The Quilcom Phadex: A Phase Distortion Explorer

[Spogg]

A big HELLO to all my wonderful FS friends!

Here’s my Quilcom Phadex which is designed for you to be able to explore the sounds of Phase Distortion:

https://www.dropbox.com/s/z4w7tq9heuxbt ... 2.zip?dl=0

I also made a YouTube demo:

https://youtu.be/M9HODOcsRbg

Many thanks must go to Martin Vicanek whose wonderful curve-making Ruby code I prised out of his brilliant drawable filter and bent to my needs. And also for all the other creations of his I use all the time.

I hope you get some interest and fun with this thing.

Cheers

Spogg

[trogluddite]

Another wonderful design, Spogg (not to mention the usual excellent manual and resources). The range of sounds available from a single oscillator is great, even before throwing the other features into a patch. The curving of the phase/window controls works really well for taming some of the rougher edges of the linear-only plots of the original PD synths.

Phadex has earned itself the honour of being the first brand-new VST added to my shiny new PC!

[Spogg]

Thank you SO much trog. Your positive and encouraging comments always mean a lot to me.

And I wish you a Happy New PC!

Cheers

Spogg

[BobF]

Hello Spogg,

WoW, this is fantastic! When I talked to you on Christmas, I too was working on a "Phase Distortion Synth" but when you told me you were also working on one I immediately stopped . I knew right then mine could not compare to yours and I was right. This is a power house and as trogluddite said the range of sounds are truly great and I have only played with it for 15 min or so. Like I said before your Synths just keep getting better and better. Ok, back to digging into this Synth some more !

Have a great day, BobF.....

[k brown]

So cool - can't wait to try this out. In the mid '90s I had a Casio CZ101 for a short time; I could never get comfortable with it - not a great UI and some strange controls, did have some very pretty presets though.

I always wondered if PD could be done in SM/FS, I figured it would take some custom coding to do it - so that left me out . I probably wouldn't be able to tell form the schematic - did you do this as Casio did, with shifting the phase angle of sine waves? - or did you get to the same result by a different road?

[Spogg]

Many thanks to Bob and Kevin!

Kevin, if you look into the schematic I’m sure you’ll see what I did there.

Briefly though, I have a reference ramp generator whose output creates an index range for a waveform table which is loaded with the base wave. So the waveform table has 256 index values and this linear ramp runs between 0-255. The reference ramp generator also reads out a table based on the Shape curve. Thus you get two index ramps: the reference linear one and the transformed or distorted one. The amount of PD, which can be modulated, is created by a linear crossfade of the reference linear ramp index stream and the “distorted” index ramp.
For windowing, the reference ramp reads out the curve created for windowing, and applies this to the waveform amplitude via a simple multiplier.

By far the trickiest part was to figure out how to wrap-around to zero and keep the interpolation happy. Martin’s solution didn’t seem to work well with the Phadex, probably because of the weird indexing created. My solution isn’t perfect, as you can hear if you choose a pure sinewave and play a bass sound (you get a little background noise), but it works well with Cosine waves which have minimal changes at wrap-around. My technique involved creating a special situation for when one index is maximum and the other index (for interpolation) is minimum.

The technique I used reflects what I read about the Casio system. I initially tried using Phase Modulation of Martin’s sine osc, but the problem was creating a modulating waveform which always completed in exactly one cycle, so for example, if the first part was fast the last part had to be slower, for any amount of distortion applied. It’s quite possible that someone with astounding maths and code skills could achieve it, but that’s not me.

Cheers

Spogg

[k brown]

Yeah, I saw the ramp generator in there at start of everything, but what you did with it after that was way beyond me.

[BobF]

Me too, that's why his is so much better than the one I was going to post. Maybe someday, ha,ha.....

[MichaelBenjamin]

.

[Spogg]

i only comment on the video: very good, no overly long talking intro, right into hearing the sounds and explaining inbetween. this is how a synth demo is nicely to watch.

Thank you Michael.

I'll probably stick with that approach for any future videos. I appreciate the feedback very much.

Cheers

Spogg