How to select proper transformer for tube amplifier builds Example 6AQ5 Class A guitar amp 

Thanks Terry, it took me a long time to figure that part out.. Under load is a completely different situation. You are really helping people with this project and modules ; great stuff - Ron

Last weekend I took a class learning how to build a tweedy Princeton 5F2A circuit, tweaked by my instructor Matt Dawson to be even better and run quieter. It may look like a simple circuit, but now I know how complicated it is, and while I built it that doesn't mean I understand what all the components do - far from it. But I understand more than I did previously, and have a cool little Princeton to play with, which is basically a tweed champ with a tone pot in a larger cab with 10" speaker (Legend 1028K - similar to P10R). A very pure sounding class A single-ended amp, the tone pot and larger cab/speaker make a huge difference - it gets loud and has tight lows. The components are the best Matt could source, including "Sour Sound" transformers for the three used in that circuit: power, output, and choke. Brian Sour is right next-door to Dawson Amp Repair where I took the class, and they have a working relationship. Soursound makes some of the best "vintage" transformers you can buy, they sound great in my new little Princetone!

These videos bring back memories of my vacuum tube setups from 50 years ago, when I was a kid. And of course, what's really messed with my mind is see new VT amps with 1930s 300B power output tubes, as well as a Blue Tooth dongle type thing(!)

Great information Terry. I really enjoy the application of theory to practical implementations.

Cool video. Thanks alot. I like the introduction of your "proprietary" circuit boards for your designs.

Terry, You consistently produce some of the best tube electronics videos on RU-vid. Thanks, I know it takes a lot of time and effort to share your knowledge. I appreciate each one of them.

I can't wait to get my hands on some of those boards to use for homebrew AM TX's. Thanks Terry! You are awesome!

"You dont have to be a star fleet science officer to figure this one out." But, the pointed ears add a half-octave to the HF response of your hearing! :-) Nice channel, subscribed!

This is a great video ! Awesome content from Dlab as usual.

One thing I really appreciated from Classictone was the loaded voltage documentation with their power transformers. You have to contact other manufacturers for that information.

That Command Chief case reminds me of a power supply I had for an old O-scale model train.

I had carnhills installed in my preamp. They sound great.

Always good education! Thanks.

Nice Terry !

Very interesting, thanks for that.

Great video as always Terry. Mr. Fender must not have ever seen a receiving manual, because the RCA sheet for a 6v6gt says 350v max on the plates, where my Deluxe Reverb has closer to 450v. I'm sure there is a very good explanation, that is far above my skill/pay grade though. Cheers from Australia

Excellent. Thank you.

Thank you for a very good video

Hey I just plugged in the secondary winding into a 6 ohm speaker parallel with an 8 ohm speaker and it sounded wounderfol, I was able to hear perfect tone quality at full audio volume (18-36 watts)

I thought the reason you were doing these videos was so you could sip red wine. ,🥳

Wow, great video. However, you lost me after that part where you said, "Welcome to D-Lab everybody". I think I'll just pay a professional for this type of work 😂

Wow!

Are you going to cover what the Corn Cobb does? Nice vid Terry.🙃

Hi Terry, what values did you choose for Electrolytics ? I saw at least one 22mfd,but I expect you used other values as well and built it for long term reliability. You and Uncle Doug are the best teachers about this art. Many thanks again, Daniel

Good video and great tips can you just recommend some transformer models that will work for 6QA5 builds? How can you test a power transformer under load before you buy it? What is the one you are using there?

Soy de combia ..y no he podido armar un preamplificador por falta de bases para tubos ya en este pais no se trabaja con eso desde hace años..

Hola terry, muy buenos videos, pregunta para un el34 en single ended deberia probar mi transformador con una carga de 10 k u otra? Gracias.

I have just lucked out on some very nice Stromberg Carlson Amps. One runs 4, 6550's and some of those military Metal incased 6????. There is huge iron in all these amps. I think they were designed for 100 watts (or more) output. Probably huge voltage in these. Will your class a boards be okay here and need costs and shipping info. Plan to build a single ended, 1 swappable power tube for different sounds, volume and tone. Cautions , schematics, ideas?...your clips are very helpful and many thanks...Daniel

Great video. When are you going to build a BASS amp, though? Cater to us lower down the sound spectrum a bit! ;)

Lovin' the Soft Kitty tee shirt.

Great video Terry. I wonder can I take a liberty and ask a PT question please? I am building a clone Fender Deluxe Reverb amp ( AB763 but without the vibrato circuit ) and I think I have purchased the wrong PT. I have a Hammond 372FX which will give 600v CT @173ma but I should have got their 290BEX which provides 660v CT @138ma, Could you advise if my transformer will still work and if it will affect the tone please. Much appreciated.

Question. Does the load on the filament winding also pull the CT HV winding output voltage down a bit more too?

Hey Terry, I have a P.T. with a 0v-120v 100mA High Voltage winding, and a 0v-12v 2A filament winding. Do you think I could power a pair of 6AQ5's if I used a voltage doubler to get 250v DC? Should I run them a bit cold if I do that?

Drinking red wine out of a lowball glass, really Terry?

Question...do these Nickle plated or pin striped plates on the transformers reduce the Henries and are they better for audio use.???

I've had bad luck with ceramic 9-pin tube sockets... love the belton micalex. I can only find ceramic 7-pin miniature for the 6AQ5. Do you have any recommendations?

hi about lepy lp 2020a i plugged in correctly turning the volume up i heard a buzzing sound in speakers and the volume kept going off then on when i increased the volume from the amp now one of my speakers has stopped working what caused this before i used the amp i could turn the volume up on the speaker all the way and it was clear sound also could it have been the underpowered power supply that it came with some people recommend a 6amp power supply. i also used presonus eris e4.5 studio monitors 75w with the amp also is using a amplifier with studio monitors dangerous because the studio monitor has a built in amplifier. and the amp is 20w and the speakers are 75w could it be because the speakers are more powerful.

Тэрри, большой тебе привет!

What about the audio output transformer? I want to wind my own transformer for a Dynaco 60 amp. Circuit drawing shows 5Kohm, 8ohm to speaker. Audio output transformer calculator says 25 : 1 turn ratio. Specs say, 60w transformer need to be 60 x 5 = 300w so peak pulses do not get cut off. The question I have is, I know 8 ohm winding can not be 1 turn. How many turns on the 8 ohm winding? I the secondary is 20 turns then the primary should be 20 x 25 = 500 turns.

Terry, I have concerns. The RCA tube manual lists the maximum plate voltage as 250V. (Tung-sol says 275). But before the tube warms up and draws current, you're likely to see 300V as you're using solid state rectifiers that lack the time delay of tube rectifiers. Also, you didn't show what your wall voltage was at the time. The voltage could go higher if the amp is plugged into a outlet supplying 125 VAC. Personally, I'd be looking at something that supplies 250 VDC unloaded and somewhere in the mid-point of the 180-250V suggested operating range when loaded. Hopefully in the 210 to 230V range.

What about for El 84's

D LAB, what formula are you using? AC voltage X 1.414 = DC Voltage?

Awesome🤤 😅💋

Where is Priscilla, as promised?

If it converts ac to smoke then its the wrong power transformer :D

Too bad Classic Tone Transformers (Magnetic Components Inc.) has gone out of business.