Make Noise QPAS

I’m just double checking, that R is for resonance? Because there is also a Radiate parameter.

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I think thats res - this is just the filter core that he’s sharing

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R = resonance. @biminiroad is correct, this is just the filter core for an SVF filter I built a while back. I thought it would make a good building block for the stereo unit. :cowboy_hat_face:


QPAS Core proto v0.1.audulus (496.9 KB)

I worked it out eventually. Here’s my best guess as to how the QPAS filter core works, I’m still trying to decipher what radiate and smile pass filters actually mean.


Smile pass sounds like an allpass maybe? Or like a multiple peak notch?

Radiate seems to leave the frequency center peak at center, but then moves the other two peaks both apart in frequency and to the edges of the stereo field - so it’s like you have 5 peaks if you spread left radiate to left and right radiate to right, and each are along the stereo spectrum.

My gut says you can accomplish this by making a knob that controls both the spread of the frequency and a pan, and then just duplicate that for two controls.


Good explanation of Smile Pass from the demo at Perfect Circuit yesterday.


Wow, I gotta watch that whole video now :wink:


Does he actually say what kind of filter response it is? I just watched that part and he doesn’t really go deeper than the explanation that’s in the product description.


I’m looking forward to fooling around with this myself, but at the moment I’m kind of on a random kick. I’m working on a random waveform oscillator at the moment. Random Waveform VCO (WIP) I think it will pair well with the QPA when we get it finished. (if anything in Audulus is ever really finished!:cowboy_hat_face:)


K-PASA Proto 0.1 copy.audulus (691.4 KB)

Ok I got some semblance of the patch working. I think I need to work on the pitch scaling and may rebuild the whole thing from scratch as the next step, but I think it sounds pretty awesome running a single sawtooth wave though it and giving it some modulation.

edit: Also, obviously this patch benefits from a good stereo listening environment or headphones.


Interesting break down of the QPAS with less of the poetic MN framing of the device.


I seem to miss all the good threads!

The night of the annoucement I watched Tony’s presentation at Perfect Circuit and drafted up this module:

CutePAS-version-0.1.audulus (459.9 KB)

It’s pretty broken once you look at how I manage radiate controls and stuff. And the core filters I’m using don’t sound great for this job but I’ll worry about that later. I’m also not worrying about CPU usage at all. I got the 4 peaks dancing and that makes me happy! :slight_smile:

(No HP and SP outputs yet either. I’m treating SP as a Notch Filter for now)


¡¡16 core filter!! :star_struck:


Sounds great so far! Thick!

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okay, I cleaned up a lot of the mess in the previous version and pretty much started over. This one only has the LPF portion, since making the other ones is just a matter of copy-paste once I’ve got things ironed out. Still using the BiQuad filters, and still doing 16 cores because I want to keep the simultaneous outputs of all filter types.

CutiePAS-version-0.2.audulus (139.0 KB)

One thing I don’t understand about the BiQuad LPFs: When Q=0, they all start screaming in self-oscillation. I really don’t know why this happens when there are 4 filters but not when it’s just one on its own. For this reason I’m clamping Q so it doesn’t go below .01.

I also fixed the behavior of the Radiate controls after watching Loopop’s explanation.

The stereo effect now sounds quite good!


I was refacing the Audulus library and realized that HPF-LPF sounds a bit like SP. It at least does what the description is - keeps highs and lows balanced, but still kinda sounds like a filter.

Possible Smile Pass.audulus (80.9 KB)

Did you get beyond your “proto” version of K-PASA? I have been using it and I like it.

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Not yet. I have had too many plates spinning for a while now. But I definitely will return to this.

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I added all filter types to my QPAS emulation. Here is alpha 2. Using Biquad Notch in place of Smile Pass.

CutiePAS-alpha-2.audulus (226.2 KB)

I just noticed that @biminiroad made a SP emulation. I will check out how it sounds and try integrating it to CutiePAS :slight_smile:

I haven’t got the Radiate controls right yet - I need testing on a real QPAS to understand them fully. Also, Notch and Bandpass filters have a “width” control that may or may not sound the same as the Q control of the QPAS module.

Unless people show strong interest in this I’m gonna move it down my priority list.


I was reading about dipole on wikipedia. Which is kind of funny because I got there reading about dielectric grease for a boat wiring application. That new SSF dipole filter, also being a quad; well I thought the whole thing gets more interesting once you dig into the Quantum mechanical dipole operator and the transition dipole moment.

It reminds me of @stschoen’s comments about TZFM and time. I guess what I want to say is that both QPAS and the SSF dipole filter need to be theoretically explored – or, at least, it sure gets more exciting once we dive into understanding electromagnetic fields.

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