Tube Amp Archive

Thanks for all the help and suggestions. Before I read these latest comments what I did was swap out the 100k V1B plate resistor for 200k. It dropped the voltage to 246v. It definitely has some breakup now and cleans up sweet when I back off a little. Overall, I think it's not as loud as before but ...

I took all voltage measurements again- B+ - 392v B+1 - 374v B+2 - 306v B+3 - 305v V1 Pin-1 - 202v V1 Pin-3 - 1.5v V1 Pin-6 - 269v V1 Pin-8 - 2.7v 6v6 Pin-3 - 365v 6v6 Pin-4 - 306v 6v6 Pin-8 - 16v Makes no sense to me that pin 6 is so high since it's connected at the same supply as pin 1, then both h...

at wide open volume and pushing the strings hard I get to the edge of breakup. But it really sounds great at any volume, and I love it. The tremolo is amazing. The sustain is great. I was just looking for that point where you can dig in without having to be wide open then ease up when you want to cl...

Thanks for the info. I admit I couldn't figure out what MV stood for until it was explained. I hear other champs that have easy break up and a lot of times I read where they would like less of that and more headroom. I've got a ton of headroom and wouldn't mind a bit less. Also, I have and use a rea...

I finished my first aa764 build and it sounds pretty amazing. I only wish it would break up a little. I installed an NFB switch but it only seems to boost highs and still no breakup. Then I did the mod where you reverse the 10k and the 1k on the power rail. I like the sound of that mod a little bett...

Thanks for your help

I replaced the 330R on the B+ with a 470R. Voltages came down a little. These are at idle: B+ - 377v B+1 - 356v B+2 - 346v B+3 - 324v Pin 3 - 344v Pin 8 - 19.7v In your formula, where does the 470 ohms from? Were you saying I should use a 470 ohm at B+? Amp is way loud and I don't get much breakup. ...

You're right, it was a typo, thanks - 6v6 pin 8 is 20v. So, I should increase the 330-3W resistor to drop B+1 a little more? I suppose that would drop all the other B+ too. I want to check plate dissipation as soon as learn about that. Rectifier and power tubes are pretty hot to the touch, but not r...

Thanks for the info. I finished wiring the input, then started it up and it had a high pitch that was trying to run away. I switched the OT primary polarity and that went away. It sounds pretty good and clean. Very slight buzz. Tremolo sounds good so far. I have not pushed it into breakup yet. I wan...

I put the voltages on the diy layout file--

Hello, I'm new to posting in the forum but have read quite a lot here. I started a VC project and with all I had read, it seemed best to make a couple mods. Like keeping the signal ground separated from the power ground. Also adding a filter stage before the first B+. It's not a kit since I ordered ...