Gibson GA-1RVT Build: Part 3 (of 4)
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- Опубликовано: 12 июл 2024
- In this Part 3 episode (of 4 Parts) we will reveal the existence and actual build numbers of this elusive amplifier. Then we will return to the construction of our clone, with a discussion of techniques to assist in the translation from schematic to actual circuit. Once completed, the circuit will be plugged in and initial testing will begin. Please note that a list of topics and times will be pinned at the start of the Comment section to allow viewers to select specific topics to view. In addition we will have a feral cat update and will open a very special gift.
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Here is the link to the color-changing LED Pilot Light, which is known as The Carty Mod, for its illustrious inventor, Rob Carty :) www.pinballbulbs.com/products... Here is the link to the smooth, white Pilot Light Jewel:
www.amplifiedparts.com/produc...
Table of Contents:
GA1 RVT Update 0:00
Introduction 3:29
Tremolo Circuit Part 1 7:40
Casey the Feral Cat 19:16
Tremolo Circuit Part 2 19:55
Open Special Gift 25:35
Control Panel & Input Jacks 26:12
Ollie the Feral Cat Tribute 41:27
Switchable NFB Loop 43:14
6.3VAC Filament Wiring 44:35
6EU7 Wiring 48:23
6AN8 Wiring 52:35
Tone Control Addition 59:14
Double Check All Work 1:01:25
Power Up and Prelim. Testing 1:02:30
Closing Discussion 1:08:04
Farewell Messages 1:09:43 
Видеоклипы
GA1 RVT Update 0:00
Introduction 3:29
Tremolo Circuit Part 1 7:40
Casey the Feral Cat 19:16
Tremolo Circuit Part 2 19:55
Open Special Gift 25:35
Control Panel & Input Jacks 26:12
Ollie the Feral Cat Tribute 41:27
Switchable NFB Loop 43:14
6.3VAC Filament Wiring 44:35
6EU7 Wiring 48:23
6AN8 Wiring 52:35
Tone Control Addition 59:14
Double Check All Work 1:01:25
Power Up and Prelim. Testing 1:02:30
Closing Discussion 1:08:04
Farewell Messages 1:09:43
If you add this in the video description, youtube will automatically divide the video into chapters...
Uncle Doug, I own the earlier tweed version of the Maestro GA1RVT. I got it years ago and ashamed to say that I haven't taken the time to get it operating properly. I need to review this series and get it going.
Thanks for all your great videos and for sharing your knowledge in an entertaining manner. Sorry for the loss of your pet 😢
@@rodneykroetsch2924 Thanks for your input and nice comments, Rodney. Would you consider posting photos of the RVT on my FB page: Uncle Doug's Vintage Amps ? Best of luck with your repair of the amp.
@@rodneykroetsch2924 Thanks for your input, Rodney, and best of luck repairing your RVT.
@@UncleDoug I will absolutely share pics and info on your FB page. I wish I thought about it earlier and could have sent it your way to include on your video build series. It appears to be all original!
43:30 “It doesn’t have to be DPDT, but that’s the only microswitch I had on hand, so I used it.”
I love moments like these. The DIY mentality is so important; use what you have if it works!
I work spontaneously, generally without any plans, and modifications have to be made on the spot......plus, it's more fun that way :)
I’m so sorry hear about Ollie, Doug. The guitar demos just won’t be the same without her.
Thanks, Brad. We're hoping Mitzy can take over for Ollie. We'll see in Part 4.
Although I'm over the moon with the operational success of this build, I can't help but feel saddened to learn of Ollie's passing. I am sincerely sorry for your loss, uncle. I hope you take solace in knowing that you both gave Ollie a chance at a quality existence, as opposed to the maniacal danger of an undomesticated life. Needless to say, the stirrings of life to your creation is exciting. I can't wait till Chapter IV (A New Beginning). Enjoy the weekend, dear uncle. Try to stay cool, hydrated, and away from the infernal sun's wrath.
Thanks so much for all your helpful observations and comments, Alex. We appreciate hearing from you.
@@UncleDougso sorry to hear of your families loss Uncle Doug. We never forget them ❤
@@MrPnew1 Thank you for your kind words.
RIP Ollie. You’re a saint. Not to mention your patience and generosity in passing on your vast knowledge to thousands of people. Bless you Doug.
Thanks, Phoenix. She was a gentle, sweet family member and we miss her deeply.
You gave Ollie a great life Doug, my condolences to your family. Thank you for sharing your precious time and wisdom with us.
Thanks so much, Alex. It was an honor to do so.
RIP Ollie. Respect Uncle Doug for showing compassion and nurturing strays. Being a little older in years and hobbiest I can attest to some strange looking interpretations of circuit diagrams over the years 😀. Like you point out look for common denominators, ground, signal, power etc and break it down to blocks , whilst playing chess - think ahead 3 or 4 steps.
Thanks for your nice comments and input, Pat.
Another Great video Uncle Doug!! Like so many people , I struggle converting a schematic into a wiring diagram. Thanks you your help. RIP Ollie
You're welcome, Joe, and thanks for your nice comments.
I can't believe I teared up with the knowledge of Ollie's passing. She was a good guitar player and a great companion though the years of me watching.
I hope young people are watching, paying attention, and learning your teachings both when it comes to amp building, less that knowledge be lost and your compassion for both your students and furries. Thank you Ollie's for being in my life.
Thank you for your very kind words, David. We truly appreciate them.
G'day Uncle Doug,
Sots & I are saddened by the news of Ollie's passing - we'll miss her. R.I.P Ollie.
Andrew & Sots
Thanks so much, Andrew & Sots. We appreciate your kind words.
My first DIY tube projects were with MOD kits, I loved how they showed the schematic and the wiring diagrams just like you see it with the point to point wiring, useful, but quite a work. I enjoyed how you explained with cable colors, tags and names. Once one get use to it the brain re wires and it get easier.
I love this projects from scratch!!
Cheers Uncle Doug!!
When I make point to point connections (or even in pcb boards) I like to sketch in order to avoid confusions, sometimes I forget some ground connection or any lose component, and that helps before soldering.
Thanks for your input, Cris. I'm glad the videos are helpful :)
RIP 'Ollie'. :( I'm a cat person. I've had 5 cats so far. My first feral cat that I saw born in 1973 lived to be age 20. My last rescued cat lived to be 3 months short of age 22. We hit the bars on his 21st birthday. ;) I rescued my current cat at age 13, she turned age 17 yesterday.
You must be a good "parent" for your furry children to live such lengthy lives, Tony.
Rusty is looking after Ollie now ❤🐈⬛🐕
I hope you're right, RJ. Thanks :)
God has a special place for his creatures and those who look after them,,,I'm told they will be in heaven when we get there, looking forward to seeing mine, God Bless Uncle Doug
Thanks so much, Tom. It is comforting to think of an eventual grand reunion with all my furry and feathered pals.
I’m always saddened to hear of the passing of a dear pet, I offer my condolences. Thank you for sharing your special friends with us as well as your teaching abilities to educate and inform us on amplifier building repair, and hot rods. Hope you have a Happy Memorial Day!
Thanks so much, Michael. Likewise to you and your family.
Once a teacher always a teacher. Your explanation/lecture starting at aprox. 33 min. mark is excellent, well done. Thank You Sir,
It's great to hear that. I'm glad the video is helpful.
Sorry hear about Ollie, though I take much comfort knowing how you and your family provided for her - and that she had a great life as a result and had your paths not crossed, most likely her life would not have been as long and dignified. It's never easy to let them go.
I learned a TON in this video - it put me light years ahead on trying to decipher an easy to understand way of thinking to help me devise a method for point to point. I believe I can do it now. Thank you so much!
Thanks, OLW. It's great to hear that the video was helpful :)
Long time subscriber here. I'm really enjoying this series! I'm doing a tube preamp for bass series right now and kind of got in my head over reversing the physical layout of the controls from standard. I'm going Drive, Treble, Middle, Bass and Volume from right to left. It was really encouraging to see you take flipping the input layout on your chassis in stride. There are no mistakes, only features! LOL.
Thanks so much for being such an awesome resource!
RIP Ollie
Thanks so much, Jag. We're glad the video has been helpful :)
Sorry to hear about Ollie. Never easy to lose our little friends
Thanks, Capt. No, it isn't.
Sorry to hear about Ollie... It`s never easy. I lived for 20 years with my 5 cats and when they passed, by their own time, I felt really sad. But when I`m mot fine I can feel their presence near me.
Excellent video, as always. Very informative and precise. This amplifier is a good challenge!
Hope to hear from you soon.
Thanks for your very kind thoughts and words, Marcel.
My heartfelt condolences regarding Ollie. I remember when she first arrived. It’s such a shame when they leave - always too soon. Stay strong, and know that, thanks to you, she had a wonderful life.
Thanks so much for your very kind thoughts and words, Dave.
HOW AM I UP UNTIL 10AM and missed a new Uncle Doug video?!! And Uncle Doug,
I am old, and therefore have been up since just before 5 AM here in DFW. Thanks, I am enjoying this "kit from scratch" series. And indeed, the cabinet you are installing it into is a gem.
FWIW, Uncle Doug "high spots" still provide elucidation for we pedestrians! 🙂
I hope you enjoy our latest episode, Ken. Thanks so much :)
My condolences to you, Uncle Doug for your loss of Ollie. She was a Jewell to you and your family. Her musical talents will be missed.
Mitzy has some big paws to fill.
Thank you, again for your gentle and informative teaching on building this circuit.
As I look forward to part four of this series, and as a compassionate animal lover as you, I suspect Ollie is purring her heart out at your progress and, with you in spirit, when the sound tests commence.
-Dan
Thanks so much for your very kind thoughts and words, Dan.
Hello Doug, My sincere condolences to you for the loss of Ollie. Our furry companions make a difference to our lives and what a huge difference you made to hers. Can't imagine how she would have ended up without the home you provided. Thank you for your marathon effort putting this video together. It surely will be very instructive to viewers who haven't built an amp. For those of us who have, it's always good to see how someone else approaches such a project. All the best to you and yours, Regards, Jeff.
Thanks for your very kind thoughts and words, Jeff :)
Very thorough walk through Doug. A great lesson for newbies like myself
That's great to hear, Ex. Thanks :)
Once again, I am bowled over by your instruction. I am one of the Troglodytes who have a devil of a time translating a schematic to a physical circuit. You have a gift that has provided me with a number of A-HA!!! moments over the years I have watched your videos. Thanks once again, Uncle Doug! I am so very sorry to hear about Ollie. May Ollie and Jack rest in peace.
It's great to hear that the videos are helpful, Michael. Jack is still alive and well, but Ollie has passed on. Thank you for your kind words.
@@UncleDoug Oops! I meant Rusty. :-)
Sorry to hear about your buddy Ollie. I'm sure you gave her a great life.
Thanks, SBE. We did our best.
Late to this video, but so sad to hear of your loss. Always hard to take the loss of our four-legged family members.
Thanks, B :)
Long live the brotherhood of feral cat herders. ❤
Amen, brother :)
This series is a jewel. Thanks Uncle Doug.
Glad you enjoy it, Alan :)
I do not know what you used to do for a living as I guess you might be "retired" now but if you were not a teacher or a journeyman who worked with apprentices, your teaching gift would have been. thanks for the all patience and hard work.
lost was lost
Thanks. I was a math and science teacher for many years.
Thankyou Doug I learnt so much in this video. You are a superb teacher and mentor I can't wait to hear this amp !!
You're welcome, Mark. The audio testing is complete and I think you'll be pleased.
Hey Doug ..Just fab...! Watching and learning all the time .Great tuition, info and fun..Great amp...Ed .uk..😊
We're glad you're enjoying it, Ed :)
Sorry to hear about Ollie, UD. Ollie and Rusty are partying together again…building amps, playing in a band, drag racing…etc. Thanks for the great video!
Thanks for the kind words, Tommy :)
I can't believe this video is free
You are welcome to support our channel if you wish, Billy.
Excellent teaching, even though I don’t plan to build any amplifiers, I’m jazzed to see this and understand more.
Who knows, I might step out there and try a small build.
Thanks, David. By all means, give it a try :)
Deepest condolences on the loss of Ollie, Uncle Doug.
Thanks, Dainis.
Uncle Doug and co you are one of my favorite shows on the entire web
Thanks so much, 20.
Sorry to hear about Ollie the cat. I had 2 sister cats who lived to 18+ years old and passed 9 days apart 2 years ago. I can understand most schematics, but have trouble translating that information into a layout. Thankfully, for most of my Fender amps, the layouts are available. I have a BS in accounting and an MBA, but that doesn't help much with electrical understanding. Thanks to your videos and a few others, I have been able to service my old Fenders and keep them going strong.
2 Wiring mistakes, Oh no😰
Thanks, Michael. I would think that the meticulous thinking of an accountant would be a great asset in the electronic field. Best of luck with your continued self-education.
Very sorry for your loss! They always leave us far too soon
Thanks, Nicholas. Indeed, they do :(
Quality information as always. Sorry for your loss - RIP Ollie.
Thanks, Steve :)
You hit on something that has been a huge block for me. It's like a schematic is music notation and I need amp tablature. Thank you for what you're doing.
I think this is a common problem, Jim, and I hope that the different approaches I take in Part 3 facilitate the transition from schematic to circuit.
hi uncle doug! on the schematic~circuit translation issue i had to laugh. david hafler did it for his kits. even though it was step by step there were still some we sold that had to be 'corrected' because the assembler still didn't grasp the concept. sometimes it's all about the ron white effect no matter how hard we try. hope all is well with you and yours my good man.
=dok=
Thanks so much for your input, Gizmo. I guess there are always some who require heroic assistance, but I'd like to think that we can effectively reach most viewers.
I thought the same thing about that protruding nut (my first instinct was to cut off and sacrifice the two lugs next to it) and I also had a head scratch when the double-pot solution was offered in the previous video, but figured you must be using it as a VR! I'm learning!!!
Condolences for Ollie! She found a good home to live out his later years in. (Apologies for misgendering her originally.)
Thanks for your input, AQ. The double-pot solution was wishful thinking, I guess :)
@@UncleDoug It's a good idea for VRs that I'll try to keep in mind for the future.
Cheers!
Sorry to hear about Ollie Uncle Doug - always a difficult time. My guess is another lucky panther will seek you out whether you're ready or not. Really enjoying this series UD and looking forward to part 4.
Thanks or your kind words, GG. We're glad you're enjoying the series.
Nice use of the 6BM8. ❤️🌹👍You can come help clean my bench. 😃🤣🤣Sorry about the Kitty. They was very integral to the set n story. God bless you sir. Thanks for the filament wire trick. 😃😃😃😃👍❤️
Thanks so much for your nice comments, 3PB.
Doug, you have made me move a little 🥹. I hope that now Rusty and her will cuddle each other in the animal paradise. I don't trust in any god, but i hope that there is a place for their pure souls, where they can be happy. And maybe once we're dead too, we will be able to hug them for one last time. You always make my day, thanks!
Thanks or your very nice comments, Federico. I agree, babies and animals must have the purest souls of all :)
❤
Both Dee and Chubby would be proud of that filament wiring Doug! Thanks for another great video, RIP Ollie.
Thanks, Tony. Glad you and the gang liked it :)
Sorry to hear about Ollie, I know the feeling when a formerly feral cat adopts you as their pet. Great idea on filiment wiring, I'll try it on my next build. When I use a 3-way switch for NFB, I use a resistor instead of a jumper to give 3 choices of NFB.
Thanks so much, Richard. The NFB approach you recommend is actually one of the 14 alterations I referred to :)
Casey's a little beaut ! 😊
Thanks, McS. She gets plenty of "beauty sleep" :)
Oh Doug, so sorry to hear about Ollie, a heartfelt tribute. As always thank you so much for your priceless wisdom sir.
Thanks so much, Milo :)
You’re a great teacher sir. Thx for sharing. 👍
Thanks, Claes. Glad you enjoyed it.
Your experimental teaching strategy was a great success for me, all kinds of fog cleared away.
That's great to hear, Brian. Thanks !!!
Rest in peace Ollie. Send our greetings to Rusty.
This video series is great.
Thanks so much, Hal.
Thanks again for your work and sharing your experience and knowledge. Very sad to hear of Ollie passing. You gave Ollie an opportunity to be a part of your, and thus our lives.
You're welcome. Thanks for the nice comments.
Esperamos con ansias la próxima parte de este destacado Amplificador. Saludos cordiales maestro!!.
Thanks, Angel. We appreciate your kind words and interest.
Uncle Doug, I think a video of you discussing amp voltages while running them on the now elevated wall voltages, the effects and what solutions are available would be quite entertaining and valuable.
Thanks for the input, Joe. If the output tubes are properly biased, the higher operating voltage doesn't seem to cause problems, at least in my experience.
always excellent, Uncle Doug!
Thanks, Andy :)
I made this my evenings viewing and really enjoyed it. I've been watching your channel from the start and have to say that me and my wife who always asks after your cats was very sad to hear about the passing of Ollie. May he rest in peace with Rusty.
We're glad you enjoy our videos, Martin, and truly appreciate your very kind words.
You’re awesome man. Thanks for everything. 🤘🏼
You're welcome, Aden :)
RIP Ollie, sorry Uncle.
Thanks, AF.
Wow, what a great series. You have taught me so much over the years and I continue to be amazed by your expertise and craftsmanship. You are an excellent teacher and a true treasure to the tube amp community. Wishing you peace, health, and prosperity, brother man. Keep on rockin UD.
Wow.....Thanks so much, JT. We really appreciate your kind words :)
Thanks for the latest update, great to see how its going
Thanks. I hope you enjoy it.
Aw, Ollie! So sorry to hear that. We’re thinking of you.
Thanks, HE :)
Alright! Was waiting for this!
I hope you enjoy it, BSF.
IT'S ALIVE !!!
Yes, indeed :)
Hello UD ! It’s always so sad when our four legged companions leave … I’m looking forward to watching part 4 😊
Thanks, 74. Part 4 preparation is underway.
Another fine production U D ... Thx
Thanks, Eddy..
I came across your channel to refresh my circuit repairing/diagnostic skills to help a friend's vintage Fender tube twin reverb- it's been decades since I did such things. His amp tech missed a short . Now I am fascinated/ addicted to your channel especially the made from scratch amps.
Thanks so much, Edward. We're glad you found us :)
Amen to the input circuit being deceptively complex. I had to read Rob Robinettes site several times to understand the fender input circuit. It looks so simple, but it ain’t.
Some vulgar knave decided to turn my silverface champ’s input #2 into a “direct out”. In order to return it to stock I had to follow Rob’s site and both inputs had the same volume level. I finally realized that same milksop rabble had bent the grounding leaf away from the other leaf which permanently opened that circuit.
The nerve of some people…
It's a tricky circuit because it's dynamic, Joe......it changes when you plug into it. If you can locate the knave, Jack & I will hold him while you administer a beating.
Pretty impressive I wish I knew how to do that
You've made two big steps in the right direction, SL......you've seen it and you want to do it. Next step is to learn how to do it, i.e.by watching our videos.
Next life. Because when I come back the kids are all wearing helmets now. I hit my head too many times when I was a kid so....
Good stuff !!
Thanks, Mr. CC.
My condolences for Ollie's passing. As a parent to four adopted stray cats and a rez dog, the hardest part of them joining your family is when they say goodbye. They certainly enrich our lives while they're with us.
Thanks for your very kind thoughts and words, NN.
Enjoying the build series Doug, hope you and the cats are doing well.
Glad to hear it, GF :)
Condolences. Always hard to lose a good friend.
Yes, it is. Thanks, SF.
You know UD, something that would be super helpful is going over the ohm's law math to calculate the load resistance in the circuit. If you think so-- 😊
Sadly, OAR, calculating plate load resistance is a very complex process.......way beyond Ohm's Law.
Great treatment of a challenging topic - translating from as-drawn schematic to as-built layout! Drawing out the Fender-style Hi & Lo input circuit was a nice example. Also, it's cool that this time you color-coded the B+ leads from the various nodes of the power supply. Good lesson to second-check before testing and make sure EVERY junction is accounted for.
Thanks, Gary, for your kind words.
Aways Great learning
Glad to hear it, Lane :)
Dear OD, how good to find the next instalment of your current video series, and a pleasure to hear your appreciation for your felines. Very sorry about Ollie's passing, but she certainly had the best possible outcome for her life with you taking her in. And I believe Mitzy 'has it' to step into Ollie's paw prints!
Good decision to emphasize on the 'translation' from schematic into the physical circuit, and this will be very helpful for beginners of electronic builds.
As you speak of the surprise about the sound of this amp at the end of the vid, you might have already done the remedial work on the 6BM8 bias anyway...
Nevertheless, my thoughts on this: Reducing the plate voltage - depending on the supply voltage situation in the preluding circuit, ether a resistor between rectifier tube and the node where supply goes to the output transformer, or after that node in the branch to the OPT, before the reservoir cap.
Also, with the level of voltage on the output tube plate as in the schematic (minus cathode resistor drop) and accordingly lower plate current than in the data sheet, the matching impedance that the OPT needs to provide is significantly higher than that given for 200V/35 mA biasing, so 7 to 8 kOhms would be right. Great choice of yours for the OPT with option of 5 or 8kOhms primary!
I'm not a guitarist, but tremolo and reverb seem good! Looking forward to the final with full demonstration! Greetings!
Without revealing too much about Part 4, your analysis of the situation is almost exactly what I did, short of altering the input impedance to 8K......which is still a consideration. Thanks for your very helpful input.
@@UncleDoug Great pleasure! ...And I realized I used the initial of the German word for 'uncle'! Apologies!
@@regaldf.9493 None needed, Regal. We appreciate multilingual input :)
Mahalo Uncle Doug
Likewise, Victor. Thanks :)
I was lucky when I started building circuits. It never occurred to me that I should make it look like the schematic,lol! I just started connecting this thingamajig to that doohicky and hid behind a chair while using a 2x2 to flip the power switch! Eventually I got fairly good at making quiet twangs be loud twangs. Your videos were extremely valuable,of course!😊 Amp’s looking good as always UD! Can’t wait to hear her. Oh no ,Ollie ! 😿 PS-WHERE BEN FIND PILOT LIGHT WRENCH!!!
Thanks !! That's where the idea of "translation" becomes useful, William. Part 4 is posted for Patreon patrons and will go public soon.
Hi uncle Doug. This is a fantastic series. Im gonna have to rewatch it another day. My ability to concentrate took a crap when you mentioned Ollie. We chatted back an forth before about my feral kitties. We lost our big bobtail cat back on presidents day an my wife, me, an his little running mate are still trying to get over it. For what i could get out of the rest of this amp build an maybe its just me getting older an dumber, ha ha, but for a small amp DAMN that thing is complicated! Thanks again Uncle Doug.
Thanks for joining us in mourning the loss of Ollie, SC. Since each tube is double, it's like wiring a 6-tube amp with reverb and tremolo......i.e. a Fender Princeton Reverb.
Sincere condolences on your loss of Ollie, She could not have found a better caretaker than You. Hopefully an equally talented "Cool Cat" will show up to play!
Thanks, RW. Hopefully, Mitzy will rise to the occasion.
That point to point build approach is very compact and minimizes signal path length and parasitic oscillation risk. No turret board + long wire spaghetti. Very nice. 👍.
I am planning to build an amp which has preamp tubes located very near to front panel pots and switches and jacks, so there is no need to use turret board and that typical long wire spaghetti to turret board which is between tubes and pots + bright switches etc.
That OT low end response which is hopefully perfectly good enough for guitar use but does not go near to trem osc frequencies obviously seemed to filter out that trem osc thumping surprisingly well.
Thanks for your favorable analysis, J, and best of luck with your own project.
That piggy-back switch is exactly what I've been looking for to use as a tone control for my guitar. It can take the tone control out of the circuit completely when not in use for zero ohms to the cap. I didn't know such a thing existed. Thanks for showing it, and where it came from. I learn something valuble in every video.
I'm glad the video was helpful, Qua.
The old schematics can get crazy, I forget what it was, I think a television, but there I am following the diagram all the way over to the next page and a half, but in circuit it's less than an inch away, there is a radio that went into production, the dac90a, and because the schematic shows an indirect ground, a well known issue is a slight hum, which can be solved by moving a single resistor 1.5cm away to a direct ground, so it isn't only people today who might get mixed up, these things went into production and were all like that😅
In a sense, you're lucky, because I've yet to see an amplifier that contains a component that has no modern equivalent and simply isn't made any more 😂
Sorry to hear about your cat, you gave her a better life than she could ever have had otherwise🍁
Indeed, P. I still occasionally encounter schematics that do not comply with the visual style that I am familiar with.......and have a heck of a time interpreting them. It's sometimes advantageous to redraw them to a more familiar style. In so doing, you can detect mistakes and become much more familiar with the circuit.
@@UncleDoug exactly! I'm trying to think if there is anything else you can do that with, but I have looked at sheet music before and either there are glaring errors or it just cannot be translated 😂 an electrical schematic must be unique in it's ability to be reread and rewritten
@@phonotical We trust them to be accurate, P, but errors and omissions do occur. I still wonder why they can't be more consistent in their style of drawing the schematic.
Good Lord. These point to point builds are insane. I remember years ago I had an amp building acquaintance who had a Silvertone 1484 that had been recapped and was an absolute nightmare. He had spent about 6 months converting schematics to layouts and still had severe hum problems and some other problems that he hadn't been able to completely solve.
I have had few problems converting schematics to layouts on amps with fiberboard or garolite custom boards but keeping everything straight on the point to point designs requires a lot more discipline.
Doug - Do you have any RUclipss that assist with diagnosing and troubleshooting parasitic coupling in 60's tube amps?
Thank you so much for your videos. I have built about 20 tube amps, some from scratch, some from upgraded kits and have really enjoyed the experience. I have also brought one completely unique Canadian lap steel amp back to life that I am sure was built by a hobbyist during the 50's or very late 40's. Your videos have helped me refresh my skills on replacing tubes and biasing the power amps stages mostly on 6V6 and 6L6 power amp designs from the 50's and 60's.
Love your channel, thanks.
Thanks for your very nice comments, RM. I have not produced any videos regarding parasitic coupling, and to be honest, don't recall ever encountering the issue. I would assume that grid blocker resistors would be a good solution.
Sorry to hear about Ollie. My condolences.
Thanks, Nevin.
Thanks, Nevin.
Was the great Leo Fender the first person/company to replace terminal strip hand-wiring in amps to hand-wired circuit boards that didn't look like a rat's nest. The good news, both were fairly easy to service compared to modern amps. :)
He was definitely among the first to adopt pre-built eyelet boards allowing rapid finish wiring (by skilled ladies) to facilitate mass production, Tony.
So sad to hear about Ollie . . . I have three feral cats here and they are enjoying " home living " . . . like little kids 🐱🐱🐱
Thanks, Tom. Regards to your furry pals :)
Sorry you lost Ollie. Looking forward to part 4, paint speckles and how to tape a speaker cone. :))
Thanks, Andrew. Part 4 is under way :)
Here's another good choice for the input tube: the 6KT8 whose triode section has a mu of 100.
Thanks for the info, D. I am not at all familiar with that tube, but will look it up.
the Warehouse G12Q speaker would be a nice fit for that build, being a twelve inch and all.
You're close, Daryl. I ended up using a vintage 1960's Jensen C12Q
That will be a great combo, Can't wait!
@@darylstillman1 Thanks, Daryl. I hope you're right :)
Aww Ollie
Thanks, Billy.
Very sad to hear of Ollie's passing. All my condolences Uncle Doug. I'm sure she'd want you to keep doing what you're doing! How's Jacky? Give him an extra scratch on the top of his head & under his chin for me!
Amps looking great mate! Good to hear (not hear) the hum went away when you plugged the tank in! With all the shielded cabling & careful star-earthing you've used, this girl should be as quiet as a mouse!
It seems you think well of the 'orange drop' caps which is good, cos I've chosen them too for repairs & builds. I noticed you've used a couple of those yellow cylindrical caps as well.
Hey, are there any current cap types or brands which should be avoided then? - Or are they all mostly pretty good? Just wonderin.
Good onya for explaining the process of implementing a circuit diagram into an actual physical circuit! Very thoughtful of you! I did 5 years at tech. college learning this stuff, so for people who are just learning this as a hobby, it must be difficult. I'm sure you helped a lot of people with your explanation using a 'layout' diagram. I noticed the input jacks aren't drawn very well on your circuit. pin 2 isn't even drawn!
Anyway, great video & hangin' for the next one! 14 Mods? To make it sound even better? We might need 2 more videos to see all that! Aw no dangblastit! Gotta watch TWO more Uncle Doug video's now! Only kidding Uncle! It's gunna be cool!
Thanks for all your interesting comments and observations, Neville. So far, I have not had any issues with any of the capacitors offered by Antique Electronic Supply.
Great presentation and understanding. I always find it interesting would like to learn why that before the 12AX7/12AT7 type tubes that are now ubiquitous, why were they initially not being used.
They were in general use quite early in guitar amp evolution, Tony, and are superior in many ways to the octals and pentodes they replaced. Watch Part 4 to see what I mean.
Thanks for the great video, Uncle Doug. Very cool that you found an actual example of a GA-1RVT. Judging from the cosmetics (the brown bark covering and the red arrow knobs), this is one of the 321 units made in 1963. Interestingly, I purchased a TWEED version last week that has an early-mid 1962 power transformer date code and the earlier brown chicken head knobs. Is it the only tweed model shipped in 62? Maybe so. Also, the cabinet is identical to the RT model. The reverb tank is the smaller 9 inch long unit, rather than the typical unit used in the RT, and there are no extra screw holes to indicate it is not original.
Greetings, SG. Are you certain you bought an RVT, not an RT? If so, please post photos on my FB page: Uncle Doug's Vintage Amps. I'm not sure about the '62 version being tweed. To be honest, I'm not really sure about anything related to this amplifier.
@@UncleDoug yes sir. I own three other GA-1RT models. This is an RVT. At first I thought it was a modded RT. But the control panel has the factory reverb control between the two other controls, as well as the RVT model name. I was frankly shocked to see it.
I also own a couple of the GA-2RT models, one from 1961 and one from 1962, as well as several other vintage Gibson amps.
@@sologuitarssc6037 Thanks for the info, SG. Please post some photos if you get a chance.
@@UncleDoug Will do. The biggest surprise? There is an extra preamp tube, a fully original 6EU7 that was common for Gibson at the time. If you look at the pic of the gray covered one at the beginning of this video, you can also make out a third tube in the preamp area on the left side. I wonder if all of them were like this, or if some were like the actual schematic. It's Gibson. Are we really surprised?
@@sologuitarssc6037 Is not it normal for there to be 3 amplification tubes?
@21:47 do I spot a vintage Stackpole pot used just to the right of the tremolo control 😳 34th week of 1964?? Thats some pricey spare Uncle Doug🤣
Thanks for the informative input, HH :)
Here for the party 🎉
You came to the right place, WFB :)
BTW Uncle Doug, many Gibson amps were also Epiphone but with a different model name. For example, my Epiphone Pacemaker EA50T is the same as a Gibson GA5T.
Thanks for the input, RC :)
Even then, one wants to ask, which version of the GA5T is your er Epiphone similar to? There were several versions of the GA5T....