CORRECTIONS: 1.) I misspoke regarding the insertion point of the "wet" reverb signal. It is fed into the grid of the upper 6EU7 triode along with the dry signal from the 6AN8 triode.
I understand that you are trying to clone the Gibson circuit exactly; but you, or anyone who follows in your footsteps in trying to build one of these, could save the cost of the reverb-drive transformer (and some space on the chassis) by using a capacitor-coupled reverb circuit and a tank of the correct impedance for that type of drive. After all, capacitor-drive reverb was good enough for the famous Ampeg Reverborocket and for vintage Magnatone amplifiers! The only minor disadvantage is that a Fender style reverb tank wouldn't work.
Uncle Doug I have a question. I have an old western auto Riviera AM fm high Fidelity stereo receiver with a turntable. It belong to my parents and I would like to restore it. There is no information on the model number or serial number. Is there anyway to find the schematic for this item? Thank you.
Yes he is. And his dry sense of humor is awesome. The neighbors need to understand that they are host to a national treasure. One that raises their property values.
Someone asked on Peavey Forum about good books to explain how tube amps work. I told him that Uncle Doug's videos are far and away the best explanations I've ever found.
Dang if it weren't just last night I found myself thinkin about my dear ole Uncle Doug,,,wish you lived closer,you could have free reign in my fab shop
@@UncleDoug Yeah, but you could *really* use a nice big set of Greenlee chassis punches! If I find myself with $1K of spare cash I'll send you a set. It's just kinda painful seeing you have to do all that deburring and chamfering when there's an easier way... 😉
@@UncleDoug I suppose that depends on the specific punches. I know that at least some Greenlees will punch 30mm holes in 12ga panels for mounting switches without damage or complaint.
Love these videos. It's like I'm "going to school". Thank you Uncle Doug! You're the teacher I've always wanted to find. Sorta like finding the wise man on top of the mountain. Your content and lessons are very appreciated.
Yay!!! Just got out of the shower, ate food and played with my cats, and there's a new Uncle Doug video one hour ago!!! Maybe I should buy a lotto ticket
I was very happy with my mojotone cabinet. A GA-5 8 inch combo cabinet with white tolex and ox blood grill cloth. Wood and metal working are the big obstacles to my enjoyment of this hobby. Now I buy broken amps on reverb, gut them and use the cabinets, chassis and transformers if they work. Very excited for the rest of the project. Thanks for the video.
During the pandemic I came across this awesome channel. How transformers works.. vacuum tubes.. etc The way I was able to understand it was unreal. You are so good at teaching that made me fall in love with this world. I’m starting an electrical engineering degree at 28 😂 😂 Better late than never!! Thanks for your work and effort. It really inspires other people. Greetings from Andalucia!!
Your videos are my therapy!! Thanks for all you’ve taught to this community. I’m an Electrical Engineering professor and use your analogies in my class to explain how devices amplify. Thank you 🙏
Awhile back I built an amp and cabinet per your videos. Lots of fun. A tip for those of us who don’t weld: the chassis ends can be filled with 1/4” to 1/2” hardwood blocks epoxied in. Works fine.
Find a small local fab shop or laser cutting place with a TIG welder, us welders are very food motivated, like labradors. Take some chocolates in and those corners will be welded up in 5 minutes.
Gerald Weber was an author of several books about tube guitar amps and circuits, published through Kendrick Books. As well as a top technician, designer and manufacturer of tube guitar amps: Kendrick Amps. Not to be confused with Ted A. Weber, founder and designer of Weber Speakers, who is also departed to my understanding.
Let's hope the journey ends well, Brad :) I cannot find any reference to this particular amp or RVT circuit on Reverb, the VG Price Guide, or other sites. I wonder if it ever really existed ??
Wow! , I've been looking for a single ended tremelo/ reverb schematic . I'm glad you showed this, this looks like a really cool project, can't wait to see it finished.
Hey Uncle Doug! Thanks for all the amp wisdom and humor and cars! Tung Sol has started to make 6EU7s again. So anyone building your version will not have a problem sourcing them.
I just love this stuff! I too had the let’s build an amp from “scratch”bug many years ago. What a challenge, no internet. Fortunately there were Uncle Doug’s clones everywhere. Still have it and with your videos It keeps pumping out great tones. FYI I had a guitar playing friend bring me his Fender amp to see if I could figure out why the amp had a low but annoying buzz. Couldn’t find anything obvious until I realized the jewel light was way too bright, so I took it out and realized it was LED. Replaced it with the standard bulb and the low buzz went away??? Looking forward to next part.
Amazing as usual Doug . I'd love to make this amp just can't afford it right now , but one day soon it's going to happen. Thankyou so much for the inspiration Mark
Incredible project - looking forward to the next video. Great job on the chassis design and build! I've often found myself fantasizing that the engineers that design transformers would simply include a piece of paper that's a template for cutting the opening they should fit into. But then I realize that if they did that, I'd never have the chance to exercise my collection of cuss words and I'd never have the chance to ask my wife, "Honey, where's that new box of bandaids we bought last year?"
Man I wish we lived closer to one another. I have my great grandpas old Gibson amp (all I can read is GA then it dives under the body of the cabinet). It isn't this circuit (based on the tubes), but I'd love for you to look under the hood. It works fine, but of there's anyone I'd trust to look it over, it'd be you. Thanks for the great content! By the way, your videos and advice helped me bring my grandpas old Silvertone back to life from being utterly broken to fully functional. Thanks for that too!!!
Hiya Uncle Doug!!😃 Y'know, when you think about it there are very few guys who are proficient in building a circuit like this as well as the metal fabrication, PLUS the woodworking skills to build the cabinet. Not to mention the tweed covering. Well done indeed. Thanks for sharing it.
Doug. That's a great great idea! Potential to go very viral not that you probably care. Awesome idea, reverb, trem, crunch at low volumes. Perfect I will be building along in some form.
Nice to see you give old Gibson amps some love. Folks might be surprised to know which of their favorite albums this amp was used on. I heard Jack saying the same thing in the start of the video ;-)
Well heck I wasn’t planning on building anything until July or August but since you went through the trouble of making a very thoughtful parts list, I’m tempted to solder one of these together!
Take the parts list with a grain of salt, William. I was a little imprecise with the smaller components and I encourage personalization by the builder. Good luck :)
Another wonderful project Uncle Doug. Your videos continue inspire, both as templates for creating fun and useful amplifiers, and also as templates for how to share knowledge with the less well informed. And, I like the fact that you're using an unusual design with tubes that aren't often used. This series is truly creative in every sense. I confess I still reminisce about the Supro S6422RT outtakes, but understand not everyone enjoys horror movies. The hot roll you're using is covered in mill scale that forms when the steel comes out of the rolling mill and is cooled and coiled. The oxidization forms a coating that is later removed in an acid bath (the "pickling" process) before going through a gauge reduction mill, annealing and final tempering. Cold rolled steel is typically harder and stronger than standard hot rolled steel, so the cursing and bruising indexes are higher by a significant factor. Good choice.
Great to see you again, Uncle Doug! I've been wondering if such an animal existed, and if not why not, and out of the blue you show up with a build video for one. I'm excited to see and hear the final result. Hope all is well.
That is awesome that you built your own break to make your own chassis. Your work is inspiring. Great job! I am really looking forward to the series to see how this amp works out.
It's good to see you, Doug! Your channel hasn't popped up on my TV in a while, and it's nice to hear your voice again. I hope you've been well. That's quite a clever circuit you've got there. Looking forward to hearing it.
Your chassis hand tooling is exemplary and impressive ,😇👍 looking forward patiently to the next exciting instalments ... thanks so much uncle doug, creating an oasis of sanity in this batshit crazy world😎😊
Those mojotone cabs are amazing quality. Especially the lacquered tweed. I believe mojotone has the contract to build cabs for some major amp builders.
Hello Uncle Doug. Thank you so much for this new series on a fascinating circuit. I pray you, the wife, an the kittys are all very well. There is not, or will there ever be a channel that comes close to what you put out for us.
Ya I sidestepped the 6C10 compactron at 100 bones and up! with a couple more readily available tubes 12ax7, 12au7, 12at7's also gives you opportunity to roll tubes for optimum tone works in Super Twin Reverb, six reverb, Champ, Ampeg Jet. I tune in for the chalk talk and the rods appreciate ya always a stellar production. Always "Diggin Doug".
Hello Doug, I enjoy all your videos but the ones where you build something from scratch are the best, particularly when the project is one of the more unusual amplifiers. We all love a 5E3 but those Nationals from the 40s/50s and the early Gibsons you repaired have a special tone. Looking forward to seeing and hearing the result of your latest labours. Your metal work skill is to the fore again. With a plate dissipation of 2.8W for its triode I think the 6AN8 will drive the reverb well. Stay healthy. Regards, Jeff.
Wow this is going to be good! I have a Gibson Kalamazoo Reverb 12. It's circuit is very similar except it's double ended and uses 12ax7s and 6BQ5s, Terrible hum! Good Luck!
My first amp was a 1947 Gibson BR-1 that my dad had for his steel guitar (he had the guitar too!) this was late 60’s when he got it repaired for me! It was great for a beginner because it had mic inputs too!! Powered our whole little band! Then I bought a 68 Bandmaster (tall speaker cab) later a Dual Showman! Several Twin Reverbs…. Now I bought an Epiphone Blues Classic 30w… has incredible clean tone! Weighs a ton however!
Wow! What a great looking project! You have amazing talent. I love buying from Antique Electronic Supply. I've bought from them for 30+ years without any issues and they are about the cheapest around, especially for the price. Those tapered drill bits are a MUST for thin metal! (unless you LIKE stitches). I'm looking forward to hearing it play. Take care.
Thanks so much for the new video. Your teaching style dovetails nicely with my learning style. I know basic electronics and you make it easy to understand these amplifiers. I have learned a tremendous amount watching you and thank you for including a parts list on this one and plans in the future.
Hello Uncle Doug. I was wondering when you'd release your next video -- and to my delight, it's the first of a 3-part series of another scratch build! Can't wait for the next part.
Another great video series from our beloved Uncle Doug like the robot amp built - so gorgeous and I can't wait for part two and three. Many greetings from Germany Chris
Always great to see another build! You are an inspiration to many! I am very surprised to see that you're building the same circuit as me! I may focus on a different circuit and let you work out some kinks. I'm planning on using a 6U8A and 12AX7. I am relieved to find that you came to the same conclusion with the reverb transformer and tank. I can't wait for the next two videos!
@@UncleDoug I'm sure you'll right any wrongs! I'm curious if you find the trem on the output tube "flappy". I read discussions of unwanted pulsing. Will you insert the trem on the 6EU7? Will it sound great without challenges? I'm riveted and awaiting the next two episodes!
@@gavinclarke76 I'm prepared to attach it to the 6EU7 cathode if the grid insertion makes unwanted noise. Meanwhile, I'm wondering about the value of the resistor that connects to the Trem Speed wiper ;)
@@UncleDoug I'd be happy to send you a schematic that a guy on TDPRI used. They made some choices I wouldn't, but they used a 100K on the wiper and added a 1M for intensity control, which seems reasonable.
The top control opening in that cabinet is 2-1/8" X 12-3/8", and the corners are significantly rounded (so stay clear of the corners). I just measured it on mine.
6EA8 and 6GH8 are the other tubes that are similar to a 6U8 and conceptually similar to the 7199. There is also a 6AN8 but like the 7199 those are pretty uncommon nowadays. I have to wonder if owners of vintage Dynaco hi fi amplifiers snagged up all the 7199 and 6AN8 tubes.
I love a scratch build series and that's a cool circuit design. I'm a hop, skip and a jump from where the Gibson factory was in Kalamazoo but I've never owned anything Gibson. I don't know if you've pre-shot this series and it's all done but using heat to "blue" that steel to a straw color and clear coat it would be pretty unique. I built the mojotone champ kit several years ago and the cabinet was very nice. I had an issue with the speaker it included and customer service was excellent.
I thought about clear-coating the blued steel, JV, but on this build will probably go with a colored lacquer finish. The Mojotone cabinet arrived today and is spectacularly nice. I am quite pleased.
Oops, I'm a bit behind, but great to find a new video of yours, and even the first of a mini series! Although, I'm very surprised about that concept - both reverb and tremolo, but with that SE 6BM8 it's only to give about 3.5 watt! Here in Britain they call this 'fur coat but no knickers'! So, I'm curious as to the sound verdict. Looking forward to the next instalment!
Greetings, Reg. Recall that the first Fender Champ amplifiers had only 3.5 watts and nobody seems to complain about their tone and power :) Hopefully the mighty Gibson will sound as good.
Antique Electronics suggests a 6U8A as a replacement for the 7199. They provide instructions for moving 3 wires on the socket. I did the 6U8A/7199 swap in a mid 60's Ampeg Gemini 1, which uses it for the phase inverter. Works great!
I finally got a break from honey-do's and was able to watch this. Fantastic content as always. Your attention to detail is a mark of a true artisan and an inspiration to us in the next generation.. My only concern was with the multi-colored LED. Some of these devices operate off a PWM, which uses an oscillator and a counter to regulate how much red, green, and blue LED is used for each color. Depending on the oscillator's frequency and the refresh period, it could be a noise source for the audio signal. I thought a flicker bulb would be a cool pilot light for a build a couple years ago, but it inserted too much digital noise into the circuit. Of course anything can be filtered or shielded if one is determined enough.
Doug! I have built from scratch/scrap numerous amp cabinets complete with tolex/tweed covering. Like you I would not do it for someone else for any amount of money. Buy the mojo!
Are you SURE that you have a GA-1RVT......and not a GA-1RT? I have never seen or heard of an RVT actually existing, but the RT model is relatively common.
I followed your directions for scratch building a cabinet once and that was the last time I will ever do that. Just take the glue, after about 5 minutes slathering all over the cabinet and tolex I was hallucinating and drooling and my long dead grandfather came pedaling in on a unicycle wearing a tutu and singing Deutschland Uber Alles. No thanks, nobody needs that, I'm with you, shell out the $350 for a pre built one.
6GH8 is a good sub for 7199, AND there's a plug in adapter for the conversion if you've got an old Ampeg or Seeburg that needed 7199. I have a pair of 6GH8 in my Seeburg and it works well.
I used some colour change LEDs in a fuzz box once, looked cool but they were noisy - there seems to be a tiny chip in the LED which ramps the individual red, green and blue LED sections up and down in brightness and - no doubt due to the high gain of the fuzz - was audible on the signal. I managed to reduce it by adding significant decoupling caps on the LED power but it was less than ideal. Of course, a vintage amp is very different to a fuzz box so chances are you will be fine with those LED indicators but thought it was worth sharing my experiences.
Those are some tricky tubes to find...I used to have two different amps one took a 7199 one took a 6EU7. Both were hard to find I think the 6EU7s were always microphonic
@@UncleDoug I havent watched the whole vid so I'm guessing it cant be a direct swap but a rewiring job - which is why Im here - trying to learn more about building tube amps...I had an old Sunn amp that ran 6550s and a 7199 and I ended up selling the head without the 7199 - I couldnt find one at any price at the time - apx 2010s maybe they are easier to find now...I'll watch the whole thing and report back if necessary
@@leveractiongypsy1848 Yes, the tube socket must be wired differently, but that's simply a matter of numbering the socket connections properly in the schematic for the tube actually being used.
CORRECTIONS:
1.) I misspoke regarding the insertion point of the "wet" reverb signal. It is fed into the grid of the upper 6EU7 triode along with the dry signal from the 6AN8 triode.
I understand that you are trying to clone the Gibson circuit exactly; but you, or anyone who follows in your footsteps in trying to build one of these, could save the cost of the reverb-drive transformer (and some space on the chassis) by using a capacitor-coupled reverb circuit and a tank of the correct impedance for that type of drive. After all, capacitor-drive reverb was good enough for the famous Ampeg Reverborocket and for vintage Magnatone amplifiers! The only minor disadvantage is that a Fender style reverb tank wouldn't work.
@@goodun2974 Thanks for your helpful input, GU, but the $11 cost of the reverb driver was not exactly a financial burden.
@@UncleDoug I was thinking more in terms of saving some real estate space on the chassis...
@@goodun2974 It's a very compact transformer, GU.
Uncle Doug I have a question. I have an old western auto Riviera AM fm high Fidelity stereo receiver with a turntable. It belong to my parents and I would like to restore it. There is no information on the model number or serial number. Is there anyway to find the schematic for this item? Thank you.
Uncle Doug is a National Treasure.
You are too kind, BH. Thanks :)
Yes he is. And his dry sense of humor is awesome. The neighbors need to understand that they are host to a national treasure. One that raises their property values.
@@peteleoni9665 Thanks, Pete, but higher property values mean higher property taxes ;)
@UncleDoug
As a guy that refuses to leave his swamp house for life you'd think I would understand. Yep you are right.
Someone asked on Peavey Forum about good books to explain how tube amps work. I told him that Uncle Doug's videos are far and away the best explanations I've ever found.
All is right with the world...an new video from "Uncle Doug"!
Thanks so much, ID :)
Uncle Doug, you're just what my inner peace needed this afternoon.
That's great to hear, Dr. D :)
......and a 3 part series.😎
@@PetraKann To be honest, it may even go 4 episodes, depending on the fine tuning required.
@@UncleDoug No complaints here champ
Cheers
Dang if it weren't just last night I found myself thinkin about my dear ole Uncle Doug,,,wish you lived closer,you could have free reign in my fab shop
I would enjoy the "free reign" a great deal......but at least I'm no longer using a sledge hammer to form chasses ;)
@@UncleDoug Yeah, but you could *really* use a nice big set of Greenlee chassis punches! If I find myself with $1K of spare cash I'll send you a set. It's just kinda painful seeing you have to do all that deburring and chamfering when there's an easier way... 😉
@@sootikins Thanks, Sooti, but I have a set. I didn't think they were useable with 16 gauge hot rolled steel.
@@UncleDoug I suppose that depends on the specific punches. I know that at least some Greenlees will punch 30mm holes in 12ga panels for mounting switches without damage or complaint.
@@sootikins I'll bet a challenge like that would require a hydraulic ram rather than the manual wrench and bolt.
Love these videos. It's like I'm "going to school". Thank you Uncle Doug! You're the teacher I've always wanted to find. Sorta like finding the wise man on top of the mountain. Your content and lessons are very appreciated.
That's great to hear, Chad. We're glad the videos are helpful and appreciated.
Glad to hear it, Chad. Thanks !!
Happy days are here again! A new Uncle Doug video! 👍
Posted just for you, AA :)
Yay!!! Just got out of the shower, ate food and played with my cats, and there's a new Uncle Doug video one hour ago!!! Maybe I should buy a lotto ticket
It's YOUR day, Nick :)
I was very happy with my mojotone cabinet. A GA-5 8 inch combo cabinet with white tolex and ox blood grill cloth.
Wood and metal working are the big obstacles to my enjoyment of this hobby. Now I buy broken amps on reverb, gut them and use the cabinets, chassis and transformers if they work.
Very excited for the rest of the project. Thanks for the video.
You're welcome, FJ. I hope you enjoy it.
During the pandemic I came across this awesome channel. How transformers works.. vacuum tubes.. etc
The way I was able to understand it was unreal. You are so good at teaching that made me fall in love with this world. I’m starting an electrical engineering degree at 28 😂 😂 Better late than never!!
Thanks for your work and effort. It really inspires other people.
Greetings from Andalucia!!
Wow!! That's great news, Alva. Thanks so much.....and best wishes for success with your continuing education.
Uncle Doug for President!!! You sir are a GEM!
Thanks so much, Lynn :)
Uncle Doug is lucid and sane, and he has actual skills. He is therefore overqualified for that position.
Your videos are my therapy!! Thanks for all you’ve taught to this community. I’m an Electrical Engineering professor and use your analogies in my class to explain how devices amplify. Thank you 🙏
I am quite flattered to hear that, Jorge. Thanks so much for your kind words :)
It's going to be an epic low-watt amp! Thanks, Uncle Doug!
I sure hope so, Ken. It's getting to be a fairly expensive, time-consuming build....but I'm quite optimistic :)
This circuit looks really fascinating. I want to hear how this sounds before picking my next build now… can’t wait to hear the finished product!
I too am curious about the outcome, VS. Will the output power, tremolo, and reverb all be worth the time, trouble, and expense? We'll see.
@@UncleDoug😮😮
Neither can I, VS. Thanks !!
Awhile back I built an amp and cabinet per your videos. Lots of fun. A tip for those of us who don’t weld: the chassis ends can be filled with 1/4” to 1/2” hardwood blocks epoxied in. Works fine.
Find a small local fab shop or laser cutting place with a TIG welder, us welders are very food motivated, like labradors. Take some chocolates in and those corners will be welded up in 5 minutes.
That's a trick that Valco used a lot, Sax, but they used screws instead of epoxy.
@@Jonathan_Doe_ Chocolate......or 44 oz. Polar Pops work for me :)
19:45 RIP Gerald Weber , who recently passed! Great project Doug!
Fortunately, I believe his business lives on.....
Gerald Weber was an author of several books about tube guitar amps and circuits, published through Kendrick Books. As well as a top technician, designer and manufacturer of tube guitar amps: Kendrick Amps. Not to be confused with Ted A. Weber, founder and designer of Weber Speakers, who is also departed to my understanding.
Good to see this project underway, Doug.
Let's hope the journey ends well, Brad :) I cannot find any reference to this particular amp or RVT circuit on Reverb, the VG Price Guide, or other sites. I wonder if it ever really existed ??
Finally I've arrived at more recent episodes... Uncle Doug is the man!
We're glad you're enjoying our videos, Capt.
Filled my mouth with cheese and waited with baited breath for another spectacular video! Thank you, Uncle Doug. Can’t wait for parts two and three!
Thanks, A. I was wondering where all my cheese went ;)
Wow! , I've been looking for a single ended tremelo/ reverb schematic . I'm glad you showed this, this looks like a really cool project, can't wait to see it finished.
Nor can I, Daryl. The wiring is proving to be quite a challenge within the rather claustrophobic chassis. Thanks !!
I heard it helps youtube channels if we comment so, great job and thanks for all the years of teaching and sharing!
It helps me when I hear from viewers, Steve. Thanks to you too.
Hey Uncle Doug! Thanks for all the amp wisdom and humor and cars! Tung Sol has started to make 6EU7s again. So anyone building your version will not have a problem sourcing them.
Greetings, Rob. Thanks for the helpful info :)
Nothing better than a UD scratch build series.
I hope it lives up to your expectations, Tommy :)
New "Let's make..." video - new tips and secrets from our dear Uncle Doug. What a nice day!
I hope you enjoy it. Thanks !!
I just love this stuff! I too had the let’s build an amp from “scratch”bug many years ago. What a challenge, no internet. Fortunately there were Uncle Doug’s clones everywhere. Still have it and with your videos It keeps pumping out great tones. FYI I had a guitar playing friend bring me his Fender amp to see if I could figure out why the amp had a low but annoying buzz. Couldn’t find anything obvious until I realized the jewel light was way too bright, so I took it out and realized it was LED. Replaced it with the standard bulb and the low buzz went away??? Looking forward to next part.
We're glad the videos have been helpful, BK :)
Amazing as usual Doug . I'd love to make this amp just can't afford it right now , but one day soon it's going to happen. Thankyou so much for the inspiration Mark
Thanks, Mark :)
Incredible project - looking forward to the next video. Great job on the chassis design and build! I've often found myself fantasizing that the engineers that design transformers would simply include a piece of paper that's a template for cutting the opening they should fit into. But then I realize that if they did that, I'd never have the chance to exercise my collection of cuss words and I'd never have the chance to ask my wife, "Honey, where's that new box of bandaids we bought last year?"
Thanks, OLW. So true. Even sinks come with cut-out templates :) Also, no matter how careful I am, the holes (all five) have to altered somewhat.
@@UncleDoug Same here - every damn time.
Man I wish we lived closer to one another. I have my great grandpas old Gibson amp (all I can read is GA then it dives under the body of the cabinet). It isn't this circuit (based on the tubes), but I'd love for you to look under the hood. It works fine, but of there's anyone I'd trust to look it over, it'd be you. Thanks for the great content!
By the way, your videos and advice helped me bring my grandpas old Silvertone back to life from being utterly broken to fully functional. Thanks for that too!!!
You can send some photos of the Gibson "mystery amp" to my FB page Uncle Doug's Vintage Amps. I'm glad the videos have been helpful :)
Thank you for doing this, this might be even more enjoyable than your repair videos.
You're welcome, BMD. I'm glad you enjoyed it.
I can hear someone in the future calling that chassis a gem !
Great work UD
Stewart 👍🏴
I sure hope so, Stewart. Thanks !!
YAY! Another Uncle Doug video! Thank you sir!
Our pleasure, MJ :)
Thanks UD! My fave TH-camr! Great to see you, or rather, hear you. Hope you are well. 👍🏻
Never better, PS. I hope you enjoy it :)
Hiya Uncle Doug!!😃 Y'know, when you think about it there are very few guys who are proficient in building a circuit like this as well as the metal fabrication, PLUS the woodworking skills to build the cabinet. Not to mention the tweed covering. Well done indeed. Thanks for sharing it.
You're welcome, Dale. I hope you enjoy it :)
Doug. That's a great great idea! Potential to go very viral not that you probably care. Awesome idea, reverb, trem, crunch at low volumes. Perfect I will be building along in some form.
Thanks !! The circuit will be improved as it takes shape, Pete, so be patient.....or creative :)
Nice to see you give old Gibson amps some love. Folks might be surprised to know which of their favorite albums this amp was used on. I heard Jack saying the same thing in the start of the video ;-)
We hope you enjoy the series, Charlie :)
Well heck I wasn’t planning on building anything until July or August but since you went through the trouble of making a very thoughtful parts list, I’m tempted to solder one of these together!
Take the parts list with a grain of salt, William. I was a little imprecise with the smaller components and I encourage personalization by the builder. Good luck :)
Let us know ho it turns out, William :)
The tube never tells me about your videos anymore? I guess they wanna decide what we watch. Glad I check on my own!!!
It's a conspiracy, Ben ;) Possibly because we don't monetize our videos.
Another wonderful project Uncle Doug. Your videos continue inspire, both as templates for creating fun and useful amplifiers, and also as templates for how to share knowledge with the less well informed. And, I like the fact that you're using an unusual design with tubes that aren't often used. This series is truly creative in every sense. I confess I still reminisce about the Supro S6422RT outtakes, but understand not everyone enjoys horror movies. The hot roll you're using is covered in mill scale that forms when the steel comes out of the rolling mill and is cooled and coiled. The oxidization forms a coating that is later removed in an acid bath (the "pickling" process) before going through a gauge reduction mill, annealing and final tempering. Cold rolled steel is typically harder and stronger than standard hot rolled steel, so the cursing and bruising indexes are higher by a significant factor. Good choice.
Thanks for the informative input, GF. Between the grooving and the metal brake, I thought the bends came out quite well.
Great to see you again, Uncle Doug! I've been wondering if such an animal existed, and if not why not, and out of the blue you show up with a build video for one. I'm excited to see and hear the final result.
Hope all is well.
It's always a pleasure to hear from you, Randy. We're doing quite well indeed. You too, I hope.
This looks really interesting. I was considering a bassman clone but this one is intriguing. I’m on board. Let’s do it!!!
I'm glad you share my interest in this efficient little circuit, David :)
That is awesome that you built your own break to make your own chassis. Your work is inspiring. Great job! I am really looking forward to the series to see how this amp works out.
Thanks, EWR. I too am wondering how it's going to sound. Fingers crossed that it sounds great ;)
It's good to see you, Doug! Your channel hasn't popped up on my TV in a while, and it's nice to hear your voice again. I hope you've been well.
That's quite a clever circuit you've got there. Looking forward to hearing it.
Never better, KW. Thanks so much :)
Your chassis hand tooling is exemplary and impressive ,😇👍
looking forward patiently to the next exciting instalments ...
thanks so much uncle doug, creating an oasis of sanity in this
batshit crazy world😎😊
Thanks so much, MT. It's good therapy for me too.
A great video once again, Uncle Doug! Let's hope your neighbours get well soon!
Thanks, Hal......I'm sure they agree :)
Those mojotone cabs are amazing quality. Especially the lacquered tweed. I believe mojotone has the contract to build cabs for some major amp builders.
It arrived and exceeded all expectations.......beautiful !!
They build some Gibson amps
Admire Uncle Doug’s work and was very excited to find this today
Thanks, AQ. I hope it exceeds your expectations :)
Thanks UD. Looking forward to part 2.
It’s nice seing you again ;)
Part 2 will be posted in early May, Aden. Thanks !!
Hello Uncle Doug. Thank you so much for this new series on a fascinating circuit. I pray you, the wife, an the kittys are all very well. There is not, or will there ever be a channel that comes close to what you put out for us.
Thanks so much for your kind words and wishes, SC. We really appreciate them :)
Best YT channel ever, thanks uncle.
Wow.....Thanks so much, HV :)
Ya I sidestepped the 6C10 compactron at 100 bones and up! with a couple more readily available tubes 12ax7, 12au7, 12at7's also gives you opportunity to roll tubes for optimum tone works in Super Twin Reverb, six reverb, Champ, Ampeg Jet. I tune in for the chalk talk and the rods appreciate ya always a stellar production. Always "Diggin Doug".
Thanks for your nice comments, A. We're glad you enjoy our videos.
Nice work as usual Doug. I see the cuts on your hands are related to the amount of metalwork completed 😂
It's all Hollywood makeup to promote pity contributions :)
@@UncleDoug 😂😂
Still without an equal the coolest dude on TH-cam bar none.
Wow....You are too kind, Tony. Thanks !!
Uncle D - love this type of content! Resurrection of old amps! Hope all's well.
Glad to hear it, TAG :) Never better.
A great little amp this will be. Hello Uncle Doug !
I hope so, Tim. Thanks !!
@@UncleDoug A 12" speaker is a good choice for this one...And having the pre-made cabinet all ready to load is worth it X 2..
Cheers !
@@timbuckxxi9690 I thought so too, Tim. The Mojotone cabinet is magnificent.....at twice the price :)
Hello Doug, I enjoy all your videos but the ones where you build something from scratch are the best, particularly when the project is one of the more unusual amplifiers. We all love a 5E3 but those Nationals from the 40s/50s and the early Gibsons you repaired have a special tone. Looking forward to seeing and hearing the result of your latest labours. Your metal work skill is to the fore again. With a plate dissipation of 2.8W for its triode I think the 6AN8 will drive the reverb well. Stay healthy. Regards, Jeff.
Greetings, Jeff, and thanks for your very nice comments. Likewise on the good wishes :)
Wow this is going to be good! I have a Gibson Kalamazoo Reverb 12. It's circuit is very similar except it's double ended and uses 12ax7s and 6BQ5s, Terrible hum! Good Luck!
Thanks, OMG. I hope you're right :)
What an interesting project. I can't wait to see parts 2 and 3. School is back in session and I couldn't be happier.
That's great to hear, TJ. Thanks !!
My first amp was a 1947 Gibson BR-1 that my dad had for his steel guitar (he had the guitar too!) this was late 60’s when he got it repaired for me! It was great for a beginner because it had mic inputs too!! Powered our whole little band! Then I bought a 68 Bandmaster (tall speaker cab) later a Dual Showman! Several Twin Reverbs…. Now I bought an Epiphone Blues Classic 30w… has incredible clean tone! Weighs a ton however!
You've had some fine equipment, Bob. I hope you enjoy our series :)
Great start to another project Doug. Looking forward to part 2
Thanks, Ex :)
Wow! What a great looking project! You have amazing talent. I love buying from Antique Electronic Supply. I've bought from them for 30+ years without any issues and they are about the cheapest around, especially for the price. Those tapered drill bits are a MUST for thin metal! (unless you LIKE stitches). I'm looking forward to hearing it play. Take care.
Thanks, W1. Let's hope it sounds even better than we expect ;)
Thanks so much for the new video. Your teaching style dovetails nicely with my learning style. I know basic electronics and you make it easy to understand these amplifiers. I have learned a tremendous amount watching you and thank you for including a parts list on this one and plans in the future.
You're very welcome, Michael :)
Hello Uncle Doug. I was wondering when you'd release your next video -- and to my delight, it's the first of a 3-part series of another scratch build! Can't wait for the next part.
I hope you enjoy the series, Reggie :)
Thank you for leading us on another cool new adventure. I learn somuch from following these builds!
You're welcome, Peter. That's great to hear :)
Another great video series from our beloved Uncle Doug like the robot amp built - so gorgeous and I can't wait for part two and three. Many greetings from Germany Chris
Thanks so much, Chris. We hope to live up to your expectations.
glad to see you on air! always informative video!
Thanks, William :)
Always great to see another build! You are an inspiration to many! I am very surprised to see that you're building the same circuit as me! I may focus on a different circuit and let you work out some kinks. I'm planning on using a 6U8A and 12AX7. I am relieved to find that you came to the same conclusion with the reverb transformer and tank. I can't wait for the next two videos!
Thanks, Gavin That is quite a coincidence. Hopefully, if kinks occur, they can be promptly straightened out ;)
@@UncleDoug I'm sure you'll right any wrongs! I'm curious if you find the trem on the output tube "flappy". I read discussions of unwanted pulsing. Will you insert the trem on the 6EU7? Will it sound great without challenges? I'm riveted and awaiting the next two episodes!
@@gavinclarke76 I'm prepared to attach it to the 6EU7 cathode if the grid insertion makes unwanted noise. Meanwhile, I'm wondering about the value of the resistor that connects to the Trem Speed wiper ;)
@@UncleDoug I'd be happy to send you a schematic that a guy on TDPRI used. They made some choices I wouldn't, but they used a 100K on the wiper and added a 1M for intensity control, which seems reasonable.
@@gavinclarke76 Thanks for the input, Gavin. I'll take it into consideration.
Uncle Doug is a true jewel 💎
Thanks, Mr P. You are too kind.
The top control opening in that cabinet is 2-1/8" X 12-3/8", and the corners are significantly rounded (so stay clear of the corners). I just measured it on mine.
Thanks, RB. The cabinet arrived immediately after Part 1 was posted (as predicted) and the chassis has been fitted to it.
Always great to see a new Uncle Doug vid. Thanks for your knowledge and lessons.
Thanks !! It's our pleasure, Rick :)
I've built two mojotone amplifier kits (Tweed Vibrolux, Marshall 18W) and agree with you on their cabinets...worth every penny.
Thanks for the positive input, CHM. It was even better than I hoped.
A "festivus miracle"! 😂 Shipping is chaos these days...thankfully you got the goods
Indeed. I have noticed a huge decline in shipping efficiency lately. I guess the world's madness has rubbed off on the transportation industry.
Powder coat that thing. Very interesting. I look forward to the rest of the build. Thanks.
That requires outside help, Hugh, which I avoid at all costs.......other than the cabinet for this build (and it showed up a week late).
Wow! A new UDoug vid just minutes ago! So happy to see you back on my TH-cam channel
Thanks, Rich. It's good to be back :)
Glad to see you Doug! Thankyou as always for the continued sharing of your immense wisdom :)
It's our pleasure, Milo :)
Great project! I started building one of these a while back using a 6U8a for the input pentode and reverb driver. Can't wait to see how this goes!
6EA8 and 6GH8 are the other tubes that are similar to a 6U8 and conceptually similar to the 7199. There is also a 6AN8 but like the 7199 those are pretty uncommon nowadays. I have to wonder if owners of vintage Dynaco hi fi amplifiers snagged up all the 7199 and 6AN8 tubes.
I considered using a 6U8, Martin, but was able to find a really nice 6AN8 at a reasonable price.
I love a scratch build series and that's a cool circuit design. I'm a hop, skip and a jump from where the Gibson factory was in Kalamazoo but I've never owned anything Gibson. I don't know if you've pre-shot this series and it's all done but using heat to "blue" that steel to a straw color and clear coat it would be pretty unique. I built the mojotone champ kit several years ago and the cabinet was very nice. I had an issue with the speaker it included and customer service was excellent.
I thought about clear-coating the blued steel, JV, but on this build will probably go with a colored lacquer finish. The Mojotone cabinet arrived today and is spectacularly nice. I am quite pleased.
Rummaged thru the crates, I found a whole sleeve of NOS 6GM8s, and that was it dang it! So close, lolol!!
Close.....but no BM. Wow, that doesn't sound good ;)
Can hardly wait for part 2 ... Thx
It's in the works, Eddy.
Great to see another build series coming up!
We hope you enjoy it, Matt.
Great to see another educational and informative video! That metal work appears to very tough on your hands with several wounds appearing.
Thanks, Harvey. The wounds are all fake......to stimulate pity contributions ;)
Can’t wait for parts 2&3 Uncle Doug
Part 2 is almost finished, Blair :)
Oops, I'm a bit behind, but great to find a new video of yours, and even the first of a mini series! Although, I'm very surprised about that concept - both reverb and tremolo, but with that SE 6BM8 it's only to give about 3.5 watt! Here in Britain they call this 'fur coat but no knickers'! So, I'm curious as to the sound verdict. Looking forward to the next instalment!
Greetings, Reg. Recall that the first Fender Champ amplifiers had only 3.5 watts and nobody seems to complain about their tone and power :) Hopefully the mighty Gibson will sound as good.
Uncleeeee.
Another great project as always.
Nice to see you!
Thanks, ITR :)
Wow Doug...Just a fab project..Love it and all the info is incredible to this newbie here..Looking forward to the next videos...Take care..Ed..UK..😄
Thanks, Ed. It's always good to hear from you :)
been watching since i was 14, now im 24. time flies
...particularly as you get older...
.....especially if you're having fun ;)
you're the man, Uncle Doug
Thanks, TM :)
Dug deeper in the crates, found a pair of 6GW8/ECL86 beauties, one's a Mullard! Game on!!
You're well on your way to a successful project, OAR :)
Antique Electronics suggests a 6U8A as a replacement for the 7199. They provide instructions for moving 3 wires on the socket.
I did the 6U8A/7199 swap in a mid 60's Ampeg Gemini 1, which uses it for the phase inverter. Works great!
The 6U8 is indeed another good choice to replace the rare and expensive 7199, Dan.
I finally got a break from honey-do's and was able to watch this. Fantastic content as always. Your attention to detail is a mark of a true artisan and an inspiration to us in the next generation..
My only concern was with the multi-colored LED. Some of these devices operate off a PWM, which uses an oscillator and a counter to regulate how much red, green, and blue LED is used for each color. Depending on the oscillator's frequency and the refresh period, it could be a noise source for the audio signal. I thought a flicker bulb would be a cool pilot light for a build a couple years ago, but it inserted too much digital noise into the circuit. Of course anything can be filtered or shielded if one is determined enough.
I appreciate the helpful input, NN, and will heed your warning. It's such a neat effect I hope it causes no noise. We'll see.
Doug! I have built from scratch/scrap numerous amp cabinets complete with tolex/tweed covering. Like you I would not do it for someone else for any amount of money. Buy the mojo!
Agreed, Rich, especially when Mojo is so reasonable.
Doug; I have one of these amps if you need photos. The tank was dead when I got it so we put in a long tank.
Are you SURE that you have a GA-1RVT......and not a GA-1RT? I have never seen or heard of an RVT actually existing, but the RT model is relatively common.
Great to see a new video!
Glad to hear it, Magnus :)
Thanks Uncle Doug for you are!
You're welcome, Kir.
I followed your directions for scratch building a cabinet once and that was the last time I will ever do that. Just take the glue, after about 5 minutes slathering all over the cabinet and tolex I was hallucinating and drooling and my long dead grandfather came pedaling in on a unicycle wearing a tutu and singing Deutschland Uber Alles. No thanks, nobody needs that, I'm with you, shell out the $350 for a pre built one.
Agreed, M7, especially with the discount......only $315 !! Regards to your grandfather ;)
6GH8 is a good sub for 7199, AND there's a plug in adapter for the conversion if you've got an old Ampeg or Seeburg that needed 7199. I have a pair of 6GH8 in my Seeburg and it works well.
I hope the 6AN8 works out well, DK :)
I used some colour change LEDs in a fuzz box once, looked cool but they were noisy - there seems to be a tiny chip in the LED which ramps the individual red, green and blue LED sections up and down in brightness and - no doubt due to the high gain of the fuzz - was audible on the signal. I managed to reduce it by adding significant decoupling caps on the LED power but it was less than ideal. Of course, a vintage amp is very different to a fuzz box so chances are you will be fine with those LED indicators but thought it was worth sharing my experiences.
Thanks for the input. The fellow I got them from warned about possible noise. We'll see :)
Fun new project, looking forward to more.
Thanks, Andrew :)
Uncle Doug I missed this one❤❤
We're glad you found it, Charles :)
Those are some tricky tubes to find...I used to have two different amps one took a 7199 one took a 6EU7. Both were hard to find I think the 6EU7s were always microphonic
If the 6EU7 acts up, I'll switch to a 12AX7, LAJ :)
@@UncleDoug I havent watched the whole vid so I'm guessing it cant be a direct swap but a rewiring job - which is why Im here - trying to learn more about building tube amps...I had an old Sunn amp that ran 6550s and a 7199 and I ended up selling the head without the 7199 - I couldnt find one at any price at the time - apx 2010s maybe they are easier to find now...I'll watch the whole thing and report back if necessary
@@leveractiongypsy1848 Yes, the tube socket must be wired differently, but that's simply a matter of numbering the socket connections properly in the schematic for the tube actually being used.
Still fun Doug. Thx.
I hope the audio testing is fun also ;)