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Analog FM

JayT

Analog FM
« on: July 23, 2021, 12:54:19 PM »
Hi,

iíd 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? Iím well aware that I could use any DX7 clone to do this, but Iím curious if this could also be done with the PRO 3.

Best regards. JayT.

Re: Analog FM
« Reply #1 on: July 23, 2021, 05:38:46 PM »
I think youíre 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 itís 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 youíre doing already. I like to use an envelope to control amount even if itís subtle.

You can also try using the digital sine as the modulator rather than a VCO. In my experience itís a clean wave and works well. Then adding the second wave in usefulópartly to help with retuning the other VCO if necessary. But then you can crank it up a couple of octaves to get that extra ďtingĒ 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 donít think Iíve tried FMing a Pro-3 filter. Only one of the filters tracks well. If I recall itís the OTA.

JayT

Re: Analog FM
« Reply #2 on: July 24, 2021, 02:09:30 AM »
Thanks a lot. I'll try everything. :)