Collosalus question - changing LFO shapes?

[zilla]

I've seen the Subdecay Starlight flanger which is supposed to be a modified MXR 117 flanger, but he has switchable LFO modes on it.  I was wondering how to go about modding the Collosalus to have these different LFO shapes?

Thanks

[midwayfair]

The LFO is IC3. I'm pretty sure you can short pins 3 and 5 for a square wave, or switch a diode before the Sweep lug 3 to make a ramp wave. Removing R21 might also do something but I don't know how noticeable it will be.

But comb filtering effects rely on crossover between the out-of-phase bands. There are a limited number of waveforms that work well. Square (on-off) waveforms usually result in very little effect and ramp waveforms probably won't sound very pleasant. There's no reason not to try it, because the worst that happens is that you have to rebuild a complicated PCB (...), but I have a hard time imagining the sounds you get being very useful.

I looked up the Subdecay ... it clearly has a digital LFO. Square-triangle mix is a pretty decent description of the 117's waveform. Removing R21 gives you the triangle. You'll notice they don't give you a square wave on its own ... the steps are probably slightly gradual changes (i.e., a square-triangle mix, but sequenced) and not "blinks" like e.g. the Seqwah. Sample and hold is probably random steps.

[zilla]

Thanks for the insights, Jon.

[neandrewthal]

I always just assumed it would be a good idea to have other waveforms.

Watch this video starting at about 8:00 to hear some non traditional flanging lfo shapes.

https://www.youtube.com/watch?v=QW2vZzn7e8Y

It appears that Jon is right in that the sharp edges of square and saw waves sound extra abrupt compared to how they would sound on a phaser or whatnot, but I like the mix of smooth and abrupt with the ramp and saw. I bet the square would sound cool in conjuntion with modulating the depth and/or initial delay.