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FM Sound Design




Thanks for refreshing my memory on that - you’re totally right, and I had forgotten! It is always touted as an FM synth, but it’s not - quite. :slight_smile: So observing what a DX7 does here is kind of irrelevant.


I guess just since we’ve already done such an in depth comparison, here’s the Cyclonix Shapeshifter oscillator phase modulating itself, and sweeping the mod index. The result is not really so dissimilar from FM.

It also does not match the behavior of the Zeroscillator. :slight_smile:

To my ear it does have the least deviation from the pitch.


fm sounds so good on the er301.
here’s a snippet of random tones where the modulator is an mmf-1 sine wave:

i hear a little bit of pitching, i guess even the cwejman isn’t dc free!


Very nice kilchofer.


Awsome @kilchhofer love those tones!


That sounds so good would you care sharing this patch?


thanks guys!
@fabrice.million, there’s not much to share…it’s just the internal sine wave being modulated tzfm with an external sine wave. fm index fully open eg 5000 and a vca in between modulator and carrier. this vca gets opened by a dusg envelope which also opens the vca after the sinewave, so just the volume envelope. i manually adjust the envelopes shapes which is in cycle mode so you get these fast exponential shapes. i patched up some self fm too which i manually introduce at some spots.
ah and random pitch from a synced rg6. pretty much everything comes from outside except the carrier wave and vca’s. so i’m using the 301 “only” as an awesome digital tzfm sine oscillator. i love the depth of the fm, i wonder if it even could get higher than 5000? :slight_smile:


Thanks for the patch notes dude, will try this out as soon as my er-301 lands! Please @odevices make it quick!


thanks for the video!
i just tried it, and i wonder why it sounds so differently from the “feedback” parameter in the sine osc…
isn´t the “feedback” parameter a frequency feedback?


The feedback parameter in the Sine Osc unit is affecting the phase not the frequency.

x(t) = sin(2*pi*(freq(t)*t + phase(t) + x(t-1)*feedback(t)))

It was a lot more stable this way.


Love your soundcloud man(@kilchhofer ), awesome stuff in there!


I’m just catching up on the threads and reading about the updates. Thought I’d mention that every fm voice needs a reset gate (can be the same one used to trigger vca’s) applied to each of its operators so that the phases are constantly synchronized. IMO that’s when fm starts to sound nice and becomes super fun to program, playing with envelopes and ratios etc…

Here’s an old video I made using 4 fm sine wave voices—I think 3 operators per voice before I started getting distortion at 69% critical load and had to delete a sine unit:


Interesting. Would not have thought syncing on “note on” would have made much difference in the timbre. Will have to try it out!


Absolutely… Didn’t we do this in Evil Twin - I forget! :thinking:


Don’t believe so. Think the operators are free running.


Hmmm. I seem to remember trying it, but I might be wrong; might have to revisit that! :slight_smile:


I think we tried adding more of a traditional hard sync option but abandoned the idea (don’t remember why though!) :slight_smile:


I need to change this in the 3op fm synth custom unit. Interesting, thanks!


do you use the SYNC input on sine osc for phase reset? i’m also of the opinion a phase reset is needed. i did one test this morning but i think that using a gate on the sync input inserts clicks in the audio path if you use short attack times for both carrier and modulator. how you solved it? thanks!