Best waveform (LFO) of a chorus pedal?

[nguitar12]

Just build a little angel chorus pedal. I find the the LFO of this pedal is something like sawtooth and make the vibrato a bit noticeable.
Is the ideal wave form of a chorus pedal would be a Sine?
If so how can I improve the waveform of the little angel chorus pedal?

Thanks in advanced.

[samhay]

The LFO should be generating a triangle(ish) waveform. Problem is that wiggling the reference voltage of a PT2399 with a triangular LFO doesn't necessarily translate to a triangular modulation of the pitch.
Does the depth pot change the feel of the LFO waveform?

[teemuk]

Is the ideal wave form of a chorus pedal would be a Sine?

Practically all waveforms will work, the ideal one, for you, is the one YOU prefer.

Old Roland JC-120 amps used a triangular wave for the chorus effect and a sinusoidal waveform for the vibrato effect. In the early 1980's they changed the design so that both used a triangular waveform, one LFO less but a different tone.

As you figured it out: It's a "flavour" thing. There really isn't an ideal waveform, there are just individual preferences concerning the tone of the effect. Kinda like generic tremolo effects, the LFO outputs in different amps range from generic sinusoidal, triangular, sawtooth or square waveforms to all kinds of combinations, and that even when a component like LDR that has inherent hysteresis and saturation isn't thrown in. The difference? Well, if one prefers "choppy" tremolo than gradually changing waveforms like sine waves are probably worse selection than square-ish waveforms. But it's still just a matter of individual preference.

Then, it's wortwhile to heed that LFO is just one ingredient. Many chorus circuits have pre and post -effect signal processing. In simplest form it limits to low-pass filtering the signal to get rid of BBD noise, but in many chorus effect embodiments the signal also goes through one or many compander stages for deliberate dynamics processing (whether compression or expansion), and even the EQ treatment for the signal can make a big difference to the overall tone. JC-120 amps, for example, have a prominent upper mid-range boost in the signal fed to the BBD, and that even when excluding the deliberate bandwidth limit to remove BBD noise.

[nguitar12]

The LFO should be generating a triangle(ish) waveform. Problem is that wiggling the reference voltage of a PT2399 with a triangular LFO doesn't necessarily translate to a triangular modulation of the pitch.
Does the depth pot change the feel of the LFO waveform?

The depth pot only make the waveform change more noticeable.
It don't sound anything like a triangle(ish) waveform.

[nguitar12]

Is the ideal wave form of a chorus pedal would be a Sine?

Practically all waveforms will work, the ideal one, for you, is the one YOU prefer.

Old Roland JC-120 amps used a triangular wave for the chorus effect and a sinusoidal waveform for the vibrato effect. In the early 1980's they changed the design so that both used a triangular waveform, one LFO less but a different tone.

As you figured it out: It's a "flavour" thing. There really isn't an ideal waveform, there are just individual preferences concerning the tone of the effect. Kinda like generic tremolo effects, the LFO outputs in different amps range from generic sinusoidal, triangular, sawtooth or square waveforms to all kinds of combinations, and that even when a component like LDR that has inherent hysteresis and saturation isn't thrown in. The difference? Well, if one prefers "choppy" tremolo than gradually changing waveforms like sine waves are probably worse selection than square-ish waveforms. But it's still just a matter of individual preference.

Then, it's wortwhile to heed that LFO is just one ingredient. Many chorus circuits have pre and post -effect signal processing. In simplest form it limits to low-pass filtering the signal to get rid of BBD noise, but in many chorus effect embodiments the signal also goes through one or many compander stages for deliberate dynamics processing (whether compression or expansion), and even the EQ treatment for the signal can make a big difference to the overall tone. JC-120 amps, for example, have a prominent upper mid-range boost in the signal fed to the BBD, and that even when excluding the deliberate bandwidth limit to remove BBD noise.

Thanks foe detail explanation
So if there any simple way to make the LFO in little angel chorus more symmetric?

[samhay]

If you built this version:
http://www.diystompboxes.com/smfforum/index.php?topic=86297.0
The LFO asymmetry is largely determined by the 100k and 47k resistors hanging of the (+) input of the LFO op-amp bottom left. Try increasing the 47k to 100k.

[nguitar12]

If you built this version:
http://www.diystompboxes.com/smfforum/index.php?topic=86297.0
The LFO asymmetry is largely determined by the 100k and 47k resistors hanging of the (+) input of the LFO op-amp bottom left. Try increasing the 47k to 100k.

WOW thanks.
Will try this out tonight.

[samhay]

No problem.
If you find something that works better, please let us know.