Trem and Bias

[trem]

Would it work to use this single 12AX7 (except my tube would be a 6SL7) Tremolo Circuit..... into this dual fixed bias circuit.?
That is, to use it as a Bias Vary Trem into my bias circuit. My Intensity Pot is a dual 250k. The power tubes are 2x 6K6.
Thank You

[trem]

Anybody want to take a shot at this.?
What I am wondering is.....is there a schematic (Fender perhaps) that I can use with my bias circuit.?
On my bias schem, where it says LFO, can I run "any" of the Fender Trem Circuits into that area.?
Can any Trem Circuit be used as a Bias Very Tremolo.
I am hoping to do this with a 6SL7.
Thank You

[Enzo]

ANy trem has two parts, the LFO, and an interface. LFOs tend to be more or less the same, all they are is a low freq oscillator. The output of the LFO can drive a neon bulb in a roach, it can drive the bias, and there are other strategies.

[MusikalienATX]

I'm partial to the Blackface Princeton AA964 tremolo, fwiw. Seems like it would work with a 6SL7 since you only need one triode. I've read that LFOs need to run at high voltages to get them to oscillate, btw.

[trem]

Yeah...my mistake...getting what I have to oscillate has been a problem.
What I should be asking is.....Using a 6SL7, what trem circuit would you guys use...for bias vary trem...into dual bias pots...for a pair of 6K6.?
Thank You

[ron vogel]

watch the filter cap on the trem tube...too high a value will mess up it's operation in my experience. Can't put in a 25uf like a preamp filter cap and expect it to osc slow. I ran into this problem on my brown Princeton. Slow trem speeds would be very weak until I used 10uF or less.

[Chuck H]

This thread just gave me a clever idea. Looking at the scenario I thought about the possibility of an imbalanced LFO at the grids. Being as there may be some difference in the static bias of each grid to start with, an equal LFO would spoil that. Or, if the intensity pots are imbalanced the same thing. But in my own experience bias vary trems seem to sound best when there is some imbalance of the output tubes. A perfect balance seems to accentuate any crossover distortion caused when the bias is driven to cold side causing garble and hash to be audible at some point in the warble. This seems most problematic with high plate volts where a hotter bias can't be used. Possibly not an issue on lower Vp circuits. But I was thinking...

Why not add a fixed resistor of 22k to one side of the LFO output circuit and a trim pot of 50k to the other side?!? Then you can tune the LFO for balance (or intentional imbalance) with the new trim pot. Without worrying whether it's balanced or not you can just set the trimmer where the trem sounds and performs best

[trem]

I'm partial to the Blackface Princeton AA964 tremolo, fwiw. Seems like it would work with a 6SL7 since you only need one triode. I've read that LFOs need to run at high voltages to get them to oscillate, btw.

OK...looking at your idea.
I would add another 0.10 cap after the 1Meg/0.02 junction...just duplicate what is there...add another 0.10 cap, and then run each of those (0.10) to my dual 250k Intensity Pot.
Should it just, kind of, be that simple.?
Thank You

Looking at my own schem, I already have those 2x 0.10 caps. So, where my schem says LFO, I would substitute THAT junction for the 1M/0.02 point on the Fender schem below.