Mutable Instruments FM Synth?

I’m not really a technical person so I don’t know how feasible this would be but how about a little ATMega based 4 or 6 op FM synth with a filter section? Something along the lines of a smaller more compact dx200 but fully editable from the front panel?

Feasible. Indeed it could run on the same hardware as the Shruthi - it’s only a firmware modification.

The DX200 is 16-voices. On an AVR I won’t go further than 2 OP / voice (either mono 4 OP or duo 2 OP)

Would there be other waveforms than sinus possible? I’d prefer letting go OPs for more Waveforms as i have good memories of my TX81z. What about a 4-OP wavetable FM-Synth (nice idea besides the parametrization…) ???

There’s zero overhead in allowing different waveforms - it’s a lookup table anyway.

Ok, ist there enough power left for scannining a wavetable (that makes an additional envelope per OP) ??

There’s enough computational power for 2 cross-faded interpolated oscillators, or 4 interpolated oscillators, or 4 cross-faded non-interpolated oscillators, or 8 non-interpolated oscillators.

If you want 4 OP, you have either the interpolation and no wavescan, or a non-interpolated (= shitty, full of aliasing sound) with wavescan.

Almost everything on the Shruthi is currently done with cross-faded and interpolated oscillators. The exception is the square with a ratio different from 50% which needs 2 pairs of cross-faded, interpolated oscillators - and that’s why it runs at 20kHz and is lacking a bit of brilliance.

Bump! Apologies for dusting off this thread…

Are there any plans for a dedicated FM (or phase mod, which I always found kinder to the thinking muscles) synth? I’m veering toward a preenFM, but I’d love something from the Mutable stable to keep the Shruthi company.

I finished my PreenFM today. It’s a really easy build and sounds like I remember FM. Will have to do some sound programming to leave a total verdict but this far it sounds good. It has a 72MHZ ARM Cortex…

Not interested in doing FM at the moment…

If you’d ever get interested, could we expect silly things like Wavetables instead of simple Waveforms or more than 6 Operators?

SammichFM is still available and that thing sounds a lot better than preenFM imho. Plus if you squint you wont be able to tell that its not a shurthi :slight_smile:


I built myself a SammichFM a while back. They do sound nice. The random patch generator is the best feature, I think. Very addictive! In Terms of flexibility, it’s a mixed bag. It’s essentially a 4-operator synth, like Yamaha’s later DX-11/TX-81Z synths, but the range of a lot of the parameters is pretty limited. The additional tempo-syncable LFOs and other features added by the MIDIBox FM software add a nice twist, though.


Looks like I have a bunch of internet research to do… :slight_smile:

> could we expect silly things like Wavetables instead of simple Waveforms or more than 6 Operators?

As long as you don’t mind the aliasing

The SammichFM is different from PreenFM, or anything that could be coded from scratch on an AVR or other chip, in that the sound-generation is all done by a Yamaha FM chip of the type used in 90s ‘Soundblaster’ PC soundcards. The MIDIBox guys have done an amazing job of writing an operating-system to squeeze the most out of the core functionality provided my the chip. They’ve done a similar trick with the Commodore 64 SID chip with SammichSID project, which I’d highly recommend, also.