Really Interesting patch! I dig how the layers of filtering make the FM really gooey sounding.
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I plan to resume some work on TZFM. It seems like some of these synthesis techniques hold much more treasure than I have yet seen. This write up on the SSF Zero Point Oscillator peaked my interest again.
“Through-Zero FM is a form of frequency modulation that produces much deeper and useful FM tones than a typical VCO can accomplish. New techniques have been discovered that not only improve the performance of TZFM, but also grant additional benefits as will be explained. The ZPO’s modulation section is a hybrid involving both TZFM (frequency modulation) and TZAM (amplitude modulation). Coupling these two techniques substantially expands the performance and tonal shaping possibilities, beyond traditional TZFM. The results are more stable and balanced across the modulation bandwidth and both TZFM and TZAM can function together or independently, and anywhere in between.”
So I thought I would post this. Has anyone managed to get sonically further with TZFM than with just FM/PM? It would be cool if someone could share a convincing patch.
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I would assume that TZAM inverts the signal when the modulator goes negative . Don’t know if anyone has tried that with Audulus, but it would be pretty straightforward. The only practical way to implement TZFM in Audulus (at least that I’ve been able to come up with) uses a phasor as the oscillator core. This works fine if you’re using a sine as the carrier but using other waveforms will introduce some significant aliasing. I’m not sure how much of the final product is truly the result of TZFM and how much is a byproduct of the approach used to generate it.
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Sometimes I just keep going, even if I know I might be missing the point. I grabbed one of those TZFM patches and started switching old modules for newer ones. One discovery I made was that, in this patch, the injected wavefolder at that specific stage, really sharpens up the bass tones, but maintains the analog ‘weight’. Much credit, again, to @biminiroad for his amazing filter refaces!
TZFM Tests 6.2.audulus (859.4 KB)
I think it also matters that the physical speakers/headphones get properly driven at the end – ie. crank it.
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Indeed, that is one of the main reasons that most of these TZFM oscillators coming out have analog designs. The core will typically have some sort of quadrature waveform (trapezoidal or sinusoidal) and TZFM comes from manipulating these core outputs. The analog versions are still quirky I might add.
Well TZFM is just PM rephrased in terms of FM, so it’s not necessarily going to sound any different. I think the main interface difference is most TZFM will have a linear dc offset for the incoming FM signal (here it’s called zero point) that is basically a second channel of FM input.
You know what would be really nice on a TZFM/PM oscillator? Some sort of indicator that lights up, or reads some number, that tells you that you have gone through zero. Maybe even by how much.
That’s a pretty easy request. Here is a little recreation of my doepfer TZFM oscillator. I think they are great building blocks and the only thing to keep in mind is that the lower octaves are affected disproportionately to upper octaves because they are located closer to zero.
TZFM OSC MINI.audulus (205.1 KB)
TZFM patcholopy.audulus (587.6 KB)
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This sounds awesome.
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