Tremolo effect pedal build

[blindboybenton]

Hi

I want to build a tremolo pedal for my own use

I have built it and it works, But not as well as i hoped

The main problem is the depth. When i turn it fully off it increases the volume and only starts to work at about 12 o'clock
The speed is better but i would like it to be more controllable, again it dont really work much until 12 o'clock
I have made it exactly to the circuit
I was going to try audio taper pots, but before i rip it out any idea's

BBB

[Mick Bailey]

If it only starts to work at 12 o'clock with linear pots then with log it will be worse. With linear, 1/2 rotation is 50% of the resistance, with (most commercial) log pots this equates to 10% of the resistance.

Try wiring up a log pot backwards to simulate a C taper pot. If that works OK either leave it like with reverse-operation controls, or order some C taper pots.

The volume shift is a characteristic of the design. Amongst other things the NFB changes due to the varying cathode resistance - more NFB as the depth increases, so lower effective gain.

[Chuck H]

I can't look at the circuit and determine how it sounds. Is this a known good circuit. "Known good" being relative. As in did some guy say he made this and it's good or is it a popular design that is known? Many tremolo circuits use reverse audio pots. It's possible the behavior is "normal" with linear pots. The increase in volume with the trem off is a problem to be sure though. If you have a scope you can monitor signal swing to see if the trem is biased a little cold relative to when it's off. Properly, the trem will be a bit hot on peaks and, obviously very cold on the low volume or off modulation.

[Mick Bailey]

See post #222 here to reconfigure the depth control and add a cathode bypass cap (to remove the variable NFB, though the post refers to this as an anti-pop cap);

Vibracaster - or "How to turn your Valvecaster into a Tremolo"

[blindboybenton]

Thank you. I will look into the changes

BBB