1968 Fender AB763 Twin Reverb: Evaluation, Modification, Extended Audio Demo

This video features a 1968 Fender AB-763 Fender Twin Reverb (a black-face circuit in a silver-face cabinet). The amp was recently purchased and sent directly to me by the owner for a complete evaluation, tune up, and modification, as-needed. The prior work appeared to be of good quality, so I focused on testing and replacing components as needed; installing and biasing a new Quad of 6L6GC's, rewiring the primary AC circuit and creating a switchable NFB loop with the Ground toggle, and slowing down the Tremolo. To prove functionality, we performed an extended audio demo, with 21 different tunes utilizing all possible combinations of inputs, channels, guitar pickups, reverb, and tremolo.
In addition, our Part 2 Video features a drone flight into a rocky canyon to an ancient rock house, with a comparison of this house to more recent ones which have "sprung up" in the neighborhood ;)
If you are interested in viewing a Technical Video explaining the theory and practice of biasing double and quad-ended amps, here is the link: • How to Bias a Quad or ...
If you enjoy advertising-free videos like this one, be sure to SUBSCRIBE to our channel and consider becoming a Patreon patron at / uncledougsvintageamps or making a PayPal contribution to [e-mail]. Thanks for watching !!!

[@analognoir7398]

2:03 First look at the amp 4:32 Dog house filter caps 11:36 First look at the circuit 15:12 350 volts of fun 15:47 Removal of 2nd power transformer center tap 19:13 Grid stoppers 20:04 Current limiter and biasing 4 output tubes 22:11 Finding plate voltages for 6L6B tubes 24:57 *Uncle Doug’s video on biasing double/quad ended amps 25:06 New (plate current) matched tubes 26:20 Amp biasing with only a multimeter 26:40 Identifying output tube pairs in a quad ended amp 37:55 Signal generator (400HZ tone) 41:26 Slowing the trem 42:45 Capacitor inventory 43:35 Alligator clipping capacitors into the trem circuit 44:10 Reverb tank and circuit evaluation 45:34 Negative feedback switch / Rewiring power cord 49:40 NFB loop - audio demonstration 50:55 P-90 pickup - audio demonstration 56:42 Single coil - audio demonstratio 1:00:21 Humbucker - audio demonstration 1:03:05 Humbucker + reverb - audio demonstration 1:06:33 Final thoughts 1:08:40 Texas drone blues

[@ucanliv4ever]

Gee thanks for spoiling it for me... maybe Uncle Doug should consider doing alternate ending out takes to keep the element of surprise

[@captcdd]

Uncle Doug, I recently bought a 68 silver drip face at a great price. When I got it home and after reading how to tell the difference I discovered the reason for the great price was it had the AC 568 circuit even though labeled AB 763. Made week 34 on 1968 I would like to get it back the the best of the AB 763. I see several mentions of this up/down grade on the interwebs but wanted to know if you have anything on this. I don't mind spending money on it because of love the twin reverb sound. After watching most of your videos and subscribing, I think I would like to tackle the job myself to feed my true geek desire.. Any thoughts on that as well? I would like to also implement some of the audio improvement you did in this video. Thanks for your videos on this stuff. I find myself watching them for hours and learning much.. Dave

[@UncleDoug]

Wow....thanks for the detailed Table of Contents, LB :)

[@UncleDoug]

Greetings, Dave. If you feel qualified to perform the modifications, by all means do so. Some will probably yield little or no improvement in tone, but that's for you to discover. Good luck.

[@xavibsa]

Hi Uncle Doug. I just want to tell you that please, don't never die. We need you!! Take care.

[@UncleDoug]

I can assure you that I'll do everything I can to follow your advice, BSA :)

[@robinosborne266]

Another lovely long video from Uncle Doug!!! I have health problems which mean that I have trouble sleeping so am out of bed around 4.45am each morning. I love it when I check KZbin and find a long video like this from Uncle Doug - it really passes the time until the rest of the world surfaces. Thank you again for the brilliant videos and please keep them coming.

[@UncleDoug]

Thanks so much, Robin. We're glad you enjoy the videos.

[@edwardebel1847]

You know, opening up a box on any other channel would be positively soporific...But for Uncle Doug its his best standup material!

[@UncleDoug]

We try to live up the otherwise dull process :)

[@ManMartin]

LOVE your radio voice and your sens of humor. Cheers from Majorca island, Spain.

[@UncleDoug]

Wow, thank you, MM. What an exotic location. Jack and I are jealous ;)

[@Tonetwisters]

For sure! I told him he ought to be reading Bible verses onto tape with that high quality voice!

[@backspin6698]

Dear Uncle Doug. May you live forever. Cheers from an ampoholic from Sweden.

[@UncleDoug]

Thanks so much, B66......and may you do the same ;)

[@timothyandrews2157]

Thanks again Uncle Doug. I watched this video when it first came out. Watching it again shows me how much I've learned from you. This time I knew what you were talking about and was even able to successfully guess your next move a couple of times. The best part of this for me was watching you bias the amp without the eurotubes probes. Now I understand how to bias, something I was struggling with.👍

[@UncleDoug]

It's great to hear that the videos have been informative, Tim. Best wishes for continued success with your self-education program.

[@jimhibert]

Makes the 4th of July look like Labor Day weekend. Priceless.

[@blairpenney7967]

Another excellent amp tune-up video, sounds great!

[@UncleDoug]

Thanks, Blair. Glad you liked it :)

[@hahaagi]

Great Video. Thanks Always!

[@UncleDoug]

Our pleasure :)

[@lancehenderson6467]

Hi Uncle Doug! Wanted to let you know that I think your videos are the best - I learn so much! I actually have a 1968 AB763 Silverface Fender Twin Reverb exactly like the one you work on in this video. I have just finished a complete restoration of my Twin and I relied heavily on your video. My Twin sounds amazing and is now good for another few decades. Thank you so much for the entertaining educational videos. You're the best - love your cats too!

[@abubakr6939]

You really played nice on this video!

[@UncleDoug]

Thanks, Abu. I'll pass your compliment on to Los Gatos :)

[@texanfournow]

23:05 You tune in for the electronics, you stay for the jokes. :)

[@UncleDoug]

Just as long as you tune in, T4 :)

[@rádiosantigos1958]

Congrats again Uncle Doug! A nice demonstration.

[@UncleDoug]

Thanks for watching, RA :)

[@Wildman9]

Getting better all the time . These videos are priceless to us Fender Fanatics . Thanks Doug. 🎸😎

[@UncleDoug]

Glad you like them, Bob. Thanks !!

[@gareths9574]

I'm glad there's people like you around. Passing knowledge and keeping records of old vintage amps. Your videos are great and are so informative, great guy,

[@UncleDoug]

Thanks so much, Gareth.

[@spacegoat77]

Thank you, thank you, thank you. Great bias explanation for a twin reverb!! Managed to get mine set perfect

[@UncleDoug]

That's great to hear, Steve. Have a wonderful Christmas.

[@ima640]

Great work Doug, nice tune up, sounding very nice. Thanks for posting and putting smiles on viewers faces.

[@UncleDoug]

Thanks so much, Ima. Glad you enjoyed it :)

[@brianspilsted7320]

Another first class video Doug. I thoroughly enjoyed watching this as I have for all of your postings.

[@UncleDoug]

Thanks, Brian. Glad you enjoyed it :)

[@flaconsius]

Thank you very much for all the information that you share. Your Videos are a great Resource for those who are triyng to learn this area of electronics. Cheers.

[@UncleDoug]

You're very welcome. Glad the videos are helpful.

[@Byron_Blue]

Good catch on the output tubes. Best to question any changes. Rock on lad!

[@UncleDoug]

Thanks, Byron. Will do :)

[@stratdude83]

Doug, you remind me of Tim's neighbor Wilson from home improvement. Your friendly neighborhood amp tech guy!

[@UncleDoug]

I guess there are some similarities, SD. I wish my neighbor was more like Tim Allen.

[@jwingo7257]

Uncle Doug’s voice reminds me of Gene Shepherd’s narration voice especially in his movie, A Christmas Story.

[@williambock1821]

Great soundtrack for the drone footage!

[@UncleDoug]

Thanks 👍

[@s.thompson867]

Excellent content as usual. Loved the Crossroads reference!

[@UncleDoug]

Glad you enjoyed it, ST.

[@TonyAllmanMusic]

Uncle Dough: Thank you for another fun yet informative video. My questions on biasing my twin have been answered. Great reference material. Thanks

[@UncleDoug]

You're quite welcome, Anthony. That's good to hear.

[@JS-ol9ou]

Thank you Uncle Doug for the thorough demonstration and explanation of the manual tube biasing process for fixed bias amps. Highly appreciated!

[@UncleDoug]

You're welcome, JS. Glad it was helpful :)

[@jeffmitchell9214]

U. Doug, I just have to tell you that this video is so very outstanding. I cannot remember a better time in quite a while. Thanks

[@UncleDoug]

Glad you enjoyed it, Jeff. Thanks.

[@DNFADV]

Appreciate all your videos. And that dry humor well. Keep it up! The occasional outburst of uncontrollable laughter is the most welcomed.

[@UncleDoug]

Glad you like them, SP. They say that laughter is the best medicine :)

[@DNFADV]

@@UncleDoug cost effective!

[@analognoir7398]

I just want to take a moment to thank you for your time and effort in passing on this valuable information. You’ve helped me diagnose and repair 4 vintage amps since I started watching your channel. Ive already saved at least 1000 and still the information you’ve taught me is far more valuable. Anyway, thanks again Uncle Doug (: Keep those equations coming!

[@UncleDoug]

You are quite welcome, LR. I'm glad to hear that the videos are helpful......and profitable ;)

[@jeremiahlyleseditor437]

Great Video and Tutorial

[@UncleDoug]

Thanks, Jeremiah :)

[@raycochrane3971]

Another wonderful walk through.

[@UncleDoug]

Glad you enjoyed it, Ray.

[@plgplgplg]

Another great video

[@UncleDoug]

Thanks, P3 :)

[@brianm9282]

My father used to always say "we must quell these strident tones". He passed in 1989 but you remind me of him in many good ways.

[@UncleDoug]

Your father was right, Brian. Strident is best reserved for fingernail on blackboards......not amps ;)

[@brianm9282]

@@UncleDoug funny you mentioned blackboards, he was a Chicago Public School Teacher.

[@rjprivate]

Thanks uncle Doug. By far the best electronics videos on youtube

[@UncleDoug]

Wow, thanks, RJ. Glad you like them :)

[@MegaTubescreamer]

right in the pocket ,thats as good as any amp could wish to sound, every setting /pickup combination was excellent, fine job uncle doug, flawless !

[@UncleDoug]

Glad you liked it, William. Thanks !!!

[@amoruzz]

Great job!

[@UncleDoug]

Thanks, Amo :)

[@adzbasslines268]

I enjoy this channel for the preposterous metaphors! We expect this in general conversation here in Australia!

[@UncleDoug]

As a charter member of The Society for Preposterous, Asinine Metaphors, i.e. SPAM, I thank you.

[@66g0yy]

Love your show, I thought you switched to cars, you made that fun too, thankyou uncle Doug, and all pets, so glad you back or never left ..stay safe an happy

[@UncleDoug]

Thanks so much, Michelle. We started a second YT channel dedicated to hot rods: Uncle Doug's Hot Rod Garage. Please check it out if you have the time.

[@timka880057]

Hey Uncle Doug! I've learned allot watching you and Brad the Guitologist and a few others over the years on KZbin. Here again, another great video, be safe, thanks so much!

[@UncleDoug]

You're welcome, CTE. Glad the videos are helpful :)

[@bobboyle7629]

Love the Channel. Here it is 2:30am, and I'm looking for more Uncle Doug vids for my playlist. Thanks so much for these informative and thoroughly entertaining videos!! For Fenderholics like myself, there ain't a better channel around, man! Thanks again.

[@UncleDoug]

You're welcome, Bob.

[@nathanwatrous1519]

I have been experimenting with variable negative feed back using a low value pot, I decided to try this after watching your mod with using the left over ground switch. I have been really happy with the results.

[@UncleDoug]

I'm glad it worked for you, Nathan.

[@adenihil]

Definitely my FAVORITE uncle! Thanks man.

[@UncleDoug]

It's always good to hear from my long-lost nephew, Adrien. You're welcome.

[@cassvirgillo3395]

Hello Uncle Doug& Family, Another quality repair, you take pride and care in your craftsmanship. What a great tutorial video, great detail and explanations, as only Uncle Doug can do. Glad your doing well and staying busy. Back to normal in Oregon, four days of upper 80's, then Winter. All the best, C. P.S. It sounded awesome.

[@UncleDoug]

Thanks so much, Cass. It's always good to hear from you. Today felt like our first day of Fall.....breezy and cooler, with temp. in the 70"s.

[@icanfixanything4u2]

that was one sweet build.

[@UncleDoug]

Glad you liked it, ICFA :)

[@Ron_Padgett]

Another awesome video, and I love your sense of humor you crack me up man lol.

[@UncleDoug]

Thanks, Ron :)

[@edwardhannigan6324]

Teriffic stuff Doug..Sunday treat for us all with a wonderful amp, and another entertaining knowledge packed video for us 'wet behind the ears' budding ampaholics..Thank you for sharing your knowledge. Love the drone flight and that little glimpse of the workshop guru waving at the end..!.Look forward to the next..Ed..U.K..😊

[@UncleDoug]

Thanks so much, Ed. Stay tuned......a special video is on the way :)

[@edwardhannigan6324]

@@UncleDoug Look forward to it..😊

[@perrydela-hamaide8353]

Thanks for the education, I recently acquired a silverface Bassman , I know I’ll be able to recap and bias the amp safely without any smoke ,thanks again

[@UncleDoug]

Be very careful, Perry, and good luck with your repairs.

[@johntilson2535]

TAD tubes blow HEAT on GT's. I had GT's (6L6) in my new Fender Deville from the factory. Smoked em 3 months later at a gig. Luckily I had a back up amp. Bought a USED matched pair of TADs and here it is 10 years later and they're STILL going strong

[@UncleDoug]

Thanks for the info, John. So far, I am really happy with the TAD tubes I have installed.

[@BillyBongwaters]

You are a great detective...and yes I have had some good first dates with a hint of wood

[@UncleDoug]

Thanks, Billy. It's always the hint that makes it exciting.

[@knucklefist8535]

Thanks Uncle Doug!

[@UncleDoug]

Our pleasure, Jason. We hope you enjoyed it.

[@k.d.mccarty7194]

Great video, keep rocking and moding 👍👏

[@UncleDoug]

Thanks, KD. Will do :)

[@billguitarvin]

LOL! Only 15 seconds into this video and already you have me laughing hysterically at your comparison of the huge box to an AC-30. Felt compelled to stop right there and write this before I enjoy watching the rest of it. Thanks so much for all the videos you have made over the years and sharing your knowledge with all of us. Because of you I have learned a lot about tube electronics. All the best to you, your family and take care!

[@UncleDoug]

Wow.....thanks so much, Bill. So glad to hear that you enjoyed the video :)

[@nathanbouton6700]

This is so helpful. Just got a '69 Silverface. Beautiful amp. Clean bill of heath from the local tech,. AB763 Master Volume added to the rear panel already. It'll have a switchable NFB loop tomorrow.

[@UncleDoug]

That's great to hear, Nathan. Best of luck with your new acquisition.

[@charleslambiase5670]

I'm a player but I love my amplifiers and I still use in my home my vintage fender bassman amps as well as buying Marshall major which I play bass through knowing what goes on inside these amps makes it easier to play these amplifiers better thank you Uncle Doug!!!!

[@UncleDoug]

You're quite welcome, Charles. We're glad the videos are helpful :)

[@charleslambiase5670]

Uncle Doug you are on the roll!!!!☺️

[@UncleDoug]

I really enjoyed making this video, Charles :)

[@charleslambiase5670]

@@UncleDoug I know you did ,and you show it! You keep us attracted , LOL we don't know what's coming next, the suspense!!!!!

[@alexdeleon7135]

Thank you for pointing out that the amp jewel was on. A bit passive aggressive, but the message was received. I will curb my enthusiasm in the future. You did an amazing job. The Twin sounds vintage, yet spongy with P-90s. Ventures'esqe" with single coils. It is also bluesy and ballsy when pushed with humbuckers. Thank you for sharing. Enjoy the rest of you week, uncle.

[@UncleDoug]

You're welcome, Alex. Thanks for the interesting analysis of the audio demo and your nice comments.

[@beng6144]

I LOVE my preposterous metaphors with a beer, in an Uncle Doug video. Thanks UD!

[@UncleDoug]

Then you've come to the right place, Beneharo :)

[@PandemoniumMeltDown]

Ah man! you're priceless. I just love your channel. The little details. I really hope people pay attention, the ones less versed in the fine art of safely working with powered circuits, when you said ( 33:39 ) "with an insulated screwdriver"... I immensly appreciate how you jam pack your videos with safety at every turn. You're a precious ressource.

[@UncleDoug]

I appreciate your kind words, PM.....Thanks !!

[@cheeze_pizza]

Uncle Doug, I owe you many thanks! This is the video that helped me crack the code of why my ‘76 SF Twin Reverb sounded so terrible and would breakup very quickly. Most of my theories pointed me to the Output Transformer as the culprit but it seems it works just fine. Turns out the amp was biased super cold. Like 8% of max dissipation (MD)… I used this video to learn how to properly use the multimeter to calculate the bias. This particular amp had been modded to a Bias level from the original Bia Balance pot in the chassis. After taking several measurements and slowly adjusting the bias higher, I settled in at about 52% of MD. The tone has improved remarkably but there is still some noise to suss out. For now, I’ve re-assembled the amp and have been enjoying it. Next month, I’ll pull it open again for another health check. Thanks again for the many hours you have put into this channel. The information here is truly valuable if not priceless. I’ve learned so much in the past 6 months yet I see I still have much to learn. Keep the awesome videos coming Uncle Doug. We all appreciate it and owe you a great debt of gratitude. Take care for now, -Scott

[@UncleDoug]

You're welcome, Scott. We're glad the video was helpful :)

[@50gary]

Before box is even opened, one of my secret favorite amps (I need a Twin Reverb like I need a hole in the head but have always wanted one 1968 is my favorite too.) More after the repair. Edit: Very thorough, that little mod. on the vibrato speed is so right on the money a must for these. Fenders I.M.O, Ditto for the NFB loop. Great job UD

[@UncleDoug]

I hope you enjoyed it, 50G.

[@jamesadams1064]

Another good one

[@UncleDoug]

Thanks, James :)

[@klontart]

Oh boy do I love that NFB switch.

[@UncleDoug]

It made even more difference in person......like night and day :)

[@timpayne8238]

Great work Doug, I love the wine tasting references to the valves; in my experience everyone's got their preferred brand(s), much like strings.

[@UncleDoug]

Yes, they do, Tim, and companies pay millions to influence those preferences ;)

[@Rightnow0101]

Thanks to Uncle Doug I powered up my signal tracer! The last time I looked at the Eico 147-A I had no clue what I was looking at. This weekend, after tutoring under your channel, it became clear how much like a guitar amp it is. I checked the transformers windings, measured the resistors, checked the ESR and values of the caps, fixed a broken wafer switch and installed a 3- wire cord. Bringing it up slow on a variac I checked for potential between chassis and the line ground. Then disassembled a 50k pot for cleaning and cleaned the rectifier socket to bring it back from it's decades long slumber. Pretty cool to have an idea of what is going on and some confidence I'm doing it right. Next the Eico 232 VTVM. I did get it powered up after checking it the same way but I have 50v AC from chassis to ground.? It is diode rectified and I'm not sure just yet exactly how it's circuits function. I think the potential to line ground is a concern. I love your channel and thanks again!

[@UncleDoug]

Wow, it sounds like you're ready for your own YT channel, CR. I'm really glad the videos have been helpful.

[@Rightnow0101]

@@UncleDoug my contribution to YT is to help creators like you who keep ads to the minimum by like, comment and subscribe. I'm of a mind to make a monetary contribution to your patreon.

[@artsmith8082]

NICE drone shots. I did bootcamp and AIT there off of dyer st in 1989. we did not have a whole lot of time for site seeing or exploring . I did enjoy it out there. I think the Dyer st "camp"{ is long gone. Thank you for doing what you do.

[@UncleDoug]

Thanks, Art. Glad you enjoyed the video and your stay in our sunny metropolis :)

[@marccarter1350]

It's Sunday afternoon. Time for another treat from Uncle Doug. Loving that reverb tank. Want one for my Vox AC-15, yes I know, one never came with it, but it's a great add on. I will never part with it anyway!. Greetings from sunny England Doug.

[@UncleDoug]

Greetings to you all, Marc. I hope you enjoyed the video.

[@Rich915]

Really enjoyed watching this one! U crack me up...lol Was worth it for me since I have an Early 70’s Silverface.that I had made into a head. At one point, someone suggested it needed a Master Vol installed, which I’ve since immensely regretted! Needs to be put back to it’s orig state. In doing that, the Tremolo & Intensity functions were disabled...I mean wtf!!! Thx for all your great Vids 😎

[@UncleDoug]

I'm glad you enjoyed the video, Rich. What a shame (the MVC). Hopefully you'll be able to get it back to normal.

[@stratcat4450]

Excellent presentation as always. I'm surprised you were able to record even at volume settings of 3.5 to 4 with that amp. I had a early silverface like that decades ago and still remember how LOUD it was! Anymore I rarely crank my champ up past 3. That mod reverb tank sounds great. Thanks again for such a quality presentation. Your one of a kind.

[@UncleDoug]

Thanks, S66. Trust me, it was plenty loud. I had some paper napkins stuck in my ears.

[@pyroman6000]

@@UncleDoug Johan Segeborn has a video of him playing a Les Paul thru one of these CRANKED. He's wearing ear muffs, and still wincing at the thunderous volume. Great sounding distortion, but even he admitted he may have gotten a bit over ambitious doing this, lol. Also, he was standing behind the amp, not in front of it...

[@UncleDoug]

@@pyroman6000 Definitely not my cup of tea, Pyro, especially if the amp and speakers belong to someone else.

[@pyroman6000]

@@UncleDoug i figured. That was mostly aimed at folks who might wonder what a twin reverb sounds like dimed. Most likely wont get the opportunity, lol- not for the faint of heart!

[@UncleDoug]

@@pyroman6000 Not an experience that I would relish, P. To me, in close quarters, 2 to 2.5 is max volume.

[@michaelrash1478]

I'm impressed, ac30's are pretty heavy, but you lifted it with absolutely no problem. Lol, great video.

[@UncleDoug]

Yep.....I may be old, but I'm still in good shape ;)

[@travishein]

I know feel I need to look for "shipping dimensions" when I order my tubes. This is a critical piece of information i have been missing :)

[@UncleDoug]

Indeed, Travis. I think they should also describe the color of the box in which they will be sent ;)

[@davec991]

A good belly laugh is priceless and so are you. Thanks.

[@UncleDoug]

Thanks, David. Glad you enjoyed it :)

[@faultlessguitarsandamps1116]

Loving your music in the drone flight . It brings Peter Greens Splinter Group to my mind . Sadly he has recently passed away . He had such a great touch .

[@UncleDoug]

Wow.....I am flattered beyond words. Any comparison to Peter Green is as good as it gets. Thanks !!!

[@andrewdenine1685]

I love watching this stuff. They scare the crap out of me even though I'm a electrician and have serviced equipment with way more power .

[@UncleDoug]

If you know and practice all the safety rules, Andrew, you are (probably) quite safe ;)

[@bluemule3891]

Bahaha ac30 great bit, the laugh I needed this morning Blue

[@UncleDoug]

Glad you enjoyed it, Blue :)

[@geraldolourenco644]

brazil very good, thank you doug

[@UncleDoug]

Glad to hear it, Geraldo. Our pleasure :)

[@donaldfilbert4832]

WOW !! Looking at that VOX - the box isn't the only thing that's big !! Your hand is HUGE !!!!!! ;)

[@UncleDoug]

Yes, you know what they say about men with big hands ;)

[@WaywardWhiteWalker]

Sounds like a first date... instant classic

[@UncleDoug]

Glad you enjoyed it, WW.

[@steelcity321pb6]

Hi Douglas, Many decades ago here in England, mains leads were red Live; black Neutral, and green was the Earth wire. Then that changed when we joined Europe: Live became the blue wire; Neutral became the brown wire, and Earth became a spiralled green and yellow coloured wire. The reason was to enable colour blind people wire a mains plug onto a mains lead correctly. Not personally suffering from this disability, it is said that the colours green and red look very similar to a colour blind person (brown), therefore, Live could easily be mistaken for the Earth, or vice-versa. 73 from Phil.

[@alexbozas887]

It used to be red live, black neutral, green earth in south Africa too, until they changed to European standard. Should be the same worldwide.

[@UncleDoug]

Thanks for the info, Phil. I thought brown was the hot wire.

[@stevehead365]

@@UncleDoug Brown is the hot wire in Europe, Blue is the neutral, assuming the power cord was assembled correctly (made in china?). Might be worth checking. Great sound, the Fender twin. I once sat in front of one whilst busking Johnny B. Goode on the fiddle. Very enjoyable, then, as we were packing up there was a bar fight... that's Essex for yer. I love your amp repair videos. Cheers, Steve.

[@steelcity321pb6]

Oh, what a bugger! I’ve completely got the blue and brown mains wires the wrong way round: blue is neutral, and brown is live. That will teach me for posting comments seconds before snuggling down into bed LOL. Phil.

[@alexbozas887]

@@UncleDoug brown is the hot one.

[@chrislleeyt]

Great video! I just recently found a nearly identical "Drip Edge" Twin Reverb for sale -- totally original, including all the original caps, 2 wire cord, 4 black plate RCA 6L6s and RCA and Telefunken small tubes, original footswitch, reverb tank, and Jensen speakers. The stamps on the chassis are all late 1967, and all the other dates match up. The Tolex is perfect, and there is even an original tag hanging on the handle all about caring for the Tolex covering. The Twin Reverb is way more amp than I need (or could possibly use), but I couldn't pass it up for the price. The seller claims to have been the original owner who had played it in a band in the late 60s and early 70s and stored it since then. As far as I could tell, I was the first to have it apart. So far, The 1K resistor under the doghouse had cracked, and one of the grounds had come loose where the main board flexed, but fixing those brought it back to life. I already installed the 3 wire cord to your specs, and I've got new caps and a few resistors to go in this week. I might add the NFB and Tremolo speed mods while I'm in here working on it. Oh yeah, it sounds great, and it's LOUD! Thanks for the great videos. I love guitars and electronics and you have inspired me to take on doing some work on these cool old amps. I just finished my first restoration on a pretty rough Pro Reverb that turned out really nice and took on this Twin as my second project. The payoff is huge when I hear how great these sound and think about what they'd cost to buy new today. Keep up the great work!

[@UncleDoug]

Congratulations on a great acquisition and repair, Chris. Silverface Fenders are generally bargains.....and great amps to boot. We're glad the videos were helpful.

[@nevillegoddard4966]

Oh that's so good you got that amp going mate, & at a great price too huh? Double congrats then! UD will be proud of you!

[@davidklang8174]

That's a great choice for 6L6 replacements. Those are made for TAD by Shuguang (which is a quality manufacturer) and TAD does a super job testing and matching the tubes before they're sold.

[@UncleDoug]

Thanks, David. I have been very pleased with the TAD tubes.

[@southboundsuarez9832]

You know, I find it amazing how man different flavors and styles of tubes are being rebranded and sold by so many distributors when in fact the majority of every new tube being sold in this new millennium are being produced by only as few as three different factories worldwide! What is more perplexing is that even many of the exact same brands made by the same factories are sold by many different distributors and retailers, yet the quality sold by the various sources of those same tubes can vary vastly in quality. It's commonly assumed that these factories wholes large lots of various grades of tubes and that the bigger distributors cherry pick the best production runs . Letting nothing go to waste, seconds or even thirds production stock, perhaps even many other various rejection stock is sold and blown out at discounts to any wholesaler that will bid on them??? It would be interesting to hear from a real tube insider that could give us the true story of how tubes are produced and distributed these days. Unfortunately, most factories are located in foreign countries that aren't known for being very forthright about disclosing much about the workings of their infrastructure. Aspen Pittman did alot to bring new production tubes to the free world. However, over the years his eccentricities has seemed to obscure his credibility in the opinion of many folks. Regardless, he created a new niche industry of grading and marketing of audio vacuum tubes. Some might even say letting nothing go to waste. Unfortunately, it is still buyer beware, even with some of the "premium" vendors vs value vendors. It isn't always you get what you pay for... Obviously consistency is a major key characteristic of good quality tubes. However, consistency is all relative, with some major silk-screened fancy labeled tubes even being consistently poorer than others, yet they maintain intially consistent electrical characteristics. The major emphasis on static dissapation. I have been finding that the tubes being rebranded as the newly licensed Tung -Sol have been most satisfactory and most welcome addition in my shop. They came onto the scene just when I had just given up on all forms of new production tubes, including and especially J-J's ! It certainly is much easier to buy a usable new production tube than to have to go on safari and procure lots of used vintage tubes and wade thru piles, grading them yourself. (I don't believe in the term NOS tubes as they don't really exist or if they aren't extinct are likely new old b stock or rejected orig stock... NOS Tubes are USED vintage tubes that test as if they were new stock) Vintage tubes require careful selection, just as many new production tubes. Fortunately, new production tubes are getting better & better.

[@MrLooperg]

The superlatives are outstanding.

[@UncleDoug]

Glad you liked it, Graeme.

[@kevinwager9284]

I love my Silver face a tech from the North Eastern parts of the USA went through it and I couldn't be more happy. His name is Chris Davis in case anyone from that geographical area is in need of a quality tech.

[@UncleDoug]

Thanks for the recommendation, Kevin. People ask me all the time for the names of good regional techs.

[@brianfletcher9774]

“The only time brown gets hot is when you eat spicy food”.....and I nearly spray my drink like a sneeze ! Good one Doug !

[@UncleDoug]

Glad you liked it, Brian :)

[@patrickconnelly2904]

@@UncleDoug That's why you have to eat ice cream for dessert, "Come on ice cream..."

[@jeremiahlyleseditor437]

Great drone footage. It's quite amazing that people will live that far away, even from the supermarket. 40 minutes one direction is ridiculous.

[@UncleDoug]

I wonder about their houses sliding down the side of the hill during a hard rain storm, Jeremiah. It would be a memorable ride ;)

[@jeremiahlyleseditor437]

@@UncleDoug Very many houses like that in Beverly Hills, Studio City. They've built up on stilts on the side of the mountain and with the earthquakes here, it's a perilous way to live.

[@andydengel]

Thank you, for another cool, informative video! Cool, Tube Amp Doctor, near where I live, in Rhineland Palatine/ Germany. Greetings, you are awesome!

[@UncleDoug]

You're welcome, Andreas. Tell those TAD fellows that Ollie & Jack really like their tubes :)

[@renegade44040]

The owner of that amp is a very fortunate person.

[@UncleDoug]

Also a very nice person, JJ, as are all our viewers and other amp customers. It's a real pleasure to get to know you all.

[@tonymanns8249]

I've have always used JJ tubes, and usually their 6L6 GC tubes. I use them on my Fender/Dumble clone 135 watt clone Twin amp that has almost 500 vdc on the plates, and they have worked very well without any failures. I have tested that amp and it outputs a consistent non-distorted 125 watts RMS.

[@UncleDoug]

Wow.....what a powerful amp. Thanks for your input, Tony.

[@hippyamp]

watching this makes me tempted to grab this quad reverb that is fairly cheap locally

[@UncleDoug]

Be sure it's in working condition, HA. They can be a handful if the chimps have been at work on them.

[@alexbozas887]

The sarcophagus of king tut turned out bè a fine house for the holy followers of King Doug. What an awesome sounding amp, èsp the vibrato channel.

[@UncleDoug]

Thanks for joining me on this archeological expedition, Alex :)

[@glennselwitz1377]

Thats the most I've ever seen of our uncle at the very end.......uncle Doug is in very good shape!...........

[@UncleDoug]

Thanks, Glenn. I'm on a catnip and beer diet :)

[@ryanfulldark2775]

Best sounding twin I’ve heard I think, fantastic! I’m a bit biased toward P90s though lol

[@UncleDoug]

Glad you liked it, Ryan.

[@WillyMcCoy50]

First amp was a blackface Twin I bought for $350 (1977). Loved it but was pretty shrill. But I always had it dimed. Wish I still had it along with my '67 Rickenbacker 360. Good job on the Twin Reverb Doug!

[@UncleDoug]

Thanks, KM. If you still had it, we could fix the shrillness and make it sound like $1Million.

[@WillyMcCoy50]

@@UncleDoug that negative feedback loop you introduced to the circuit gives the Twin a whole new voicing. 100% more useful for folks like me that aren't asking for a lot of headroom.

[@bishlap]

Tutankhamun/Burial chamber/sarcophagus - BRILLIANT.

[@UncleDoug]

That's what it reminded me of :)

[@r3tr0nic]

"The only time brown ever gets hot is when you've eaten a lot of spicy food" Tehehe! Hope you've been doing well my friend, your videos are always a blast to watch, and some of the best guitar amp engineering content. I find myself diving back and watching many over and over when I have that vacuum tube bug hit me (stares at new 100W Marshall OPT and MOD reverb tank sitting on my shelve). Yeah, that bug is coming back again. Just wish I had more time away from work. Too bad there isn't more Marshall on the 'tube. I've had a watch of some other people, but when I see them do things like discharging a cap by shorting it to the chassis (and thusly causing a vintage chassis to have a scorch/gouge mark, besides the insanity) def is not my fancy. Thank you as always for the amazing content!

[@UncleDoug]

Thanks so much for the very nice comments, Retro. I hope you find the time to get back into tube electronics.....and wish you the best when you do :) Arcing to the chassis is like dry-firing a weapon, it's damaging, particularly in the long run.

[@Eddy63]

Gees U. D. ... Your vid was exactly 2 shots of Vodka and 2 Miller Lite chasers long ... And I enjoyed both the same ... Lol ... Great vid and nice amp ...

[@UncleDoug]

I like that prescription, Ed. Thanks !!

[@phillindower8550]

Good information. I think I'll try that switchable NFB on the reverberocket and champ circuits Ive built.

[@UncleDoug]

It really works well on some circuits, Phil. Good luck.

[@monkeyboy4746]

A while back I worked with a guy from Arizona, he said coming to North Carolina was like coming to the "jungle". Looking at the drone footage, I can see where he was coming from.

[@UncleDoug]

Our vegetation is a wee bit sparser than yours, I would venture to guess ;)

[@Crisdapari]

I just Laugh Out Laud hearing and imagining "swing the chassis around your head" when Uncle Doug spoke about verifying the center tap´s solder. The Egyptian and wine jokes were a good touch too.

[@UncleDoug]

Glad you enjoyed the festivities, S. Fixing amps can be fun :)

[@Crisdapari]

​@@UncleDoug Of course is fun! It's a rewarding puzzle, not as painstaking as fixing surface components boards.

[@dougtaylor7724]

I could imagine Chuck Norris stepping in to swing the amp chassis at six plus G’s. Then he sits it down to and tells Doug he’s good to go.

[@michaelhager4270]

Hi Uncle Doug, greetings from Australia. Here in Melbourne we haver the same crazy weather, it all depends on where the wind comes from. A northerly brings hot dry from the desert, a southerly brings the ice and rain from Antartica. Thanks for another great video. As usual I wish I could ask you a thousand questions. All the best, Mic

[@UncleDoug]

Greetings, Mic. Pictures of Australia remind me of where I live. I guess the weather is the same too :)

[@1959Berre]

NFB off, when your playing "Running with the Devil" along with Eddy Van Halen (R.I.P.). As today the world lost one of the most innovative guitar players of the 20th century. He left us a splendid heritage.

[@UncleDoug]

Indeed, Berre. One of the all-time greats.