Tube Amp Archive

Thanks for the replies! I am using 6p3s Soviet tubes which I hear are the equivalent of 5881's. They are biased pretty cold. In fact the bias was cold enough so that I could also try 6v6 tubes to see if I got a better trem strength. When I put 6v6 in, I did hear a slight difference, but not much. So...

Hello all! I posted this on TDPRI but wanted to get your take as well. I recently built this amplifier: https://youtu.be/JvMwktF8tW0 The tremolo I used is from a Silvertone 1482. (6AU6 Oscillator) When I first installed the circuit, the tremolo had no effect. I read online that I could change the va...

You are right. The issue was that the ground wire shown in Rob's schematic coming off of the board and linking to the ground terminal on the high jack was actually grounded on the potentiometer ground bus. I don't know how this is any different, since they all link to chassis ground, and the jacks a...

Hello all, I recently finished a Tweed Twin 5f8A build. I am very pleased with it. However, I noticed that when the bright volume is maxed out along with the normal volume, I get a 60 cycle hum. I think this is because the low jacks are not grounded to the switch (ring), so all signal is allowed to ...

Yes, correct, but you should add balance resistors across the caps to insure that they share voltage equally, like this: https://www.vishay.com/docs/48296/_did-you-know_aluminum-balancing_vmn-ms7375-1709.pdf From that article Rmax = (2*Vmax - V)/Ileak. If you assume that the caps are run at rated v...

Hi all,

I have a very simple question.

I need to replace a 100v 10uf capacitor.

Can I safely use two 22uf 50 v capacitors in series?

Will this total 11uf at 100v?

Thank you!

Edit: I did this on a repair recently and the amp seems to function great. Will there be issues down the road?

Hello all, I recently recapped and increased the tremolo intensity on my Ampeg Gemini VI. It now sounds much more intense and wonderful like a Fender. However, upon increasing the intensity , I lost the "After-Beat" click click click effect. When I engage the intensity switch it appears to keep the ...

First off your not a fool, as fools never learn! Anyway, All’s well that ends well, especially if some new knowledge comes along with it ! Enjoy! PS. Over the passed winter I had one of those that drove me to the edge nuts with crackling in that reverb circuit that got way worse with temperature ri...

Charlie Wilson wrote: ↑Thu Aug 18, 2022 5:19 pm A little off topic, but when you replaced the electrolytic capacitors I hope you used insulated cap cans.
CW

Yes, the cans were insulated!

I got them from Fliptops and paid the extra $. Also I steamed off the cardboard tubes just for a more original look, though I regret that decision now.

The side of the reverb pan labeled output can not be on the same side of the amp as the power transformer. It may be that the pan was remove once to check it, repair it or replaced it and it was reinstalled wrong on the lid of the amp. Also confirm that the sheild of the cable on the output side of...

bepone wrote: ↑Thu Aug 18, 2022 3:54 pm

Stovemananon wrote: ↑Thu Aug 18, 2022 3:30 pm That makes sense, but if it were a grounding issue in the tank why would the buzz persist without the tank in the amp ?

because you have open /unterminated cable connected to very sensitive amp grid=?

I follow now. I'll take a look inside the tank. Thank you!

Does anyone know the function of C16 in the bias section? (schematic below) this is to create negative bias . if you changed this value, you are also changed bias voltage too. need to recheck all tubes now. I will put a .15 uf in series with the .068 since I do not have any .047's on hand. Thank you!

Update: Thanks to all that have helped out in this discussion! I replaced all polarized capacitors and the hum lessened. I replaced C16 .047 uf capacitor with a .068 uf capacitor and all of the sudden the hum reduced to a very tolerable level. I think every capacitor in this amp has now been replace...

the oxide on the reverb tank connectors? or cable broken inside the tank? or grounding wire on the reverb tank inside? when connected all , power off, test with the multimeter ground continuity from amp chassis to reverb tank chassis=? Thanks for the response! It appears that even with the tank rem...

Check the integrity of that output cable, does the sheild connection at the board have contenuity to the rca end? If that test good then place a short right across that rca end, when doing that does the hum stop? Thanks for the advice! When you say “shorting” do you mean to short the rca end to the...