Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: W5FH on March 11, 2023, 11:13:37 pm

Title: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: W5FH on March 11, 2023, 11:13:37 pm

Hello-
    As it ends up I may be looking at putting the Sluckey Trem-O-Nator on one side and a reverb recovery amp on the other side in a 12AX7 envelope. Does anyone foresee a problem with the oscillator getting into the reverb recovery amp? Thought I would ask in case someone else has had an issue with something like this or similar. Thanks.

Title: Re: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: sluckey on March 12, 2023, 09:22:16 am

I haven't tried it and ain't gonna. The oscillator produces a HUGE signal. On my Band Master it is 110V_rms. That's 311V_pp. And the reverb recovery deals with the smallest signal in the amp. Seems like an invitation to trouble to me.   :dontknow:

Title: Re: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: W5FH on March 12, 2023, 10:20:52 pm

Thank you Sluckey. I agree with you now that you have enlightened me on the strength of the osc signal! Scrap that plan, for sure.
Thanks, Byron

Title: Re: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: PRR on March 13, 2023, 12:44:37 am

Quote from: sluckey on March 12, 2023, 09:22:16 am

...The oscillator produces a HUGE signal. On my Band Master... 311V_pp.

A healthy oscillator, without fancy amplitude control, will make very nearly its supply voltage as peak-peak output. It wants to "grow without limit" but it can't exceed, or closely approach, its supply voltage. Seeing 311Vpp suggests a 350V or so supply, maybe 400V if you load it hard. (Yes, I also get a clue by knowing about what a Bandmaster is; but the same relationship applies in 3V systems or 100KW radar modulators.)

OTOH, 10Hz wobbles don't couple like radio waves. I can believe someone has done and lived, even thrived. But it seems a less-good bet.

Title: Re: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: astronomicum on March 15, 2023, 08:28:19 am

Quote from: PRR on March 13, 2023, 12:44:37 am

I can believe someone has done and lived...

The Univox models U-320, 1221, 1226, 1000, and 1011 had the LFO and reverb recovery in one 12AX7.

Title: Re: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: W5FH on March 16, 2023, 09:03:55 am

Very Interesting -
    Thank you for this information showing it being done, I will research it. Maybe just for the knowledge, but nevertheless a learning experience.

Title: Re: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: tdvt on March 16, 2023, 11:53:45 am

Not to totally hijack the thread.... but what other circuits would be a less iffy use of the unused triode with the Trem-o-nator circuit?

Title: Re: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: sluckey on March 16, 2023, 12:40:43 pm

I don't have any qualms about leaving half of a 12AX7 unused. It's not a sin. But if it bothers you, switch to a 6AV6. Then ponder what to do with the two unused diodes.   :l2:

Title: Re: Trem-O-Nator Sharing Envelope With Reverb Recovery-OK?
Post by: tubeswell on March 17, 2023, 12:23:42 am

I’ve tried a LFO in the same 12AX7 tube as an ordinary gain Stage and got unwanted cross talk (‘thumping’), which was cured by separating the stages into different tubes.


Princeton Reverbs have the LFO on in the same 12AX7 as the cathodyne PI and get away with it (because a properly set up cathodyne has good common mode rejection).