I realize that technical videos are not as entertaining or popular as regular videos, but I felt compelled to post an easily searchable how-to video on a frequently-requested topic. As mentioned, the '69 Twin Reverb Extravaganza will be posted soon.....so turn your beer coolers down to 31.9 degrees F and get ready !!!

@billgreen4592

3 жыл бұрын

For those of us the fix/build amps, these videos are what really makes you channel valuable! Thanks for this content.

@paulvale2985

3 жыл бұрын

Informative AND entertaining Unc, Keep up the good work 🔊

@knifeswitch5973

3 жыл бұрын

You do what ever the hell videos you want to do Doug. It’s all brain candy and it’s all good

@jogreeen

3 жыл бұрын

I love watching Jack riff on refurbished amps, but these tech vids are some of your best, there aren't many people doing this stuff on KZread.

@Wildman9

3 жыл бұрын

A AN 764 model Twin Reverb,whoops. These type videos are just fine for those of us who like to do biasing , on our own and doing it right. By the book.📖 🎸👍

Uncle Dougski is one Fantastic Teacher..!!! some teenager in 2056 will need to watch this video after inheriting a Fender Amp and purchasing new output tubes.

@UncleDoug

3 жыл бұрын

Thanks so much. I sure hope so, Mr. G. :)

I’m going through all these technical videos again preparing for my second amp build. Got to say doing a hands on project really helps me understand the nuances of these excellent videos. I’m having so much fun doing these projects and I don’t know if I could do it without Uncle Doug.

@UncleDoug

11 күн бұрын

That's great to hear, Will, and the perfect way to master a new skill.....develop a solid foundation through study, then put what you know into practical use.

As Alanis Morissette once sang, "I've got one hand in my pocket, and the other one is measuring plate voltage"

@UncleDoug

3 жыл бұрын

Alanis was one of our best students, Shek ;)

@Rightnow0101

3 жыл бұрын

I thought that but didn't want to post it. :)

@Rightnow0101

3 жыл бұрын

@@DL-oy2qn Yeah, I really do think....and I've seen the effect of grounding a metal watch band to a chassis in person. It leaves a mark for sure.

@PandemoniumMeltDown

3 жыл бұрын

@@DL-oy2qn Don't you think? A little toooo ironic... yeah!

@billguitarvin

3 жыл бұрын

shekador - LOL!!!!! I got a good laugh from your comment. Thanks for the funny comment. Always wondered what the lyrics were in that part of the song. 🙂

Thanks again Doug! I remember watching these videos a few years ago and having no idea how to even start touching tube amps. I've since then become a part of a small repair tech team and am making an alright side business with it. A big start and encouragement for me were your videos. So I'd like to thank you once again for making such great videos!

@UncleDoug

5 ай бұрын

That's great too hear, Elmo. We're glad the videos were informative and helpful :)

Thanks man. I've been racking my brain for days... and everyone else on youtube or forums likes to beat around the bush and/or give poor incomplete information. I owe ya one!

@UncleDoug

4 ай бұрын

We're glad the info was helpful, Jeremiah.

Love your videos Uncle Doug! With all due respect I would like to point out one thing. In your example of the quad output tubes (14:28) you discuss plate voltages on the two plates which are connected in parallel. The voltage measurements will be the same, they will not differ on the two tubes. What will be different, unless the two tubes are perfectly matched is the plate current of each tube. The rules for a parallel circuit are as follows: The voltage on each branch of a parallel circuit is the same, the branch currents add up to equal the total current. Thank you for making these great videos.

@UncleDoug

3 жыл бұрын

Good point, Anthony. Thanks for your helpful input. I have added a statement to the video description clarifying this issue. Regardless of the relative current flow through the paired, parallel tubes, the voltage measured at the plate (anode) will be the same.

@rossthompson1635

3 жыл бұрын

I thought that but then I wondered - yes that would be true for grid biased tubes (ground to the common point between the plates), but wouldn't the voltage still differ for cathode biased tubes - i.e. you are measuring voltage across the tube which will be proportional to the current through each?

@Dr_Reason

3 жыл бұрын

@@rossthompson1635 I think they cannot vary in voltage since they are connected to the same voltage source. Their amp flow can vary if the tubes vary.

@bobvecchi7981

3 жыл бұрын

@@rossthompson1635 no, the voltage will be the same, but the current will be proportional as a result of the tube’s internal resistance being different, hence the term mismatch”.

@ichbinnutzlos5561

10 ай бұрын

Change one opposite pair of tubes to check wether plate current changes without changing bias.

Thank you Uncle Doug!! I have learned so much from you this year, since I started watching. I was an electrical engineer for 34 years in the Air Force (civilian), and I retired on 31 December 2019. I have always strived to be able to explain things easily like you do and keep the calculus out! I like to understand what is really happening and why - that is the way to solve problems! You are a master at teaching! Stay healthy!

@UncleDoug

3 жыл бұрын

Thanks so much, Bruce. Will do......you too, I hope :)

VIDEO REQUEST Please do a video about the relationship of the tube output impedance and transformer impedance when using a quad of tubes, As a follow up to this video and your series regarding output transformers. Thank you! PS I love your videos! These are the best, easiest to understand, tutorials I have ever seen.

@UncleDoug

3 жыл бұрын

As you probably know, Scott, identical resistors in parallel have a total resistance equal to half of either of the individual resistances.....i.e. two 100 Ohm resistors in parallel have an effective combined resistance of 50 Ohms. The same is true with quad tube sets. The Load Resistance is one-half that of a double-ended pair.

@scottbc31h22

3 жыл бұрын

@@UncleDoug Thank You.

One of the best videos on the internet

@UncleDoug

2 жыл бұрын

Thanks, Svart :)

Technical videos are the reason I fell in love with your channel. I don't know if I love you or hate you (LOL), but having worked on just about everything in my lifetime (I'm sure, just like you), your "How Tubes Work Videos" set me on a path. Again, I don't know if that was a good thing, because I've had to fix a ton of amps for my musician friends (and I have many) over that last few years. And I have fixed a bunch of circuit board amps (which I know you don't like to do), Peavey 6534+, 5150, Marshall 800, 900, 2000, etc. My background is in computers so I was used to circuit boards. This was all thanks to your very clear and precise explanations on the "WHY and HOW" it works like that (for tubes and amps). To me, at least, that's top of the list. You must have been a hell of a teacher. We need more teachers like you in this day and age, and I don't mean to embarrass you, that's just a fact. God bless you and thanks for all you do.

@UncleDoug

3 жыл бұрын

Wow, thanks so much for your very nice comments, Bert. Hearing from viewers like you makes it all worthwhile :) Likewise on the blessings.

Great information, as usual. I always appreciate those willing to share their knowledge. Thanks!

@UncleDoug

3 жыл бұрын

Our pleasure, Z. Thanks for watching :)

Дуже дякую вам за відео і чудову інформацію ! 👍👍👍🙂

@UncleDoug

2 ай бұрын

You're welcome. I'm glad you enjoyed it.

Excellent lesson! Glad you gave us the safety precautions too.

@UncleDoug

3 жыл бұрын

Glad you liked it, Robert. Be safe :)

Amazing all the detail and take our hands though you do! You are such a kind individual on your teaching! Thank you uncle Doug

@UncleDoug

3 жыл бұрын

You are very welcome, Edson. Thanks for your nice comments.

Execellent explaination of the subject without very deep maths. Just ohms law, thats it !

@UncleDoug

2 жыл бұрын

Glad you enjoyed it, Roland :)

A great teacher at work is a real blessing!

@UncleDoug

3 жыл бұрын

Thanks so much, Rich.

Another excellent video , I very much appreciate your time and effort in putting forth these technical videos and enjoy them very much.

@UncleDoug

3 жыл бұрын

Thanks so much, Benny. Glad you enjoy them.

Amplifiers are very dangerous to work on unless you know what you are doing. Think safety ,safety ,safety. Plug your amp into an isolation transformer while working on one if you need to power it up to test voltages and currents. If after you do power an amp up do not assume the electrolytic capacitors are safe to work on because they can still hold a lethal voltage as well. They must be discharged through a resistor . They can hold a high voltage for hours or even days. Thanks for the biasing output tube video professor Doug! Always something new to learn!

@UncleDoug

3 жыл бұрын

Thank you for your wise advice, HM :)

Thanks, Uncle Doug. I just started studying these circuits in the last week. This is a big help.

@UncleDoug

3 жыл бұрын

I'm glad to hear it, Stephen. Best of luck with your self-education.

Thanks Uncle Doug, that is perfect information for my Vox AC30. You're the best!

@UncleDoug

3 жыл бұрын

Glad to help, Andrew. Thanks !!

I really enjoy the tech segments.....good lessons for my little brain...

@UncleDoug

3 жыл бұрын

Glad you enjoy them, Lee. Thanks !!!

Once again, excellent information. I'm working on a another Peavey Classic 50 2x12. Having issues with reverb, so I'm hitting up your Reberb videos again. You are a virtual book of info.. love it..

@UncleDoug

3 жыл бұрын

You're quite welcome, James. Best of luck with your repair.

This is gold! Thank you. If I had this useful application of math in high school, I might have retained it back then. Thank you Uncle Doug ( and all your supporters) for sharing these videos and tutorials.

@UncleDoug

3 жыл бұрын

You're quite welcome, ER. Glad you enjoyed the video.

That was the best explanation/presentation of the process of biasing that I have ever seen. You are a really good teacher!!!!

@UncleDoug

3 жыл бұрын

Wow, thank you, Jason.

I applaud you for you detailed safety brief when working with energised equipment. 👍🏻👍🏻👍🏻😀

@UncleDoug

3 жыл бұрын

Thanks, Alasdair. I hope it leaves a lasting impression :)

Another excellent tutorial! Thank you UD for all this great content!

@UncleDoug

9 ай бұрын

You're welcome, S-L :)

I love the technical videos the best, but its great when you mix it up.

@UncleDoug

2 ай бұрын

Thanks, IM.

Nice Video, for anyone looking for this info, this is definitive. Wish i Had your Vids 10 years ago! Thanks Doug

@UncleDoug

3 жыл бұрын

Thanks, Gavin. I wanted to release a dedicated, searchable video on the subject, so people could access it when needed.

This Video is very informative and right on time. i look forward to part two in order to observe your actual measurements and calculations on this twin. i am currently working on my twin Reverb AA769. This sure does help. Thanks Uncle Dough.

@UncleDoug

3 жыл бұрын

Glad it was helpful, Anthony. Best of luck with your project.

I personally really like your technical videos! Thank you.

@UncleDoug

Жыл бұрын

I'm glad to hear that, Jedi :)

I have been enjoying your video so much as of late. Thank you so much, please keep it up, and keep us informed on the subject matters.

@UncleDoug

Жыл бұрын

Thanks, J. Will do :)

I love your technical videos...I always learn something from you! Cheers!

@UncleDoug

3 жыл бұрын

Glad to hear it, Suomi :)

Thank you so much for posting this Uncle Doug, I am about to check the bias on my Princeton Reverb.

@UncleDoug

3 жыл бұрын

Glad it was helpful, GS. Good luck with your project.

Your technical videos is what led me to subscribe to your channel in the first place.

@UncleDoug

3 жыл бұрын

That's great to hear, Richard. Thanks !!!

Excellent explanation! Short, sweet and to the point. Thank you for stressing the ' keep one hand in your pocket' safety rule...it saves lives. 😀😀👍👍👌👌☕☕🤗🤗

@UncleDoug

3 жыл бұрын

Glad it was helpful, FB. Thanks !!!

Superb video! Of course we want the practical demo!! Thanks!

@UncleDoug

3 жыл бұрын

Coming soon, Oli.

Awesome! Going to watch that again.

@UncleDoug

3 жыл бұрын

Things generally make more sense the second time around, Kirk :)

Just realised that for both scenarios you could measure plate to cathode as a grid biased amp would have cathode connected to ground anyway. That saves me trying to remember. Thanks for another great video UD and all the best from Australia!

@UncleDoug

3 жыл бұрын

You're right, Dean. You can't go wrong with plate-to-cathode.

Very useful and as always interesting to learn. Thanks uncle Doug

@UncleDoug

3 жыл бұрын

You're very welcome, RJ.

Hi Doug, I've just picked up Epiphone's answer to a twin style, quad output guitar amp. I'm reviewing two of the videos you've done on the Fender Twin models (1968 and 1978) and this video on biasing quad output tubes, couldn't be more valuable. The Epiphone Embassy is very similar to the Gibson GA-95RVT, other than one of the 9 pin tube locations using a 12AU7 (Epi) instead of a 12AX7 (Gibson). The Epiphone I've picked up is from 1966. The amp had been "serviced", but the tech hadn't realized that someone before him had added a 6th 9 pin tube (12AX7) to the chassis in a factory opening - probably used in another model that used the same chassis. Now I'm in the midst of going over the schematics for the Embassy amp, the GA95RVT (which the tech who had checked the amp out figured was closer to the amp) and a fabulous find - a meticulously created drawing of the eyelet board for a GA95RVT that I found on a blog. Like the 1978 Fender Twin you went over, this amp has to be checked end to end to figure out where I'm starting at - a very good part of this educational journey. Getting there, thanks to what I've learned from watching a multitude of the videos you've created! While the more technical videos may not get as many folks viewing, they are greatly appreciated by folks like me!! Cheers from the wet coast of Canada!!

@UncleDoug

Жыл бұрын

Wow.....Thanks for sharing this with us, Donn. It sounds like quite an excellent acquisition. Best wishes for continued success with your circuit overhaul.....and for a wonderful holiday season.

Thanks Doug, for another Jem info video. Best regards, John.

@UncleDoug

3 жыл бұрын

You're very welcome, John :)

Clear and concise and informative as always. Thanks! I've been steadily adding 1% 1 ohm resistors to the cathodes of my grid bias amps to get quick and easy bias readings at each tube. It's a little work initially, but the end result is easier than fumbling around with hot tubes and bias probes. The manual math method is about as true as it gets though.

@UncleDoug

3 жыл бұрын

Thanks, GL. That's one way to determine the PC matching within each pair of tubes......instead of just getting the average.

I love the more technical videos!

@UncleDoug

3 жыл бұрын

Thanks, Magnus. They aren't as popular as my regular videos, but it's important to have this information on YT as reference material for viewers needing help.

@magnusekhall

3 жыл бұрын

@@UncleDoug To me the technical videos are at least as interesting as the regular ones. I have learned so much from watching your technical videos. I don't think I've seen better videos explaining how electronics with tubes works.

Thanks for the insights, humor and nice choice of songs for strumming on the guitar ;)

@UncleDoug

3 жыл бұрын

The pleasure is ours, Ken :)

Another great educational video Uncle Doug!!

@UncleDoug

3 жыл бұрын

Glad you enjoyed it, Big Joe.

Wonderful information as always, and thanks uncle Doug!

@UncleDoug

3 жыл бұрын

My pleasure, Vince :)

Learned a lot from this conversation here of yours today!!!!!

@UncleDoug

3 жыл бұрын

That's great news, Charles.

Hi Doug, I just wanted to extend my heartfelt thanks! I've just completed (all bar the faceplate) a conversion of a horrible, noisy Hayden PCB-based amp into a Brownface Princeton clone. Only the chassis and cabinet made it all the way thru the process, which are fine, sturdy items. The end results sound great, it's very quiet -noise-wise- and the bias-vary tremolo is just as nice as I hoped. I couldn't have even attempted such an undertaking without your valuable tutelage. Thanks again!

@UncleDoug

3 жыл бұрын

That's great news, Gerry. It's really gratifying to hear that our videos have been put to good, practical use. Thanks for making our day :)

@RHR-221b

3 жыл бұрын

@@UncleDoug 💚

Thanks Doug, always good information from your channel

@UncleDoug

3 жыл бұрын

You're very welcome, OG.

There is an error at 14:39 when describing the plate voltages of tubes with dissimilar plate current. Because the tubes are hardwired in parallel they will always have identical plate voltages regardless of the plate current each carries. It is identical to two resistors in parallel but having dissimilar resistances - the voltage measured across them will not change but the current they carry will be different. With tubes this simply means the tubes have dissimilar internal resistance. In cathode biased circuits the cathode to ground voltage will be very different between parallel tubes. The cause of unbalanced plate current could indicate a manufacturing error or external component/soldering problems (screen or cathode resistors, for example). Thank you for all you do to educate all of us. These technical discussions are fascinating to this old tube amp engineer.

@UncleDoug

5 ай бұрын

Thanks for your knowledgeable input, LG.

Thanks Uncle Doug. A great video.

@UncleDoug

3 жыл бұрын

Glad you enjoyed it, Bob.

Great video, Doug!

@UncleDoug

3 жыл бұрын

Thanks, Tommy. Glad you enjoyed it.

save lives with this video.,. Thanks uncle

@UncleDoug

3 жыл бұрын

That would be wonderful. Thanks, Orlando.

Hi Doug! once again, another valuable and informative video. Entertainment is one thing, but the young and upcoming techs NEED to watch the most important videos such as this one. I like entertaining videos, but I also like the meat and potatoes when it comes to the theory. Your explanation is spot on. Without the theory, the how and why remains unknown, and its like shooting in the dark without a flashlight which isn't good; the bullets can fly anywhere. There are so many different ways to measure and set bias, but a VTVM and pencil and paper tells the accurate truth which I feel is important. I think a balance of both, entertainment and theory would be the best direction to go in. You will have it all covered on both ends that way. I enjoy the non-entertaining as well; that's why your past videos were a great teaching aid when I taught at the vocational school. Keep this great flow and balance going. you're onto something good :)

@UncleDoug

3 жыл бұрын

Wow, thanks so much for your very nice comments, Frank. Coming from you, they mean a lot.

Thank you for another informative video.

@UncleDoug

3 жыл бұрын

Our pleasure, Matt.

Thirsty for theory , thanks alot for a great video. All thumbs Up!

@UncleDoug

3 жыл бұрын

Glad you enjoyed it, Dr. H.

Hi, I love your video’s. Very educational and inspiring. I love to build tweed amps. They sounds great en and they’re easy to modify. Ive learnt a lot from you. Many thanks. Greetings from Holland. Drebus

@UncleDoug

3 жыл бұрын

Thanks so much, Andre. We're glad to hear that our videos are helpful. Continued good luck with your projects.

Hello Uncle Doug & Family, What a great tutorial, you are a really good teacher. Always great to see an Uncle Doug video. After nine days of smoke, starting on Labor Day, the air is clear and have had some good rainfall. Catching up as have been working some crazy long day's at work, 10 to12+ hours a day. Glad you are doing well. Checking the Hot Rod channel as am able. Lately, bed has sounded pretty good. Came through the fires OK, closest was 10 to 15 miles away, nothing in my immediate area. Like Arnold might say, "If you want to live, keep one hand in your pocket". Be good, all the best from Oregon, Cass.

@UncleDoug

3 жыл бұрын

Thanks for the update, Cass. It's great to hear that you came through the conflagration unscathed, especially your left hand. Catch up on your sleep and stay healthy.

I’ve been ready Uncle Doug!

@UncleDoug

3 жыл бұрын

Good to hear, Alex :)

Great and informative video as always Mr. Doug. Thank you, Roger in San Angelo.

@UncleDoug

3 жыл бұрын

Our pleasure, Roger. Always good to hear from a fellow Texan.

Thanks UD. You too. Great vid as always.

@UncleDoug

3 жыл бұрын

Our pleasure, RSF :)

Thank you very much for the video .. Top shelf info

@UncleDoug

3 жыл бұрын

Glad it was helpful, Chad. Thanks !!

Great video. Got a little confused at first because you mentioned 6L6s in the intro, but your paperwork used a 6V6 example. However, I understood perfectly what you were explaining. Cheers!

@UncleDoug

3 жыл бұрын

I'm glad it made sense, Bill. Thanks !!!

Interesting theory and technical content as always!

@UncleDoug

3 жыл бұрын

Thanks, CR. I hope it's helpful.

@Rightnow0101

3 жыл бұрын

@@UncleDoug Very helpful. Soon I plan to begin going through a signal tracer and vtvm by Eico (kits my dad assembled) and a millivoltmeter by Leader. I've also been restoring my 1928 Brunswick 5N0 (RCA Rodiola 60). I'm a machinist by trade but electronics have become a new hobby. I also turn wrenches from time to time hince the caveman. repair name.

Great Video...! Thank you ..... Indecently Defibrillators DO NOT Restart a heart....They will not deliver a shock unless they sense a rhythm....Defibrillators are intended only to correct a life threatening rhythm....Like Vtach or Atrial Fibrillation that causes loss of consciousness and impending death. If the heart is in asystole (no detectable rhythm) then you need to continue CPR until the problem is found and corrected.

@UncleDoug

3 жыл бұрын

So those little paddles they apply to start a stopped heart after surgery or a transplant are just TV make believe, GH ?? Those lying phonies !!

another great video. thank you!

@UncleDoug

3 жыл бұрын

My pleasure, Mike.

Hi Doug,, Super Great Tech Video,,,, Thank you for posting it,,,

@UncleDoug

3 жыл бұрын

You're very welcome, Terence. Thanks !!!

Thanks UD!

Always good to revisit the basics every now and then, especially the "keep one hand in your pocket" rule for measuring voltages greater than your shoe size. I wish that I worked on hollowstate devices more often (and actually charged for it.) Then I could afford a Eurotubes Bias Probe.

@UncleDoug

3 жыл бұрын

We're glad you joined us, DB. Best of luck to you :)

Congratulations... Real good explanation. Lots off sucess for you my friend, big hug from Holland.

@UncleDoug

3 жыл бұрын

Thank you very much, Nelson. Likewise on the hug :)

super good video. many thanks

@UncleDoug

3 жыл бұрын

You're welcome, E. Glad you enjoyed it.

Doug you read my mind!

@UncleDoug

3 жыл бұрын

That's great news, G. I hope the video is helpful.

@gerrabath

3 жыл бұрын

@@UncleDoug Doug my friend your videos are never anything but helpful. You have taught me so much over the years. Thank you.

Great explanation..... thanks for sharing your knowledge to a new tube guy.....!

@UncleDoug

2 ай бұрын

Thanks, Ken. Glad you enjoyed it :)

@kenporonin1

2 ай бұрын

@@UncleDoug Thank you uncle Doug. I recently purchased a Dual Mono Block Marshall EL-34 100/100 which I plan to use as an audio amp/receiver (not as it's intended use as a guitar amp). I don't think the tubes need repacing as everything sounds pretty good as is. However, I was interested was interested in tube biasing when the need comes.

@UncleDoug

2 ай бұрын

@@kenporonin1 It's best to check the biasing before use, Ken. I have found it hazardous to trust previous owners.....or even builders.....to adhere to proper biasing levels.

@kenporonin1

2 ай бұрын

@@UncleDoug Thank you..... I will check them myself.

@UncleDoug

2 ай бұрын

@@kenporonin1 You may be surprised by what you find. Good luck :)

A great explanation video of how to measure plate current Doug. Looking forward to the video showing how you actually set the bias on both cathode bias and grid bias. I'm guessing with the cathode bias you add to the plate resistance and with grid bias you change the grid voltage.

@UncleDoug

3 жыл бұрын

Thanks, George. In cathode bias the cathode bias resistor value is adjusted to alter the negative charge on the grid, relative to the cathode.

Thank you for a great video !

@UncleDoug

3 жыл бұрын

My pleasure, CC. Best of luck :)

Great informative vid ...

@UncleDoug

3 жыл бұрын

Thanks, Eddy.

I'm watchin' and learnin' !!

@UncleDoug

3 жыл бұрын

Good news, Mr. CC :)

I'm a big fan of these videos, I've learned incredibly useful things from these tech talks. Would you touch the topic of cold/hot biasing and how it changes the behavior and sound?

@UncleDoug

3 жыл бұрын

That's good to hear, Yup. I have been considering such a side-by-side comparison for quite a while. To be honest, much that I have read about the effects of hot/cold biasing does not seem to be accurate. Such a comparison might be very interesting.....so stay tuned.

Excellent!

@UncleDoug

3 жыл бұрын

Glad you liked it, Rich.

And this is why I stick with single ended class A amplifiers. My brain can’t comprehend anything more than simplicity. But, I appreciate your videos. God bless!

@UncleDoug

3 жыл бұрын

Thanks, Nick. Likewise on the blessing.

@nickdevriese

3 жыл бұрын

Uncle Doug On a side note, which brand of current production tubes you recommend? Obviously NOS will always prevail. But, money is tight at the moment. Just an honest question.

very usefull video doug thanks

@UncleDoug

3 жыл бұрын

Glad it was helpful, Remi.

If I had such a teacher in my electronics class in high school, I would surely remember anything :-)

@UncleDoug

3 жыл бұрын

Thanks, DR :)

Obrigado mestre

@UncleDoug

3 жыл бұрын

Likewise, Jorge :)

am so honored, sir~....jayster~

@UncleDoug

3 жыл бұрын

I thought your painting really looked great in the video, Jay. Just wait until Twin Reverb video in a week or so. Both the paintings and you get recognition.

Still subscribed! Thanks for sharing!

@UncleDoug

3 жыл бұрын

Good to hear, Dan. You're quite welcome.

A1 as as usual.

@UncleDoug

3 жыл бұрын

Wow, thanks!

Great video Doug, so much information and especially the safety instruction..I'm still learning...Look forward to more videos.I'm like a kid in a sweet ( candy) shop..Geat stuff Doug, thank you once again for sharing your knowledge..Ed..U.K.

@UncleDoug

3 жыл бұрын

You're quite welcome, Ed. Best of luck with your continuing education.

Another wonderful video, thank you!! By far you have the most informative youtube tube amp channel. Any chance you could explain an ultralinear amp to power low efficiency speakers? Thanks again!

@UncleDoug

3 жыл бұрын

Thanks so much, CB. I will keep your suggestion in mind.

I just purchased a 1990? Fender Twin Amp. It was just missing 2 output tubes, all the pots needed Deoxit cleaning and the 2 speakers were out of phase. I purchased a matched quad set of tubes and installed them. Luckily on the back panel there is a bias adjustment pot, test points and output balance adjustment

@UncleDoug

3 жыл бұрын

I hope it turned out to be a great amp, Mr. G.

@MrGTO-ze7vb

3 жыл бұрын

@@UncleDoug So far ... Very good.!! Someone replaced lots of the caps!! It does put out some great tones..! Thank you Uncle Doug..!!

I do wish you posted a Eurotubes probe owners version too! I think most of your fans have bought them and would love a tutorial!

@UncleDoug

3 жыл бұрын

It's so easy with the Eurotubes probes that you really don't need a video, Steve. Just march down the line and get measurements from each tube.

@steverollinson6906

3 жыл бұрын

@@UncleDoug Thanks!

Thanks In Advance...!!!

@UncleDoug

3 жыл бұрын

Our pleasure, Antonio.

First of all, who wouldn't find this interesting? In fact, just last night part of that question came up. I was looking over the specs of my recently purchased Deluxe Reverb, saw the output tube specs of(2) 6v6s. The amp is 22 watts and fits everything I need in home or occasional performance use, especially these days where we mic all the instruments for a performance. But then, I remember in my band during high school years back in the 70s, the guitar players had Twin Reverbs. A 65 Twin reissue has 85 watts and in the70s I think it was closer to 100 watts. Why did we have those high wattage amps? We didn't have the$$$ for 20+ channel boards and we had to be louder than the drummer. So we sacrificed sound quality for sound quantity. Anyway, I was looking up the tube complement for a 65 Twin Reissue and it is (4) 6L6. Hmm UD has never talked about 4 output tubes... But wait, now he has provided instructions on how to bias the tubes. The only thing left is how does the push pull work with four output tubes? Well I guess that's for another video.

@UncleDoug

3 жыл бұрын

Thanks for your comments, JD. The pairs operate exactly like single tubes do in DE amps. One pair "pushes" while the other pair "pulls".....but since each pair is twice as powerful as a single tube, the output from the amp is much greater.

Just a few extra steps for the quad. Surviving amp repair made easy. :))

@UncleDoug

3 жыл бұрын

Yes, it's just a couple extra steps, but it seems to cause a lot of consternation among quad owners :)

How could anyone thumbs down this???

@UncleDoug

3 жыл бұрын

I have asked myself this question, Scot, and have come to the conclusion that somewhere in a basement in the mid-West, there must be a lunatic asylum with computer access ;)

Hey Doug, love the channel - my friend turned me onto it over the weekend.. Hoping I can find a tech in AZ to help build a custom low watt amp from a 1950/51 Magnavox entertainment console amp.. Not sure where to start. thanks for all the videos!! These are great.

@UncleDoug

3 жыл бұрын

Welcome aboard, David. Maybe one of our viewers will step forward to help you out. Best of luck.

@nicewilbur1

3 жыл бұрын

@@UncleDoug it's all I can hope for.. :) I have the two 12" 5-prong plug speakers, too..

Hello, enjoyed the video, in fact, I enjoy all your videos. One thing though, if you have two anodes (plates) tied together, the anode (plate) voltage is going to be the same irrespective of the current flowing through the valves. So I don't quite get your comment on if one tube is worse/better than the other.

@UncleDoug

3 жыл бұрын

You're right, Bill. This has all been explained by a note in the video description.

👍

👍😊

Thank you for the video. Turns out things wasn't as complicated as I thought. I was wondering what happens to load resistance in quad and parallel se circuits and how to impedance match them.

@ImmitH

3 жыл бұрын

I realized that you already answered this in a comment down below. I tend to miss what is right under my nose. Have a great day

@UncleDoug

3 жыл бұрын

Glad it helped, Ikoll