Let's Build the Gibson GA-1RVT Part 2 (of 4)....Evaluate Cabinet, Finish Chassis, Begin Wiring

In this Part 2 Video (of 4), we will receive and evaluate the Lacquered Tweed Mojotone 5E3 cabinet; complete the chassis painting, machining, and labeling.....and begin wiring the circuit, including transformers, power supply, and tremolo. There is a discussion of the possibility that this amplifier was never actually built or sold by Gibson or Maestro, as well as explanations of a Distributed Star Ground, and Distributed B+ Voltage Scheme.
Here is the link to the Parts List: app.box.com/s/...
If you enjoy advertising-free videos like this one (we do not monetize our videos), then please SUBSCRIBE and consider becoming a Patreon patron at / uncledougsvintageamps or making a PayPal contribution to [e-mail]. Thanks for watching.
NOTE: If you wish to purchase an identical 5E3 cabinet from Mojotone, please use the code: UD5E3 to receive a 10% discount. Here is a source for 2-wire shielded cable: Surplus Sales of Nebraska. www.surplussal...

[@woodhonky3890]

I was one of those poor little orphan children, and I can attest to the fact that after you have touched high voltage a couple of times, you learn not to.

[@UncleDoug]

Those were the good old days, WH......playing with mercury, skating in your underwear, and getting the hell shocked out of you on a daily basis.

[@davidfellows6250]

@@UncleDoug yes but also making love in the grass, getting sent home by a cop that new you really shouldn't be driving, and buying that car for a hundred dollars that you drove for four more years. Cigarettes 19 cents, Gass 22. There was some good stuff.

[@UncleDoug]

@@davidfellows6250 Yes, indeed :)

[@stevenclarke5606]

I’m from the UK and as a child from the 60’s , I remember getting shocked and thrown across the room when I inserted the plug with my fingers touching the pins ! Ouch that hurt, I never made the same mistake again

[@goodun2974]

@@stevenclarke5606 , the UK redesigned all of its' electrical plugs after that incident, all because of your accident! 😉 A smart thing to do considering that your standard wall voltage is 240, twice what we see here in the US. (The latest UK plug design has partially insulated prongs that conduct only at their very tips, and the power is disconnected as soon as you start to pull the plug out of the wall even a little bit).

[@matthewf1979]

Beautiful tribute to ol’ Rusty. The Supreme Doggo, Best of Boys.

[@julesl6910]

Rusty has been immortalized in these videos, which will be the supreme analogue amplification series for learning, for all future generations. He'll be remembered for all time.

[@UncleDoug]

What wonderful, kind thoughts from both of you. Thanks so much. Rusty and I really appreciate it.

[@nicholashumphreys74]

Dear Uncle Doug, You really do feel like my old uncle. Your videos have brought me so much happiness, education, camaraderie and joy. Thank you so much for all the time, labor, experience and effort you put into every single one of your videos. You’re beautifully archiving a skill and knowledge base that will become harder and harder to find as the decades go by. And you do it in such a lovely, friendly and genuine way that is unrivaled in its ability to make me feel good. Thank you for letting me spend so much time with you. I would do anything to have someone like you in my life I could hang out in their garage with as they practice their craft. Thank you so much for all that you’ve done. A massive fan forever, -Nick

[@andrewgillis8572]

ditto! the chassis paint against grommets & red wire - a virtual Rosebud sled.

[@UncleDoug]

I am truly flattered, Nick. Thanks so much for your wonderful comments. Our very best to you and yours :)

[@rafaelallenblock]

@@UncleDoug Hey Uncle Doug: I love your channel. I have a question for you: Do you know of a way to determine a power transformers power rating? it's simple to find the voltages but I was wondering if there is any method to determine from its size or whatever how many mA the secondary can supply? Thanks for all your content.

[@UncleDoug]

@@rafaelallenblock Thanks, Rafael. All you can do is guess, based on mass and wire gauges.

[@rafaelallenblock]

@@UncleDoug Thanks!

[@CraigHollabaugh]

Uncle Doug's "Tube Amp Building" Masterclass continues!

[@UncleDoug]

Thanks, Craig. I hope you enjoy the video :)

[@davidfellows6250]

Im laying here dieing with no plans of building an amp and i wouldn't miss not one of these videos between you and The lobster Leon I can't wait for these to come out.​@UncleDoug

[@UncleDoug]

@@davidfellows6250 Glad to hear it, David.....the part about building an amp, not dying ;). I hope you enjoy the video.

[@TheTrueVoiceOfReason]

"Not On" - So reminds me of the old Petticoat Junction episode when they got walkie-talkies, and Joe would never answer. (I think it was) Steve asked him why he never replied, and Joe showed him the switch on the side that said "NO": "I never mess with anything that says no.", then Steve turned the W-T right side up: "It says ON." Joe: "Oh." Thanks for the trip back in time.

[@GilgaFrank]

This series is proving invaluable to me as I am building a Supa Deluxe from Modulus Amplification right now. Thanks Doug! And thanks to poor old Rusty, sadly missed and never to be forgotten.

[@UncleDoug]

That's great to hear, Frank. Amen, his absence is sorely missed.

[@ET_Don]

"On" "Not On"! 😂 You crack me up Uncle Doug.

[@UncleDoug]

Glad you enjoyed it, Don.

[@scottbc31h22]

A suggestion for the NFB loop. Since you have an ON-OFF-ON switch, use one ON position with the specified feedback resistor, and use a different value resistor on the other ON position. giving you two different levels of NFB.

[@UncleDoug]

Great idea, Scott. I wish I'd thought of it. I may go back and do this.

[@leveractiongypsy1848]

You know I was thinking to myself, building an amp like this why " its kind of like thawing out a little wolly mammoth or something'.....so I was quite shocked to hear you say it in the video! Great minds think alike!

[@UncleDoug]

Indeed they do, LA......and I used to collect Model 94 Winchesters ;)

[@leveractiongypsy1848]

@@UncleDoug Awesome! A vid somewhere on your channel? I do have an old 1952 Remington 760 and a 1949 Remington 141...what I wish I had in my collection is a 1966-1968 Marshall....but my 1983 JCM 800 4010 will have to suffice haha - next comment I will leave from my 'musician' channel :)

[@UncleDoug]

@@leveractiongypsy1848 Thanks for your input, LAG. You're always welcome :)

[@ImTheReal]

Yeaaaaaaah. You're Great Uncle 😃 Thank you for being with us and sharing a piece of yours.

[@UncleDoug]

You're welcome, ITR. The pleasure is all mine.

[@abelincoln95]

Rusty is chasing the hell out of a ball somewhere!!!! Love you, Unc.....

[@UncleDoug]

I sure hope so, Abel. Thanks :)

[@captainfineweather5610]

Hey ya, I thought I'd just drop by and say cheerie-bye, so - Cheerie-Bye!

[@kyledriscollmusic]

Rusty will live forever thanks to your videos

[@UncleDoug]

Thanks, Kyle. I hope you're right..... he was a very special friend.

[@GeeBee135]

Great tutorial, Doug! I like the idea of color-coding HVDC wires to correspond to their particular node from the power supply rail.

[@UncleDoug]

Thanks, Gary. I don't usually do this, but I thought it might be helpful for those contemplating a build of their own.

[@chriswareham]

Fantastic tribute to Rusty. This is going to be such a great amp - the reverb and tremolo make it an "all in one" unit with what I consider the essential effects for guitar.

[@UncleDoug]

Thanks so much, Chris. I share your enthusiasm, and remain optimistic that it will be worth all the time, effort, and expense. If not, however, it'll make a great target for plinking in the desert 🙂

[@cdemike7517]

Very sorry to hear about Rusty. On a brighter note, I’m really enjoying this series-especially after finding out this was a paper circuit that’s finally coming to life! I’ve been kicking around some ideas to use a 6AN8A as a distorting stage with a built-in cathode follower, but it’s so hard to find examples of amps using them.

[@UncleDoug]

Thanks for your kind words, Mike. I'm glad you're enjoying the series :)

[@jorgearodriguezdiez]

I’m taking the rest of the day off at work to watch this video! Always a joy and I’ve learned so much. Thanks Uncle Doug

[@UncleDoug]

I'm sure your boss will appreciate your priorities, Jorge. If not, it's time to find a new job :-)

[@DeadCat-42]

A good friend just gave me a Giant box full of brand new(old stock) tubes!! Literally dozens of them still in the packages and three Crosley radios!

[@UncleDoug]

I wish I had friends like that, DC. All I get from mine are loan requests and empty beer bottles.🙂

[@goodun2974]

List the tube numbers here and we will tell you if they are of any use today....

[@vintagetubeamplifiers]

I've had a few bad weeks and really needed this, thanks Uncle Doug my favorite Uncle!

[@stratcat4450]

@vintagetubeamplifiers that would have been my exact comment. I hope things get better soon.

[@vintagetubeamplifiers]

@@stratcat4450 Thanks, you too.

[@UncleDoug]

Sorry to hear it, VTA. I hope the situation improves.

[@julesl6910]

This was the video when a lot of the knowledge you've shared actually clicked with me. I now know that a center tapped output transformer allowed for push-pull operation, and the absence would require a single ended circuit. Seeing you refer to schematics and writing diagrams out to understand a circuit are all things I've been able to apply to my builds. I do have one question - why the use of metal oxide resistors instead of metal film?

[@UncleDoug]

That's good to hear, Jules. I'm glad the videos are helpful. I decided to use metal oxide resistors for this build. They are precise and long lived. I'm not a big fan of the theory that resistor composition affects tone audibly.

[@petejandrell4512]

Yes, Bank Holiday bonus! (It's a UK thing)

[@UncleDoug]

Glad to hear it, Pete. Enjoy the day..... and the video.

[@davidshutt2273]

Your teaching experience shows. Good work, Uncle D.

[@UncleDoug]

Thanks, David :)

[@zachsmith3376]

Gibso made a wild amp circa 1960 GA83S that has stereo tremolo with 4-8' inch speakers up the side of the amp, along with a single 12' in regular position. Crazy project for the maestro uncle Doug perhaps? Thank you Uncle Doug for your dedication to us.

[@UncleDoug]

Thanks for the info, Zach.

[@PetraKann]

Everything in the circuit is explained very clearly by the Magnificent Uncle Doug. 😎

[@UncleDoug]

Thanks so much, Petra. You are too kind :)

[@badscrew4023]

Very keen to hear the end result. Interesting how they used a relatively powerful penthode at the first input stage. I'm absolutely going to building a variant of this amp too, but with slightly different tubes.

[@UncleDoug]

Thanks, BS. Best of luck when you do.

[@Richard56er]

When I was in the motor trade there were pop rivets available with longer mandrels. This would allow you to rivet in tighter places as you could extend the nozzle of the rivet gun with a thin hollow tube.

[@UncleDoug]

That sounds like a nice option, Richard. I'll see if I can find one like that.

[@a.k.4550]

Thanks for your continued delivery of detailed and informative content, I look forward to watching the rest of this series! On the topic of shielded cable, this may not be a solution for everyone, but there is an industrial small gauge (usually 18awg or less) shielded cable known as "RTD extension cable". It is generally rated for 300v and can be bought by the spool with any number of shielded twisted pairs and outer jacket compositions.

[@UncleDoug]

Thanks for the nice comments and very helpful info, AK.

[@alvagoldbook2]

Hey Uncle D! I recently rewired my Fender Hot Rod Deville amp. The stock amp used a solid state reverb driver and I wanted to make it all tube. So I drilled the chassis for a 4th preamp tube. I tried using a single 12AT7 to drive the reverb and to act as the reverb recovery but it didn’t work out very well. So I redesigned the circuit and instead used a 6BM8 as the reverb tube. The pentode side was the driver, and works very well, similar to the old early 60’s Fender reverb units that used 6k6’s and 6v6’s. And the other half of the 6BM8 acts as the recovery. The 6BM8 triode is very similar to a 12ax7 triode, but the cathode takes a very VERY wide range of resistors. In a 12ax7 you might see a range from say 820R to 3k3, but usually nothing beyond that. After running the load lines for the 6BM8 I discovered it would take anything from 1k to 12k!!! A 4k7 or 5k1 would be a perfectly suitable bias resistor for the triode. Normal 100k on the plate works just fine.

[@UncleDoug]

Thanks for your detailed input, Alva :)

[@skullheadwater9839]

This looks fantastic so far. I want one already, but I am the sort who plays with uncommon tubes for fun.

[@UncleDoug]

It could be yours, SHW :)

[@skullheadwater9839]

@UncleDoug Are we hinting at a give away drawing?

[@UncleDoug]

@@skullheadwater9839 I wish I could afford to do that, SHW, but I'll have too much invested.....almost $500 just in the cabinet and speaker :O

[@skullheadwater9839]

@@UncleDoug I understand, and I don't blame you. Just shipping would be expensive. Your first comment got me excited though, I guess the only realistic way would be a raffle with $50 tickets. In this case there may not be as much interest as I display but I do silly things like build amps and overdrives with 6U8's, EL-86's, 6BQ6's etc. I am even building a single ended amp using a 77, and 75, pre with a 42 power amp and an 80 recti in a 1935 Philco chassis. Cheers Sir.

[@UncleDoug]

@@skullheadwater9839 Thanks, SHW :)

[@rocket400what]

Uncle doug does it again. Been watching your videos for a decade or more and still will watch a long format video even though I already graduated from Doug U. I've watched videos of yours while my dad was listening and he appreciates your humor as much as I do. Thank you for being an educator of amp tech and kitty treats.

[@UncleDoug]

Thanks so much, RW.

[@ineedcbsi]

Hi uncle Doug. I'm a believer in fuse first. The way the fuse holder is designed is that the power comes into the tip. When you pull the fuse holder, it disconnects from the tip killing power. It needs to be wired that the power comes in the tip first but that should be common knowledge. Nice build though :)

[@UncleDoug]

Thanks for sharing. I appreciate your input on this issue.

[@rossthompson1635]

It is usually fuse first here in the UK - and as @ineedcbsi says, with the live (hot) to the tip (for designs where the fuse is extracted with the holder). But - and this applies whether (single pole) switch or fuse first, you should always exercise care removing or inserting a fuse in case the outlet polarity is wrong.

[@ineedcbsi]

@@rossthompson1635 good point on polarity.

[@UncleDoug]

@@rossthompson1635 I understand that fuse first theory predominates, Ross, but I feel that my option offers greater safety and practicality. When a power switch is "off" I expect all portions of the circuit, including the primary of the power transformer, to actually be "off". Also, while some fuse holders allow the fuse to be removed with the cap, most do not, and for this reason I continue to prefer my method. This is a personal judgment and I am not pressuring others to follow my lead. Thanks for your input. .

[@rossthompson1635]

​​@@UncleDoug I actually agree with your view, and I enjoyed your presentation of the case for each side in the video. In the UK, we have a similar problem: In the county of Devon, cream goes on your scone first before the jam. In Cornwall, the jam goes on first and then the cream. This issue creates a similar amount of very heated debate! (are scones a thing in the USA?).

[@TheGuitologist]

52:43 In every case you mentioned for the other devices in the home, the switches were insulated in plastics. In the case of many amps, including those Carlings, the switch is made of metal, along with the chassis. Fun Series, Doug!

[@UncleDoug]

Carling switches are all housed within an insulated Bakelite housing, Brad. The toggle itself may be metal, but so are the pull chains on many, many lamps and light fixtures. Glad you're enjoying it :)

[@michaelogden5958]

Calcutta. An obscure reference. 🙂 Cheers to the Rusty doghouse commemoration. Another fascinating video.

[@UncleDoug]

Yes, but a dark and meaningful one. 🙂 Thanks so much.

[@chriswareham]

It's something my mother used to refer to when describing the chaos of my teenage bedroom, "it's like the black hole of Calcutta in here".

[@stevejones4618]

@@chriswareham You have to be a certain age. Unfortunately I got the reference too 🤣

[@UncleDoug]

@@chriswareham With all the astronomers looking for black holes, apparently none thought of looking for them in Calcutta. Too bad they didn't listen to your mother and me. 🙂

[@JobyP]

“El Rancho Rusty” ❤

[@UncleDoug]

Glad you liked it, Joby.

[@alexdeleon7135]

This sequel was full of lessons for safety, and wiring schemes. I am now excited that instead of a trilogy, this series has now become a tetralogy! The appeal that this single-ended design was never offered to the masses makes this build unique. We will be hearing this amp for the first time in history! Kudos for this endeavor, dear uncle. I now wait for the third installment of this spine-tingling series. Stay safe, and out of the summer's searing grip.

[@hamish93]

to quote Richard Adams, author of 'hitchhikers guide to the galaxy' , it's a trilogy in four parts.

[@UncleDoug]

That's great to hear, Alex. I hope it lives up to your expectations. Will do.....you too :)

[@ourlifeinwyoming4654]

I like the name Wooly Mammoth for the amp - very fitting. Looking good! Learned ALLOT as usual. The discussion on fuse location in the circuit was most revealing to me. If I may add please - I tell people that trust me with their amp for repairs, etc. - if the fuse blows, unplug it and get it to a tech. Don't keep feeding it fuses and don't attempt a repair unless you're 100% certain you know what you're doing, because it can ruin your day in many ways. Can't wait to hear this amp Uncle Doug!

[@UncleDoug]

Thanks so much, OLW. Agreed..... it's always best to unplug any electrical device before working on it, even superficially.

[@patoneill3373]

Well Uncle Doug when I'm playing Wembeley here in England I have the roadie attend to the fuse while I keep the wild groupies in check 😂😂. Great vid as ever and it is alway worth remembering beloved, no longer with us, companions.

[@UncleDoug]

Thanks for sharing, Pat. Roadies are expendable, but wild groupies must be carefully dealt with. I admire your dedication to your art ;) Thanks so much.

[@chokkan7]

I always learn something from your videos, UD. Thank you for this project and its presentation.

[@UncleDoug]

That's good to hear, C7. You're welcome🙂

[@shannonharris2816]

Lovely job, uncle Doug. You move like a surgeon.

[@UncleDoug]

Thanks, Shannon. Wiring the circuit within this small chassis was like performing open heart surgery on a hummingbird. 🙂

[@goodun2974]

​​@@UncleDoug, have you ever watched a guitar tech replace the pots and selector switch inside an F-hole archtop guitar that has no access panel other than through the F-holes or perhaps the pickup cavities? Psionic Audio posted a video recently where he replaced 4 pots and a switch inside a modern Epiphone Casino reissue guitar, and you really should watch how he assembled and soldered the whole thing together from outside the guitar by using the template. It occurs to me that if you make a cardboard or Masonite template that exactly matches the mounting holes for the terminal strips, you could do something similar, mounting the terminal strips to the template, wiring the components to the terminals, and soldering them, before unscrewing the terminal strips from the template and installing the whole shebang into the chassis. This way, the only thing you would have left to hook up to the terminal strips after mounting the terminal strips ---- with components pre-attached ---- into the chassis would be the wires going to the pots and sockets, and even some of that could probably be wired to the terminals in advance.

[@UncleDoug]

@@goodun2974 That's a very interesting idea, GU, much like the advantages provided by eyelet boards......as Leo discovered and implemented. I will definitely keep this in mind for future builds using claustrophobic chasses.

[@goodun2974]

@@UncleDoug , I haven't watched the entire video yet (been super busy: we're fostering another rescued dog, and he's running us ragged), but if you didn't pre-tin all the terminals of the terminal strips with solder before installing them into the chassis and adding components, I would strongly recommend it. If it's really tight in there, sometimes I'll even pre-tin the component leads! And if you haven't already, you should really watch that Psionic Audio video that I referred to. ( The puppy we are fostering is a 4 month old German Shepherd/ Great Pyrenees mix that already weighs 50 pounds ---- very smart, but impulsive and high energy. I fully expect he'll easily go 110 to 120 pounds, perhaps more, when he's fully grown. This is a dog that's going to need a job! The German half of him wants to stand at attention while guarding the perimeter and awaiting fur-ther orders 😉 while the Pyrenees part wants to wrestle unruly sheep and push or pull them back into the herd, and chase wolves back up into the mountains! My similarly sized Lab mix (rescued from TX, btw) is not real happy about having this new interloper, but my 105 pound female Anatolian has adopted the puppy, plays with him, and issues corrective measures as needed).

[@UncleDoug]

@@goodun2974 Thanks for your helpful input, GU.

[@alexbozas887]

14 mins: " i asked my wife if i could use her new blouse and dress on the mahogany table to protect it from the spray job , and she declined" U Doug you really crack me up, made my day..thanks so much

[@UncleDoug]

It never hurts to ask, Alex......actually, in this case it did hurt ;)

[@alexbozas887]

@@UncleDoug ouch, we feel your pain.

[@UncleDoug]

@@alexbozas887 Especially on Mother's Day ;)

[@oldasrocks9121]

Use microphone cable for the reverb tank input lead: Mogami W2552 at Parts Express is one example, Belden makes similar shielded 2 conductor cable. At the tank side you can easily run a heat shrunk soldered jumper from the input shielding to the grounded shield side of the output connector.

[@UncleDoug]

Thanks for your helpful input, OAR.

[@nevillegoddard4966]

@@oldasrocks9121 Yeah ya beat me to it mate! I was gonna mention mic cable too! It would be neater than the fugly hand-made shielded cable, effective & all as it is, of course!

[@UncleDoug]

@@nevillegoddard4966 Thanks for the tip. Now I'll know what to use if the need ever arises again.

[@briansilcox5720]

Clostrophobic is a good description. Very nicely executed and presented. Best to Jack…

[@UncleDoug]

Thanks, Brian. Now I know what open heart surgery on a hummingbird feels like 🙂

[@reggiewallace260]

Thank you Uncle Doug. An excellent video on this interesting build. I'm looking forward to the next installment.

[@UncleDoug]

You're welcome, Reggie :)

[@josephsichting8162]

What a fantastic build! I am always amazed with your electrical craftsmanship. Can't wait to see the finished product!

[@UncleDoug]

Thanks so much, Joseph :)

[@W1RMD]

Thanks Uncle Doug! You are a true craftsman and I LOVE that gold color! It's not that 1990's yellow (trashy) brass, but a mid- century classy gold like what was used on my grandmother's Hi-Fi. Thanks to this video, some poor bastard will go to the auto parts store thinking he's getting some engine paint to finish up restoring his 1973 Olds rocket 350, and He'll be out of luck! Anyway, that cat looks like she's not a prime candidate for an ASPCA commercial any time soon! It looks like she's okay with the build of this amp. Take care of yourself and pets!

[@UncleDoug]

Thanks so much for the nice comments, W1. Glad you approve of the color choice. Mitzi has indeed adapted to the good life indoors 🙂

[@goodun2974]

The paint color looks almost identical to a pair of Heathkit monoblock W5M hifi amplifiers that I own.

[@UncleDoug]

@@goodun2974 Glad you approve, GU. It just seemed like a natural choice :)

[@goodun2974]

@@UncleDoug , although, thee bent rear lip or flange that is exposed when you remove the wooden back should really have some areas on it where the paint is removed down to shiny metal,, so that you can apply some aluminum foil tape as shielding to the back panel and it will make contact with the chassis to form a complete shielded cage around the circuitry.

[@UncleDoug]

@@goodun2974 Thanks for your input, GU. It's not a provision that I normally make, but I'll keep it in mind.

[@captainfineweather5610]

Dear Uncle, I thought you might like to know that I've been attending your seminars for quite some time now. I did my homework all along and am now confident enough to start work on my VOX AC15C1 and Harley Benton Tube 5, the latter being the identical twin of the 5W Stage Right amp that you made a demo of. The goal is to make the VOX rock as much like a 60s JMI as possible, inspired by Lyle Caldwell. I could have followed his instructions without further ado, but then I would have had no idea what I was doing. Thanks to you, and that is an enormous THANKS, I am not that ignorant anymore. I'll also try and steer the HB 5 a bit more into the direction of a Champ 5F1, since you covered it frequently and aptly. I learned the most from that. You Sir, along with Richard Stallman and a few others, are social role models, keeping up the conviction that knowledge should be encyclopedic, that is, belong to everybody. I will dedicate my next LP to you, Rusty, and the kittens. A propos, since the trick with Lou Reed seemed to work, let's try again: www .youtube .com/watch?v=ikRPmoC9F2o Just eliminate the gaps after the double slash, "www", and "youtube" after insertion into the address bar. (I have to warn you though that I'm neither a Jack nor an Ollie and it might be that after having listenend, you'll ask me NOT to honour you with a dedication... ) Anyhow : THANK YOU again! 🤠 (the Stetson seems to have suffered a bit of shrinkage, but that's the best the emoji section on KZbin can do)

[@UncleDoug]

Thanks again for the nice comments and best of luck with your projects, Capt. I listened to the entire album and enjoyed it. Thanks for sending the link.

[@captainfineweather5610]

@@UncleDoug Thanks for listening and approving! It really means something. If you'd like to spread the word, feel free to do so.

[@UncleDoug]

@@captainfineweather5610 Will do, Capt.

[@LukeRauch]

Hi Uncle Doug, Long time listener...first time caller. I am moved to comment about the fuse wiring section of your video. I really appreciate the level of thought and detail you put into your explanation. I would like to mention as an electrician that fuses and breakers are for protection of the wiring that comes after them not the people. Many of the appliances you highlight have non-user serviceable fuses inside. However, I also submit that the way you wire the fuse holder absolutely makes a difference similar to the screw shell of a light bulb socket. It is important to have the hot contact of either be the the tab at the bottom. When you push in and twist the fuse holder the spring should disconnect the unblown fuse from power. You wired yours that way. Am I missing something? Big Fan!!!!!

[@UncleDoug]

Greetings, Luke. Many of the fuse holders used in amplifiers do have a spring at the bottom to push the fuse upward and assist in its removal, but the spring is actually the AC contact to energize the fuse. Thus, in a properly wired fuse holder, with the "hot" wire soldered to the lug at the distal (spring) tip of the holder, the exposed end of an unblown fuse is energized.

[@LukeRauch]

@@UncleDoug Thank you for replying. I appreciate your kind rebuttal. I went down to my stash of old organ parts and found a loose fuse holder and I see that you're absolutely correct. It's great for electrical contact....not so great for orphans.

[@UncleDoug]

@@LukeRauch Thanks for your personal investigation and verification, Luke. It's nice to hear from someone who puts in a little effort to find the truth, rather than simply mouth traditional platitudes.

[@snyd3rj]

Thanks for the in-depth analysis of "fuse before or after the switch" (47:04). Another consideration (or perhaps I missed it) is that the amp user likely won't know (or not think about) which way the amp is wired. My view is to weigh heavily toward "in use" protection and expect (hope) that working with the fuse is to be done while unplugged.

[@UncleDoug]

You're welcome, S. I tried to present both sides so the viewer could decide which to utilize. Since I have never, in all my years, experienced any issues with internal toggle-switch short circuits, the choice was obvious for me. Also, both methods provide fused "in use" protection.

[@highpath4776]

@@UncleDoug I have had toggle switches fail on the wafers / return springs where fitted but generally not accross the insulating wafers. Do you think it is worth checking new components for resistance continuity/insulation in these days of cheap mass production ?

[@UncleDoug]

@@highpath4776 Greetings, HP. I too have had old/vintage toggle switches fail but never have they created a short to the chassis in which they were mounted. I don't routinely test new toggle switches for issues, as I have yet to encounter any problems with new ones.

[@adenihil]

Dear U.D… I love you man! 😂 Thanks for all your efforts & comments.

[@UncleDoug]

Thanks, Aden. We love our viewers :)

[@shannonharris2816]

With your consummate professionalism, Uncle Doug - you make it look easy.

[@UncleDoug]

Thanks so much, Shannon.....but in this case, it's really not ;)

[@scottyotoole6125]

Thank you Uncle Doug! Another great video! My cat Georgie thanks you for the kitty centerfold shot. Missy is a hottie and has distracted him while he tries to help me rebuild a Deluxe Reverb. Now he's useless for the rest of the day 🤣

[@UncleDoug]

You're quite welcome, Scotty. Regards to Georgie :)

[@tommymcentyre]

I thoroughly enjoy your video!!! I wish I had you as a teacher when I was in Tech School and eventually in EE school. I’ve built lots of circuits but have learned a tremendous amount of tips/tricks from your videos!!! Keep up the good work.

[@UncleDoug]

That's great news, Tommy. Will do :)

[@PennStacker]

Just incredible! Thank you for your videos. Ever think about writing a book? Your knowledge of these amps is unmatched.

[@UncleDoug]

Thanks so much, PS. I thought that the internet, particularly KZbin, made books obsolete ;)

[@avi8tor13]

Uncle Doug, “Complex” in your narrative is an understatement! ; ) But none the less, fascinating to watch and learn from your soothing and thorough explanations. Thank you, again. Looking forward to parts 3 and 4 and the sound check. Wishing you the best of health, Dan

[@UncleDoug]

Greetings, Dan. I'm glad you're enjoying the video series. Likewise on the good wishes :)

[@davidfellows6250]

5000 views and 671 likes? Come on people! This is if nothing eles some of the finest content/ comedy on you tube. Do it for the cats.

[@UncleDoug]

Thanks so much, David. Jack sends his love :)

[@danielsaturnino5715]

Thanks Uncle Doug

[@UncleDoug]

Our pleasure, Daniel.

[@briansilcox5720]

That gold reminds me of the Heathkit amp my dad built in the 50’s. Very appropriate.

[@goodun2974]

I have a pair of Heathkit W5M mono block amps and I thought the same thing!

[@UncleDoug]

Thanks. It has a nice, mellow, aged look :)

[@Timberon]

Uncle Doug! We enjoyed the video - your secret fans in Las Cruces.

[@UncleDoug]

Glad to hear it.....you scoundrels !!!

[@rustyrobinson8027]

Thanks again Uncle Doug ❤️🇺🇸

[@UncleDoug]

Thanks for watching, RR.

[@nickbruni8041]

Even though I have limited experience with circuits …. You make me feel like I do with Your patience and candor … O ..and .. how’s the street rod doin ?⛽️✊🏼👌🏼🐾

[@UncleDoug]

Glad to hear it, Nick. It's running quite well indeed. In fact, we went to a car show yesterday.

[@noelgraham4607]

That was quite a thorough lesson on reverb tank cables. Much appreciated

[@UncleDoug]

Glad you liked it. It's a topic we had never previously discussed, Noel.

[@waynerick5755]

Another great Uncle Doug video😊😊😊😊😊😊😊

[@UncleDoug]

Glad you enjoyed it, Wayne :)

[@isoguy.]

I'm so disappointed when I look at my tube notifications and there isn't an uncle Doug vid to be seen, awesome series. Just a thought. If a user of an amp is concerned about electrocution they can purchase an in line residual current device (RCD) for around $20, this will restrict any electrical shock to 20 or 30 mA. Also really enjoyed the drone flight series, will there be any more? As always thanks for taking the time to make such interesting content to teach lesser mortals like myself.

[@UncleDoug]

Thanks for your nice comments and helpful safety suggestion, Iso. I have not flown the drone in several years, but still have it.....so more flights are a possibility.

[@MrTimcoronel]

Happy rescue cats, neat and interesting amp builds, droll commentary. Je suis riveted.

[@UncleDoug]

Glad you enjoyed it, Tim.

[@paulvale2985]

Fuse first here in the UK would be illegal. Further (and I don't understand how this could be) some power cords are not rated for 15 amp therefore becoming a fire risk in the USA. All cords plugged into UK sockets have an appropriate sized fuse for the gauge of wiring. I know people are going to jump all over this comment but I'm just stating facts regarding electrical safety. Love the cabinet Unc, totally professional.

[@ChuckKirchner-se6ib]

As an American, I don't always understand BS7671, but I do understand what they are TRYING to do by implementing it. Some parts of that standard SHOULD be implemented worldwide, but alas, it will never happen. All the fuseholders I use retain the fuse as the cover is removed (or they are replaced quickly), or there is a built in indicator to tell if the fuse is blown. That being said, I unplug before working on electrics, anyway. Totally safe, even at Wembley Stadium .

[@rossthompson1635]

I don't think that is right - in an appliance, fuse first is the norm in the UK surely?

[@UncleDoug]

Thanks for you input, Paul.

[@williswet]

I have 6 of them in closet with the hang tags and all 😊 You rock Doug. Cool amps and Hot Rods. I think you may really be my uncle!

[@UncleDoug]

Darn....and I thought they were rare ;) Thanks, Will.

[@-dazz-]

That's going to be a special amp if I ever saw one: built by Uncle Doug, based on a circuit by Gibson never released, and with a tribute to El Gran Rusty on top of that. Congrats in advance to whoever gets to purchase that thing of beauty

[@UncleDoug]

Thanks so much, D :)

[@stratcat4450]

Thank you uncle Doug.

[@UncleDoug]

You're welcome, SC :)

[@dale1956ties]

I always wanted to build a single ended amp with reverb but never got around to it. Also always wondered why you don't see them in the wild. A Champ Reverb would be cool. BTW I've build a couple of amps using Mojotone cabinets and think they're excellent. After building a couple of my own, I decided for the money it just wasn't worth building one at home. Thanks Uncle Doug. Great stuff!

[@UncleDoug]

Greetings, Dale. I agree, and a Vibro Champ Reverb Would really be the cats meow. I was thoroughly impressed with the Mojotone cabinet and will probably never build another one myself. It's simply no longer worth the time, money, and considerable effort.

[@dale1956ties]

@@UncleDoug Several year ago I saw a post online from a guy who scratch built one. I think. It's been a long time and he may have converted a Champ or VibroChamp to a reverb model. Anyway, I looked for it again o provide you with a link but couldn't find it. I don't know if it's been removed or just drowned out by the myriad of Fender links but either way, if I ever do find it I'll send you a link to it. It was very interesting.

[@UncleDoug]

@@dale1956ties Thanks, Dale. I'm thinking that adding Reverb to a fender Vibro Champ might be a great future project.

[@dale1956ties]

@@UncleDoug I have another idea that may interest you. I've seen you switch the NFB loop on a number of units and modify the trem circuit on others with a different value cap when it modulated too quickly. I've wondered about switching (with an actual switch, not just replacing) a couple of different value caps in the trem circuit to allow for either faster or slower modulation according to the needs of the player. I dunno, it may not be worth he effort but it's crossed my mind occasionally.

[@UncleDoug]

@@dale1956ties Thanks for sharing your ideas with us, Dale. An easier solution is to replace one of the resistors in the oscillation loop RC pairs of a fixed-rate trem with a potentiometer. This will allow for infinite variation of the trem speed.

I am hooked to your channel, Uncle. Watched the Oscilloscope Part 1 and 2. Hope your tongue is better now after all that oiling 🙂

[@UncleDoug]

Welcome aboard. I'm feelin mush bedder, Tanks. ;)

[@skullheadwater9839]

Must say, love the welded ground lug idea, may have to steal it.

[@goodun2974]

For those who don't have access to welding equipment, a simpler solution would be to cut three slots in the side of the chassis (Dremel tool and carbide cutting wheel) to form a rectangular tab or flap that you can bend inwards, into the chassis, and solder or bolt the ground wire to it.

[@UncleDoug]

Glad you liked it, SHW :)

[@Basslice120]

Love it! Such great videos!! A better and safer alternative (but more expensive) way to securely attach the reverb would be to use a triaxial connector. I'd worry about how the home made cable you made will hold up.

[@UncleDoug]

By coincidence, I remade the cables today, Bass. The 8 Ohm cable actually did not have to have 2 shielded wires after all.

[@Basslice120]

@@UncleDoug Interesting! Is there not a lot of current in that part of the circuit? Very cool design. I cannot wait for Part III!

[@highpath4776]

Dont forget in the UK MOST mains plugs are fused (15Amp on "round pin large - rarely found but have there uses ) 3amp or 5amp in "Small" round pin triangluar plugs - often used on stage lighting where a normal standard UK plug and socket is just too unwieldy. And then our trusty "13amp" Plug - which can optionally have a 3 or 5 amp fuse substituted as necessary , 3pin Plug. So circuit breaker (nowadays RCBO) after the meter ( and a whacking "mains fuse" before that (I have blown those a few times too !) , and appliance fuse seems to be a literal belt and braces protection. Obviously that wont necessarily protect you if you have mis-routed your B+ circuit still allowing say a "live" mike stand espectially when its rectified to one way DC)

[@UncleDoug]

Thanks for sharing, HP. After reading all the safety provisions you described, I'm confused...... and I don't even live in the UK :-)

[@sologuitarssc6037]

Looks great Uncle Doug! Can't wait for part 3...

[@UncleDoug]

Thanks, SG.

[@alvarofalcon7136]

Hi Uncle Doug, glad you’re back! Rgds!

[@UncleDoug]

Thanks, Alvaro. It's good to be back 🙂

[@patriottothecore6215]

This could be the amp equivalent of finding King Tutankhamen’s tomb. Can’t wait to hear this jewel. Thanks for this UD. BTW have you seen the build video of Dr Z’s Zwreck amp? Very interesting. He started by putting shrink tubing onto the wires coming out of the transformers to act like a grommet.

[@UncleDoug]

Let's hope there is no curse attached to this project, PTC :) Thanks !!

[@NasirAli-lu4it]

Another fantastic video. Thank you

[@UncleDoug]

Glad you enjoyed it, Nasir.

[@davidlemnah4938]

Hi Uncle Doug, I really enjoy both your approach towards building amps as well as your selection of what to build. One tube from my past I've always found interesting is the 6GH8A Pentode/Triode 9 pin. The downside is many of these I've found to be extremely harmonic, but the good ones are pure magic. Dave

[@UncleDoug]

Thanks, David.

[@DetroitWrecker666]

That's very interesting. I may just build one of these.

[@UncleDoug]

Please do, DW. Let us know how it turns out.

[@tonymanns8249]

I'm a huge fan of Mojotone. The tweed Fender Super cabinet amp kit I bought from Mojotone was perfect. The cabinet was even higher quality than the very expensive hand-wired Fender '57 tweed Bandmaster reissue amp & cabinet I bought from Fender.

[@UncleDoug]

Thanks for sharing, Tony. I'm a believer :)

[@stevenmoffitt1643]

On a slightly different topic. I just bought a copy of Radiotron Designer's Handbook-1954 Edition. It has a lot of information on tubes, circuits, and uses. The book must be 3 inches thick!

[@UncleDoug]

I have a similar edition....not sure what year.

[@ChuckKirchner-se6ib]

I am in awe of your choice of amp case. That one is so beautiful!!! You'll be the talk of the town! Even in Calcutta. (I did not get that joke, btw). I might add that you're pushing limits with the insulation in the doghouse, though. Quite radical. Keep smiling, friend (it keeps your enemies on their toes).

[@UncleDoug]

Glad you enjoyed it, Chuck. I really think that 1/8" of rubber should be adequate, but I guess we'll see when the cover gets installed ;) Here is a link to the Calcutta reference: en.wikipedia.org/wiki/Black_Hole_of_Calcutta

[@300poundbassman]

I'm not worthy,I LOVE IT. Taught me so much. Just this time. What's your cat's name? I'm. Deaf too. 🤣. Have a good evening. Your a mentor too me Doug😎❤️🌹

[@UncleDoug]

That's great to hear (the part about loving the video.....not your deafness ;), 300. The white cat is Mitzy.

[@Gumaamug]

Well, you got me Doug. I watched the first part two weeks ago, I watched this part yesterday, and I bought the cabinet using your code late last night. I hope part 3 includes more of the wiring process between what you show at the cut at 1:04:15 otherwise I'll be a little lost! Thanks for your videos and for your encouraging style -- it's a real motivation for people like myself who love to do projects like this.

[@UncleDoug]

That's great news, G. You're going to love the Mojo tone cabinet. Part 3 does include the final wiring steps as well as some additional tips. We're glad the videos are helpful.

[@cjay2]

Regarding the wiring process, just follow the schematic, make NO errors, check your work again at the end, and check Doug's videos for any modifications he may have made. And take your time. Do it right the first time, so you don't have problems. Enjoy!

[@UncleDoug]

@@cjay2 Well said, CJ, but sometimes easier said than done. Let's always strive for the best, however :)

[@lamppostwillie]

Thanks much, Doug. Loving this series. One minor criticism of the cab- no cup washers on the rear panels. Other than that, it looks great.

[@UncleDoug]

Glad to hear it, WR. You're right, that would be a nice addition.

[@milofh550]

Pleasure to see you again Doug, all the best to you! :)

[@UncleDoug]

Thanks, Milo. Likewise :)

[@bullthrush]

Thank you for all the tips and tricks along the way. The switchable NFB loop is a nice addition for the extra hole.

[@UncleDoug]

You're welcome, Andrew. Sometimes desperation leads to successful invention. 🙂

[@exeterslab7781]

Great work Doug and a thorough explanation of what you did. You're a marvel, please keep it up :)

[@UncleDoug]

Thanks, EL. Will do :)

[@kendavis8046]

Thanks, Uncle Doug. Another great informative video, and that cabinet indeed looks as though it is wonderfully built.

[@UncleDoug]

You're welcome, Ken. We're glad you enjoyed both the video and the cabinet.

[@hereonmars]

Uncle Doug, i used to comment a lot here under a different channel. Im sad to learn of Rusty, but I know he's up there. This is an awesome project. I have built tons of pedals and even racked a couple vintage mic pres, but my true dream is to build an amp someday.

[@UncleDoug]

Thanks, HoM. Glad to hear it. If you do, let us know how it turns out.

[@jaysorensenIBEW]

Yes, outstanding once again, sir. I've got projects with a few amps that I neglect for lengths of time, and your videos are the ones that get me back solderin'. Thanks, UD. Nice work 🎸

[@UncleDoug]

Thanks, Jay :)

[@tonymanns8249]

I like unique stuff. I've longed wanted to make a 20-25 watt RMS guitar amplifier that looks like a vintage radio transmitter, similar to the old Heathkit 'DX-60b'; especially if it looks like military issue.

[@UncleDoug]

If you build it, Tony, be sure to let us know how it turns out.

[@tonymanns8249]

@@UncleDoug LOL. I don't have the talent that you do to do such a a project.

[@PeterDyall-bn7ut]

Great episode and really interesting series.

[@UncleDoug]

Thanks, Peter. I'm glad you enjoyed it.

[@phil36135]

I built a tweed deluxe cabinet, and it turned out ok, but not as good as mojos cabinet. It is very hard to get those strips lined up like that. And I tryed and tryed over and over again but I never got it right.They are a lot of work involved and like you say it is an art. kudos to Mojo Tone. Also I must say you do some very impressive work yourself and I really enjoy your videos. I've learned a lot from you over the years.Thank you very much

[@UncleDoug]

Thanks or the very nice comments, Phil. No one can ever know what a nightmare working with tweed is, until they try it themselves.

[@adam411]

I appreciate your explanation on the PT fuse debate. I think another way to explain it is that PT fuses are designed to protect the amp, and mains breakers are designed to protect everything upstream, including the people. They work together. If you wire it with the amp PT fuse after the switch, it allows both to do their job most effectively (without killing you).

[@brucepickess8097]

Not sure about that comment regarding will also protect people. Only a circuit breaker which is of an RCD design ( Residual Current Device) will offer protection in terms of an electric shock hazard. The RCD detects imbalance in the circuit and isolates the circuit if excessive leakage current is detected, thus limits the current passed through the human body. We have these in the UK not sure about the US. 🤔📡🇬🇧

[@adam411]

​@@brucepickess8097 Yes, they're called GFCIs in the US, which I agree offers the most protection against shock. But I was referring to overcurrent protection. Not counting potential protection from fires, overcurrent circuit breakers do still also reduce (not eliminate) risks of shock in cases of a short, which causes current spike. For example, if an amp or appliance shorts to ground, then the enclosure may becomes electrified. Normally, this will trip a breaker because it is drawing excess current. Not always, but usually. Granted, if a person touched it before it trips they will still get a jolt. That's where a GFCI is a step better.

[@UncleDoug]

Thanks for your input on this complex topic.

[@goodun2974]

​@@brucepickess8097, Given that the innate electrical resistance of the human body doesn't want to pass a huge amount of current, it's difficult to imagine a scenario in which a human could pass 15 amps of current at 120 Volts through themselves and thereby trip a breaker; and if you did, it wouldn't matter that the breaker tripped because 15 amps passing through your chest would certainly stop your heart.

[@briansilcox5720]

I built a Mojo Princeton Reverb…cannot say enough for their cabinet/ tolex quality.

[@UncleDoug]

I believe you, Brian. The cabinet is extremely nice.

[@goodun2974]

"El Rancho Rusty" 👍. We do love our pups, including those who are no longer with us. In addition to our own 3 dogs (see video on my channel) we are fostering a German Shepherd/ Great Pyrenees mix puppy, 50 pounds at 4 months old. Very smart but energetic, and mischievous; quite a handful (working breed genetics, definitely needs a job). Gonna have to tell the rescue agency we volunteer for that my wife and I are a little too old for fostering puppies! Luckily our female Anatolian Shepherd is big, strong and agile but very patient and will happily play with the puppy and issue corrections as needed if the pup gets out of hand. Periodically we have to referee before the young gun starts trouble with our other 2 dogs.....

[@UncleDoug]

Thanks for sharing this with us, GU. For us old timers, our pets become our family :)

[@goodun2974]

@@UncleDoug , My wife and I are also of an age where it would be inappropriate to adopt a puppy or really young dog because we don't want a situation where the dog outlives us and has to go to another home somewhere. We used to have a Cairn terrier we adopted at age 7 who had been given as a puppy to a 70-year-old woman who had the beginnings of Alzheimer's. The elderly owner died when the pup was only 7, and so the dog came to us and lived another 7 years.

[@UncleDoug]

@@goodun2974 I understand completely, GU, and no longer seek to adopt animals with lifespans that could exceed my own. It's unfair to both the survivors and to the pet.

[@FranklyScott7483]

Hi Uncle Doug, Always enjoy your videos and have learned a lot through them on my tube amp building journey. I humbly submit that I believe I have found a production model of this circuit. It was the Maestro M-1SVT Amp. I came across a blog from 2019 of a guy who built a moded GA1-SVT style amp and actually posted pictures of an M-1SVT amp. I tried to post the link here, but it seems to be blocked. I mapped a bit of it from the picture and the resistors, caps, tubes, reverb transformer and layout all appear to be the exact GA-1 SVT circuit you are discussing here. I can provide more detail on my analysis if needed. Very interested to hear your thoughts on this.

[@UncleDoug]

Thanks for your input. Several viewers have provided proof of existence and production numbers for the RVT model, Frank. All will be revealed in the Part 3 video.

[@phonotical]

Now you know why we started putting the fuses in the plugs (at least in the uk!) the colour was a nice finish, I think the only minor detractor were those two vertical scratches🙈 Could you get away without using shielded rca cables by twisting them? I liked also the added nod to rusty, it's nice you still think of him

[@UncleDoug]

I've seen Christmas lights with fused plugs, P, and although they're small and fussy to work with, they do seem effective. Trying to sand out those scratches would have reduced the sheet metal from 16 gauge down to 22 gauge, so I took the lazy way out. :-) I guess so, as long as the cables remained twisted. Thanks.

[@noel3422]

Awesome tutorial Doug, would like to hear the amp and then another clip after carbon comp resistors are used in the ht nodes instead of film resistors.

[@UncleDoug]

Thanks, Noel. I'm afraid you'll have a long wait. I'm not a believer that resistor composition affects tone..... especially in the power supply circuit.