FM Buzzing Noise when using Sine Waves with OSC 2 in Hard Sync mode

I’m getting a bit deeper in FM at the moment so thought I would try and create some sounds on the S6. Is this buzzing I’m getting normal? I’m wondering if it’s to do with the hard sync being enabled but don’t yet know enough about it.

To do this I started with the default patch set both DDS1/2 to sine wave. enabled hard sync on DDS 2. Then added in modulation from ENV 1 to XMOD and dialled in the ENV1 decay/amount of XMOD. ENV1 Sustain is at 0.

Attached is an audio file of the sound and the patch in case it’s useful. Thanks, loving the synth and didn’t buy it for FM so just curious.

FM Buzz Recording

p1_FM_Buzz.s6 (35.6 KB)

Just to add I’m on the latest firmware.

From my experience with eurorack VCOs and FM, if you hard sync a carrier oscillator, the reset that happens due to the sync will cause a sharp edge to form where the waveform deviates from the one it is sync’d to, resulting in a click/buzzing sound. I’ll try it on the S6 tonight, but like like you, I didn’t get the S6 for FM… I’ll stick to my Complex Oscillators for that, many of them with Thru-zero linear FM.

Ah thanks so much for the explanation. That makes sense. I’m just starting to get to grips with all of these things like Ring Mod, FM, Hard Sync etc.

I had to google Thru-zero linear FM and found this video if anyone else is wondering the same thing:


Furthrrrr Generator 2/5: Exponential, Linear, and Through Zero FM (LMS EEP)