Percussa for 16-voice FM

For FM-Synthesis, how many Operators and how many Voices can “Percussa System 8” support, till it reaches its limit?

I’ll let the scientist/engineer handle this one. (Paging @bert)

However, the system 8 and SSP have the same engine under the hood. :+1: Super solid platform.

The un-precise answer to your question is that you can use as many voices as possible. I’ve done 8 voices consisting of 2 Wavetable oscillator modules, and LFO, and envelope each. And there was room to do more.

It really just depends on how complex your voices are. If they are pretty basic, you could theoretically do 32 or 64, for example.

is the following scenario feasible, for about 4 hours without any performance-issues: 6 operators + 16 voices ?

Do you mean 6 modulators per carrier?

I mean you can do whatever you want, but depending on how the modulator signals are setup, I think you’d pretty much just get noise.

Depends on what the carrier signal is. Is it a complex wavetable or granular module, or just a regular oscillator?

“6 Operators” (oscillator modulators) as referring to the legendary DX7

So 6 sine wave oscillators per voice.

I’ll try to load up something like that on my SSP and get back with it. It’s late here, so probably tomorrow.

Edit: was too curious so I set up a single voice like so:


As you can see from the CPU meter next to sample rate indicator, the CPU is barely pegged at ~3%.

Currently the LFO module can be used as a regular oscillator (tri, sine, saw, square) or an LFO (same forms) outputing a saw to the output module. The 6 additional LFO modules are outputing audio rate sine waves to the saw oscillators freq input. (Could have used them at LFO rates, but figured this would be a better stress test.) I have one midi module outputing pitch and gate to the saw oscillator, and the other MIDI module sending velocity on information to the freq inputs of the 6 sine modulators.

You could get way more complex than that, but for testing purposes, I thought it should be good. Someone else could chime in if I’m off base here as I’m not familiar with the DX7.

So based on what I’m seeing here, it looks like 16 voices is possible and would use 45-80% CPU. (also note that this is at a fidelity far beyond what the dx7 was able to produce back in 87.) As the voice count increases the overhead will increase, so my cpu estimations could be off. However, currently the MIDI module only supports 8 voices. So you could have 16 voices but would be controlling them through 8.

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You might have a look at the FM patches which we’ve created for the SSP. We uploaded a set of 60 presets in one of the latest software updates (see preset corner). Bert discusses 2 FM patches in the Percussa SSP talk/demo video @ analogue haven

@15:48 multi-timbral / multi-voice FM patch
@10:16 polyphonic granular FM patch

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Most of the info has already been posted here by @celine and @2disbetter but you can basically create whatever synthesis architecture you want in the patching grid. You can use the LFO module (which is just a normal oscillator, with sine/saw/square/triangle waveforms), as FM operator, it has detune and ratio settings to help with FM patches and I’ve created several example FM patches including the typical FM bell sound. They are in the patch collection available here in the forum (60+ patches) and I play them in the walkthrough video too.

So to answer your question, yes you can create a 6-operator architecture. I have no idea how many voices you will get, I haven’t built a 16 voice patch yet with 6 operators each. The largest patch I’ve built is the 8 voice wavetable synthesis patch, which has

  • 8x wavetable oscillator with 3D morphing
  • 8x envelope generator
  • 8x MIDI module
  • 8x BUS module
  • 8x input module
  • FX chain (bus + reverb + delay + out module)

so in total 43 modules roughly and there is still CPU power left.

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Many thx. So one could create “Linear” as well as “Exponential” FM?

yes, there are both type of modulation inputs