I think the tldr is: spacing pot affects the duty cycle of the oscillator - with the pot in the middle, the duty cycle is approximately 50/50 and the extremes of the pot vary the duty between 20/80 to 80/20 (illustrative suggestion only).
Varying the duty cycle is more noticeable with the square wave sound, but from memory, the spacing pot does have some effect on the shape of the slope/ramp at the triangle/sawtooth end of the wave pot, but nothing like as much as the (diode-based) ramp mod would.
I didn't bother with the spacing pot on my tremlune tremelo pedal as I was happy with a 50/50 square wave trem, but when I made a synthy filter pedal that used the tremlune LFO, I did include the spacing pot as it gave more interesting variations when sweeping a filter rather than just modulating the amplitude of the signal.
I was talking about the Symmetry pot, the one that makes the sawtooth wave. I was wondering if it's always on or if it goes off with the pot at zero. But thank you anyway!!! The link provides a great detailed info :) I find this really helpful.
Anyone? I'd like to know if the Symmetry pot is always doing stuff to the audio signal. I know that the Spacing pot at 12:00 it's like if it weren't there. I was wondering if it's the same case for the Symmetry pot.
first off, great pedal.
in my experience with it, the symmetry pot acts the same as the spacing, 12:00 is "neutral". not affecting the wave shape at all.
thats one feature that makes this circuit a must build. from square wave with fat to narrow pulses to triangles shifting to up or down ramps and more ( can it do a true sine wave? i don't have an oscilloscope.), the control set is fantastic.
Thanks clockman! That's exactly what I wanted to know. I built the Depth-Speed-Wave version a few months ago and now I'm with the full 6 pot version. But the Spacing & Symmetry don't seem to do much...I think they are working fine since they affect the speed of the lfo when I set them to their extremes.
I'm also getting a bit of distortion which is annoying me. Maybe the LDR+Led are too close...
I've had good results with the six knob version.
I find the symmetry knob more useful than the spacing.
Easy way to check sym control. Set a slow speed with a triangle wave. CCW setting on sym should be ramp down, CW should be ramp up. I may have that reversed but they are extreme opposites and very defined.
Regarding distortion, have you tweaked the internal trimmer to set unity gain? that thing can add quite a boost if needed.
swap op amps? I'm using the TL062 and 4558 combo suggested and its clean.
the LDR is an old unbranded Radio Shack (the large one that came in a multi pack) and a red diffused LED in black shrink wrap.
I built it years ago and haven't had to build another trem for myself since.
Hi clockman! You were right about the trimmer. I set the amp about to breaking up, so the slightest gain provided by any pedal is easy be to noticed. I had a 20k trimmer, too much. I swapped it for a 5k one and now I can easily set it to unity.
I used TL072 and TL062 for the LFO. Next time I want to try a TL022
Everything is working great so far :)
I want to share something. The 100r at 9v gave me problems. Well, not exactly...The pedal worked without problems but just after that resistor there was a 1v drop. I removed it and no voltage drop. I think that resistor should be in series with the DC jack +v or use two resistors: one for each opamp.