1966 Ampeg J12D Jet from Craigslist.....Junk or Gem ???

This week I found a 1966 Ampeg J12D Jet listed on Craigslist as "Project Amp.....Not Working", and out of curiosity I bought it. This video documents my evaluation of it and the repairs necessary to make it function well again, focusing on the transformers, since the seller insisted they were both "bad". Naturally, there were some surprises along the way, which you may find informative and amusing, and you'll actually get to witness a "sniff test".
If you enjoy videos such as this, please consider becoming a patron of this channel. You can make a pledge per video, with a monthly maximum limit, if you wish. Here is our site on Patreon: / uncledougsvintageamps Thanks !!!

[@ix-Xafra]

'Uncle Doug' : the only KZbin channel I watch reruns of. Sir, you should be lauded as a national treasure and international ambassador of tone!!

[@rogertaylor6]

"The highest praise a transformer can get!" Haha, great job Rusty!

[@UncleDoug]

Yep, when he snorts like that, you know the transformers are good :)

[@mjt11860]

lol, such a good dog! i love rusty.

[@AdamRainStopper]

Oh god, the moment I saw the first head-on shot of the Jet, I choked. That was my dad's first amp, and then mine. Between the two of us, we killed the original speaker, so he ordered a ceramic celestion (I think it was an early 90's Vintage 30), and it was suddenly louder and far less compressed. My dad built me a "pedal/preamp" using a pair of 12ax7's in a 4 stage cascade (full plate voltage on the tubes, kinda marshally crunch) with a slight high-pass filter off the first stage, and I used the Jet as a clean "platform amp" to amplify the distorted signal from that. I have been trying to recreate that sound ever since then. I would ask my dad what he used as a schematic for the basis of that preamp, but unfortunately he is unavailable for comment. I have his (ok, it is technically mine, but....) Reverberocket now, and I think if I had the pedal/preamp to put in front of it, I would get pretty close, but I can't find it in his paperwork. If I manage to keep the state from taking his (my) house, and manage to get back on my feet financially, I might buy or even build something like the Effectrode Tube Drive. The Ampeg cleans are great, I like them better than Fender clean, and it would essentially turn it into a footswitchable two-channel amp that would be ideal for playing hybrid reggae-punk stuff at small bars, where I'm playing clean reggae rhythm during the verse and dirty puck rock during the chorus (or vice versa), also for recording the same. There are so many thing I wish I could ask my dad.

[@UncleDoug]

It's a shame that we only fully appreciate our parents after they pass away. Like you, I often come up with questions that I should have asked. We're glad the video brought back some memories, Adam. Best of luck.

[@joesimon2018]

Try a Bad Cat 2 Tone or Matchless Hotbox for that dual 12AX7 pedal. Schematics are available online if you search

[@Frank-in-NY]

Nice troubleshooting! I used to be a a Marine Electronics Tech back in the 70's, this brought back great memories. I went from Marine Electronics to mainframe computers and I/O, to teaching software, to sales support. Thought I'd never get my face out of a book. I truly understand now what a old timer said to me when I was starting out as a tech. He looked at me and said "Kid, I've forgotten more than you know"...Thanks for the video, really enjoyed it.

[@UncleDoug]

You're welcome, FC.....glad you enjoyed the video :)

[@ElPasoTubeAmps]

Very nice, Doug. I always enjoy seeing you bring these old jewels back to life again. You and Rusty and Jack always make good videos.

[@UncleDoug]

Thanks, David. Now that I have a kitty that looks like yours, diagnosis and repair have become even easier and more fun :)

[@kenjimac2211]

Gotta love Rusty, the hardest working dog on KZbin :)

[@UncleDoug]

He was a bundle of energy :)

[@lawrencegenereux8567]

Uncle Doug;. The screw you encountered on this amp is known as a "clutch head". I had an Ampeg VT-22 back in the day, and it too used those screw heads. Fortunately for me at the time, my parents had a travel trailer that just happened to use clutch head screws for almost everything, so my dad had the required driver in the house. If you ever run across a VT-22 in decent condition, it's quite the amp. 100 HONEST watts RMS, 4 EL34 output tubes, a tube rectifier, 2 12" speakers (I had Altec Lansing speakers in mine), shock-mounted amp chassis, mechanical reverb tank lock for transport, and with the Alec's, over 90 pounds in weight. The tone was amazingly clear and full. It was also loud beyond belief! Being the volume head I was back then, I bought an Ampeg B25B cabinet to go with it, and loaded it with 2 15" Altec Lansing speakers. Since the amp had an output impedance selector, it would develop all 100 watts into the 2 12's or the 2 12, 2 15 speaker combination. When using all of the speakers (both the combo and the cabinet) it was frighteningly loud. Ahhhh... the good ole days.

[@UncleDoug]

I looked the screws up on the Internet and sources agree with your identification of them as being "clutch head" screws, Lawrence. I ground down a blade screwdriver a wee bit and had them out of the cabinet rapidly and easily. That VT-22 sounds like a real beast. Hopefully your hearing withstood such horrendous volume levels better than mine did over the years :)

[@tjrobil]

Uncle Doug, Those screws are "clutch head" screws. They were also used in Holley carburetors secondary metering plates. I remember them from my mechanic days. I still have the screwdrivers in my tool box.

[@UncleDoug]

Thanks for the info, T.J. :)

[@lawrencegenereux8567]

Uncle Doug WHAT???

[@UncleDoug]

I can't hear you, Lawrence :)

[@ImTheReal]

So. Finally I take a time to appreciate your videos Uncle Doug. I had a lot of work in last three months, and really, I don't have any moment of peace to watch and enjoy. Thank you again to share a piece of your time with us. Congrats \o/

[@UncleDoug]

We're glad to see you back in the audience, Humberto. Thanks for watching :)

[@rrobinson3738]

I was surprised by the orderly layout of the chassis. Thanks Uncle Doug. Atta boy Rusty!

[@UncleDoug]

You're welcome, RR, from both of us :)

[@tablaturebutler2823]

VERY evocative of its time, tone-wise. I'd love to play this amp for hours. Thanks as always...

[@UncleDoug]

You're welcome, TB. We're glad you liked the Ampeg :)

[@halbertking2683]

Uncle, that was my first amp. My dad bought for me in Pittsburgh Pa, It cost $109 and change in about 1967 or 1968 at Turner Music. Harry Turner played in a band called Marshmellow Steamshovel and then in a band called Sweet Lightning with Sid McGinnes who now plays on the Letterman Show.My little brother still has it.That 6bk11 was a pain in the butt even back then. Ah, the memories. Thanks, boss.

[@UncleDoug]

Glad you enjoyed the video, Halbert.

[@markanthony653]

Nice buy Uncle Doug nice buy ,nice little amp I learned a lot that's the most important thing that's a 675 about a $700 amp over here in Hawaii that would retail for, but if I could be upfront with your Uncle Doug whatever you were playing on your guitar almost had me in tears, signed your nephew absorbing information thank you sir.

[@UncleDoug]

Thanks so much, Mark. I hope they were good tears :) You're welcome.

[@joegile]

Hi Uncle Doug and Rusty. Thanks for the excellent video as always!!!

[@UncleDoug]

You're welcome, Joe.....glad you liked it :)

[@tricko2286]

Uncle Doug your videos are incredibly helpful and inspire me to stick my fingers into high voltage devices 😵 let us know if you ever figure out the 60 cycle hum issue. Thanks!

[@UncleDoug]

You're welcome, Tricko. I will :)

[@davidpatricklemos]

I got a '67 SB-12 with some hum. Nothing noticeable then playing, but I'd be interested on the fix as well! -Dave

[@UncleDoug]

I've been real busy with other chores and hobbies lately, Dave, but do intend to get to it soon. Unfortunately, since there are so many possible causes of 60Hz hum, it's unlikely that our problems share the same cause.

[@joesimon2018]

Uncle Doug Maybe it's the filter caps? Or filament supply?

[@jeffbrooks7246]

Once again, an excellent demonstration of tube amp savvy. Thank you - wish I could find things like you find (such as this sweet little Ampeg).

[@UncleDoug]

You're welcome, Jeff. If items like this exist in my area, they exist everywhere. It's just a matter of persistent searching. Good luck :)

[@wim-1944]

Uncle Doug, You are a great teacher ! Like the video' s a lot and learned a lot . I own a 1964 Jet with the 6v6gt and 6sl7 tubes ( sounds a bit harsh , could be the speaker) so thumbs up ! greetings from The Netherlands (also to Rusty from our wheaten terrier Floss)

[@UncleDoug]

Thanks so much, Willem. A vintage Jet shouldn't sound harsh. You might want to check for low-value (generally in the pf range) capacitor(s) bridging a volume or tone control.....they will allow an excess of (possibly harsh) high frequencies to reach the output section. Regards to Floss :)

[@MichaelLloyd]

What a gorgeous amp! Nice work (as always) finding the issues and fixing them. PS- Rusty is amazing. I can't get over how much energy he puts into your videos.

[@UncleDoug]

Thanks, Michael, especially for acknowledging Rusty's hard work and enthusiasm. He is definitely a furry dynamo.

[@jameswatkins7263]

Ok, this was a very educational tool for me. I have a Peavey Classic 50 that I thought might have either a bad power transformer or output transformer, and in one video, you have shown me how to check them. Simply mind blowing... thanks Uncle Doug..

[@UncleDoug]

I hope it works for you, James. Good luck.

[@rusholmemike]

Another fantastic video - and Rusty wasexceptional again, such controlled enthusiasm. thanks for taking the time and putting in the effort to make them - they are entertaining and informative. You've enthused me to start having a go at repairing my "junk pile" (wife's name for it)

[@UncleDoug]

Thanks so much, RM. Rusty is a master of enthusiasm concealment......which makes him a deadly poker player. He's been banned from several casinos in Las Vegas and now just spends his time fleecing the dogs in the neighborhood :) Best of luck with your "pile". KZbin rules prevent me from telling you what my wife calls mine.

[@makemyday2560]

Thanks Uncle Doug..! Great diagnostics and Rusty has a trained nose for smoked components.!

[@UncleDoug]

You're welcome, Rick. Rusty is the best sniffer in the business :)

[@SpaceAgeTech1]

As always another great video Doug & Rusty ! Alway love seeing new and different things on your YT channel , love the complete conversions from some other application like PA or old radio conversions and I have shared your instructional videos with friends as they are well done and very informative. Our generation has a small edge on these videos , I took Electronic Engineering in College and was the last class to learn Slide-Rule and next semester first to take scientific Calculator & FCC Radio. LAFF ! those first calculators were the size and weight of a house brick , and the HP used reverse Polish Notation, and didn't look as dorky hanging on your belt like the slide-rules, ahhh fun times.

[@UncleDoug]

Thanks so much, Dan. I too learned logarithms in school and used a slide rule. I bought a compact model that could be hidden in my pocket, so I didn't appear to be (quite as) dorky. My first calculator could only do simple math....no square roots !......was a little smaller than a brick, but nearly as heavy, and cost $80 !!! I was thrilled with it (for a while).

[@profxpedals2009]

Great video as usual! Thank you for the excellent troubleshooting tips Uncle Doug! Rusty is a real time saver with his sniff test.

[@UncleDoug]

You're welcome, Prof. X, and thanks for your nice comments :)

[@peterbustin8604]

Ah. Wonderful Rusty ! Aloof as usual !!

[@toneyisaiah408]

I enjoy Watching old music videos and checking equipment that guitarists use.

[@stupidjubei]

Sounds pretty good! Thanks for making your videos, I find them very informative, and the format is easy to understand.

[@UncleDoug]

Thanks for watching and commenting, Michael.

[@strangersound]

Great video, as usual. I can see why you were running after dropping that $100 bill in his hand. That's a sweet little amp. Jack's stardom must be going to his head, he's getting more screen time and material. Does he make you take all the brown M&Ms out of the bowl? ;) Thanks, Uncle Doug, for sharing the awesome find and diagnosis! It's always a treat and you're such a great teacher. I can't emphasize enough how well you present information in clear and concise, and easy to understand manner. By far, the best tube amp channel on KZbin, and one of the best for those into electrical engineering. You have a great knack for demystifying a schematic. And my understanding of electronics has benefited greatly from your lessons...and Rusty...and whatshisname the cat. ;) I love this era of electronics. It's all art, but the point to point wiring, the tubes, and vintage components just has an aesthetic you don't get from an integrated circuit...and it sounds better, too. ;)

[@UncleDoug]

Wow, thanks so much for the very nice comments, SS. I really like your final paragraph, in which you mention the "artistry" of vintage circuitry. It really is an art form that is, sadly, giving way to soul-less modern technology, where profit and ease of manufacture are of prime importance. Let's hope we can recruit new members from the younger generations to perpetuate this dying art.

[@stephensepan291]

I worked for Ampeg in the 60's screw used is called a "clutch head"made it tamper proof. Jensen speaker was standard. very strong tremolo and reverb when equiped. normally very quiet amp. recording studios loved it.

[@UncleDoug]

Thanks for your contribution to our hobby, Stephen.

[@Dennis-mq6or]

Another one of your 'oldies' that I am watching and enjoying tonight.. I couldn't help but notice how unusual the vibrato circuit is in that amplifier. The first thing you have to notice is that the vibrato signal is being connected to both the grid and the plate of a phase inverting stage. That means the two vibrato signals are working against each other instead of aiding each other. Also notice that the two paralleled triodes are not really acting as 'active' devices, because they have no path from the plates to any high voltage. Ampex is using them as variable resistance devices that are driven by the vibrato oscillator as you would expect, but they are only acting as variable resistors that shunt some of the first amplifier stage's signal to ground at the vibrato rate... A very unusual and interesting circuit that may also be the source of your hum. Pull the vibrato tube and see if the hum goes away. I think I would also use your current measuring too to verify the currents in both output tubes are close to being balanced; or possibly add 1 ohm resistors to each tube cathode and verify balance by comparing the voltage drop across the resistors... I am getting an education by watching your videos and getting the opportunity of analyzing amplifier circuitry I would have never seen otherwise...

[@UncleDoug]

Thanks for the detailed analysis and helpful tips, Dennis.

[@johnnieguitar5724]

Great purchase! Great sleuthing to fix it. I'm a player not a tech but enjoy trying to follow your excellent explanations to further my understanding of tube amps. You are a good teacher. :)

[@UncleDoug]

Thanks so much, Johnnie :)

[@SiliconSet]

Great video Doug. So many thanks for sharing. I owned a VT-22 100w Ampeg for about 20 years. A great amp. It used a 6K11 and 7027A power tubes.

[@UncleDoug]

You're welcome, SS, and thanks for your nice comments. It's our first Ampeg, and we both love it !!

[@peterjlindley]

Another great video. Thanks to both you and Rusty for the diagnostic advice. I think it'll help when I start checking out my old Ace Tone amp.

[@UncleDoug]

You're welcome, Peter, and thanks for the nice comments. Best of luck with the Ace Tone (great name for an amp:)

[@benitomgomez3290]

Ace Tone was the first name for Roland , , ,,! 😜

[@rogercheese634]

Hi Doug. There are quite a few tube amp based videos on You Tube, but I find that yours are the ones that I keep going back to. What impresses me is not so much the technical information, although this is great, but the integrity of your approach. Second best is never good enough. I wish that there were more people like you in the world. Best wishes. Roger from Scotland UK

[@UncleDoug]

Greetings, Roger. Thanks so much for the very nice comments :)

[@TheRoiderien]

Many years ago I gigged with a jazz guitarist who had an Ampeg Gemini II from the same era. What a sweet sounding amp that was. Ampeg defied the zeitgeist and designed low distortion amps--they knew their stuff.

[@UncleDoug]

Yes, indeed. Ampeg amps are more commonly associated with bass guitar, but their regular guitar amps are excellent too. They were less common than several other brands, but held their own when it came to quality and sound.

[@cjsima]

I have a Gemini ii, it's amazing

[@owejohnson938]

Uncle Doug your videos are incredibly good ! And love how you are including Rusty. Big thanks from Amp healer in Sweden.

[@UncleDoug]

You're welcome, Owe. Rusty and I really appreciate your nice comments and thank you for watching :)

[@Slugg-O]

Hi Uncle Doug. Your self restraint and video skills are amazing. From stem to stern you meticulously recorded and explained every troubleshooting step needed to determine the problem before plugging in the guitar. If I came home with something like that it probably would have been dismantled in minutes with a video of me checking the floor for dropped parts. Thanks again for another great video.

[@UncleDoug]

You're welcome, Randy, and thanks for your nice comments. My wife would probably disagree with the "self restraint" part, especially while pointing to my room full o' amps and saying "Just how many of these %@&%?@% things do you really need?". The answer of course is......all of them :)

[@twerpeater]

Nice work. I'm always pleased to see a new Uncle Doug and Rusty video. Keep 'em coming sir. I too love the cosmetics of the old Ampegs. And tell your wife (and mine?) that you need them all.

[@UncleDoug]

Thanks, we will :)

[@johnfriedrich8608]

"See if Rusty and i hit a home run, or if we took it in the shorts"!!.....lol...thats worth the price of admission alone!!....great vid Uncle Doug...

[@UncleDoug]

Thanks, John. We've eaten it a few times, but lately our batting average has improved a lot. Glad you enjoyed the video :)

[@rickjorstad6666]

Thanks for the great video. I particularly enjoyed the step-by-step way that you went thru the amp to trouble-shoot it. . Very informative as usual! I had an opportunity to buy one on these years ago, but didn't really care for the tone, so I passed. I wish now that I had picked it up.

[@UncleDoug]

You're welcome, Rick. Maybe the one you saw was ailing, because this one really sounds great (hum aside.....and soon to be eliminated).

[@kauairalph108]

Aloha Uncle Doug and Rusty I love watching your videos. I wanted to share I found a 68 Band Master reverb a week ago for only 60 bucks, it was really dirty and rusty. I got it home plugged it in. only hum. I noticed the speaker which is a 15 inch was plugged into the extention Jack. I could barely plug my guitar into dirty jacks I cleaned it up and to my amazement wow sounds good. yesterday I put new in tubes in it and got a double peddal. wow the trem and reverb was awesom. Slight hum. I opened the foot switch and noticed the ground came loose fixed it much less hum. I am surprised it worked at all. hope you don't mind me sharing. That Ampeg sounds awesome.

[@UncleDoug]

On the contrary, we love to hear from our viewers about their amp experiences, Ralph. Thanks so much for your nice comments and for your interesting input.

[@toxicgraphix]

I'd bet a dog really could smell a bad component. .... just a reminder, for those canines that are not as experienced as Rusty, it would be wise to drain those capacitors before sniffing around inside a tube amp with a wet nose! Thanks to Rusty and Uncle Doug for another great video.

[@UncleDoug]

You're welcome, TG, and thanks for the helpful reminder. A dog standing on a concrete floor, sniffing a fully charged filter cap could get electrocuted......so be sure they're fully discharged prior to any sniff testing.

[@jjheaphy]

Excellent! Thanks Uncle Doug and Rusty.

[@UncleDoug]

You're welcome, John :)

[@zarbog8618]

Great job! Great simple, thorough walk through to determine the status o the P/S. Should be required viewing by those starting out in tube amp repairs!

[@UncleDoug]

Thanks, Z61.....glad you liked it :)

[@chrisw5077]

Nice seeing this as my first rebuild was the reissue of yours (SJ-12T) in mine the previous owner had disconnected the speaker to do some testing with another head unit. then a couple days later fired it up without the speaker attached. likewise the transformers wore good but almost everything else required replacement. it would have failed the sniff test ... :) thanks for the video.

[@UncleDoug]

You're welcome, Chris. I guess there would be no non-working bargain amps.....if there were no careless, forgetful previous owners :)

[@Finom1]

God Bless Rusty in doggy Heaven. Bless you and your wonderful family. My wife and I love going back and watching the old videos together. Rusty really stole the show:) Thank you for taking the times and sharing your wisdom with us in all your educational videos.

[@UncleDoug]

Thanks so much, F1, for your very nice comments. Likewise on the blessings :)

[@stevenwilliamdewitt]

Great video. Really great troubleshooting methodology. The "sniff" test is critical. Thanks!

[@UncleDoug]

You're welcome, Steve. Thanks for the nice comments :)

[@gripper021164]

Loving your vids Doug, very informative, I work on old Valve radios (Tube radio to your good self) and have a lot of pleasure doing so, I have rebuilt a few valve amps too, my favourite being the Vox AC15 which I kept for myself, so I find vids like this invaluable....Keep up the great work and I love your doggie Rusty, great character, so laid back Lol....All the very best from Oswestry U.K

[@UncleDoug]

Greetings, Gripper, and thanks for your nice comments. It's always good to hear from international viewers. Best wishes from Texas, USA.

[@TheRadioShop]

Love your videos and explanation of the troubleshooting skills. Also great to see Rusty and Jack in there with you.

[@UncleDoug]

Thanks, RS....we're glad to hear that you enjoy our antics :)

[@undefinedname1398]

Even though Rusty wasn't very enthusiastic about the amp, he does play the guitar like a rock star. And operates the camera nicely.

[@UncleDoug]

He's like a bright kid.....he only applies himself to what he personally likes, and to heck with all the rest :)

[@TheGuitologist]

Great video as usual, Doug. Cool amp as well! I have yet to find an Ampeg I did not like. Their guitar amps are really underrated. Most people have this mistaken belief they only do bass stuff. But anyway, one observation when testing transformers for continuity, you might get a false reading on the OT secondary if there is a NFB, because there may still be continuity even in the event of a blown secondary. But the resistance will be way higher than you should expect on an OT secondary, and instead will be the sum of the NFB resistor and the tube to which it connects' bias resistor.

[@TheGuitologist]

...if one side of the secondary is grounded, I should say.

[@UncleDoug]

Thanks, Brad, and thank you for the clarification on the continuity measurement of the secondary. I should have mentioned the possibility of a high reading with a NFB and that it would indicate an open secondary winding.

[@TheGuitologist]

No sweat...I'm always forgetting to mention stuff. Sometimes too much information goes in and not enough comes out the mouth, at least with me. :P

[@Shawn-uc6ds]

Great video. And a good find too. Power cord, tube, and 4 caps, makes a very good find. thanks for your video's, I hope to see more.

[@UncleDoug]

You're welcome, Shawn, and thanks for your nice comments.

[@utubehound69]

You hit a Home Run I think. $130 for Ampeg Tube Amp? Yes!!!!

[@UncleDoug]

Thanks, W4. Rusty and I celebrated late into the night, feasting on barbecue spare ribs and Coors Lite. He's still sleeping it off, while I had to get up to check on KZbin correspondence :)

[@nigeldurrant7868]

for what it's worth, the NF resistor was the culprit, changed it out and now the amps quiet as a mouse with no input signal, loud as you want when cranked. this is a "D " version with factory 7868 Output Tubes

[@UncleDoug]

Congratulations, Nigel, on a difficult repair.

[@pancakes1983]

Love watching your videos mate! I've learn heaps from them, keep up the good work!

[@UncleDoug]

Thanks so much, Brett.....glad to hear that the videos were helpful. Regards to the pup in your icon photo :)

[@stephengent9974]

At least a triple there Doug. I hope rusty got a suitable reward for his hard work. You would be lost without him

[@UncleDoug]

Darn, I was hoping for at least an infield home run :) Thanks, Stephen. Never fear, Rusty's contract stipulates generous compensation and bonuses for his sniffing skills.

[@daveb9370]

Another great video Uncle Doug, and sweet score! Rusty is so damn cute too.

[@UncleDoug]

Thanks, Dave. Rusty says, "Thanks" too :)

[@gregmath314]

Thanks a lot for your videos. They are very fun to watch, and I'm learning a lot!

[@UncleDoug]

You're welcome, Greg :)

[@audiotechlabs4650]

Great new post! I had an Ampeg amp in the 70's. It was smaller than this one. It had the same 12 pin preamp tube which was bad. could not find one at the time. Should have kept it. Thankz

[@UncleDoug]

You're welcome, ATL. Yes, I understand the Compactrons have been elusive for quite a while. I'm going to check around to see if I can find a couple extras, just in case I need one in the future.

[@carlpaulsen3996]

Fabulous! I just got one that needs cap replacement at least. This will be helpful as a guide while I refurbish my amp. Thank you! BGTW, mine is the same model, with 6BK11 preamp and tremolo and 7591 output tubes and solid state rectifier.

[@UncleDoug]

Good luck with your project, Carl.

[@CharlieTechie]

Excellent Job Uncle Doug!

[@UncleDoug]

Thanks, Chuck :)

[@Bigjoedo66]

Great Find Uncle Doug!! Rusty has been posting the he was looking for as different brand of Amplifier, on his blog

[@UncleDoug]

Thanks, Joe. Well, he definitely found one. It's the first non-bass Ampeg I have ever seen for sale in this area. Now, we're anxious to find more :)

[@GregsGarage]

I have to agree about the covering. Very cool. Rusty's nose for quality comes through again! Fun to follow along with the diagnostics.

[@UncleDoug]

Thanks, Greg.....glad you liked it :)

[@EmbelekoBand]

Thanks for sharing Uncle Doug & Rusty. Nice amp for your collection.

[@UncleDoug]

You're welcome, Gil. Yes, we really like it :)

[@EmbelekoBand]

+Uncle Doug hope you enjoy it. Looking forward to the next video on the slightly hum. It's not that bad though. It's not really noticeable. 👍👍

[@UncleDoug]

Thanks, Gil. People are always asking me for help with hum problems. I think this demonstrates just how tough it can be to track them down.

[@AHLAudio]

nice find! :)

[@UncleDoug]

Thanks, AHL. I watch CL every day and something like this turns up every few months, so the looking-to-finding ratio is quite high.....but worth the effort :)

[@tectalabyss]

Hi Doug. I finely got your video watched. Great tips has always. All my best to all of you. Bobby

[@UncleDoug]

Thanks, Bobby......glad you enjoyed it :)

[@greglivo]

Interesting to see the 7591's in a guitar amp. I have an early 60's Sherwood S-7000 stereo receiver that uses a quartet of them in the power amp. I never realized that they were used outside of hi-fi equipment.

[@UncleDoug]

Ampeg tends to use unconventional tubes in their amps, Greg, as do several other manufacturers, who also use 7591's.

[@howarddavies280]

Heathkits used them in their stereo (and mono) audio amps in the mid-late 60s.

[@garynash7594]

Oh Boy ! An Ampeg Jet !!!! I've got about 80 amps , Never have had a chance to buy one , New a guy who had one, Fantastic amp. 7591's badass.

[@UncleDoug]

Glad you enjoyed the video, Gary.

[@andydokken1012]

It's a good job you have Rusty there to advise. I'm not sure you could have got the Ampeg working without his invaluable help........Excellent Video - Thanks.

[@UncleDoug]

You're welcome, Andy, and thanks for your kind appraisal. You're absolutely right about Rusty's guidance......without it, I would be lost for sure :)

[@pauldow1648]

killer Craigslist find. beautiful production of your diagnostic/rehab. thanks.

[@UncleDoug]

You're welcome, Paul. We sincerely appreciate your kind words.

[@biffedya]

rusty is the best amp tech dog on youtube his ability to sniff out bad caps is amazing give him an extra snacktreat for me will ya....excellent videos learn alot from you thanks

[@UncleDoug]

You're welcome, Tim. Rusty is indeed a great asset to our organization.....and a loyal friend. We will both share some treats once I sign off of KZbin :)

[@PeterDad60]

Flawless playing and great tone!

[@UncleDoug]

Wow.....thanks so much, PD :)

[@alexkatsaros6180]

I blame you Uncle Doug! I’ve gone plumb guitar amp crazy! It’s all I think of! Thanks Uncle Doug!

[@UncleDoug]

You're welcome, Alex. There are far worse things to become obsessed with ;)

[@carlrudd1858]

oh, just excellent. This is your best, I think. So straightforward, so logical.

[@UncleDoug]

Thanks so much, Carl :)

[@wildbillhackett]

I was never a fan of Ampegs, but I always loved the sound of their reverb units. I had some cheap solid state Ampeg from the 70s that I used as a practice amp years ago, and even that cheap little SS amp had a great sounding reverb. I don't know what makes them so unique sounding, but that reverb was very cool.

[@UncleDoug]

I would love to experience an Ampeg reverb first hand, Billy. Let's hope that one shows up on Craigslist in the next few months :)

[@kloner]

Hmmm...no white paint. That IS a rare find. Thanks for the cool diagnostics.

[@UncleDoug]

Indeed.....another reason I initially suspected it of being a re-issue :) You're welcome. Thanks for watching.

[@theedrstrangelove]

Those are clutch head screws. I have a 90's re-issue of this. 26L6's 3 12ax7's and an added reverb. But I just opened mine and damned if it's not very similar.

[@timothyb1559]

Unfortunately my dog doesn't have as refined a sniffer. Another fantastic video with invaluable information. Thank you, Uncle Doug!

[@UncleDoug]

It was our pleasure, Tim :)

[@djfrank59]

This amplifier is a great find! I've had many modern day tubes with a H2C shorts. Not surprising these days...The hum could be from lead dress, but more likely from leaky bypass caps. Ampegs were in a class by themselves. very different from the Fender. These amps were actually built here in New Jersey. I have a few friends who used to work for Ampeg as service technicians. The company was excellent in supporting independent technicians. I used to get parts delivered sometimes, the same day! But, Ampeg now, isn't the same company as we knew it. It's now owned by Loud Technologies...

[@UncleDoug]

Thanks, Frank. I will focus on the bypass caps. One of them had a different ESR value than the others.....maybe it's the culprit.

[@A.WebbAndFriends]

I'm with you Frank, VINTAGE IS WAY BETTER. as I was saying to Doug I must have bought & sold approx 15 tube amps in my day. As for LOUD TECHNOLOGIES, I run Hot & Cold with LOUD Tech. The vintage all tube V50 & V32 are very sought after amps. I have them and love them. For the Studio I also have a 5 Watt V58 (not the VC508 - crappy amp) BUT ON THE OTHER HAND I ALSO had the BlackHeart "Little Giant" - where the tone was so generic it felt like playing through a cheap solid state amp. Had to use a Boss Blues Overdrive pedal just to get any semblance of a tube tone amp.Sold that POS real quick. Now down to 7 amps and 3 of them are all tube vintage CRATES.

[@djfrank59]

To be honest Molson, I repair these amplifiers for a living, and I've seen over the years how the quality and workmanship has gone down hill. Most of the reissue amps are very poorly made, and I DO NOT like the idea of putting output tube sockets on a PCB. I've had many Fender reissues and other amplifiers come in with completely chard circuit boards beyond repair. An output tube shorts, takes out the screen resistors, and burns holes right through the board. I've taken a few Fender Blues Jr's and gutted the board out and did point to point wiring. There's a reason why the amp is under $500. To sum it up simply in one word...China. You take it from there LOL :) If you find certain amplifiers that are hand-wired, point to point, you pay a hefty price for them.

[@djfrank59]

Also a little note to add...Ampeg's were also notorious for poor grounds. once these minor issues are solved, they are quiet as a kitten.

[@UncleDoug]

I will use that info while trouble-shooting, Frank. Thanks :)

[@ivandee4011]

Thank you so much for posting. I am now a new subscriber! All the best for the new year!

[@UncleDoug]

You're welcome, Ivan. Welcome to our channel !! Regards for the coming new year.

[@MisterTalkingMachine]

Never before had I seen compactrons outside a TV. Interesting little device.

[@UncleDoug]

This was my first experience with them, Mr. T. They are pretty snazzy :)

[@jagtone]

As the owner of a J12D, I very much enjoyed this video. I have a bunch of Fenders, but this is the sweetest amp I own, and a great one to control from the guitar--just crank the amp, dial back the guitar, and you get all the tones you really need (i.e. one, but a really good one). Those compactrons scare the heck out of me because the amp might as well be powered by unicorn teeth, but they are tough little suckers, and so far so good.

[@UncleDoug]

Thanks for your input, Ben. I agree with all, including the scariness of having a Compactron fail :(

[@raymondtheroux2472]

Thank you and Rusty, great vid always look forward to your videos

[@UncleDoug]

You're welcome, Raymond. We appreciate it :)

[@Calcouk]

Nice outro .. love that Tremolo... and a WOOF to Rusty on his hard work on those Transformers :)

[@UncleDoug]

Thanks, Calco. Rusty made it all possible :)

[@DeadKoby]

I just finished a short series on a 1967 Ampeg Portaflex SB-12. Turns out it was owned by "Polka Royalty" in this territory. Similar to a few you've seen, all it really needed was a bath, as the circuit was still completely healthy.

[@UncleDoug]

I guess it's natural for a polka amp to get a little soiled from all the beer and bratwurst flying around during a performance.

[@blackdogbite]

Doug...I love these. Got a Jet J12 B with the 6SN7 preamp and 6V6s rather than the BK11 and the 7591s. Jensen Concert Alnico 12...wonderful tone with humbuckers!!! Great value there Im envious! Perfect tolex. The handle is a replacement I'm sure. One of the major bugaboos with these is that the chassis/ panel rusts like crazy. I think if it stays in Aunt Tilly's basement for more than 5 minutes that plated finish is just dying to corrode. Just the cabinet, tolex, intact rust-free chassis is worth it! Oh yeah...the tremolo on this is so thick and rich...my favorite! Plug a 335 into that and crank the volume to 7! Sweet! PS..I hear Peter Frampton used to take on on the road packed in a big road case. He mic'ed the amp inside the cabinet...with the cover ON and cranked it. I don't know if this was to prevent bleed into the mic from other sources on stage or if it just really drove the mic hard.

[@UncleDoug]

Thanks so much for your interesting input, BDB.

[@blackdogbite]

UD... Did you find out what the 60 Hz hum was?

[@redfishbum]

Another Great video Uncle Doug!

[@UncleDoug]

Thanks, Bart :)

[@krang07]

Another great and super informative video Unc. Cheers.

[@UncleDoug]

Thanks, August :)

[@krang07]

to add, gem! seller took it in the shorts. lol cheers.

[@UncleDoug]

He did indeed, August, but I had mine at half mast for a while.....until it became apparent that the amp was basically quite nice. It's always a crap shoot (no pun intended) :)

[@cisc0kid1957]

Very nice and informative video.. Go Rusty!

[@UncleDoug]

Thanks, Danny :)

[@LincolnFStern]

I've been looking at building a 6SL7 based amp, which the earlier Jet J12s are based on. Thanks for this video!

[@UncleDoug]

You're welcome, Lincoln. Good luck with your project.

[@natskiman]

Hi,Doug,i have the ReverbeRocket model R-R12, Ampeg ,guitar,accordion,mic inputs,vibrato and echo peddle,the speaker is 12 inch Concert loudspeaker Radio speakers of Canada limited.Jensen,same handle and tolex? material,its warm and and way loud ,works fine.nice vid ,was very surprised to see the jet.

[@UncleDoug]

We were surprised to find a 60's Ampeg guitar (not bass) amp locally too, Nat. Hopefully, there will be more :)

[@jenniferwhitewolf3784]

Refreshing you know Ohm’s law, and how to continuity test transformers from easy to access points. Hope some of the others learn from this.. and HI to Rusty, from me and my collies.

[@UncleDoug]

Thanks, JW. I will......

[@cunning4nik8er]

Years ago, I bought a J12 for $25 from my girlfriend at the time. It had been bought brand new by her father, played a few times and then, after he suffered a minor stroke, boxed up and put into storage. It was literally in perfect condition when I bought it. Not a scratch, no corrosion... perfect. I lost my job and needed $100 that day to pay my rent and sold it for $100. It wasn't until I heard that this guy was bragging to his friends about taking advantage of some dumbass (me) that I realized what I'd done. This video literally made me break down and cry. Sorry, just had to get that off my chest. Thanks for your awesome videos, Unkie Doug

[@UncleDoug]

Nothing makes you feel worse than hearing some jerk bragging about getting the best of you, CF. I think we've all been forced to sell items we shouldn't, when the situation demanded it. To make you feel better, many years ago as part of a divorce settlement, I was forced to sell a mint 1962 Fuel Injected Corvette (Roman Red, Black interior, 4-speed, etc.) for $10K. Nowadays, every time I see one of them sell for over $150K at Barrett-Jackson, I get sick to my stomach. So don't feel alone. We all have our personal horror stories to recall :)

[@UncleDoug]

P.S. You're welcome for the videos. Best of luck :)

[@VIDS2013]

Ah, yes--I am quite familiar with the abusive divorce settlement! I highly recommend watching the film Divorce Corp, if you haven't seen it.

[@charleslambiase5670]

Happy Sunday morning I caught this video as well Rusty knows Best 🤫💜

[@UncleDoug]

Likewise, Charles. Yes, he did :)

[@charleslambiase5670]

@@UncleDoug you're cool Uncle Doug keep the videos coming I really honestlyI'm more of the player who goes after sound especially with my base but learning why things do certain things make it easier for me to come to conclusions on how to get to that point ♥️

[@amoruzz]

That's a great speaker you have in there too. A great score, congratulations! I've got a mid 60's Reverb O Rocket RT that sounded beautiful and has the Echo option with pedal that sounds killer with a strong dry signal that has a natural decay and doesn't get all cloudy or tinny like a SF Fender does, this is more wet. One day it made a "pop" and quit working like it was blowing speakers? It has one of those BK11's too and another short fatty? 6EU7's and a pair of 7868 output tubes. I was so disgusted with it that day, years back, that I just put it away somewhere? Your absolutely right about that blue covering! It's just beautiful when clean. It's a bit darker sounding amp, imo, but still nice. I actually prefer the earlier models from the early 60's with octagonal tubes, more simple and they sound really phatt and open paired with the right speaker. Many years back, I was offered a large stash of 6EU7's cheap and I passed them up. Never turn down good deals on nos tubes, lol! I was advised to swap the amp over to 12AX7's and possibly different output tubes as well in it, idk? I just parked it.. Too many irons in the fire at the time, etc.

[@UncleDoug]

Thanks for the nice comments and for sharing your experiences with us, Amo.

[@jmonk77]

This is like finding a 67 mustang fastback in the neighbors barn. I can't find any thing like that in my craigslist. Tell Rusty hi from Dandy.

[@UncleDoug]

Believe me, it's not common on our CL either, JD. There are generally loads of Fender Squiers with warped necks, non-working $25 SS amps, and drum sets that were run over by a truck. It took several months of looking for the Ampeg to appear. However, over the years, I have found a mint Fender SF Champ and VibroChamp, a Kustom K200B4, and a bunch of really nice PA amps.....so I must admit that it is worth the time each day to look at CL. Rusty says "Hi".

[@michaeljohnson7892]

I Love my JET, mine is a reissue I believe it was built in the 1990’s mine is a reverb, Tremolo was an option you could purchase separately. 1st time I turned it on I knew it was one of the few really great combo’s I would ever own for a very small amount of Cash !!! Yes it’s a keeper.

[@UncleDoug]

Ampeg makes a fine amp, Michael.

[@steelcity321pb6]

A super find, as well as a super bargain, you have there ...very nice indeed Doulas. The noun 'compactron' is certainly new to me (closest I've heard to that one is 'dekatron'). Never, in all of the thirty-six years in Audio, and television, servicing did I ever come across that terminology even though I worked with MVEs (multivalve envelopes) like, for example, EBL31 (double diode pentode), and UABC80 (triple diode triode). Another type of noun I have recently become acquainted is 'nuvistor'. It is certainly true, we never cease learning. When I saw those Roberson screws holding the back cover of your Ampeg J12D, I had to smile as it reminded me of the tamper preventative screws we occasionally fitted, like also torx, spanner slotted, tri-wing, mor-torq, spline etc., to certain (pain in the butt) customers television, radio, radiogram, or record player who appeared unable to resist the temptation of unscrewing, and removing, the back cover to determine whether the recent repair work, and the amount, and types, of components fitted, was as it was written on the invoice, whilst also taking a clandestine poke around in the back at the same time LOL. Regards, Phil.

[@audiotechlabs4650]

Those type screws were used in the late 60's into the 70's mobile home industry. If you could not find a screw bit to fit them, you had to grind a thick flat head screwdriver into one or even worst, drill them out with a drill bit. Thankz

[@UncleDoug]

Thanks, Phil. I tend to think the odd screws were to discourage tampering, but they can be fairly easily removed with a slotted screw driver (as I did).

[@UncleDoug]

I was able to remove them with a modified flat blade screwdriver, ATL, with no harm to the screw head.

[@audiotechlabs4650]

+Uncle Doug Back in the day, I rehabbed several rental trailers and the older ones always had those type of screws although the trailers. I'm so glad you had had no trouble with them! Thankz

[@UncleDoug]

I got them out without any problems, ATL.

[@charris939]

I haven't even watched this video yet, and I'm in love already!

[@UncleDoug]

Wait until you see Rusty in action, Colin. He steals the show :)

[@rustyaxelrod]

Thanks for the straight forward troubleshooting tips. The mic you are recording with sounds very nice also. New sub.

[@UncleDoug]

You're quite welcome, ARB. I really appreciate a positive comment about my microphone......Thanks !!!

[@greggraham8532]

Hi Uncle Doug... what an excellent video! Your testing techniques are fast, simple, and use minimal gear. And Rusty's diagnostic ability is uncanny. What could be better? BTW, the screws are called Robertson, a Canadian invention. Since they have four sides, they can torqued easier than a slotted screw, and the head of the driver is inside the screw, so fasteners don't get damaged as much. The Robertson bits hold a screw well, so also easier to start a screw one-handed or upside down. Same concept as Philips and Torx. I used to work for a Canadian company that exhibited at trade shows in the US, and we would have to take Robertson screwdrivers with us -- our booth was assembled with Robertson screws and the local tradesmen usually didn't have the right screwdrivers. Anyway, congratulations to you and Rusty for another top-notch video.

[@UncleDoug]

Thanks so much, Greg. Rusty and I really enjoy hearing nice comments from viewers (like you :)

[@Joe-mz6dc]

I bet Rusty does most of the work but he's just really humble.

[@UncleDoug]

If you ask him, he does ALL the work, Joe......but, just like Igor was to Dr. Frankenstein, he is a wonderful assistant :)

[@surgingcircuits6955]

You know, Uncle Doug, I kinda get the feeling that Rusty might be pulling the wool over your eyes a bit. Yeah, he was right about the transformers, and that is helpful, but I would suggest putting him to the test and see if he can run down that little bit of hum that's left. He'll probably try to shortcut you and blame it on a double ground somewhere in the house circuit, but I would press a bit. Either that, or pet him and say, "What a good dog.". Thx for your excellent videos.

[@UncleDoug]

You're welcome, SC. I'll sic him on the remaining hum......whenever he wakes up from his (seventh) nap :)