The Most Powerful Tiny FM Synth: PreenFM2


The purpose of AudioCookbook is not to promote or review musical instruments, electronic hardware, or audio software. This site is a more personal (perhaps narcissistic) look at music composition and sound design techniques. “Recipes for Sound Design” is one part of that, but experimentation also plays a significant role. I understand that some my experiments are interesting for ACB readers. My approach has been, if it’s interesting to me then I’ll write about it here. In this case I’d like to highlight an extraordinary, boutique, FM synth that has been unfairly overshadowed by the Korg Volca FM. This amazing musical device for sound design and experimentation is the PreenFM2 designed by Xavier Hosxe.

This synth is by no means new. I first heard about it in August of 2013 on At that time I was fully invested in the Yamaha FS1R and didn’t see a need for another FM synth in my setup. However, more recently I started researching it because I wanted a portable polyphonic synth for live performances. I’ve brought luggable rack synths to shows including the FS1R and Roland MKS-80, but it’s expensive, awkward, and risky to transport them. I love the Korg Volcas for their sound and portability, but both the Volca Keys and Volca FM have a mere three voices available for polyphony.

The low profile and compact PreenFM2 can be purchased pre-built or in kit form with either a sturdy metal case or an elegant plexiglass design that shows off the inner workings. Either option takes up little space and is effortlessly packed up and transported. Its looks belie its broad feature set and massive capacity for sound design and experimentation. But one of the main reasons I recruited it for polyphonic duties is just that: polyphony. Depending on the algorithm the polyphony ranges from eight to fourteen voices. In comparison the Volca FM has a maximum of three voices.

Korg Volca FM

So what about the Volca FM? I had the opportunity to try one while I was at Moogfest and almost bought one. It sounds great, but I can only get limited use out of a nice evolving pad or glistening FM electric piano sound with only three voices of polyphony. Another deal breaker for me is that the velocity doesn’t natively respond to incoming keyboard velocity via MIDI. Checkout Nick Batt’s excellent review for details and a workaround for the velocity issue.

My PreenFM2 During a Recent Performance

I’ll be sharing a lot of my experiments with the PreenFM2 here on ACB within the coming months. For now I’d like to share a few reasons why it is an ideal part of my live rig and studio setup. I already mentioned polyphony as the main reason, but the PreenFM2 is also four-part multitimbral. Each of the four instruments can be assigned a separate MIDI channel or stacked for complex layered sounds. Each instrument has twelve slots in the modulation matrix. The mod sources include three LFOs, two envelopes, two step sequencers, mod wheel, pitch bend, aftertouch, velocity, two keyboard tracking values with several linear and logarithmic settings, and four performance parameters. The destinations include per-operator panning and mixing for amazing stereo spatialization possibilities, operator frequency, envelope parameters, and the list goes on. There are almost too many destinations to count! These features already put the PreenFM2 far out in front of the Volca FM. Learning the synth has been an easy process of discovery and the web-based documentation is thorough and easy to follow. Not an easy feat for a synthesizer of such depth! Here’s an audio example to whet your appetite:

This is a simple patch I made that slowly evolves by applying one of the LFOs to one of the modulation indices (how much one of the modulator frequencies is applied to a carrier frequency in the algorithm). In this case I was using FM algorithm one which only has three operators. In upcoming examples I’ll share how complex the sounds can be utilizing features like custom operator waveforms, operator level stereo panning, arpeggiation, step sequencing, and modular randomization. What I’ve discussed in this article merely scratches the surface of what is possible with this very special synth. Stay tuned. There will be much much more to come.

4 thoughts on “The Most Powerful Tiny FM Synth: PreenFM2

  1. Thanks. Lauri! This is a very simple patch. Choose algorithm 1 and set polyphony to 8 or higher. Next set LFO1 to adjust Modulation Index 1 in the Mod Matrix. Set LFO1 to a very slow rate (or faster if you prefer). Then set the operator envelopes to a nice harp-like pluck with enough release so that the decay trails overlap. Run it though an analog delay to put the icing on the cake!

  2. Hi, I bought your audio cookbook years back. It’s a great book. I just ordered a preenfm2 and I’m very excited to receive it. It’s being built so I’m going to have to wait a little while, but I was wondering if you’ve had any success getting electric piano like sounds from it. I have several FM synths such as Yamaha tx802 and tx81z as well as some synths that provide a little FM synthesis such as the blofeld. I can’t wait to get in program this thing with all its modulation possibilities.

  3. Hi Marc. Congratulations! I think you will love the PreenFM2. I think it’s really good for DX7 style EP sounds, but I rarely use it for that. Please do share with us what you think of it. BTW: I wonder what book you’re talking about since I haven’t written one yet? Thanks!

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