The Quilcom Folder: A synth to explore wave folding

[Spogg]

Hello you Flowstoners!

I knew nothing of “wave folding” until Mr K Brown mentioned it in connection with his amazing post of so many synths, all inspired by classic hardware.

viewtopic.php?f=3&t=5258

I was intrigued so I spent some time researching this technique and examining waveforms, sounds and even circuits of analogue electronic modules.

I designed a wave folder system which can reproduce the variations I came across while searching, and became very impressed at what this method can do and sound like.

This has led me to create the Quilcom Folder synth. I’ve kept the architecture dead simple because I wanted to see what could be achieved at a fairly minimal level of complexity. Naturally this principle could be integrated into a mega-synth but I like to explore individual techniques like additive, FM, subtractive, scanning, morphing and so on, in isolation.

This synth comes with 32 presets I made to explore and demonstrate what can be achieved with such limited means. The download includes a basic user guide to give a bit more background and info.

The VSTi plugin is found on http://www.flowstoners.com under Quilcom.

See (hear) what you think and I’d love a few comments please!

Cheers

Spogg

[martinvicanek]

Hey Spogg, creative as ever. Great variety of sounds in there!

[BobF]

Hi Spogg,

FANTASTIC! I do not think I or many others make as good synth's as you do. I have know about folding for some time and even made a few modules using it , but this is really great. I love the sounds it can make, you did a really great job.

Take care, BobF.....

[nix]

That's real nice!
I like how the rectified waves have no offset.

So this waveshaper could be an effect too I guess?

The diode model is my preference taste-wise.

[Spogg]

Hey thanks for your nice comments guys.

Now, using a folder as an effect... now there's a thought! Pity I'm off on my holidays or I'd be experimenting tomorrow

No, really!

Cheers

Spogg

[Julian Ray]

This synth sounds very impressive! It looks simple yet sound quality and variability are fantastic.
There is a very interesting effect what you slowly rotate Symmetry knob. I imagine that modulating Symmetry knob (unipolar for Clamped and bipolar for other modes) from a very slow LFO could give some interesting results.

I still have to understand the Assembler part inside the Folder modules

Beautiful creation, Spogg!

[Julian Ray]

Dear Spogg,

I'm trying to understand the logic behind your DSP/Assembler codes for Positive/Negative folder module...
Could you, please elaborate a little bit for FS newbie?

Cheers,
Julian

[Spogg]

Hi Julian

I had to go back and remind myself what I’d done, as is often the way for me with older projects.

The schematic contains my DSP version, which Martin Vicanek very kindly made into the ASM version.

Each of the 8 folder code modules operate in the same way.
There is a parent folder module for positive-going and for negative-going halves of any waveform. Each child module inside the folder module has a low reference value and a high one (reflow and refhigh). The values are chosen to be equally spaced up a “ladder” of values.

So, if reflow is 3 and refhigh is 4, the mid value is 3.5 and when the incoming wave goes through this range it is inverted around that mid value. So between 3 and 3.5 it passes through unaffected and between 3.5 and 4 it is inverted. The output amplitude is adjusted to fall in the 0-1 range, so with a peak input excursion of 8, all the child folder modules will give out a 0-1 signal and these signals are then summed together to give a total of 8 folds.

As I mentioned, this is repeated in a similar way on the negative-going values of the waveform. This gives a largely symmetrical bipolar waveform.

That’s the principle of operation, and I hope I’ve helped explain it a bit.

Cheers

Spogg

[Julian Ray]

Hi Spogg,

Thank you very much for the explanation - I think I understand now how it works

Cheers,
Julian