'69 Princeton Reverb.....Badly Burned, Brutally Botched, and (finally) Reborn

[@UncleDoug]

NOTES: 1.) I have upgraded to a broadband Internet provider, with uploads that are now 10X faster. I believe this has resulted in improved audio and video. See what you think. 2.) I did not realize during video production that the owner actually hand-built the replica cabinet, using vintage Fender Tolex. It completely fooled me. I thought it was an original replacement.

[@gerthalberg9735]

Hi Uncle - right on regarding video & audio

[@freepress8451]

Another fine video - do you celebrate Pancake Day (Shrove Tuesday) in US?

[@UncleDoug]

Thanks guys. No, we only celebrate Catnip Day......every day :)

[@peterespada6226]

I just discovered your videos a couple months

[@peterespada6226]

ago and am amazed with your deep erudition regarding electronics. Were you once a college professor or teacher in this field? I’ve learned so much so easily that I had always wondered about watching your videos...

[@Bbendfender]

Hey guys, I am the owner of this little Princeton Reverb. I just had to save it when I saw it. I'm not a tech so I let a "friend" look at it. He tried but couldn't do the job correctly. Along with this Princeton Reverb I also got a '63 Fender Bandmaster that was in the same burned condition of the Princeton. When I can afford it, I may get it refurbished. I know it will be another great amp. I am thankful to Uncle Doug for his great work.

[@UncleDoug]

Thanks for your comments, Bob. I hope you enjoyed the video. The PR is now one of the best sounding ones I have ever heard. We can talk about the Bandmaster. Hopefully, it hasn't been worked on previously. Also, the replica cabinet you constructed is truly outstanding. You have done us all a great favor by saving this badly damaged PR from the landfill.

[@coronadofishingclub3478]

Warm regards Uncle Doug. I enter into chemo therapy for lymphoma tomorrow and I hope to see some more videos to help me pass the time in the hospital. I wish your videos had been available 20 years ago when I started teaching myself about tube electronics, I could’ve avoided many mistakes. Thank you so much for taking the time to clarify and demystify this stuff! Once I beat the cancer I’m gonna start a new amp build and I owe it to you for re kindling my fascination for this wacky stuff. Cheers, Tim.

[@UncleDoug]

We are all wishing you the very best for a successful treatment and full recovery, Tim. The world needs all the tube amp lovers it can get. Your presence is definitely required.....so get well quick !!!

[@willford8475]

Good Luck, Mate. 👍

[@lousekoya1803]

We wanna see you back here in shape soon !!........Regards!...........Lou from Canada !!

[@FishnMusician]

Tim, get well soon man. You have folks pulling for you, whether you know it or not. Hoping for the best! Take care, and the very best of luck to you and yours.

[@tatialo37]

Praying for you!!!

[@ourlifeinwyoming4654]

It's amazing how connecting wires where they're supposed to go improves tone. This little guy was worth the effort - sounds amazing!

[@UncleDoug]

Thanks so much, OL :)

[@justinbouchard]

The alliteration in the title is fantastically fundamental for fixing fender flubs.

[@UncleDoug]

It sums up some serious shortcomings in the circuit :)

[@jagtone]

@@UncleDoug -- serious circuit silliness.

[@UncleDoug]

Amen, Ben :)

[@iskandertime747]

Well done sir, well done.

[@goodun6081]

@@UncleDoug , Snappy soldering, savvy skills, scientific study, and steely resolve surely solve somebody else's stupid snafus.

[@johntempleton6368]

You're spot on about the matching of the output tubes. A small to moderate difference in idle current does provide more harmonic content. I've found that once the difference goes beyond the 5 - 8 ma range that a bit of hum creeps in because the common mode rejection of noise is reduced. Great tip. Your trem mods are another killer tip that I've happily borrowed and used. Love your videos.

[@UncleDoug]

Thanks so much, John. Yes, excessive mismatch can result in reduced hum cancellation and core saturation......so it must be kept within reasonable limits.

[@fiddlix]

I have been doing this as well for years. We are talking about making music. Not reproducing it...!!

[@hallanvaara6106]

I haven't tried mismatched output tubes but Doug's theory about them makes perfect sense to me.

[@Geopholus]

This is a well known effect in electronic music (pulse width variation) if the upper going, wave is related to the bottom going wave by 3/4 or 4/3 it adds some pleasing even harmonics, though I'd rather be in control. of that by my playing style, picking closer the the bridge or the neck.

[@gitargris]

Wow! The audio is 100x better! Thanks! Now we can really bask in the sounds of all your great old amps!

[@UncleDoug]

Thanks, OR. I changed to a broadband Internet provider (120Mb/sec) and now the videos take 20 minutes to upload instead of 4 hours. I think the slow upload was degrading them.

[@Cdog5279]

Thank you Uncle Doug It’s almost December 24 and I’ve watched this video 15 times I learn something new each time I watch it and I thank you Uncle

[@UncleDoug]

That's great news, Cdog. Thanks for sharing :)

[@rogerraven6976]

Thank you for explaining the importance of the beaver dam in reverb setup.

[@edwardebel1847]

Your channel is the "Watch Mr. Wizard" for us aging children. So much education "disguised" as entertainment...or is it the other way around? I wish my electronic technology classes had been this engaging. Again, THANKS! 😊

[@UncleDoug]

High praise indeed, Edward. Thanks !!

[@TheGuitologist]

100% agreed on tube mismatching.

[@UncleDoug]

Thanks, Brad :)

[@fiddlix]

The Guitologist I could not agree more.

[@Dennis-mq6or]

Matched tubes might have eliminated that very small bit hum that was left in the amp because the hum would have been cancelled in the output transformer The only way to know for sure is to ground the input to the phase inverter. One other possible solution would have been to add a 100 ohm potentiometer between the two 100 ohm 'phantom ground' resistors with it's wiper attached to ground. Then adjusting that pot might be able to 'null out' the remaining hum.

[@DarthEcoli]

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts. " There's a good reason many of us choose to continue to learn before jumping into something we might make a complete mess of. Bertrand Russell couldn't have spoken truer words regarding this mess. Thank the gods you're a great troubleshooter.

[@UncleDoug]

Nice quotation, Paul......and never more accurate than in today's society.

[@kendavis8046]

Great trouble shooting and restoration of a classic amp. Thanks, Uncle Doug. If there is a future Sergio Leone, this amp can make the soundtrack! (To most young folks, that is likely a totally obscure reference.) Thumbs up!

[@UncleDoug]

You're welcome, Ken. The next time Sergio is over to visit with Jack & Ollie, I'll suggest it to him :)

[@renegade44040]

Don't like to but in...but let's give credit where it's due. Ennio Morricone is Sergio Leone's composer.

[@goodun6081]

A modern Sergio Leone movie will be titled *Twice* Upon a Time in the West. The music will be by Eno Morracowbell.....

[@kendavis8046]

@@goodun6081 He has a fever! And the only cure is Morracowbell.

[@leonardodic3po607]

It seems like the wiring of this amp was done by Sergio Aragonês!

[@andrewhodgson8895]

I think I’ve learned more from you in a week than I learned from 10 years at school. Thanks, Uncle Doug. 👍

[@UncleDoug]

Glad to hear it, Andrew. Thanks for watching :)

[@izzysantiago978]

The 2 thumbs down are the 2 idiots that messed up the wiring on this amp.

[@UncleDoug]

.......and their reward will be a colonoscopy with the unbiased 6V6 that blistered my finger :)

[@HasteFrankie]

@@UncleDoug ha! they deserve it. Hope that heals up quick. thank you for the great content as always!

[@freepress8451]

@@UncleDoug Ouch

[@jagtone]

LOL!

[@WCM1945]

@@UncleDoug _However..._ You _did_ notice the cherry-red plates, didn't you? Shouldn't that have given you a clue as to the temp of the tubes? I share you dissatisfaction with the "tech" who did the original work... He either didn't check his work for function, or just didn't give a s**t. I made some wiring errors in my time, but I would **_*never_* have let an amp in that condition leave my workbench.

[@markanthony653]

This guy could be a multi-millionaire(if he's not already) the way he fixes these amplifiers, truly one of the only people I've ever seen that can fix a amp properly, and more importantly you could trust!!! Hell, I trust him with my Marshall.

[@UncleDoug]

Thanks so much, Mark. I'm actually working on my second million dollars......I gave up on the first one :)

[@deadfreightwest5956]

_"With the axe in one hand, and the guitar in the other... which sounds redundant..."_ - I burst out laughing at that one. I don't even play guitar, but I got it.

[@UncleDoug]

Thanks, DF. Fortunately, I didn't get mixed up and play the axe while chopping with the guitar :)

[@ronniecastellanos8223]

@@UncleDoug Uncle doug I need app doctor I've been using amp for music on my phone during family functions and she started to smell smoky what do I do help Uncle duggy

[@JalopyTechnology]

I saw Uncle Doug at the ER the same day he had his finger repaired. In my case it was an index finger nail was charred by a 6v6... We both sat in the corner wearing dunce caps.

[@nelsonmedley4349]

Nice to listen and see a true master of vintage tubes. You inspire me and I learn lots with your teaching and presentations. You are realy objective and focus about electrónica thank you for teaching us. Congratulations and a big hug.

[@UncleDoug]

Thanks so much, Nelson. Likewise :)

[@vhollund]

I love watching this pretending i understand more than half of what's going on Maybe if i watch enough I'll learn it

[@soulvaccination8679]

Thats what i do...Ijust keep watching it and watching it and all of a sudden i get a moment of clarity .

[@Dennis-mq6or]

@@soulvaccination8679 Same here!

[@Mauitaoist]

I just finished rebuilding my Princeton thanks for all your help I have a 1966 original vintage

[@PrinceWesterburg]

Ace video - its nearly 3am but I'm so happy! Thanks for the plate current maths and tremolo mods, much appreciated.

[@UncleDoug]

You're welcome, Prince :)

[@carlmontney7916]

Another dandy Princeton Reverb and packed by someone who knows how to pack an amp for shipment. The mod to the tremolo circuit made a huge difference. Another great video. Excellent audio and video quality. Thanks

[@UncleDoug]

You're welcome, Carl. Yes, indeed, the owner did a great job personally packing the amp.....and, it will be easy to re-pack for its return trip. Thanks !!

[@cawfeedawg]

Doug you have super powers with bringing these beauties back to life.. we don't however want to see you in a cape and tights. 🤣

[@UncleDoug]

Thanks. No you don't, CD. In fact several of the neighbors have restraining orders against my donning such attire :)

[@bassiclogic]

You are the best Amplifier tech I have ever seen! Your skill and knowledge are on an Engineers level!

[@UncleDoug]

Wow, thanks, Michael :)

[@daleburrell6273]

27:31...the amplifier hums because it doesn't know the words(?)

[@strangersound]

Best teacher ever. Thanks, Doug. You make a circuit easy to understand. :) As for the people who wasted money on an incompetent tech...the end result is seeing Doug fix it and teach us the whole she-bang and then some (43:00). So, I'd say that was money well spent. :)

[@UncleDoug]

Thanks so much, SS. We really appreciate it :)

[@paulcargo4233]

Lets review today's lesson: Electricity like most people will take the path of least resistance.

[@UncleDoug]

So it seems, Paul :)

[@guitarocd9984]

My father was a ham radio operator. He built his own radios. I came home one day he was sitting in his chair with a spaced-out look on his face. He grabbed the wrong thing. Electricity went through his hand and blew a 2 inch hole in his leg. The doctor said it could have went to his member. LOL

[@UncleDoug]

Thank God he wasn't sitting on a metal stool, GO.

[@guitarocd9984]

The only thing that happened from it was he was mellow for a couple weeks.

[@UncleDoug]

@@guitarocd9984 I guess a shock once in a while is good for the soul :)

[@glenncollins4778]

Truly a joy to listen to and watch Uncle Doug

[@UncleDoug]

Thanks so much, Glenn.

[@jagtone]

Some people who never crank the reverb to that extreme will sub a 2M2 for the 3M3, which gives a more useable range for the reverb and gives the amp a bit more gain. But 3k3--OMG, no. Anyway, nice job on the forensics and the fixes. What great amps those are.

[@UncleDoug]

Thanks, Ben. Good advice :)

[@dwightbehm4747]

Uncle Doug saved the Day again With very logical Repairs to a nice old circuit fender design With corrections to the mistakes in parts and wiring. Hope I I'm not Annoying but I was up late could not sleep so I watched this vid again entertaining and informative exceptional way of teaching. I certainly Like it. Good luck live long

[@UncleDoug]

Viewers saying nice things are never annoying, Dwight. Thanks so much.

[@budandbean1]

Thank you Uncle Doug, this was really interesting. Excellent troubleshooting, really a fine job! Thanks for the tips about the virtual center tap too, you’ve gone over this a few times before but this time it really clicked. I just happen to have a solid state PA amp that has been humming a tiny bit since I bought it years ago that I’m going to see it this might knock that hum out of. Greatly appreciated, Buddy

[@UncleDoug]

You're welcome, Buddy. Thanks for all your very nice comments.

[@Magikflame]

@@UncleDoug I've just thoroughly enjoyed watching this vid and subbed. Yes I came across this type of thing many many years ago where there was a say 220 ohm pot across the filament winding with the wiper to earth marked as a.... Humdinger !!!! which I believe was in an old reel to reel....

[@timsterz1]

Awesome Job Uncle Doug. I'm appreciating your videos so much more, after slowly putting what you've taught me through the years, to good use. Thanks again.

[@UncleDoug]

Thanks, Tim. The learning process is definitely cumulative :)

[@0richbike]

A little bit of knowledge... Did the "rewired" amp start the fire?

[@UncleDoug]

If it had been allowed to remain "on" for very long, I think the unbiased 6V6 would have probably incinerated the entire block. Actually, I think it was a house fire and the amp, which was in good shape at the time, was a victim......not a cause.

[@russellesimonetta3835]

Like uncle doug sez if the amp looks altered keep the fire extinquisher handy and the fire department on speed dial.

[@goodun6081]

@@UncleDoug , I personally know of several cases where solid state, transistorized audio amplifiers or Hi-Fi stereos that were DC coupled and that did not have output relays, or even fuses, between the amplifier and the speakers, actually failed sufficiently to send full B+ ( anywhere from 35 volts to 150 volts, depending on the amplifier) through to the speakers and caused them to catch fire. Whenever we fix an amplifier like this at the stereo repair shop I work for, we add fuses inside the amp or supply appropriately-sized fuses and fuse holders and instruct the customer how to add them into the system between the speakers and the amplifier. The danger is if the stereo is left on while someone is away from home, or at night when everyone is sleeping, you risk Burning Down the House and maybe the occupants with it. Fortunately, most modern amplifiers , at least those used in a home audio situation, will have time delay relays that not only let the amplifier stabilize for a couple of seconds before turning on the output to the speakers, but that also disconnect the speaker wires from the amplifier internally if they sense a significant fault, any DC voltage that would cause speaker damage or worse. It bears mentioning that many high power PA amplifiers do not have relays and might not have speaker protection fuses either. A tube guitar amp, by comparison, is unlikely to set the speaker on fire, unless the output Transformer short circuits, however A Fault In The Amplifier can easily burn resistors and capacitors, then the wiring and the cabinet catches fire. or the tubes get so hot from lack of negative bias that they become cherry red glowing radiant heaters and set the cabinet and speaker on fire.

[@blairmulhall9259]

Uncle Doug is an invaluable resource, his note not to screw the reverb tank down too tight is on the money. I was once trouble shooting a reverb circuit that was feeding back uncontrollably and loosening the hold down screws solved the issue.

[@UncleDoug]

Thanks for your kind words and helpful input, Blair.

[@UBOOFTB]

Dear UD. It is Saturday afternoon, 1955. The band is practicing for the dance that night, and the tube dies in my amp. What do I do? I go down to the drugstore and buy a tube, pray when I put it in the amp it will work.Thank God, it works!. I can play at the dance tonight. Didn't even think about tube matching for a minute. :>) I love your videos don't ever stop!!

[@UncleDoug]

Those were the days, UB. I remember the big tube tester at the local Gunning Casteel (drug store) where you could test your tubes and buy new ones for 50 cents apiece.

[@grb1184]

@@UncleDoug My dad Ray had one at his stores, Colony Drugs and before that Orange Hill both in St. Pete Fla. My love for his love of this stuff brought me here.

[@WileECoyotey]

I remember tube testers in the 5&10 stores and Ace hardware .

[@russellsmith4615]

Thanks for doing these videos, Uncle Doug - I've learned so much from your video tutorials - they're thorough, well explained, and entertaining. I've been doing refurbish work on 3 Fender amps of my own as well as 3 others by friends and band mates thanks to you an a couple of others who are so kind to share their wealth of knowledge.

[@UncleDoug]

You're welcome, Russell. I'm glad the videos were helpful.

[@sting1111]

Botched and baked, a classic!

[@bruceeverett1993]

You almost( I say that with great respect) make it look easy. Glad there’s guys like you around! Thanks

[@UncleDoug]

Thank you, Bruce.

[@chrisleech1565]

Just had an idea for a series Uncle Doug, how about a Build-along-with-Doug ...DIY_Tube_Amp and one effects pedal. Plus a Speaker box or integrated like the Princeton etc. One of my favorite amps is the Roland Jazz Chorus 120 and I would love to make a smaller version of same for instance. It has stereo chorusing between each of its twin 12" speakers OMG it sounds good!! You could consider a thru hole kit build from Aliexpress maybe. Just a thought, but you could manage several vids out of that venture and have a blast at the same time.

[@UncleDoug]

Thanks for the suggestion, Chris. I have posted several video series that show all the steps in building an amp at home......strictly all-tube and point-to-point wiring.

[@Murry_in_Arizona]

Doug how tough would it be to modify a standard tremolo ( Ive got a 65 princeton reissue) or build a seperate pedal for the early 60's harmonic tremolo? I think the Lads at That Pedal Show with blues player Joey Landreth started a trend last year when they featured Joey and his vintage amps as a half a dozen new pedals with harmonic tremolo have come out.

[@UncleDoug]

If by Harmonic Tremolo, you mean the Fender circuit used in amps like the Brownface Concert, it would be a somewhat challenging multi-tube build. I would recommend that you watch my video on building a Rick-Tone Tremo-Boost. It's a relatively easy build with an inexpensive power supply and great tube tremolo effect.

[@Murry_in_Arizona]

@@UncleDoug "Harmonic Tremolo" is the part that's fascinating me U.D. The amp in question was a brown 1960 Super. Supro makes a pedal that approximates it ($250-$300) I'm at the beginner stage probably not a beginner project. FTR I've watched most of, if not all of your episodes ;0) long story short, I'm a 60 yr old retired/disabled Phx cop somehow Andertons music UK showed up in my YT feed 3 years ago and I got hooked on their guitar paradiso episodes which lead to following Mick Taylor to That Pedal show which lead to you and D-Labs when I started investigating tube amps after taking the guitar back up (starting as therapy for my hands after spinal cord injuries) after a 35 year hiatus.

[@smasica]

I'm reluctant to slag anyone else's work, but that amp tech must have worked on the amp after a rough night at the club. Wow, rookie mistakes galore. Doug, I respect your methodical, meticulous craftsmanship. I learn a bunch with every new video.

[@UncleDoug]

I agree, TM. In this case the previous work is condemnation enough :) Thanks !!!

[@justinoneil6971]

Hey, I talked to Jack Allen today about Darrel Braun’s review of the Stage Right 15 watt. He mentioned sending you some stuff and here we are...opening it up! What a crazy world we live in today

[@UncleDoug]

Yes, Jack was kind enough to send me the Alamo Futura and reverb tank shown in the video. It is indeed a small world.

[@justinoneil6971]

Uncle Doug I can make it even smaller, or at least more coincidental. I, too, live in Oklahoma and my son is named “Jack Allen O’Neil” Almost spooky.

[@williamproctor4925]

I very much enjoyed the video on the restoration of a 1969 Fender Princeton Reverb which was badly burned in a fire. I have been experimenting with a tube amp for a while now. Your insights on the workings of the tube amp are in greater detail than the information I received for ITT. Thank you for you video.

[@UncleDoug]

You're welcome, William. Glad you liked it :)

[@midnightraiin4035]

grab your surf board, we've got REvERB:)

[@UncleDoug]

Darn right, MR. Time for Jack to "Hang 8".......dew claws don't count.

[@TheFlyingRobert]

Thanks Uncle Doug, your energy and enthusiasm is very inspiring.

[@UncleDoug]

You're welcome, Robert :) Thanks !!

[@ObiTrev]

"Do it right or don't do it at all" - Everyone who does it right

[@robkal56]

Doug, ran across your channel. While not an electronics guy, I'm fascinated with your videos, maybe because they take me way back to high school and the two years of electronics I enjoyed. You are one good teacher

[@UncleDoug]

Thanks so much, Rob. Welcome to our channel.

[@billmiller7138]

Interesting, for blues harp I've been running intentionally mismatched output tube pairs for many years. Stumbled on it accidentally and it just sounded better to me.

[@UncleDoug]

I'm with you, Bill. The reason choirs sound so good is that everyone has a different voice.....and the blend is both complex and rich.

[@pharmerdavid1432]

@@UncleDoug Brilliant analogy, and we too love your videos!

[@82abn34]

Thanks Uncle Doug. Reminds me of a time I showed up to repair an electric forklift and found the house techs and already had a go. The thing was in many pieces and both techs were flummoxed. It took me several hours to reassemble before I could start the troubleshooting procedure. It turned out to be an intermittent control pot. This was always the first thing I checked for given the symptoms reported for the problem. It wasn't their fault. Their boss wanted them to take a crack at it before they called me. Those guy's were engine mechanics. They tried to save a little and winded up paying much more. Thanks to you and others, I have begun learning about tube circuits. I just refurbished a Heathkit VTVM and it works. Now I can watch a needle sweep with a high impedance meter instead of the old Simpson 260. Thanks again.

[@bemi-ton]

luckily enough there was no (virtual) center tap before as the plate was shorted to the filaments ;)

[@davidausterman5915]

...and botched. I'm glad to see you resurrected this one before the bad re-wire job finished off what the house fire started.

[@stratdude83]

The bias is set to about 900 watts! That had me rolling 😂

[@jeffm8122]

What a horrible mess that "technician" made of that amp. As a tech myself I was taught to always get someone else to check my wiring. Flying solo you can't do that so you always cross off each component and wire on the schematic as you progress. Even putting aside the wiring errors he made the sure sign of a careless repair guy is all the soldering iron burn marks to the wire insulation. He would be about as far away from Lupe Lopez standard as possible. You did a great job returning it to a fine sounding amp and thanks for the tech tips along the way. I'm sure the owner is very pleased. Regards, Jeff.

[@UncleDoug]

Thanks so much, Jeff. I agree that the original tech's eyesight may have been faulty, based on all the burnt insulation, wiring errors, and incorrect components.

[@W.E.]

04:07 How does a Fender amp chassis code of A 22264 mean 1969? Inquiring minds want to know. :)

[@erikjohansson1814]

Wayne Elliott I’d love to know the answer too...

[@budandbean1]

You have to look this one up. Fender Silver-face Princeton Reverb amps with code A21500 to A25500 were built in 1969. I have a little cheat sheet but there are tons of web sites that list the Fender number scheme.

[@UncleDoug]

Thanks, Buddy. You are right on the money :) Since the serial number was close to 21500, you can assume it was made early in the year's run.

[@W.E.]

@@budandbean1 Thanks guys; I had looked at this page superficially: www.superiormusic.com/page195.htm ... and saw "S" relating to 1969, but ... if one goes further down on the page on the right, the TRUTH will be found!

[@budandbean1]

@Wayne Elliott You know, if I had read that page, written like it is, I’d be a bit confused too. 😉

[@loopinnerthe]

You rescued it! You brought it back to a new and beautiful life. Despite the poor workmanship by the previous tech you were still graceful in your criticism of their blunders. Looks like this was a challenge that took you to very edge of your patience. At the beginning it looked like fix a shorted input jack and then just pack it back up and collect the cheque...how wrong we were, everything was wrong. Thank you for making this video UD it was a joy to watch.

[@UncleDoug]

Thanks so much, IL. Sometimes you have to be persistent to weed out all the different issues in a circuit.

[@drteming70]

Hear, hear. I purposely mismatch my output tubes in my push-pull amps. More sweet 2nd order harmonics.

[@guitarocd9984]

I know nothing about circuitry in amps. but was your statement based in science. Or just what you hear.

[@UncleDoug]

I'm glad to hear that I am not alone in this discovery. Let's hope people become more aware of the benefits of mismatching :)

[@UncleDoug]

@@guitarocd9984 Both. I have seen harmonic spectral analysis from perfectly matched vs mismatched output tubes. The spectrum is more complex for the mismatched......primarily even-order harmonics. To my ear, mismatched yields fuller, more musical output. The bottom line, however, is how it sounds to you. Do your own experimentation and see what you think.

[@guitarocd9984]

Okay I only commented because this was a new one on me. Good to know I'll definitely try it. My dad used to laugh at me when I used to tell him there is a difference in tubes. He was old school. He was dealing with televisions and Ham radios not guitar amplifiers. He's passed on but I never could convince him.

[@UncleDoug]

@@guitarocd9984 Don't be afraid to experiment with speakers either. Try a ceramic and an Alnico in the same 2 x 12 enclosure. You'll be surprised by how great they sound together.

[@Intrinsic.Recording]

After watching a second time with no distractions...it's little wonder there was a fire. Owner should be ecstatic with the amp now. Great job man.

[@UncleDoug]

He seems to be, JP. Thanks !!!

[@phonotical]

Woo

[@UncleDoug]

Hoo !

[@jakeblues3676]

Hey Uncle Doug I love you brother your humor and English prowess always brings a smile and appreciation of your efforts to help us learn how to deal with all the electronics projects.

[@UncleDoug]

Thanks so much, Jake.

[@billedwards2657]

I’d bet mojotone would have a rear face plate.

[@UncleDoug]

I'll let the owner know, Bill.

[@Starcrunch72]

@@UncleDoug Yup $24.60 SKU # 9131521

[@Bbendfender]

@@Starcrunch72 I ordered a back plate yesterday for the amp.

[@fiddlix]

You are absolutely correct about using slightly mismatched output tubes. I am glad someone else agrees with me. I'll bet Brad Lindzy would agree too.

[@UncleDoug]

Thanks, David. It's time that more people became aware of this.

[@chokkan7]

I'm fairly certain that Mojotone has interchangeable panels such as you're seeking, Uncle Doug. In addition, if needed, I can put you in touch with a vendor who can do these at very reasonable prices, although he doesn't attempt to do Fender copies...let me know... In an age of oppressive conformity such as we find ourselves, your occasional blasphemy is most welcome...

[@UncleDoug]

Hopefully, the owner will follow through with either Mojotone or your source, C7, to obtain a replacement rear panel. Yes, indeed, we specialize in blasphemy......indeed, we revel in it :)

[@timmyv694]

Uncle Doug , I’ve always thought if I keep watching your videos enough that some your vast knowledge will rub off on me and I have to say I believe it has . Several times now on your videos I have been able to come up with solutions to problems that you discover while repairing amplifiers. It turns out to be exactly what you end up doing. So maybe I am learning something . You’re a great teacher if you can teach this old dog some new tricks:) Thanks for making all your videos . Not only do I learn something but I’m also entertained while I learn .

[@UncleDoug]

That's great to hear, Tim. We're glad the videos have been helpful. You're welcome. Keep learning :)

[@Tonetwisters]

Not an amp tech here, but much agreed on the improved sound of mis-matched Output tubes ... I came from the old school where we knew nothing about matching tubes ... we just used what we had and made it work.

[@UncleDoug]

Thanks for your supportive input, TT.

[@michaelmcginley7412]

So great! Thanks, Doug. I really appreciate how you examine and explain the schematic, and then show where it is in the actual amp. It brings the whole thing together and makes it so much easier to understand.

[@UncleDoug]

You're welcome, Michael :)

[@michaelmcginley7412]

Oh, and not to bother you, but I think you might enjoy this podcast. It's called "The truth about vintage amps." www.fretboardjournal.com/podcasts/the-truth-about-tube-amps-ep.-1/

[@UncleDoug]

Thanks for the link, Michael. I will check it out when I get some free time.

[@ix-Xafra]

Great tip about how to spot loose socket connections. I fixed our bassplayers Bassman amp's intermittent output issues using the same method back in the late 80's and I also 'fattened' up the valve (tube) pins with the soldering iron. An epic repair with great sleuth work . Always enjoy your forensic detective analysis!

[@UncleDoug]

Thanks so much, Vinny :)

[@sethbrandes2979]

Was I the only one getting hungry with the cool whip containers in the background? Joking aside, what an informative session! I especially loved how you went back to the trace and explained why that incorrectly valued resistor back in the path was affecting the reverb's signal by not providing enough backpressure to force the signal down into the reverb circuit! Always learning on this channel!!! You rock Uncle Doug!!!

[@UncleDoug]

Thanks, Seth. I'm glad it all made sense. We do love our Kool Whip :)

[@andyk295]

Great video, thanks Uncle Doug. i just acquired a Princeton Reverb SF and am in the process of restoring it. Your videos help so much.

[@UncleDoug]

That's great to hear, Andy. Best of luck with your project.

[@spazimdam]

Very good demonstration of proper repair procedure. Always a treat to watch your vids Uncle Doug; they confirm methods that I have found valuable in years of tube amp repair, and a few valuable insights that are new to me. Too cool.

[@UncleDoug]

Thanks, Monte. We're glad the video was informative.

[@williamhill6705]

Nothing short of miraculous uncle doug, the amp deserves it though! i hope the owner is suitably impressed and satisfied, whatever the cost ,its a living breathing tone machine again ,beautiful and miriad musical choices of voices,

[@UncleDoug]

Thanks so much, William. The owner was indeed quite satisfied with the result.

[@hpelisr]

Great rescue Uncle Doug. I think I learned a little about the resister mixing of the reverb.When you pointed out the resister between the two stages,I seen the line running down to the reverb section,and the light bulb went on. So they say. Thanks for the great demo.

[@UncleDoug]

You're welcome, Hack. It's great that you are able to spot small details like that. Sometimes when looking at the entire circuit, the small stuff is hard to quickly detect.

[@jackallen6261]

Hey UD, I think Link Wray would be proud of your tremolo repair on this beast. Interesting repair on the reverb as well, I learn something new with every video I watch of your repairs, thank you! And you are very welcome on the old Alamo amp as well. I know it is in good hands now and am very glad you like it, I thought it was the least I could do to help out the channel since I completely learned how to work on tube amps by watching your how a tube amp works instructional videos on your channel! It's a cool hobby and I never could have done it without your helpful instruction. It amazes me how someone could stay in business as an amp tech turning out work like this. Have a wonderful day!! Oh and say hi to Jack and Ollie and now KC as well!

[@UncleDoug]

Thanks so much, Jack, for the Alamo chassis and the very nice comments. It's great to hear that the videos are helpful. Regards from all of us :)

[@jackallen6261]

Oh no, UD Thank you!! The videos are most helpful!! I would be where I am today with out your help!! Have a great day!!

[@UncleDoug]

You're quite welcome, Jack. Likewise.

[@ima640]

Hi Doug, another great video. You know your in trouble when the customer says, "someone else had a look at it, but it's still not working properly", happens all the time. I normally walk away, more trouble than its worth. Keep up the great work, very enjoyable content.

[@UncleDoug]

Thanks, Ima :)

[@lynnbath6423]

Uncle Doug, another great video. I love your persistence in not just fixing the things that are bad, but also making sure that everything is right. Whenever I work on a vintage amplifier I always check out the wiring and connections. Especially if I know that someone has worked on it. And I always find something that isn't quite right. It is a rare occasion anymore to get an amplifier that hasn't had some work done to it. I did some work on a Vox BerkeleyII for my son a while back. It wasn't working. I found several transistors that had been replaced that were installed backwards from what they should have been. And several wires that were very poorly soldered. When I got it finished, it sounded wonderful and it was a very quiet amp. Thanks for the very interesting and fun videos.

[@UncleDoug]

You're welcome, Lynn. Thanks for all your nice comments.

[@davida1hiwaaynet]

Your level of knowledge and patience never ceases to amaze me. Thanks for sharing this very tough repair job!

[@UncleDoug]

You're welcome, David. Thanks !!

[@electroKrunch]

I love these investigation/repair vids, thanks for what you do. I've got a Chinese made Crate V100 head that burned from an incorrect tube install that I've been putting off looking into for 10+ years. You are getting me motivated..... Thanks!!

[@UncleDoug]

Thanks, Karl. Get to work on that Crate amp.....if you don't fix it, who will ? :)

[@electroKrunch]

@@UncleDoug So true... I don't have staff here to call upon, hehehe. After I replace melted parts & find no love, what should I do?? I haven't found much for scheme's on this amp....

[@jordancraighead]

gives me new appreciation for printed circuit boards from a troubleshooting perspective.

[@UncleDoug]

.......and yet, those of us who prefer point-to-point circuitry would say just the opposite, Jordan. Its just a testimony to the variation in individual preferences.

[@circuitmonkey6653]

Once again, beautiful work. I have some jukebox vacuum tube amps a customer brought in for repair. I told him at the beginning that it would be a rather long wait as I have no idea what I am doing with these(I suggested he take them to someone that did, but his faith in my ability is far greater than mine). One seems to have had very little work done, at least in recent years, another has been mostly recapped and is dead as a door nail. I work on solid state, so having you explain in such painstaking detail the circuitry and theory is greatly appreciated. I don't want to be the jack wagon that returns his amps in any kind of condition that resembles the amp in this video. Sure, a lot of components have been replaced with components of reasonable quality, but clearly little testing was done to ensure the wiring was correct or proper value components were used. I will carry this with me as I slowly proceed through these repairs and into future repairs. Your work is greatly appreciated and I hope you keep it up. Thank you for teaching us.

[@UncleDoug]

You're welcome, CM. I started out working on jukebox amps from the 30's and 40's. Best of luck with them.

[@dalerobinson3091]

Wow, a lot of wiring errors you tracked down; great work. The amp owner will appreciate the reborn amp.

[@UncleDoug]

It was a real challenge, Dale. Thanks.

[@PLINKER]

Wow sounds great Uncle Doug. your touch is just what that mess needed.

[@UncleDoug]

Thanks, Tom.

[@murratosmani6517]

This was a hard test! Glad that B+ was not connected to the input jacks and nobody has been killed.

[@UncleDoug]

I'm glad too, Murrat......and a little surprised that it wasn't :)

[@Finom1]

Thank you Uncle Doug for bringing another vintage tube back from the grave, Great educational video once again,

[@UncleDoug]

You're welcome, F1.

[@MrUbiquitousTech]

When I first got into tube radio repair I bought this sad sack of a radio off of ebay. It did not work, nothing happened when you turned it on. I did the shot-gun recapping that newbies are told to do, check the tubes, power switch, etc. Got the schematic, scratched my head over it for a while before I realized (newbie recall) that someone in the past had removed the canned-ohm resistor from the radio, wired the radio with it out of circuit and no replacement resistors! Then to add insult to injury they ran both side of the line cord to one tube. So hot and common through the switch and then to different pins on the rectifier. And no power going anywhere else...... And it all looked like old work so it happened a long time ago. _Not_ a good radio to start on. Nicely done on that one Doug, sounds awesome! Glad the skin graft went well. ;o) The owner did a stellar job recreating that cabinet, never would have guessed that.

[@UncleDoug]

The really tough challenges are often the best learning experiences, Shy. Thanks !!

[@daveogarf]

Uncle Doug, I'm AMAZED that you've managed to find such Talented kitty cats! String bends, complex chords, etc. seem to be a snap for them! Thank you so much for showcasing them and their talents. That amp could've been ever so painful to repair, but by following the schematic, coupled with your pre-existing knowledge of the beast, you found small but important errors in the circuitry.

[@UncleDoug]

Thanks for your kind words, Dave. Yes, we were lucky to have adopted kitties who were also excellent musicians :)

[@jeremyacker1388]

Uncle Doug, you are amazing! I love your videos. I just wish I had your knowledge. Thank you for explaining things and using diagrams. Please don't stop!

[@UncleDoug]

You're welcome, Jeremy. We won't :)

[@daveogarf]

DAMN! Your cats are SOOOO TALENTED! Their demos of repaired products are invaluable.

[@UncleDoug]

I'd be lost without them, Dave :)

[@johnb5519]

Looks like they finally sent this one to the right guy. Your straight forward logical approach makes it look easy. Certainly the previous person couldn't read the schematics. Yes the thumbs down are disturbing. I have noticed that some youtubers have great followings even if they don't show how to do things correctly. People who don't know any better, vehemently defend them when someone suggests they do something differently. Just the way it is.

[@UncleDoug]

Thanks so much, John. Yes, you can get frustrated if you worry too much about trying to please everyone. Some people will reflexively give a thumbs down purely due to a childish inferiority complex.....others are simply assh*les :)

[@blairmulhall9259]

@@UncleDoug glad I gave this a thumbs up. Lol 😂

[@UncleDoug]

@@blairmulhall9259 So are we, Blair :)

[@birkettaustin]

so many rookie mistakes from a so called tech. another great restoration uncle doug!

[@UncleDoug]

Thanks, Austin :)

[@horsthartung4682]

Fantastic job on the restoration of this amp.....but you've really got to learn the proper way to play "Born On The Bayou"....haha

[@UncleDoug]

Thanks, Horst. The cats like to add a personal touch to their covers ;)

[@josephmagedanz4070]

Great save and lots of good teaching to boot. That's one of the things I like most about your channel. Thanks, UD.

[@UncleDoug]

You're welcome, Joseph. Thanks so much :)

[@bobross6802]

Right on, Doug. When I was repairing TV/stereos the customer would bring a TV into the shop with half the back screws missing and tell me that his friend who was an electrician had tried to fix the "no sound" fault and now the TV doesn't turn on ...... he wants an estimate. You did a great job with that amp - a story with a happy ending :0)

[@UncleDoug]

Thanks so much, Bob. You've been there and know just how bad these "pre-repaired" projects can be :)

[@pcbullets8726]

What a handful this amp was. Had faith all along you could fix it. Definitely have learned a lot watching these videos, although I am a novice myself. Great video Uncle Doug!

[@UncleDoug]

Thanks, PC :)

[@sonicweaver]

Another stellar & entertaining restoration...nice job Doug!

[@UncleDoug]

Thanks, SW :)

[@Ideal1980]

Thanks Uncle Doug, love the videos. I have an uncle too, his name is Hans. We watch all your videos, and we also watch «El Paso Tube amps», and discuss your videos at length on the phone. I hope you are doing well, and the cats.

[@UncleDoug]

You're welcome, Ideal. We're all doing quite well, thanks :)

[@rockgtr35]

These are just the best videos of this kind. Excellent explanations, camera work, and commentary!

[@UncleDoug]

Thanks so much, Jason. We appreciate it :)

[@AROSFC]

Thanks for a well spent 45min! Another gem of expertise and fine humor! Hope your fingers get well soon. I guess amps are like engines, if they were heavily serviced before, it can be a nightmare...now i'm going to watch 'Rio's carnaval' .....on the tele of course...

[@UncleDoug]

You're welcome, E1. Thanks !!

[@PeterDad60]

Great video Doug! I studied Violin and Fresco painting and ended up as a mechanical designer/engineer as my actual career. I love your in depth, thorough, logical and complete presentations of how amplifiers function. I seem to like amplifier design even more than the other livelihoods I mentioned. FWIW as my 5th Grade teacher taught us in 1961 that 1961 is one of the few numbers that when turned upside down remains the same, ie. 1961 is 1961 upside down/right side up. I mention this because I was the no. 1,961 person to hit the "Like" button for this video. A satisfying action on my part, as once I decided to hit the like button at that moment I saw and recognized the 1960 as being modified by my action to become the wonderful number 1961. I actually almost muffed it in my fast reaction, desire to enter a "Like" in time to me that person. I was 11 in 1961 so that was a special year in my life. I'm turning 70 in 4 more day's on this Monday March 23, 2020! -Peter. P.S. I only wish you that you would start a University for teaching electronics with a Major in Guitar Amplifiers. I have studied electronic/electric drafting and that was the first step in becoming a Mechanical Designer. I have drawn up many, many schematics-most of them were HVAC Control wiring circuits/diagrams.

[@UncleDoug]

Greetings, Pete. It's always good to hear from you. Thanks for sharing your observations and comments.

[@NickRatnieks]

Woodman spare that amp! Another detective story of impeccable perspicacity. As it is often said: "You can't buy experience."

[@UncleDoug]

Thanks, Nick. Be sure to watch my latest video on the Gibson ga55v cabinet :)

[@jillwas]

Thanks Doug-I'm glad you didn't axe that amp. I also wish you were my Dad so I could visit you and your shop frequently!

[@UncleDoug]

You're welcome, Jeff. If that were the case, I guess you would inherit all my amps and tools :)

[@markomaticd4106]

You are very patient & use the mistakes to teach. I think I would have had to have stripped the chassis entirely and started from scratch. There would have been none of the teaching points that you demonstrated and so much would have been missed. Thanks for another great video. I have a "project amp" with 2 6v6s I was going to sell at my rummage sale, but maybe I should re-think that.......

[@UncleDoug]

Thanks for your nice comments and observations, Mark. Good luck with your project.

[@jensenbell]

The mistakes made by the previous "tech" made my stomach hurt with anxiety... seeing it get solved with explanations not only relieved the discomfort, it gave me more confidence in the order of physics and the possibilities of this universe. I felt good about being itself because order was achieved. I think the most calming soothing balm is the thoughts and logic coming from the mind of Uncle Doug. There. I said it.

[@UncleDoug]

And we appreciate it, Jensen. Thanks !! I'm glad our repair efforts were able to quell your anxiety :)