Euro: novel cv sequencing technique

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Splashwater Boom-Boom
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Euro: novel cv sequencing technique

Post by Splashwater Boom-Boom » Thu Aug 01, 2019 11:59 pm

I've been thinking about a method to sequence cv in my rack since I first came across the tip top fold processor several months ago. It has the sub octave generator section with attenuators which is fed the peaks of the wave folder to the best of my iPad nderstanding, which sounds tough as hell, but I got to thinking about what that actually looks like and if it was fed a slow lfo (or 2) it would essentially turn into a chaotic cv sequencer, but one with a lot of control. Alas in my research I found out that the output is in fact ac coupled, so it would not be suited to this perpose, which was a real let down, but the idea hasn't left my head since, and yesterday I found a fold processor for pretty cheap used and decided to see if I could get it to do what I want with some gentle modification.
After taking the panel off and using the multimeter to trace the output back to the opamp, I was able to locate the Decoupling capacitor and just jumper a wire across it. After doing a preliminary check of the opamp datasheet and calculating the max output current if the output is grounded (about 24mA)wouldnt blow it out, I put it all back together and plugged it in and wouldn't you know it, the thing worked, however the signal was inverted, so after patching it through an inverter I was able to get some really great results out of it. The amount of folds controls the density of changes, and the attenuators control the distance between pitch changes (the interval). I've been running the output through a quantizer and getting looping repeating patterns out by sending it clocked lfos (saws and triangles mostly from the qplfo).
I've been feeling pretty triumphant about having this theory pan out to be such a useful technique and wanted to share my results. I'll follow up with a link to a quick track I recorded using this technique to demonstrate.

Splashwater Boom-Boom
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Post by Splashwater Boom-Boom » Fri Aug 02, 2019 12:10 am

Here's a video demo of the process:
Video demo

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adnauseam
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Post by adnauseam » Fri Aug 02, 2019 12:43 am

This reminds me a little of the classic clock divider outputs -> mixer -> quantizer -> oscillator patch!

it's fun to play with for sure. Are the suboctaves derived from the signal AFTER the folding has been done?
-adnauseam






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Splashwater Boom-Boom
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Post by Splashwater Boom-Boom » Mon Aug 05, 2019 4:48 pm

adnauseam wrote:This reminds me a little of the classic clock divider outputs -> mixer -> quantizer -> oscillator patch!

it's fun to play with for sure. Are the suboctaves derived from the signal AFTER the folding has been done?
As far as I'm able to tell, yes they are, I believe the peaks from the folded signal are sent to the sub octave circuit, so by adding more folds you are increasing the number of events where the pitch changes. The bias also has an effect on the cadence although it's less rewarding to change while it's playing, but offers something akin to a shuffle.

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teezdalien
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Post by teezdalien » Tue Aug 06, 2019 4:07 am

Neat! I've tried experimenting with wavefolding cv, albeit mostly unsuccessfully due to the ac coupling as you describe.. Sounds like a great idea for further module development, if it was refined and worked well I'm sure people would buy it. :tu:

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cptnal
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Post by cptnal » Wed Aug 07, 2019 5:24 am

So, cutting out the stuff about capacitors and op amps:

Square > Wavefolder > Quantizer

...?

Sounds like fun, and versatile, especially if you have PWM of the square. I'm going to give it a go anyway. :tu:

I'm already thinking about comparators and S&Hs, but one thing at a time! :omg:

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mgscheue
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Post by mgscheue » Thu Aug 08, 2019 8:07 pm

Not exactly a wavefolder, but the XAOC Drezno does interesting things to cv when bits are flipped or shuffled around.

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