doug!!! I have health problems which mean that I have trouble sleeping so am out of bed around 4.45am each morning. I love it when I check RUclips and find a long video like this from Uncle Doug - it really passes the time until the rest of the world surfaces. Thank you again for the brilliant videos and please keep them coming.
Hi Uncle Doug! Wanted to let you know that I think your videos are the best - I learn so much! I actually have a 1968 AB763 Silverface Fender Twin Reverb exactly like the one you work on in this video. I have just finished a complete restoration of my Twin and I relied heavily on your video. My Twin sounds amazing and is now good for another few decades. Thank you so much for the entertaining educational videos. You're the best - love your cats too!
Thanks again Uncle Doug. I watched this video when it first came out. Watching it again shows me how much I've learned from you. This time I knew what you were talking about and was even able to successfully guess your next move a couple of times. The best part of this for me was watching you bias the amp without the eurotubes probes. Now I understand how to bias, something I was struggling with.👍
Love the Channel. Here it is 2:30am, and I'm looking for more Uncle Doug vids for my playlist. Thanks so much for these informative and thoroughly entertaining videos!! For Fenderholics like myself, there ain't a better channel around, man! Thanks again.
Love your show, I thought you switched to cars, you made that fun too, thankyou uncle Doug, and all pets, so glad you back or never left ..stay safe an happy
Thanks to Uncle Doug I powered up my signal tracer! The last time I looked at the Eico 147-A I had no clue what I was looking at. This weekend, after tutoring under your channel, it became clear how much like a guitar amp it is. I checked the transformers windings, measured the resistors, checked the ESR and values of the caps, fixed a broken wafer switch and installed a 3- wire cord. Bringing it up slow on a variac I checked for potential between chassis and the line ground. Then disassembled a 50k pot for cleaning and cleaned the rectifier socket to bring it back from it's decades long slumber. Pretty cool to have an idea of what is going on and some confidence I'm doing it right. Next the Eico 232 VTVM. I did get it powered up after checking it the same way but I have 50v AC from chassis to ground.? It is diode rectified and I'm not sure just yet exactly how it's circuits function. I think the potential to line ground is a concern. I love your channel and thanks again!
@@UncleDoug my contribution to YT is to help creators like you who keep ads to the minimum by like, comment and subscribe. I'm of a mind to make a monetary contribution to your patreon.
I just want to take a moment to thank you for your time and effort in passing on this valuable information. You’ve helped me diagnose and repair 4 vintage amps since I started watching your channel. Ive already saved at least 1000 and still the information you’ve taught me is far more valuable. Anyway, thanks again Uncle Doug (: Keep those equations coming!
I'm glad there's people like you around. Passing knowledge and keeping records of old vintage amps. Your videos are great and are so informative, great guy,
Thanks for the education, I recently acquired a silverface Bassman , I know I’ll be able to recap and bias the amp safely without any smoke ,thanks again
Thank you for pointing out that the amp jewel was on. A bit passive aggressive, but the message was received. I will curb my enthusiasm in the future. You did an amazing job. The Twin sounds vintage, yet spongy with P-90s. Ventures'esqe" with single coils. It is also bluesy and ballsy when pushed with humbuckers. Thank you for sharing. Enjoy the rest of you week, uncle.
Loving your music in the drone flight . It brings Peter Greens Splinter Group to my mind . Sadly he has recently passed away . He had such a great touch .
Uncle Doug, I owe you many thanks! This is the video that helped me crack the code of why my ‘76 SF Twin Reverb sounded so terrible and would breakup very quickly. Most of my theories pointed me to the Output Transformer as the culprit but it seems it works just fine. Turns out the amp was biased super cold. Like 8% of max dissipation (MD)… I used this video to learn how to properly use the multimeter to calculate the bias. This particular amp had been modded to a Bias level from the original Bia Balance pot in the chassis. After taking several measurements and slowly adjusting the bias higher, I settled in at about 52% of MD. The tone has improved remarkably but there is still some noise to suss out. For now, I’ve re-assembled the amp and have been enjoying it. Next month, I’ll pull it open again for another health check. Thanks again for the many hours you have put into this channel. The information here is truly valuable if not priceless. I’ve learned so much in the past 6 months yet I see I still have much to learn. Keep the awesome videos coming Uncle Doug. We all appreciate it and owe you a great debt of gratitude. Take care for now, -Scott
That's a great choice for 6L6 replacements. Those are made for TAD by Shuguang (which is a quality manufacturer) and TAD does a super job testing and matching the tubes before they're sold.
You know, I find it amazing how man different flavors and styles of tubes are being rebranded and sold by so many distributors when in fact the majority of every new tube being sold in this new millennium are being produced by only as few as three different factories worldwide! What is more perplexing is that even many of the exact same brands made by the same factories are sold by many different distributors and retailers, yet the quality sold by the various sources of those same tubes can vary vastly in quality. It's commonly assumed that these factories wholes large lots of various grades of tubes and that the bigger distributors cherry pick the best production runs . Letting nothing go to waste, seconds or even thirds production stock, perhaps even many other various rejection stock is sold and blown out at discounts to any wholesaler that will bid on them??? It would be interesting to hear from a real tube insider that could give us the true story of how tubes are produced and distributed these days. Unfortunately, most factories are located in foreign countries that aren't known for being very forthright about disclosing much about the workings of their infrastructure. Aspen Pittman did alot to bring new production tubes to the free world. However, over the years his eccentricities has seemed to obscure his credibility in the opinion of many folks. Regardless, he created a new niche industry of grading and marketing of audio vacuum tubes. Some might even say letting nothing go to waste. Unfortunately, it is still buyer beware, even with some of the "premium" vendors vs value vendors. It isn't always you get what you pay for... Obviously consistency is a major key characteristic of good quality tubes. However, consistency is all relative, with some major silk-screened fancy labeled tubes even being consistently poorer than others, yet they maintain intially consistent electrical characteristics. The major emphasis on static dissapation. I have been finding that the tubes being rebranded as the newly licensed Tung -Sol have been most satisfactory and most welcome addition in my shop. They came onto the scene just when I had just given up on all forms of new production tubes, including and especially J-J's ! It certainly is much easier to buy a usable new production tube than to have to go on safari and procure lots of used vintage tubes and wade thru piles, grading them yourself. (I don't believe in the term NOS tubes as they don't really exist or if they aren't extinct are likely new old b stock or rejected orig stock... NOS Tubes are USED vintage tubes that test as if they were new stock) Vintage tubes require careful selection, just as many new production tubes. Fortunately, new production tubes are getting better & better.
I have been experimenting with variable negative feed back using a low value pot, I decided to try this after watching your mod with using the left over ground switch. I have been really happy with the results.
This is so helpful. Just got a '69 Silverface. Beautiful amp. Clean bill of heath from the local tech,. AB763 Master Volume added to the rear panel already. It'll have a switchable NFB loop tomorrow.
OMG Doug "The only time Brown gets hot is when you eat spicy food..." I laughed SO hard. Speaking of that, my garden of peppers and such I have been harvesting quite a bit, and I make Salsa for friends and family. My hottest recipe I call "HiHo" (hot in, hot out)
I worried that the comment might be a little "off color" (no pun intended), RR, but apparently you all are as depraved (and addicted to spicy food) as I am ;)
@@UncleDoug G'Day,Same confusion with colour of mains power leads this way,,Ozzie land,, And as for hot food ,i have a mate that keeps his pooh paper in the fridge,, Does make one wonder if Johnny Cash loved Hot food,,Burning ring of fire,??
Hello Uncle Doug& Family, Another quality repair, you take pride and care in your craftsmanship. What a great tutorial video, great detail and explanations, as only Uncle Doug can do. Glad your doing well and staying busy. Back to normal in Oregon, four days of upper 80's, then Winter. All the best, C. P.S. It sounded awesome.
LOL! Only 15 seconds into this video and already you have me laughing hysterically at your comparison of the huge box to an AC-30. Felt compelled to stop right there and write this before I enjoy watching the rest of it. Thanks so much for all the videos you have made over the years and sharing your knowledge with all of us. Because of you I have learned a lot about tube electronics. All the best to you, your family and take care!
Hey Uncle Doug! I've learned allot watching you and Brad the Guitologist and a few others over the years on RUclips. Here again, another great video, be safe, thanks so much!
NICE drone shots. I did bootcamp and AIT there off of dyer st in 1989. we did not have a whole lot of time for site seeing or exploring . I did enjoy it out there. I think the Dyer st "camp"{ is long gone. Thank you for doing what you do.
Thank you very much for all the information that you share. Your Videos are a great Resource for those who are triyng to learn this area of electronics. Cheers.
Before box is even opened, one of my secret favorite amps (I need a Twin Reverb like I need a hole in the head but have always wanted one 1968 is my favorite too.) More after the repair. Edit: Very thorough, that little mod. on the vibrato speed is so right on the money a must for these. Fenders I.M.O, Ditto for the NFB loop. Great job UD
@@UncleDoug Very many houses like that in Beverly Hills, Studio City. They've built up on stilts on the side of the mountain and with the earthquakes here, it's a perilous way to live.
Excellent presentation as always. I'm surprised you were able to record even at volume settings of 3.5 to 4 with that amp. I had a early silverface like that decades ago and still remember how LOUD it was! Anymore I rarely crank my champ up past 3. That mod reverb tank sounds great. Thanks again for such a quality presentation. Your one of a kind.
@@UncleDoug Johan Segeborn has a video of him playing a Les Paul thru one of these CRANKED. He's wearing ear muffs, and still wincing at the thunderous volume. Great sounding distortion, but even he admitted he may have gotten a bit over ambitious doing this, lol. Also, he was standing behind the amp, not in front of it...
@@UncleDoug i figured. That was mostly aimed at folks who might wonder what a twin reverb sounds like dimed. Most likely wont get the opportunity, lol- not for the faint of heart!
Teriffic stuff Doug..Sunday treat for us all with a wonderful amp, and another entertaining knowledge packed video for us 'wet behind the ears' budding ampaholics..Thank you for sharing your knowledge. Love the drone flight and that little glimpse of the workshop guru waving at the end..!.Look forward to the next..Ed..U.K..😊
Great video! I just recently found a nearly identical "Drip Edge" Twin Reverb for sale -- totally original, including all the original caps, 2 wire cord, 4 black plate RCA 6L6s and RCA and Telefunken small tubes, original footswitch, reverb tank, and Jensen speakers. The stamps on the chassis are all late 1967, and all the other dates match up. The Tolex is perfect, and there is even an original tag hanging on the handle all about caring for the Tolex covering. The Twin Reverb is way more amp than I need (or could possibly use), but I couldn't pass it up for the price. The seller claims to have been the original owner who had played it in a band in the late 60s and early 70s and stored it since then. As far as I could tell, I was the first to have it apart. So far, The 1K resistor under the doghouse had cracked, and one of the grounds had come loose where the main board flexed, but fixing those brought it back to life. I already installed the 3 wire cord to your specs, and I've got new caps and a few resistors to go in this week. I might add the NFB and Tremolo speed mods while I'm in here working on it. Oh yeah, it sounds great, and it's LOUD! Thanks for the great videos. I love guitars and electronics and you have inspired me to take on doing some work on these cool old amps. I just finished my first restoration on a pretty rough Pro Reverb that turned out really nice and took on this Twin as my second project. The payoff is huge when I hear how great these sound and think about what they'd cost to buy new today. Keep up the great work!
Congratulations on a great acquisition and repair, Chris. Silverface Fenders are generally bargains.....and great amps to boot. We're glad the videos were helpful.
It's Sunday afternoon. Time for another treat from Uncle Doug. Loving that reverb tank. Want one for my Vox AC-15, yes I know, one never came with it, but it's a great add on. I will never part with it anyway!. Greetings from sunny England Doug.
TAD tubes blow HEAT on GT's. I had GT's (6L6) in my new Fender Deville from the factory. Smoked em 3 months later at a gig. Luckily I had a back up amp. Bought a USED matched pair of TADs and here it is 10 years later and they're STILL going strong
Gees U. D. ... Your vid was exactly 2 shots of Vodka and 2 Miller Lite chasers long ... And I enjoyed both the same ... Lol ... Great vid and nice amp ...
Hi Douglas, Many decades ago here in England, mains leads were red Live; black Neutral, and green was the Earth wire. Then that changed when we joined Europe: Live became the blue wire; Neutral became the brown wire, and Earth became a spiralled green and yellow coloured wire. The reason was to enable colour blind people wire a mains plug onto a mains lead correctly. Not personally suffering from this disability, it is said that the colours green and red look very similar to a colour blind person (brown), therefore, Live could easily be mistaken for the Earth, or vice-versa. 73 from Phil.
@@UncleDoug Brown is the hot wire in Europe, Blue is the neutral, assuming the power cord was assembled correctly (made in china?). Might be worth checking. Great sound, the Fender twin. I once sat in front of one whilst busking Johnny B. Goode on the fiddle. Very enjoyable, then, as we were packing up there was a bar fight... that's Essex for yer. I love your amp repair videos. Cheers, Steve.
Oh, what a bugger! I’ve completely got the blue and brown mains wires the wrong way round: blue is neutral, and brown is live. That will teach me for posting comments seconds before snuggling down into bed LOL. Phil.
The sounds procuced during the testing part really made me all fashion of wow inside... as a movie sound effect and almost a form of percussion device for musical effects... this little box is indeed amazing.
I'm a player but I love my amplifiers and I still use in my home my vintage fender bassman amps as well as buying Marshall major which I play bass through knowing what goes on inside these amps makes it easier to play these amplifiers better thank you Uncle Doug!!!!
I love my Silver face a tech from the North Eastern parts of the USA went through it and I couldn't be more happy. His name is Chris Davis in case anyone from that geographical area is in need of a quality tech.
I believe brown was chosen for live because it was safer for electricians and techs with color blindness (not always diagnosed previously). This was a key reason for the color scheme update. Previously, red/black/green were used for live/neutral/earth. Great video as always.
I just Laugh Out Laud hearing and imagining "swing the chassis around your head" when Uncle Doug spoke about verifying the center tap´s solder. The Egyptian and wine jokes were a good touch too.
I have a very similar amp. Mine dates from late '67. From what I've been told, most of the early silverface amps have a blackface circuit because they were using up all of their old stock components before moving to the new silverface circuits. If you see a silverface amp that has solid vertical black lines on the front of the chassis then you most likely are dealing with a blackface circuit. I got mine for an absolute bargain and was confident it was an ab763 circuit even though the seller would not open it up and send me gut shots. Unfortunately UPS managed to spear the box with a forklift and completely demolished the JBL speakers and the baffle. I had a choice to file a claim with UPS and never see the amp again or to just keep it. I ended up keeping it because I had acquired it at such a cheap price.
First amp was a blackface Twin I bought for $350 (1977). Loved it but was pretty shrill. But I always had it dimed. Wish I still had it along with my '67 Rickenbacker 360. Good job on the Twin Reverb Doug!
@@UncleDoug that negative feedback loop you introduced to the circuit gives the Twin a whole new voicing. 100% more useful for folks like me that aren't asking for a lot of headroom.
"The only time brown ever gets hot is when you've eaten a lot of spicy food" Tehehe! Hope you've been doing well my friend, your videos are always a blast to watch, and some of the best guitar amp engineering content. I find myself diving back and watching many over and over when I have that vacuum tube bug hit me (stares at new 100W Marshall OPT and MOD reverb tank sitting on my shelve). Yeah, that bug is coming back again. Just wish I had more time away from work. Too bad there isn't more Marshall on the 'tube. I've had a watch of some other people, but when I see them do things like discharging a cap by shorting it to the chassis (and thusly causing a vintage chassis to have a scorch/gouge mark, besides the insanity) def is not my fancy. Thank you as always for the amazing content!
Thanks so much for the very nice comments, Retro. I hope you find the time to get back into tube electronics.....and wish you the best when you do :) Arcing to the chassis is like dry-firing a weapon, it's damaging, particularly in the long run.
Ah man! you're priceless. I just love your channel. The little details. I really hope people pay attention, the ones less versed in the fine art of safely working with powered circuits, when you said ( 33:39 ) "with an insulated screwdriver"... I immensly appreciate how you jam pack your videos with safety at every turn. You're a precious ressource.
Hi Uncle Doug, greetings from Australia. Here in Melbourne we haver the same crazy weather, it all depends on where the wind comes from. A northerly brings hot dry from the desert, a southerly brings the ice and rain from Antartica. Thanks for another great video. As usual I wish I could ask you a thousand questions. All the best, Mic
A while back I worked with a guy from Arizona, he said coming to North Carolina was like coming to the "jungle". Looking at the drone footage, I can see where he was coming from.
I live in the uk and I think its taken me three years to remember brown is live, it used to be red, and neutral was black, but it changed when we joined the EU, weirdly enough I believe a lot of lights are still red and black (because they were never replaced), the way I remembered it is neutral is calming like blue, or Bratislava , brow-is-lava, brown is live
Uncle Doug.... a Shabby Craftsman.. LOL. Fantastic Long Service Video on this AB763 circuit..!!! Thank you!! Brown is ONLY HOT When you eat spicy food..LOL
Way to go, UD. Your magic touch really breathed new life into the old gal...even made Jack's picking come through loud and clear; lots of chime and a nice mid-range warmth. I always meant to ask...how does he manage to hold a pick without an opposable digit? However he does it, he rocks...
Hi Uncle Doug, your videos are both informative and entertaining (you make a great teacher). I have a question: you indicated in another video, dealing with, I believe, biasing a quad or quartet of output tubes that you prefer to bias tubes in a grid biased circuit at 50 to 60%. Of plate dissipation. In this video however the tubes you are using have a plate dissipation of 30 watts but you biased them to just 13.2 and 13.3 watts. Why did you go low? Just curious.
Thanks, Stacey. You're right.....the bias values for the quartet appear to be quite a bit lower than I recommended in another video. Bear in mind that these values were obtained using a current limiter, which lowers the current within a large high-wattage amp like this quite a bit. Once I plugged it into a wall outlet, the PD increased dramatically.....up to 60+% of max. Not mentioning this was a serious oversight and I apologize for not doing so within the video. I will correct this error in a future video.
TAD tubes are far superior than those 6L6B 's. Plate dis. is only about 25W on those Sovtek 5881WXT compared to a normal 6L6GC which is 30W. "Hint of wood "indeed! At 43:00 those are the best plastic containers ever and found at Harbor Freight Tools. I got five of them! Yeah,they're that good and very inexpensive. Really impressed by your work especially here Uncle Doug! I bet the owner will really be very pleased for all your work and thanks for showing how you repaired this fine amp!
Hey Doug, another excellent, entertaining and educational video. In case you're curious about the European power cord color coding (although I suspect you may already know - the joke was well worth it), is so color blind people can still identify phase / neutral / earth. Previously phase was red, neutral black and earth green (without a stripe). Imagine my surprise when I first learned that U.S color coding had phase as black....
![GUILTY GEAR -STRIVE- Season Pass 4 Playable Character #1 [Queen Dizzy] Trailer](http://i.ytimg.com/vi/nXDsAgYXXv4/mqdefault.jpg)
2:03 First look at the amp
4:32 Dog house filter caps
11:36 First look at the circuit
15:12 350 volts of fun
15:47 Removal of 2nd power transformer center tap
19:13 Grid stoppers
20:04 Current limiter and biasing 4 output tubes
22:11 Finding plate voltages for 6L6B tubes
24:57 *Uncle Doug’s video on biasing double/quad ended amps
25:06 New (plate current) matched tubes
26:20 Amp biasing with only a multimeter
26:40 Identifying output tube pairs in a quad ended amp
37:55 Signal generator (400HZ tone)
41:26 Slowing the trem
42:45 Capacitor inventory
43:35 Alligator clipping capacitors into the trem circuit
44:10 Reverb tank and circuit evaluation
45:34 Negative feedback switch / Rewiring power cord
49:40 NFB loop - audio demonstration
50:55 P-90 pickup - audio demonstration
56:42 Single coil - audio demonstratio
1:00:21 Humbucker - audio demonstration
1:03:05 Humbucker + reverb - audio demonstration
1:06:33 Final thoughts
1:08:40 Texas drone blues
Gee thanks for spoiling it for me... maybe Uncle Doug should consider doing alternate ending out takes to keep the element of surprise
Uncle Doug,
I recently bought a 68 silver drip face at a great price. When I got it home and after reading how to tell the difference I discovered the reason for the great price was it had the AC 568 circuit even though labeled AB 763. Made week 34 on 1968 I would like to get it back the the best of the AB 763. I see several mentions of this up/down grade on the interwebs but wanted to know if you have anything on this. I don't mind spending money on it because of love the twin reverb sound. After watching most of your videos and subscribing, I think I would like to tackle the job myself to feed my true geek desire.. Any thoughts on that as well? I would like to also implement some of the audio improvement you did in this video. Thanks for your videos on this stuff. I find myself watching them for hours and learning much.. Dave
Wow....thanks for the detailed Table of Contents, LB :)
Greetings, Dave. If you feel qualified to perform the modifications, by all means do so. Some will probably yield little or no improvement in tone, but that's for you to discover. Good luck.
Hi Uncle Doug. I just want to tell you that please, don't never die. We need you!! Take care.
I can assure you that I'll do everything I can to follow your advice, BSA :)
Another lovely long video from Uncle Doug!!! I have health problems which mean that I have trouble sleeping so am out of bed around 4.45am each morning. I love it when I check RUclips and find a long video like this from Uncle Doug - it really passes the time until the rest of the world surfaces. Thank you again for the brilliant videos and please keep them coming.
Thanks so much, Robin. We're glad you enjoy the videos.
LOVE your radio voice and your sens of humor. Cheers from Majorca island, Spain.
Wow, thank you, MM. What an exotic location. Jack and I are jealous ;)
For sure! I told him he ought to be reading Bible verses onto tape with that high quality voice!
Hi Uncle Doug! Wanted to let you know that I think your videos are the best - I learn so much! I actually have a 1968 AB763 Silverface Fender Twin Reverb exactly like the one you work on in this video. I have just finished a complete restoration of my Twin and I relied heavily on your video. My Twin sounds amazing and is now good for another few decades. Thank you so much for the entertaining educational videos. You're the best - love your cats too!
My father used to always say "we must quell these strident tones". He passed in 1989 but you remind me of him in many good ways.
Your father was right, Brian. Strident is best reserved for fingernail on blackboards......not amps ;)
@@UncleDoug funny you mentioned blackboards, he was a Chicago Public School Teacher.
Getting better all the time . These videos are priceless to us Fender Fanatics . Thanks Doug. 🎸😎
Glad you like them, Bob. Thanks !!
Dear Uncle Doug. May you live forever. Cheers from an ampoholic from Sweden.
Thanks so much, B66......and may you do the same ;)
Thanks again Uncle Doug. I watched this video when it first came out. Watching it again shows me how much I've learned from you. This time I knew what you were talking about and was even able to successfully guess your next move a couple of times. The best part of this for me was watching you bias the amp without the eurotubes probes. Now I understand how to bias, something I was struggling with.👍
It's great to hear that the videos have been informative, Tim. Best wishes for continued success with your self-education program.
Love the Channel. Here it is 2:30am, and I'm looking for more Uncle Doug vids for my playlist. Thanks so much for these informative and thoroughly entertaining videos!! For Fenderholics like myself, there ain't a better channel around, man! Thanks again.
You're welcome, Bob.
Makes the 4th of July look like Labor Day weekend. Priceless.
Doug, you remind me of Tim's neighbor Wilson from home improvement. Your friendly neighborhood amp tech guy!
I guess there are some similarities, SD. I wish my neighbor was more like Tim Allen.
Uncle Doug’s voice reminds me of Gene Shepherd’s narration voice especially in his movie, A Christmas Story.
Love your show, I thought you switched to cars, you made that fun too, thankyou uncle Doug, and all pets, so glad you back or never left ..stay safe an happy
Thanks so much, Michelle. We started a second YT channel dedicated to hot rods: Uncle Doug's Hot Rod Garage. Please check it out if you have the time.
Thanks to Uncle Doug I powered up my signal tracer! The last time I looked at the Eico 147-A I had no clue what I was looking at. This weekend, after tutoring under your channel, it became clear how much like a guitar amp it is. I checked the transformers windings, measured the resistors, checked the ESR and values of the caps, fixed a broken wafer switch and installed a 3- wire cord. Bringing it up slow on a variac I checked for potential between chassis and the line ground. Then disassembled a 50k pot for cleaning and cleaned the rectifier socket to bring it back from it's decades long slumber. Pretty cool to have an idea of what is going on and some confidence I'm doing it right. Next the Eico 232 VTVM. I did get it powered up after checking it the same way but I have 50v AC from chassis to ground.? It is diode rectified and I'm not sure just yet exactly how it's circuits function. I think the potential to line ground is a concern. I love your channel and thanks again!
Wow, it sounds like you're ready for your own YT channel, CR. I'm really glad the videos have been helpful.
@@UncleDoug my contribution to YT is to help creators like you who keep ads to the minimum by like, comment and subscribe. I'm of a mind to make a monetary contribution to your patreon.
I just want to take a moment to thank you for your time and effort in passing on this valuable information. You’ve helped me diagnose and repair 4 vintage amps since I started watching your channel. Ive already saved at least 1000 and still the information you’ve taught me is far more valuable. Anyway, thanks again Uncle Doug (: Keep those equations coming!
You are quite welcome, LR. I'm glad to hear that the videos are helpful......and profitable ;)
Thank you Uncle Doug for the thorough demonstration and explanation of the manual tube biasing process for fixed bias amps. Highly appreciated!
You're welcome, JS. Glad it was helpful :)
Uncle Dough: Thank you for another fun yet informative video. My questions on biasing my twin have been answered. Great reference material. Thanks
You're quite welcome, Anthony. That's good to hear.
I'm glad there's people like you around. Passing knowledge and keeping records of old vintage amps. Your videos are great and are so informative, great guy,
Thanks so much, Gareth.
Thanks for the education, I recently acquired a silverface Bassman , I know I’ll be able to recap and bias the amp safely without any smoke ,thanks again
Be very careful, Perry, and good luck with your repairs.
I enjoy this channel for the preposterous metaphors! We expect this in general conversation here in Australia!
As a charter member of The Society for Preposterous, Asinine Metaphors, i.e. SPAM, I thank you.
Appreciate all your videos. And that dry humor well. Keep it up! The occasional outburst of uncontrollable laughter is the most welcomed.
Glad you like them, SP. They say that laughter is the best medicine :)
@@UncleDoug cost effective!
U. Doug, I just have to tell you that this video is so very outstanding. I cannot remember a better time in quite a while. Thanks
Glad you enjoyed it, Jeff. Thanks.
Thank you for pointing out that the amp jewel was on. A bit passive aggressive, but the message was received. I will curb my enthusiasm in the future. You did an amazing job. The Twin sounds vintage, yet spongy with P-90s. Ventures'esqe" with single coils. It is also bluesy and ballsy when pushed with humbuckers. Thank you for sharing. Enjoy the rest of you week, uncle.
You're welcome, Alex. Thanks for the interesting analysis of the audio demo and your nice comments.
Loving your music in the drone flight . It brings Peter Greens Splinter Group to my mind . Sadly he has recently passed away . He had such a great touch .
Wow.....I am flattered beyond words. Any comparison to Peter Green is as good as it gets. Thanks !!!
Uncle Doug, I owe you many thanks! This is the video that helped me crack the code of why my ‘76 SF Twin Reverb sounded so terrible and would breakup very quickly. Most of my theories pointed me to the Output Transformer as the culprit but it seems it works just fine.
Turns out the amp was biased super cold. Like 8% of max dissipation (MD)… I used this video to learn how to properly use the multimeter to calculate the bias.
This particular amp had been modded to a Bias level from the original Bia Balance pot in the chassis.
After taking several measurements and slowly adjusting the bias higher, I settled in at about 52% of MD. The tone has improved remarkably but there is still some noise to suss out. For now, I’ve re-assembled the amp and have been enjoying it. Next month, I’ll pull it open again for another health check.
Thanks again for the many hours you have put into this channel. The information here is truly valuable if not priceless. I’ve learned so much in the past 6 months yet I see I still have much to learn.
Keep the awesome videos coming Uncle Doug. We all appreciate it and owe you a great debt of gratitude.
Take care for now,
-Scott
You're welcome, Scott. We're glad the video was helpful :)
right in the pocket ,thats as good as any amp could wish to sound,
every setting /pickup combination was excellent, fine job uncle
doug, flawless !
Glad you liked it, William. Thanks !!!
You know, opening up a box on any other channel would be positively soporific...But for Uncle Doug its his best standup material!
We try to live up the otherwise dull process :)
That's a great choice for 6L6 replacements. Those are made for TAD by Shuguang (which is a quality manufacturer) and TAD does a super job testing and matching the tubes before they're sold.
Thanks, David. I have been very pleased with the TAD tubes.
You know, I find it amazing how man different flavors and styles of tubes are being rebranded and sold by so many distributors when in fact the majority of every new tube being sold in this new millennium are being produced by only as few as three different factories worldwide!
What is more perplexing is that even many of the exact same brands made by the same factories are sold by many different distributors and retailers, yet the quality sold by the various sources of those same tubes can vary vastly in quality.
It's commonly assumed that these factories wholes large lots of various grades of tubes and that the bigger distributors cherry pick the best production runs . Letting nothing go to waste, seconds or even thirds production stock, perhaps even many other various rejection stock is sold and blown out at discounts to any wholesaler that will bid on them???
It would be interesting to hear from a real tube insider that could give us the true story of how tubes are produced and distributed these days. Unfortunately, most factories are located in foreign countries that aren't known for being very forthright about disclosing much about the workings of their infrastructure. Aspen Pittman did alot to bring new production tubes to the free world. However, over the years his eccentricities has seemed to obscure his credibility in the opinion of many folks. Regardless, he created a new niche industry of grading and marketing of audio vacuum tubes. Some might even say letting nothing go to waste.
Unfortunately, it is still buyer beware, even with some of the "premium" vendors vs value vendors. It isn't always you get what you pay for...
Obviously consistency is a major key characteristic of good quality tubes. However, consistency is all relative, with some major silk-screened fancy labeled tubes even being consistently poorer than others, yet they maintain intially consistent electrical characteristics. The major emphasis on static dissapation.
I have been finding that the tubes being rebranded as the newly licensed Tung -Sol have been most satisfactory and most welcome addition in my shop. They came onto the scene just when I had just given up on all forms of new production tubes, including and especially J-J's !
It certainly is much easier to buy a usable new production tube than to have to go on safari and procure lots of used vintage tubes and wade thru piles, grading them yourself. (I don't believe in the term NOS tubes as they don't really exist or if they aren't extinct are likely new old b stock or rejected orig stock... NOS Tubes are USED vintage tubes that test as if they were new stock) Vintage tubes require careful selection, just as many new production tubes.
Fortunately, new production tubes are getting better & better.
Congrats again Uncle Doug! A nice demonstration.
Thanks for watching, RA :)
I have been experimenting with variable negative feed back using a low value pot, I decided to try this after watching your mod with using the left over ground switch. I have been really happy with the results.
I'm glad it worked for you, Nathan.
I know feel I need to look for "shipping dimensions" when I order my tubes. This is a critical piece of information i have been missing :)
Indeed, Travis. I think they should also describe the color of the box in which they will be sent ;)
This is so helpful. Just got a '69 Silverface. Beautiful amp. Clean bill of heath from the local tech,. AB763 Master Volume added to the rear panel already.
It'll have a switchable NFB loop tomorrow.
That's great to hear, Nathan. Best of luck with your new acquisition.
Thanks uncle Doug. By far the best electronics videos on youtube
Wow, thanks, RJ. Glad you like them :)
OMG Doug "The only time Brown gets hot is when you eat spicy food..." I laughed SO hard. Speaking of that, my garden of peppers and such I have been harvesting quite a bit, and I make Salsa for friends and family. My hottest recipe I call "HiHo" (hot in, hot out)
I worried that the comment might be a little "off color" (no pun intended), RR, but apparently you all are as depraved (and addicted to spicy food) as I am ;)
@@UncleDoug Is not depravity the mark of genius and adept to good humor?
LOL
BTW, did you ever hear of Stanley
the Brown Nosed Reindeer? He followed vixen a TAD to close when Santa braked hard LOL
@@UncleDoug G'Day,Same confusion with colour of mains power leads this way,,Ozzie land,,
And as for hot food ,i have a mate that keeps his pooh paper in the fridge,,
Does make one wonder if Johnny Cash loved Hot food,,Burning ring of fire,??
@@UncleDoug Keep the hits rolling! We, I believe, slightly younger folks are even more desensitized to rough comedy!
Hello Uncle Doug& Family, Another quality repair, you take pride and care in your craftsmanship. What a great tutorial video, great detail and explanations, as only Uncle Doug can do. Glad your doing well and staying busy. Back to normal in Oregon, four days of upper 80's, then Winter. All the best, C. P.S. It sounded awesome.
Thanks so much, Cass. It's always good to hear from you. Today felt like our first day of Fall.....breezy and cooler, with temp. in the 70"s.
23:05 You tune in for the electronics, you stay for the jokes. :)
Just as long as you tune in, T4 :)
LOL! Only 15 seconds into this video and already you have me laughing hysterically at your comparison of the huge box to an AC-30. Felt compelled to stop right there and write this before I enjoy watching the rest of it. Thanks so much for all the videos you have made over the years and sharing your knowledge with all of us. Because of you I have learned a lot about tube electronics. All the best to you, your family and take care!
Wow.....thanks so much, Bill. So glad to hear that you enjoyed the video :)
Great work Doug, nice tune up, sounding very nice. Thanks for posting and putting smiles on viewers faces.
Thanks so much, Ima. Glad you enjoyed it :)
Thank you, thank you, thank you. Great bias explanation for a twin reverb!! Managed to get mine set perfect
That's great to hear, Steve. Have a wonderful Christmas.
Hey Uncle Doug! I've learned allot watching you and Brad the Guitologist and a few others over the years on RUclips. Here again, another great video, be safe, thanks so much!
You're welcome, CTE. Glad the videos are helpful :)
I LOVE my preposterous metaphors with a beer, in an Uncle Doug video. Thanks UD!
Then you've come to the right place, Beneharo :)
Another first class video Doug. I thoroughly enjoyed watching this as I have for all of your postings.
Thanks, Brian. Glad you enjoyed it :)
NICE drone shots. I did bootcamp and AIT there off of dyer st in 1989. we did not have a whole lot of time for site seeing or exploring . I did enjoy it out there. I think the Dyer st "camp"{ is long gone. Thank you for doing what you do.
Thanks, Art. Glad you enjoyed the video and your stay in our sunny metropolis :)
Oh boy do I love that NFB switch.
It made even more difference in person......like night and day :)
Thank you very much for all the information that you share.
Your Videos are a great Resource for those who are triyng to learn this area of electronics. Cheers.
You're very welcome. Glad the videos are helpful.
The sarcophagus of king tut turned out bè a fine house for the holy followers of King Doug. What an awesome sounding amp, èsp the vibrato channel.
Thanks for joining me on this archeological expedition, Alex :)
Before box is even opened, one of my secret favorite amps (I need a Twin Reverb like I need a hole in the head but have always wanted one 1968 is my favorite too.) More after the repair.
Edit: Very thorough, that little mod. on the vibrato speed is so right on the money a must for these. Fenders I.M.O, Ditto for the NFB loop. Great job UD
I hope you enjoyed it, 50G.
Great drone footage.
It's quite amazing that people will live that far away, even from the supermarket.
40 minutes one direction is ridiculous.
I wonder about their houses sliding down the side of the hill during a hard rain storm, Jeremiah. It would be a memorable ride ;)
@@UncleDoug Very many houses like that in Beverly Hills, Studio City.
They've built up on stilts on the side of the mountain and with the earthquakes here, it's a perilous way to live.
Excellent presentation as always. I'm surprised you were able to record even at volume settings of 3.5 to 4 with that amp. I had a early silverface like that decades ago and still remember how LOUD it was! Anymore I rarely crank my champ up past 3. That mod reverb tank sounds great. Thanks again for such a quality presentation. Your one of a kind.
Thanks, S66. Trust me, it was plenty loud. I had some paper napkins stuck in my ears.
@@UncleDoug Johan Segeborn has a video of him playing a Les Paul thru one of these CRANKED. He's wearing ear muffs, and still wincing at the thunderous volume. Great sounding distortion, but even he admitted he may have gotten a bit over ambitious doing this, lol. Also, he was standing behind the amp, not in front of it...
@@pyroman6000 Definitely not my cup of tea, Pyro, especially if the amp and speakers belong to someone else.
@@UncleDoug i figured. That was mostly aimed at folks who might wonder what a twin reverb sounds like dimed. Most likely wont get the opportunity, lol- not for the faint of heart!
@@pyroman6000 Not an experience that I would relish, P. To me, in close quarters, 2 to 2.5 is max volume.
Teriffic stuff Doug..Sunday treat for us all with a wonderful amp, and another entertaining knowledge packed video for us 'wet behind the ears' budding ampaholics..Thank you for sharing your knowledge. Love the drone flight and that little glimpse of the workshop guru waving at the end..!.Look forward to the next..Ed..U.K..😊
Thanks so much, Ed. Stay tuned......a special video is on the way :)
@@UncleDoug Look forward to it..😊
Good catch on the output tubes. Best to question any changes. Rock on lad!
Thanks, Byron. Will do :)
WOW !! Looking at that VOX - the box isn't the only thing that's big !! Your hand is HUGE !!!!!! ;)
Yes, you know what they say about men with big hands ;)
Great video! I just recently found a nearly identical "Drip Edge" Twin Reverb for sale -- totally original, including all the original caps, 2 wire cord, 4 black plate RCA 6L6s and RCA and Telefunken small tubes, original footswitch, reverb tank, and Jensen speakers. The stamps on the chassis are all late 1967, and all the other dates match up. The Tolex is perfect, and there is even an original tag hanging on the handle all about caring for the Tolex covering. The Twin Reverb is way more amp than I need (or could possibly use), but I couldn't pass it up for the price. The seller claims to have been the original owner who had played it in a band in the late 60s and early 70s and stored it since then. As far as I could tell, I was the first to have it apart.
So far, The 1K resistor under the doghouse had cracked, and one of the grounds had come loose where the main board flexed, but fixing those brought it back to life. I already installed the 3 wire cord to your specs, and I've got new caps and a few resistors to go in this week. I might add the NFB and Tremolo speed mods while I'm in here working on it. Oh yeah, it sounds great, and it's LOUD!
Thanks for the great videos. I love guitars and electronics and you have inspired me to take on doing some work on these cool old amps. I just finished my first restoration on a pretty rough Pro Reverb that turned out really nice and took on this Twin as my second project. The payoff is huge when I hear how great these sound and think about what they'd cost to buy new today. Keep up the great work!
Congratulations on a great acquisition and repair, Chris. Silverface Fenders are generally bargains.....and great amps to boot. We're glad the videos were helpful.
Oh that's so good you got that amp going mate, & at a great price too huh? Double congrats then! UD will be proud of you!
Great soundtrack for the drone footage!
Thanks 👍
It's Sunday afternoon. Time for another treat from Uncle Doug. Loving that reverb tank. Want one for my Vox AC-15, yes I know, one never came with it, but it's a great add on. I will never part with it anyway!. Greetings from sunny England Doug.
Greetings to you all, Marc. I hope you enjoyed the video.
“The only time brown gets hot is when you eat spicy food”.....and I nearly spray my drink like a sneeze ! Good one Doug !
Glad you liked it, Brian :)
@@UncleDoug That's why you have to eat ice cream for dessert, "Come on ice cream..."
The owner of that amp is a very fortunate person.
Also a very nice person, JJ, as are all our viewers and other amp customers. It's a real pleasure to get to know you all.
You are a great detective...and yes I have had some good first dates with a hint of wood
Thanks, Billy. It's always the hint that makes it exciting.
Great Video. Thanks Always!
Our pleasure :)
TAD tubes blow HEAT on GT's. I had GT's (6L6) in my new Fender Deville from the factory. Smoked em 3 months later at a gig. Luckily I had a back up amp. Bought a USED matched pair of TADs and here it is 10 years later and they're STILL going strong
Thanks for the info, John. So far, I am really happy with the TAD tubes I have installed.
Gees U. D. ... Your vid was exactly 2 shots of Vodka and 2 Miller Lite chasers long ... And I enjoyed both the same ... Lol ... Great vid and nice amp ...
I like that prescription, Ed. Thanks !!
Hi Douglas,
Many decades ago here in England, mains leads were red Live; black Neutral, and green was the Earth wire. Then that changed when we joined Europe: Live became the blue wire; Neutral became the brown wire, and Earth became a spiralled green and yellow coloured wire.
The reason was to enable colour blind people wire a mains plug onto a mains lead correctly. Not personally suffering from this disability, it is said that the colours green and red look very similar to a colour blind person (brown), therefore, Live could easily be mistaken for the Earth, or vice-versa.
73 from Phil.
It used to be red live, black neutral, green earth in south Africa too, until they changed to European standard. Should be the same worldwide.
Thanks for the info, Phil. I thought brown was the hot wire.
@@UncleDoug Brown is the hot wire in Europe, Blue is the neutral, assuming the power cord was assembled correctly (made in china?). Might be worth checking. Great sound, the Fender twin. I once sat in front of one whilst busking Johnny B. Goode on the fiddle. Very enjoyable, then, as we were packing up there was a bar fight... that's Essex for yer. I love your amp repair videos. Cheers, Steve.
Oh, what a bugger! I’ve completely got the blue and brown mains wires the wrong way round: blue is neutral, and brown is live.
That will teach me for posting comments seconds before snuggling down into bed LOL.
Phil.
@@UncleDoug brown is the hot one.
Another excellent amp tune-up video, sounds great!
Thanks, Blair. Glad you liked it :)
The washing instructions on the VOX AC-30 say "lie flat to dry". It is clear you just threw yours in the dryer on the high temp setting.
That explains why it was still warm ;)
And here I was thinking that you were supposed to put it in a bucket of water for an hour to let it grow to full size.
Definitely my FAVORITE uncle!
Thanks man.
It's always good to hear from my long-lost nephew, Adrien. You're welcome.
The reverb is sweet on that one.
It sure is, Sean. Thanks :)
The sounds procuced during the testing part really made me all fashion of wow inside... as a movie sound effect and almost a form of percussion device for musical effects... this little box is indeed amazing.
Thanks Uncle Doug!
Our pleasure, Jason. We hope you enjoyed it.
The superlatives are outstanding.
Glad you liked it, Graeme.
Excellent content as usual. Loved the Crossroads reference!
Glad you enjoyed it, ST.
I'm impressed, ac30's are pretty heavy, but you lifted it with absolutely no problem. Lol, great video.
Yep.....I may be old, but I'm still in good shape ;)
I'm a player but I love my amplifiers and I still use in my home my vintage fender bassman amps as well as buying Marshall major which I play bass through knowing what goes on inside these amps makes it easier to play these amplifiers better thank you Uncle Doug!!!!
You're quite welcome, Charles. We're glad the videos are helpful :)
Great work Doug, I love the wine tasting references to the valves; in my experience everyone's got their preferred brand(s), much like strings.
Yes, they do, Tim, and companies pay millions to influence those preferences ;)
Thats the most I've ever seen of our uncle at the very end.......uncle Doug is in very good shape!...........
Thanks, Glenn. I'm on a catnip and beer diet :)
I love my Silver face a tech from the North Eastern parts of the USA went through it and I couldn't be more happy.
His name is Chris Davis in case anyone from that geographical area is in need of a quality tech.
Thanks for the recommendation, Kevin. People ask me all the time for the names of good regional techs.
Uncle Doug you are on the roll!!!!☺️
I really enjoyed making this video, Charles :)
@@UncleDoug I know you did ,and you show it! You keep us attracted , LOL we don't know what's coming next, the suspense!!!!!
A good belly laugh is priceless and so are you. Thanks.
Thanks, David. Glad you enjoyed it :)
I believe brown was chosen for live because it was safer for electricians and techs with color blindness (not always diagnosed previously). This was a key reason for the color scheme update. Previously, red/black/green were used for live/neutral/earth. Great video as always.
Thanks for the info, J.
I just Laugh Out Laud hearing and imagining "swing the chassis around your head" when Uncle Doug spoke about verifying the center tap´s solder. The Egyptian and wine jokes were a good touch too.
Glad you enjoyed the festivities, S. Fixing amps can be fun :)
@@UncleDoug Of course is fun! It's a rewarding puzzle, not as painstaking as fixing surface components boards.
I could imagine Chuck Norris stepping in to swing the amp chassis at six plus G’s. Then he sits it down to and tells Doug he’s good to go.
I have a very similar amp. Mine dates from late '67. From what I've been told, most of the early silverface amps have a blackface circuit because they were using up all of their old stock components before moving to the new silverface circuits. If you see a silverface amp that has solid vertical black lines on the front of the chassis then you most likely are dealing with a blackface circuit. I got mine for an absolute bargain and was confident it was an ab763 circuit even though the seller would not open it up and send me gut shots. Unfortunately UPS managed to spear the box with a forklift and completely demolished the JBL speakers and the baffle. I had a choice to file a claim with UPS and never see the amp again or to just keep it. I ended up keeping it because I had acquired it at such a cheap price.
Yes, the first few years of silverface Fenders generally had blackface circuits......and they are a bargain.
First amp was a blackface Twin I bought for $350 (1977). Loved it but was pretty shrill. But I always had it dimed. Wish I still had it along with my '67 Rickenbacker 360. Good job on the Twin Reverb Doug!
Thanks, KM. If you still had it, we could fix the shrillness and make it sound like $1Million.
@@UncleDoug that negative feedback loop you introduced to the circuit gives the Twin a whole new voicing. 100% more useful for folks like me that aren't asking for a lot of headroom.
Another wonderful walk through.
Glad you enjoyed it, Ray.
I love watching this stuff. They scare the crap out of me even though I'm a electrician and have serviced equipment with way more power .
If you know and practice all the safety rules, Andrew, you are (probably) quite safe ;)
You really played nice on this video!
Thanks, Abu. I'll pass your compliment on to Los Gatos :)
that was one sweet build.
Glad you liked it, ICFA :)
"The only time brown ever gets hot is when you've eaten a lot of spicy food"
Tehehe! Hope you've been doing well my friend, your videos are always a blast to watch, and some of the best guitar amp engineering content. I find myself diving back and watching many over and over when I have that vacuum tube bug hit me (stares at new 100W Marshall OPT and MOD reverb tank sitting on my shelve). Yeah, that bug is coming back again. Just wish I had more time away from work. Too bad there isn't more Marshall on the 'tube. I've had a watch of some other people, but when I see them do things like discharging a cap by shorting it to the chassis (and thusly causing a vintage chassis to have a scorch/gouge mark, besides the insanity) def is not my fancy. Thank you as always for the amazing content!
Thanks so much for the very nice comments, Retro. I hope you find the time to get back into tube electronics.....and wish you the best when you do :) Arcing to the chassis is like dry-firing a weapon, it's damaging, particularly in the long run.
Ah man! you're priceless. I just love your channel.
The little details. I really hope people pay attention, the ones less versed in the fine art of safely working with powered circuits, when you said ( 33:39 ) "with an insulated screwdriver"... I immensly appreciate how you jam pack your videos with safety at every turn. You're a precious ressource.
I appreciate your kind words, PM.....Thanks !!
Hi Uncle Doug, greetings from Australia. Here in Melbourne we haver the same crazy weather, it all depends on where the wind comes from. A northerly brings hot dry from the desert, a southerly brings the ice and rain from Antartica. Thanks for another great video. As usual I wish I could ask you a thousand questions. All the best, Mic
Greetings, Mic. Pictures of Australia remind me of where I live. I guess the weather is the same too :)
Full disclosure:
that stone house looks suspiciously like the night club where Doug plays with the NFB loop off.
Thanks for sharing:D
Very perceptive, Kolin. Once that NFB loop is disengaged, structural damage is sure to ensue. Thanks ;)
A while back I worked with a guy from Arizona, he said coming to North Carolina was like coming to the "jungle". Looking at the drone footage, I can see where he was coming from.
Our vegetation is a wee bit sparser than yours, I would venture to guess ;)
I live in the uk and I think its taken me three years to remember brown is live, it used to be red, and neutral was black, but it changed when we joined the EU, weirdly enough I believe a lot of lights are still red and black (because they were never replaced), the way I remembered it is neutral is calming like blue, or Bratislava , brow-is-lava, brown is live
Uncle Doug.... a Shabby Craftsman.. LOL. Fantastic Long Service Video on this AB763 circuit..!!! Thank you!! Brown is ONLY HOT When you eat spicy food..LOL
Glad you enjoyed it, Mr. G.
Way to go, UD. Your magic touch really breathed new life into the old gal...even made Jack's picking come through loud and clear; lots of chime and a nice mid-range warmth. I always meant to ask...how does he manage to hold a pick without an opposable digit? However he does it, he rocks...
He uses his dew claws, C7. It's quite a sight to see ;)
Sounds like a first date... instant classic
Glad you enjoyed it, WW.
Hi Uncle Doug, your videos are both informative and entertaining (you make a great teacher). I have a question: you indicated in another video, dealing with, I believe, biasing a quad or quartet of output tubes that you prefer to bias tubes in a grid biased circuit at 50 to 60%. Of plate dissipation. In this video however the tubes you are using have a plate dissipation of 30 watts but you biased them to just 13.2 and 13.3 watts. Why did you go low? Just curious.
Thanks, Stacey. You're right.....the bias values for the quartet appear to be quite a bit lower than I recommended in another video. Bear in mind that these values were obtained using a current limiter, which lowers the current within a large high-wattage amp like this quite a bit. Once I plugged it into a wall outlet, the PD increased dramatically.....up to 60+% of max. Not mentioning this was a serious oversight and I apologize for not doing so within the video. I will correct this error in a future video.
TAD tubes are far superior than those 6L6B 's. Plate dis. is only about 25W on those Sovtek 5881WXT compared to a normal 6L6GC which is 30W.
"Hint of wood "indeed! At 43:00 those are the best plastic containers ever and found at Harbor Freight Tools. I got five of them! Yeah,they're that good and very inexpensive.
Really impressed by your work especially here Uncle Doug! I bet the owner will really be very pleased for all your work and thanks for showing how you repaired this fine amp!
Thanks so much for all your nice comments and information, HM. We really appreciate it.
Your weather description also very much sounds like the weather we have every year in NE Ohio. haha
Now, in the middle of October, our temps are still in the low-90's. Is Fall ever going to arrive ???
The first date joke... Holy cow, uncle doug. Knocked it out of the park
Thanks, Mr. G. So glad you enjoyed it :)
Wauw. So i don't have to buy a euro tubes tester. 🎉 Im on a budget so this is very good knowledge too me. Cheers to you. Thanks a bucket of tone!
There are excellent, accurate manual methods to measure PD, C......the Eurotubes device offers greater speed and convenience.
Thank you, for another cool, informative video! Cool, Tube Amp Doctor, near where I live, in Rhineland Palatine/ Germany. Greetings, you are awesome!
You're welcome, Andreas. Tell those TAD fellows that Ollie & Jack really like their tubes :)
Hey Doug, another excellent, entertaining and educational video. In case you're curious about the European power cord color coding (although I suspect you may already know - the joke was well worth it), is so color blind people can still identify phase / neutral / earth. Previously phase was red, neutral black and earth green (without a stripe). Imagine my surprise when I first learned that U.S color coding had phase as black....
Thanks, Rodney. It would be nice if there could be worldwide agreement on the colors :)
@@UncleDoug It would indeed.