Scratch-Build of an Ultra-Rare Gibson GA-1 RVT: Part 4.....It's Finally Done :)
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- Опубликовано: 9 июн 2024
- In this Part 4 (of 4) video, the scratch-built GA-1 RVT is completed, improved, and audio tested. To optimize the tone and performance, a total of 15 different modifications were necessary, both to the original schematic and our original plans for the build. All modifications are explained in detail, and links are provided (below) to a list of modifications as well as photos of the final Master Schematic. A thorough Audio Demonstration is provided, with a short discussion at the end. In addition, we will visit Mitzy after her summmer haircut and view a musical photo montage showing the step-by-step process of another "scratch-build", of a 1929 Model A pickup hotrod.
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NOTE: Be sure to watch the supplemental video which offers a second audio demo utilizing a different, and I think better sounding, Jensen C12Q speaker: • Supplemental Audio Dem...
Link to Schematic Modifications:
app.box.com/s/8lc0k9q866us4ki...
Links to Master Schematic:
app.box.com/s/dsosnz80vhrbrzj...
app.box.com/s/w7g9npvfv7j3bky...
app.box.com/s/53mr3lv38u1swdn... 
Видеоклипы
NOTE: Be sure to watch the supplemental video which offers a second audio demo utilizing a different, and I think better sounding, Jensen C12Q speaker: ruclips.net/video/N9KXhCKjrcM/видео.html
Just as important, Doug, as is the speaker choice, or that first tube choice, must be the choice of the mic used to create the sound file? And IMHO the SM57 aimed centrally is on the harsh side. I will certainly check the supplement with the Jensen; a 2x10 format might be, genius. So, wow - this of course could be a fine harp amp. In some ways the blues harmonica mic-cupping technique poses less demand on the circuit than does an electric guitar signal, albeit the guitar pickup creates more voltage to work with, than do the vintage mic capsules. FYI fans of Doug, how about some big harmonica names, & what they played: Sugar Ray Norcia, Ampeg 4x8 combo; or a Sonny Junior; William Clarke, 59 Bassman; Rod Piazza, blackface Concert; or Harp King; Kim Wilson, GA40 in studio, Mesa with the T Birds, Bassmans lately; Jerry Portoy, two 59 Bassmans; Paul Butterfield, 59 Bassman and Fender reverb (but hey he used 57-ish Shure capsule, ha ha); Charlie Musselwhite was shown in studio with a tiny Kalamazoo, and recently, I am pleased to say. The capper must be Magic dick Salwitz who with his band Blues Time made unbelievable tone - like a mute trumpet leading a New Orleans funeral - and this was achieved with an astatic JT30 (mic of choice for all above save Butter) and - k hard to believe - a rented red-knob Twin. I kid you not. . .
I have also found the Jensen 'Q' range of speakers to be the best sounding. Great video by the way.
@@ianbanhamamprepair9457 Thanks, Ian :)
I did a scratch build about 5 years ago with the help of one of your tutorials. I had no experience. Built the cabinet, bent up and drilled the chassis and followed your instructions on all the electronics. It took awhile but I now have one of the sweetest one-off amps ever. I'd post a pic if I could . Thanks Uncle Doug.
What style amp did you build?
Great to hear, John. You can post photos on my FB page: Uncle Doug's Vintage Amps.
@@qua7771 It was modeled after early Supro
@@UncleDoug I'm not a member of FB, but I'll try.
Who needs Netflix or hbo when you have uncle Doug??
Thanks for your great videos. 🤟🏻
......and we don't charge exhorbitant fees, like Netflix :) Our pleasure, PS.
Thanks for all the wisdom and info. By watching your channel for the last 4 years I've learned to diagnose and repair issues with my tube amps. Thank you.
You're welcome, Carl. We're glad the videos have been helpful :)
Uncle Doug makes a wood door stop and then decides to make it a reverb foot switch. Necessity is the mother of invention.
I'll be selling wood doorstops on Ebay now for extra money :)
I always appreciate your thoughts,honesty, and skill. Not just with the Amps, but with the cars as well!
Thanks so much :)
This is why I love watching videos like this but why I won't build an amplifier. I have no idea what can be changed , replaced , upgraded or modified. I would either electrocute myself or some one else or set the house on fire . If I was confident and had Uncle Doug's knowledge even if it was minute I would give it a shot . Thanks Uncle Doug for the great videos . 👍😎
You're welcome, Marcus. Don't sell yourself short :)
Be safe and you won’t electrocute yourself. Maybe start with low voltage then go to tube amps but you can do this!
I takes a lot of work and devotion to get good enough to be able to figure out a circuit when you are not using the originally designed PT and OT For me it took about 3 years of reading, experimentation and watching videos by Uncle Doug and Brad the Guitologist among others to get to that level but it is attainable. Don't give up.
I started out tinkering building 9v pedals and watching uncle dougs videos and other techs to pick tips and techniques. Ive built multiple tube amps now.
@@codpug That's great to hear, CP.......makes it all worthwhile :)
I wish I had an electronics teacher like you, when I was at school. I'm 75 years old now and enjoy your video's very much and learning from them. Thank you Uncle Doug!
Thanks for your kind words, AK. We're never too old to learn new skills.
Doug, I just put the finishing touches on my own project, following almost all of your suggested modifications. Made all my bias measurements with the help of earlier videos of yours, and everything appears normal. This thing has an incredible sound and a tonal range that just blew me away. The overdrive when Tone + Volume are maxed out is so delightful. This amp is heading out tomorrow to spend a couple of days on a gig in the orchestra pit at our historic downtown theater, and right in time for me to not break my back rolling out the 4x10 Music Man I usually work with.
I am so grateful for the inspiration and knowledge that your videos provided. This was my first attempt at a scratch build. Thank you!! I'll be heading over to your PayPal to literally put my money where my gratitude is. Your neighbor in the Lone Star State - T.J.
Thanks so much for sharing this with us T.J. It's great to hear that our videos are helpful and instructive. Congratulations on such a successful outcome, and best wishes for continued success with all your projects.
nice old ford truck with a chevy engine!! cool stuff!
Glad you liked it, Richard :)
Your understanding of vacuum tube electronics surpasses anything I’ve seen anywhere. Bravo. Your playing ain’t bad either
Thanks, Doc :)
Congratulations Uncle Doug! I learned a lot in this video. Thanks!
Thanks, Marcel. That's good to hear.
Nice, Doug. I especially like the tremolo & reverb together!
Thanks, Gary. So do I :)
Fab series Doug....Great amp and sounds..Love it..More learned..Ed..uk..😄
Thanks, Ed. We're glad to hear it :)
I think the Amp worked out great in the end, not quite a GA-1 RVT but close enough 👍
Love the truck, my dream truck is a 32 pickup but with a 5 window cab.
Thanks for the kind assessment, Warnz.
Excellent job Uncle Doug! I agree with all you've said about i/p, f/b & tone settings. That tremolo is silky smooth I love it!
I would have loved to have heard you play some ac/dc, being somewhat your junior, but that's ok, this is obviously a nice sounding amp.
I like the look of those bronzed knobs; unusual & attractive!
Mitzy looks good in her new summertime hairdo! It's bloody freezing down under here at 12°C! It gets up to 42 though in the summer!
Hey did I see Rusty in one of your hot rod pics? Geez, we all miss him, none more than you of course. Pets are such priceless friends.
I love you hot rod! You started with a corroded hulk & turned it into something very impressive! A custom multi-link diff? Wow mate! That 283 should really get that girl going! It can't be a very heavy vehicle!
Thanks for a real good, entertaining video & have yourself a nice, relaxing break!😊
Thanks for all the great comments and observations, Neville. It was 107 degrees on the final day of audio testing. Yes, Rusty was still alive and helping me in the workshop, except when I got out the welder. He was (wisely) scared of it.
Amp looks great, sounds great, and the Model T is also looking mighty spiffy! Thanks, Uncle Doug!
You're welcome, Ken :)
Part 4 finally :) It's always feels good and very informative watching your videos. Thank you.
Glad you enjoyed it :)
Every time you use that Paul Westerberg riff to test out an amp, it brings a smile to my face. And did I hear a second one this time? Wonderful sounding and looking build! Thanks always Uncle Doug!
We're glad you enjoy it, Scott. Thanks so much.
Great Amp Series as always. Having done a '29 A-Bone Frame-up in the same shape as your truck, I know the tasks first-hand that you dealt with. Those trucks are a tight fit for a 6'-1" guy like me though. 🙂
Thanks, Ernie. It was a tight squeeze for me too, but worth it ;)
Just finished watching the 4th episode of Uncle Doug's scratch-built video of his scratch-built reproduction of the Gibson GA-1 RVT amplifier. Quite a journey and a very enjoyable on indeed. Very interesting to watch you go over the changes you made in the design. Actually watching the process of working out and performing those mods would have made a really interesting video or two.
I've watched the supplemental video in which you audition the amp with the Jensen Special Design speaker instead of the Alnico. I wholeheartedly agree with your ultimate selection. Thanks for the great video series..
Thanks so much for your comments, Reggie. Both audio demo's were with Jensen C12Q's.....but the second one had a stronger ceramic magnet.
Saaaaawweeeet! Both amp and truck! ✌️✌️✌️
Thanks twice, CF :)
Sounds amazing !! I've been busy modifying my harmonica set up. I replaced a single 12 with two 8s.(brand new Riftones) It sounded so good that I made another cab with two more of them. It'll take the birds off the wires !! All the best from an extremely hot Nova Scotia.
Harmonicas love multiple 8" speakers......no doubt about it :) It was 109 in my workshop at the beginning of the week. I got so dehydrated that I looked like beef jerky ;)
@@UncleDoug That's what it was here last Wednesday, 109.2 F. Hotter that a huntin' camp stove pipe.
@@MrCayoCoco ......and the really hot days are yet to come :(
Beautiful looking and superb sounding amplifier, my and no doubt many others idea of the perfect amp .in awe of your knowledge and skill. Thank you for the great content.
Wow....Thanks so much, Reggie. Glad you liked it ::)
Great work. And love your dry wit. Great sense of humour. If you're ever in the UK let me know and I'll buy you a moderately priced beer
Thanks so much, James. That's the only type we drink ;)
Unsurprisingly the amp tuned out great with your mods Uncle Doug! Sounds and looks perfect! I love that tremolo! A neat job as always. Thanks for sharing the journey sir! 👏🎸🏁
Thanks for joining us, Claes :)
At the risk of soundin' kinda i'nerant... I think this amp came out killer sounding. The warmth and clarity are amazing. I don't know how you were able to juggle the complexity, especially having had to innovate a few critical points. Great series, enjoyed every minute (that I understood).
Thanks so much, PC. Nice comments like yours make it all worthwhile :)
Excellent result! Sweet pickup hot rod, must have been a few years ago. Heading to other video now.
Thanks, Andrew. Yes, it was t least 6 or 7 years ago.
Thank you Doug highly enjoyed this series ,the hot rod was the icing on the cake thanks again
You're welcome, Leslie :)
I really like the sound a lot
That's good to hear, Billy :)
Brilliant - thanks for all the work!
Thanks, BS. Glad you enjoyed it :)
Yet another epic build comes to an end. Thank you very much!
You're welcome, LBC. I hope you enjoyed it :)
Heck yeah. What a journey and end result! Thank you for sharing it with us all UD!
Thanks so much, PG.
I love the sound of this amp ! Very nice !!
That's what counts, Michael. Thanks !!
Another fine project. Sometimes the simple amp designs have the most pleasing sounds.
Thanks, DK. I agree :)
Great Job Dougie!!!!!!
Thanks, Terry :)
Great result Doug. You are a true master of amps :)
Thanks so much, EL :)
Congratulations Uncle Doug! Truly a momentous undertaking.
Thanks, Hans. Yes, it was :)
I have been waiting. And now it is here.
I hope you enjoyed it, JM.
nice uncle doug you did great on both accounts .😀😀🥰🥰🤩🤩🙃
Thanks, Bryce :)
That’s one mighty fine looking and sounding amp. Thanks for making these excellent videos.
You're welcome, PTC. Thanks :)
I am elated this scratch build has been completed, (post mods). After listening to this amp's maiden voyage, I was greatly pleased once the high gain input was used. The low gain input seemed to experience early breakup; which is an attribute of a single-ended design.. The high gain input was very musical in timbre, and bass response. I am glad you opted for a 12" speaker; any other would have sounded anemic. This 4-part epic was a joy to behold. It not only documented the rebirth of an elusive amp, but highlighted the constant need for modifications to the circuit. All of which did result in a positive outcome. Mitzi looks comfy with her new summer cut. That truck must have been an undertaking more intense than the RVT. I imagine it was so rewarding. I hope you do enjoy a well deserved rest, dear uncle. The heat here is unbearable; along with the humidity; it's like walking through a bowl of soup. Stay cool, and have as much comfort as the air-conditioner can provide.
Thanks for all your very nice comments, Alex. Will do :)
I love these little nuggets of masterpiece you bring alive Big Unc' D. Keep up the good work my dude.
Glad to hear it, Arlo. Will do :)
Really interesting series form my favorite Uncle plus a mention of my second favorite! Thanks, Doug.
Glad you enjoyed it, Willie :)
The amp sounds absolutely fantastic. You're a true master of the art.
Wow....Thanks so much, Jeff.
Beautiful! The amp and the truck!
Thanks twice, Y :)
Cute truck!
Thanks, Allen.
What a fine end result! This has been a fascinating learning experience seeing the modifications needed to get this amplifier working as desired. The Model A truck turned out nice, that is a snazzy hot rod!
Thanks twice, Jon :)
Excellent build Uncle Doug. And good tweeks.
Thanks, Phil :)
Great stuff as always. love the amp and yes tone is great. Love the hot rod !!
Thanks, Guy
Thanks, Guy. Glad you enjoyed it.
You’re my favorite amp dude Uncle Doug. Always learn something new.
That's great to hear, Y1. Thanks !!
Totally agree about the tremolo intensity. First thing I thought when I heard it. Personally, I would add a pot to control this. Other than that, wonderful achievement. :)
Thanks for your input, Mech, but there was absolutely no room on the control panel for another pot.
You are amazing! I throughly enjoyed watching and learning from this series. Hot rod came out nice too. I like the finish, looks great.😊
Thanks twice, Phillip :)
Keep on rockin’, Mitzy!
Thanks, G. I thought she really did well, especially as a rookie :)
Thanks for the Hot Rod. You are a fine teacher!!!
Thanks, Terry :)
Uncle Doug is the man😊great video
Thanks, Wayne :)
Not only an aesthetically pleasing build, your true point to point is a real work of practical art. And the best part, it sounds even better. SWEET..Uncle Doug. Thank you 🙏..And what a treat at the end. I love Hot Rods. You rock my friend.
Thanks for your very nice comments, Fid. I'm glad you enjoyed it :)
Yes and that fabric pattern on the back cover lines up perfectly with the amp case… I love these videos.
Mojotone really did a fabulous job on the cabinet, Mr. Z. Thanks !!
I really like the tremolo. Good job.
Thanks, RM :)
What a demo ! Output tube bias and dew claws trimmed to perfection !
Amen, brother. Those cats were playing their hearts out :)
26:37 it's a fine jewel box Uncle Doug,. you are a real artisan and we thank you for all your work on this and everything that you share
Thanks so much, Mr.P :)
great tone for 4 or 5 watts. also its a beautfu amp! nice reverb and remolo!
Thanks so much for confirming our optimism in building this long-lost circuit, Richard.
Uncle Doug. I always learn so much from your videos. I’ll likely never do a scratch build but I’m going to tackle a couple of conversions of tube audio amps. Job well done!!!
That's good to hear, Tommy. Thanks :)
amp sounds good! sweet ride! the guy up the street from us has one but all original, thanks for all the work vids
Thanks. Go listen to his and let us know how it sounds ;)
Listening to your comments about continuing to tweak the circuit forever, I couldn't help think of of the old joke: "There comes a time in every project when it is necessary to shoot the engineers and begin production." 🤣
Amen, TJ. If perfection is unattainable, then its pursuit is a fool's venture.
So enjoy yours and Lyle's @ Psionic Audio channels. Absolute wealth of knowledge!
Glad to hear it, MJ. Thanks !!
a real jewel
Thanks, Tony :)
WOW Doug! You truly never fail to impress me. Your Scratch-Built /Conversion amps have always been my favorite videos to watch. I was somewhat skeptical with the unusual circuitry, and a Non DaniSonic Cabinet, but what a gem it turned out to be indeed!! One of your best..
Thanks so much, Tom. We never want to let our viewers down :)
Amazing, you are a great amp builder and designer. Thanks for sharing all of this, we really appreciate it, for its educational and entertaining value. Mitzy looks so silly with no hair fur 😂
Thanks, K. I'm glad you enjoyed it. It had to be done to get rid of all the tangles.
Hi uncle Doug. Great sounding design/rebuild of the Gibson rvt1 amp, and thanks for explaining changes, and how it affected performance. Also wonderful attachment at the end of the 2017 build of your hot rod. Was nice to see Rusty from back then as well. Thanks for sharing your skills and talents with us. The knowledge you have is priceless. 🥂
Thanks for your very nice comments, V. I'm glad you enjoyed the series :)
What an excellent amp. Mitzy really stepped up too.
Thanks, Tommy. I'll tell her you said that :)
very thorough and very thoughtful! great video series. i have a few gibson amps and they are great!
only thing i do differently with my tweed builds is to add brass screws and finishing washers. really goes well with the tweed!
Thanks for the helpful suggestion and nice comments, Michael.
There's no such thing as perfect RUclips conten... oh hang on. An absolute joy
Thanks so much, John :)
Una verdadera maravilla el Gibson, y la chata del final una reliquia única y espectacular. Saludos desde Argentina Señor Doug!!.
Thanks so much, Angel. I'm glad you enjoyed it :)
Hi Doug, great sounding amp and what a surprise, I saw good old rusty inspecting your truck build.
Thanks, M. Yes, he made it all happen.
Cool amp … with an awesome audio demonstration 👌🏼🔊….. and an even kooler hot rod !!!! I’ll bet that ol” 283 or 327 gets er down the road nicely .✊🏼👌🏼⛽️
Thanks, Nick. It was a Power Pack 283 from a '59 Impala :)
Mesmerized by every minute. The Amp build is magnificent and your manner makes me miss my father (and I am 59). My only criticism; I think you should have left the bullet holes in the Truck.
Thanks so much for your very kind words, Adam. I'll follow your advice.....on the next one :)
We love you uncle Doug
What a beautiful piece of joy
I love tube amps so much and I’m super lucky to steward a couple of them
Hand wired is my favourite for being able to mod and repair
You sir are a jem just like rusty
Shalom
תודה רבה על המילים החמות שלך.
vary nice on both builds. 😎💚💙👍👍🍺🍺🍺🍻
Thanks twice, Walter.
Thanks twice, Walter.
Hey, I really like the amp! Good to see it all built and rockin'. I also like your mods, I don't really believe in total originality for originality's sake when recreating one. Practicality beats purity; it's important to identify the critical components, circuits and layout that make the sound, other stuff can be modernized to the best practices available now.
7:00 these new cables look better, I'd still ground the shield on the reverb feed side.
13:00 I'd use an additional filter cap here to reduce hum.
28:45 the real deal!
I like the reverb footswitch, would make it a bit wider for stability unless it's gonna sit on a pedalboard.
Nice job on that ol' Ford rust bucket! That's virtually building a car from scratch.
Thanks so much for your comments and suggestions, KE.
A guitar through ..an amp.. and no effect 🤪! it had a shedload
of effects uncle doug ..trust me, sitting here with most of them
after your eagerly awaited sonic conclusion,flabbergasted 😇
good lord that tremolo on slowest,and the reverb is to die for!
a phenominal instrument, (the amp), incredible series, you just
never falter 👍i loved how the truck turned out too ,👌
yup, a well earned few weeks off ,thankyou so much.
Wow, thanks for all your very nice comments, TS :)
Love both projects. I'm not usually a fan pf the petina look on hot rods, but this is tasty. Sounds like Mitzy's guitar lessons worked well. Love the 12 bar blues at the end of the video.
Glad you enjoyed them, Dave. It was the original Moss Green paint.
I hope the groomer survived the process of giving Mitzi a makeover!
They anesthetized her......and charged $180. I needed some anesthetic also ;)
@@UncleDoug , two of my dogs (Anatolian Shepherds) are over 100 pounds but they're well-behaved during grooming and only cost $80 apiece. I like cats and have had them in the past, but these dogs won't tolerate a cat. Like yours, the cats we had were all strays that adopted us, and they were always getting into fights and various trouble and I was constantly patching them up with peroxide and antibiotic creme.
@@goodun2974 The ferals we take into the house are all tame and lovable, but the outdoor cats fight like hell and have all sorts of scars and wounds.....very distressing.
@@UncleDoug , our strays were very sweet and slept indoors at night ---- theyd curl up on the dog beds with our St Bernard and German Shepherd that we had back then ---- but spent most of the day outside. They didn't tolerate it when other strays came around to steal from the outdoor food bowl.
great work love your show Uncle Doug if I had a clone of you that lived here it would be great Happy Motoring
Thanks, G. All our clones are sold out, but a new batch is being created as we speak ;)
On the pentode vs triode, i don't even care if you use a transistor or an op-amp if it makes the end result better.
Glad you took my advice on the feedback and the shielded wires for the reverb.
That is a great amp congratulations.
Thanks so much for the kind and helpful input, KK.
If you wanted to add a separate pentode a 6AU6 would work very well; it's very similar to a 6SJ7.
6AU6 are common, and inexpensive; the only issue being you might have to try a handful of in order to find one that's low in microphonics. As for triode-pentode tubes I probably would have tried 6U8, 6EA8, 6GH8 and 6X8 as alternatives to a 6AN8 or 7199, Albeit with different pin outs
Thanks, guys, but I'm just not a fan of pentodes in the V1 position.
There are other triode/pentode tubes or other solutions for a pentode stage but you did what you could with the or socket. I think some of the mods are the result of using a bigger, better speaker instead of the student model cheap one that Gibson would’ve used. Love the build! Always informative.
Thanks for the input, Bill :)
Having good luck breadboarding a nos Amperex world logo 6GH8A. Had distortion problems with the 2 used 7199s on hand. Didn't yet try the 6AN8s.
The 6GH8As I can find in various amp schematics are used as phase inverters, notably in the Sunn Spectre.
Thanks for sharing the results of your experimentation, OAR.
Nice job on the amp build Doug. When doing the audio demos you may want to point the SM57 a little further away from the center of the speaker, and perhaps a bit off-axis. That will reduce the treble heavy sound, although I don't know how much YT's compression affects the overall sound.
Thanks, Michael. I think single-coils through a 3W amp are always going to be a bit trebelicious, but we appreciate the input.
I just used some of that Harbor Freight superglue thus morning, I was a little surprised it's a gel. THANKS UNCLE DOUG!
You're welcome, Tom :)
Than you so much for sharing this build, and I don't blame you for taking some time off from amp building, This project presented some unique challenges, but of course you pushed through and delivered another beautiful amp. When you say "scratch build" you really mean it!
The truck is amazing and the wheel choice is perfect. 283 or 327?
Thanks again, be careful and watch the heat.
Thanks, Randy. It was a low-mileage 283 Power Pack engine I personally removed from a '59 Impala. All it needed was a hone, new rings, valve job, and a massive amount of cleaning. You too.
@@UncleDoug A low mile 283 with the coveted power pack heads is a very rare find. Those are incredibly smooth and reliable engines, and tuff as nails. I knew a few hotrodders in my youth who ran them insanely hard, and they just wouldn't break.
@@Slugg-O I think the 283 was the mother of all SBC's, Randy. For its displacement, it's hard to beat.
The modifications done to Mitzy seem to agree with her. Happy cat, happy life. Cool foot switch for reverb and do agree
you need another one next to it for the tremolo. Maybe a wider wood doorstop one with a stereo plug for it. Just modify
the connection to the amp with a shielded stereo cable and stereo input jack. There is nothing more rewarding and
exciting than turning an old 1928 Ford model A into a "beast" of a hot rod under the hood but still have the original look of
the model A. You are an amazing guy Uncle. Steve from IL
Thanks for sharing your interesting observations and comments, Steve :)
Pentode purists versus triode traditionalists - well - you can't force new tricks to good old Uncle Doug. This video series is like a master's thesis on "Tube amp building". The 6BM8 - or ECL82 for us europeans - will be the main building block for my next 3 projects as well. Interesting tube choice regardless - I hope the next video feature will include a 6N6 or a similar octal anachronism.
Thanks, Mark. We have worked with octal tubes in the past and are fans of their tone. It's the 9-pin pentodes in V1 that tend to chafe a bit :)
Best sounding uses of a Pentode I’ve heard in a pre so far are the classic AC15; and the 4 channel Selmer PA amps that used them kind of like a buffer, DC coupled to the LTP phase inverter after. Really loud, clean, and warm sound.
@@Jonathan_Doe_ Thanks for your input, Jon.
Great amp build Doug. The guitar sounds great through that amplifier. When will you and your band start your world tour?😊
Thanks, John. I'm too old for the road, but Jack and Mitzy may be turing soon :)
❤
Glad to hear it :)
sounds like it's ready to record some chart topping hits .. maybe Gibson just shelved the design because they didn't have you there to finish it? , oh well.
I don't know if a Weber 15A100A would fit in there, but that would help the amp push a venue.
Thanks for the helpful input, RG :)
The 6GH8A swap in for the 7199 is the ticket UD. A (still living) tube tv repair guy I'm acquainted with insisted to pass on all but the Sylvanias, newer better.
I found 4 7199s in my stash (2 yellow labeled Sylvanias were the winners.) Breadboarded it per the original schematic with the various errata corrected and its great as is.
Sensitive to lead dress. Given Gibson's spaghetti bowl construction maybe that's why this one ended up so rare, too noisy for the kids.
Thanks for your input, OAR :)
@@UncleDoug My pleasure. If you ever return to yours to get that pentode input back in the circuit give that Sylvania 6GH8A a try, I know you'll have less difficulty than with the 6AN8.
It's fun with a pentode in front, it's got a certain gristle to it a triode doesn't
@@oldasrocks9121 Thanks for the input, OAR, but after countless hours of work, I am officially done with the RVT :)
@@UncleDoug Fair enuf! Have you ever had the chance to work on or go through a Swart? The 5 watt Atomic is more or less the very-deluxe version of the GA1-RVT, Micheal S. uses a 12DW7 to drive the reverb spring tank without a transformer interestingly enough. Super quiet single ended amp, like sorcery had to somehow be involved quiet. Spendy tho!
@@oldasrocks9121 I admire Swart products, OAR, but they are too recently made for me to work on. I stick with 1978 and earlier gear only.
I missed the first three parts but the overall construction looks like some of your best work.
On the subjet of your Ford restoration, I was surprised that you did not rust proff and paint cbefore the installation of the cab and etc.
Good job though and that hood ornament. Sarcastically flashy.
Thanks :) I did paint the frame and all exposed metal surfaces, both during and after construction, Jeremiah. The radiator ornament came with it.....it was the best part.
Ahh, Pentode preamp tubes. Trust me I get but I wouldn't say don't try it, not that you did. I have built amazing sounding amps with 6SJ7, 6U8, EF86s but never tried the 6AN8. The 12AX7 and 6SL7's are more forgiving and will take a larger range of components and voltages and still sound great. My last build was a one off using a 6SJ7 using a Revere T-100 Power Transformer and I found a similar problem to you, it ended up being the following. To me the two most important things are to make sure the plate voltage is not too high. It has to be below 100vdc, below 75vdc is better. Also, the relationship between the plate and screen voltage is difficult to balance. There seems to be a small range of these two voltages that make all of the difference and you also have to pay attention to the cap that couples the screen to ground/the cathode. As I am typing I have thought that perhaps using pots to vary the plate and screen voltage may be a good way of finding the proper values for the plate and screen resistance, I think I may build a test rig.
Thanks for your interesting input, SHW. I am a fan of pots and experimentation.
Man amazing work you do! I love playing guitar and old tubes, but doing this would be difficult for me or at the very least so time consuming I should stick to guitar and have someone else build em. I can see it now... Uncle Doug's Amplification - Made in USA - and we need some good ole made in USA right about now. I was thinking as you were scanning the circuity in the vid...its almost like "a plate of linguine with wires everywhere" in there haha
Thanks, LAG. I view my PtP wiring as anti-linguini......but beauty is in the eye of the beholder. If there were any money to be made by building amps, I might consider it......but it's generally not feasible.
@@UncleDoug I just got back from my vacation so I missed this...yes I know - music and the equipment used to make it ain't the same as the good ole days and neither is the pay. I used to gig 5 nights a week 4 hours a night for years in L.A, Seattle, Boston, Santa Barbara/Ventura...now the best gig out there for musicians is private teaching in a well-to-do area...one hour of teaching is better pay than most gigs out there nowadays...a sign of the times - still - awesome build and a great channel. I appreciate your work!
@@leveractiongypsy1848 Thanks so much, LAG. Not to mention that teaching at home does not require lugging 100 lb. amplifiers up 3 flights of stairs to an (unadvertised) gig that has no audience.....and virtually no pay.