Analog FM

[JayT]

Hi,

i’d like to get something like a bell or metallic sound using analog FM. By accident I got a cool massive bass sound with Modulator freq 1/2, but not what I was trying to achieve. I modulate Osc 1 coarse freq by osc 2, played with the amount, the octave of both of them and an envelope controlling the mod amount.

How could this be done right just for fun without wavetable? I’m well aware that I could use any DX7 clone to do this, but I’m curious if this could also be done with the PRO 3.

Best regards. JayT.

[guyaguy]

I think you’re on the right track but also discovering the limitations of analog exponential FM, which is what the Pro-3 allows for. You can still get nice tones but it’s trickier to dial in and causes the tuning to go out quickly compared to linear and especially through zero FM.

One thing you can do is sync the oscillators so that the tuning is less of an issue.

Another is adjusting the amount, which you said you’re doing already. I like to use an envelope to control amount even if it’s subtle.

You can also try using the digital sine as the modulator rather than a VCO. In my experience it’s a clean wave and works well. Then adding the second wave in useful—partly to help with retuning the other VCO if necessary. But then you can crank it up a couple of octaves to get that extra “ting” of the bell. Using an envelope to bring the level down quickly can make it sound percussive.

My last suggestion is key tracking the filter to play it as a sine and modulating that rather than an oscillator. It works really well on the Rev2 but I don’t think I’ve tried FMing a Pro-3 filter. Only one of the filters tracks well. If I recall it’s the OTA.

[JayT]

Thanks a lot. I'll try everything.