New Zebra 2 Filter Module Sample

Title link takes you to a sample of a new Zebra 2 Filter module posted by creator Urs Heckmann on this BigBlueLounge thread. I decided to go with the R2 image in the thread as there are no screens yet, and the reference below.

Some notes via Urs in the thread:
"Last year I had coincidentally discovered a way to create a filter with a really good sounding self-oscillation when a new scientific paper on Moog filter simulation came up. Latter was a great source of information, but it would still not work like I wanted, especially in terms of cpu hunger and tuning.

So I spent the holidays on getting a Moog Little Phatty and tweaking the shit out of the new filter (dubbed XMF for Croos Modulation Filter). Yesterday it came to the point where

- cpu usage is moderate (2-3% for stereo operation on an 1.83 GHz MBP @44.1 kHz)
- self-oscillation (with no input) is in almost perfect tune and nearly constant level from 50Hz to 14+kHz
- any trick used in Littly Phatty presets would work on the XMF as well
- parameter ranges exceed that of the LP
- bandpass mode works (I gave up on highpass for now)

It's not a perfect emulation of the Moog ladder filter though. But it has all of the properties of an anlogue filter, starting from the juicyness up to the self oscillation that does *not* lock into the spectrum of the incoming signal. Latter is especially interesting. There is a range of resonance where the self oscillation would "wobble" between the actual filter frequency and the closest frequency in the spectrum of the input signal. I havn't heard this in digital filters so far but it's exactly how the Moog does it.

The R2-D2 solo at the end btw. is just the filter with full resonance and a little overload. ModWheel controls filter fm by an oscillator while PitchWheel controls cutoff over several octaves.

The first solo sound (thin, voicy) features filter fm with an oscillator tuned 4 octaves up. Sounds exactly like the LP, with the difference that it's stable & in tune over the whole keyboard range.

The ultra phat guitarish solo sound is not based on hard synced oscillators, it just plain detuned sawtooths run through the bandpass mode with lots of overload.

The pad sound is a couple of detuned sawtooth/pwm oscs run through the bandpass. An lfo modulates the frequency of the bandpass in opposite polarity for right/left side which creates the panning effect.

I think it's almost ready for release, but the SSE code has yet to be rewritten in AltiVec for G4/G5 (no big deal). I'm afraid though that it will probably not work on a G3, or it would consume close to 20% on a G3 when operating mono instead of stereo... and it's gotta be fine tuned & tested for samplerates other than 44.1 kHz...

Later,

Wink Urs"

Previous posts on Zebra 2

Update via Bee Jay in the comments:
Pic for you if you want: [link]



"This is one of the phattest filters I've heard since impOscar - and the bandpass mode is also superb."