Your approach to FM synthesis?


Guys what is your approach to creating a new sounds from scratch?
I am very new to FM synthesis and feel a bit stuck - every time I get into making a sound, I and up with something crazy sounding and not usable or with an organ sound… :smiley: Yeah seriously - it sounds like and organ (although nice) or some crazy noise scaring my cat (and me as well)…
To me, the FM synthesis feels like something having some strict rules of in what order you are working with the synth engine otherwise the sound can get crazy pretty quickly - not sure if I am right or its only my feeling… When compared with some non-FM synths I am usually working with (like a Virus), FM synthesis seems not very tolerant to inaccuracy and everything needs to be somehow “mathematically” in harmony… ¯(゚•゚;)/¯

Could anyone please share some advice what to do/set in the first stage of the sound creation process, what to do in any of the later stages, what not to touch once already set otherwise everything breaks down etc.?



This book helped me get started:

I still haven’t read it all, sort of waiting until I get a Digitone myself. It’s $1.50 on the Kindle…super cheap.

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Welcome to the universe of FM sounds … really … it’s a new universe, if you are beginning to explore it and it will stay a new universe, even if you have much experience in sound design :wink:

To start a FM sound from scratch successfully, it’s very important, to have a basic understanding of how FM-synthesis works in general and what the basic methods are.

But first things first … don’t be scared, because there is no reason … it’s only new and unfamiliar. You are right that there are some “mathematical” rules, but believe me, it’s as easy as any other 101 :wink:

Second important thing … FM synthesis is hard to force to do everything we might imagine. It’s more the other way around. We have to embrace the possibilities of FM synthesis and accept, what is possible and what is not. As an example. Often it’s hard to create FM sounds, which imitate certain classical mechanical instruments accurately. The reason is that the sound creation process of FM is very different compared to the generation of mechanical vibrations.

One benefit of FM is that we can create sounds that are not only classic synth sounds, based on saw-tooth or square wave oscillators, but also bell- or metal-like, otherworldly, very complex, and beautiful sounds. Last but not least. Even a simple pair of two operators can create much more and much more complex sounds, rather than most subtractive methods.

Now some hints …

  • There are two main parameters we can use to define a FM sound. Those are the frequency ratio between modulator and carrier and - to no surprise - the intensity of modulation.
  • To find nice harmonic sounds, which are good for melodic use, we can use ratios like: 1/1, 1/2, 1/3, etc. 2/1, 2/2, 2/3, etc. 3/1, 3/2, 3/3 etc. Most digital FM synths support to define those ratios directly like this. There is no frequency-math needed.
  • Bellish- or metallic sounds are created by ratios, which do not devide as integers like 2/3 or 3/2. Keep in mind that bellish sounds have a certain ADSR shape. There is a very quick attack, no sustain and some release. A 3/2 ratio wouldn’t sound like a bell, if the envelope is more like a flute would generate, which is having a short attack, a sustain and no release.
  • Ratios like 1/2 and 2/1, or 2/3 and 3/2 create quite different sounds. The numbers are not commutative.
  • We can modulate the modulation intensity, which will keep the frequency ratio in place, but changes the sound, sometimes significantly.
  • We can modulate the frequency ratio too and this will change the sound dramatically.

My advice would be, start by using a pair of operators only, use sine-waves (or triangle-waves, but nothing more complex) and study the influence of frequency ratio and modulation intensity. This would be best supported by an oscilloscope, if at hand, because it helps to see, how the waveshapes are changing.

  • There are ratios, which generate saw-tooth or triangle like waveshapes, others create square-wave like shapes, and otheres very unique shapes for scratchy or noisy sounds etc.
  • By modulating the modulation intensity, this is how far the FM modulation will change the frequency of the carrier from the original frequency, we can create different harmonic content, which changes according to the modulation depth.
  • By modulating the frequency ratio step by step with a sequencer, we can create melodic and un-melodic sounds per step with only one pair of operators in use. This could be a base drum and a high-hat, or a flute and a scratch, or any other combination of sounds.
  • A short frequency ratio modulation at the beginning of the sound can easily imitate a noise, like the breath noise of a flute. Or it may sound like a broken bell :wink:

Typical digital FM synthesizer have at least one ADSR envelope per operator. This can be used to modulate the frequency ratio and the modulation intensity. I don’t have the Digitone and can’t tell you exactly, how it’s implemented there. The creative use of the envelopes is the entrance door to the magic of FM synthesis.

The so called “algorithms” are combinations of operators, which are building blocks and define, which operator can modulate others and how. The more operators are used, the more complex the sound can become.

Example … if we use two pairs of operators, we have two completely different sound sources, which we can layer in many ways.

Here is a brief introduction by Gordon Reid from SOS magazine:

The complete “Synth Secrets” series is a great read too:


this is absolutely amazing!!! thanks so much for such a great response!


Man, thanks heaps for this. I’ll keep it close by next time I mess with digitone. :slight_smile:


need to get home and try out my new found knowledge.

You’re welcome. It would make me happy, if this little insight gets you started.

Happy FM-ing :wink:


thats the nature of FM :smiley: If you dont wanna sound like a DX7 or if you dont love the metallic tone, FM is not for you. Thats the reason why its not for me btw :wink: FM-basses are great though! Because Sine Waves are generally great for Bass! Well worth exploring this direction of FM i assume!

Dunno if this will help, but the approach to sound design with the Digitone is quite unique. With a DX7 or similar synth, you have a lot of options for ratios or fixed audio rates, different envelopes, feedback, and algorithms. The Digitone is strongly opinionated on this and in my opinion, is geared towards knob tweaking and exploration.

My approach is generally as follows:

  1. Loosely think of an algorithm that makes sense and set up ratios.
  2. Depending on the sound I’m after, tweak the amp envelope, or experiment with operator modulation levels. (Edit: And adjust mix levels)
  3. If I like a certain range of mod level, determine if that is best managed by the mod envelope or LFO.
  4. Audition feedback and harmonics. Sometimes I’ll use harmonics on step 1 if I have a particular sound in mind that would specifically be influenced by it.
  5. (Optional) Check our other algorithms to see if that improves the sound.
  6. Tweak filter settings.
  7. Try out additional LFO’s. This usually takes me to outer space, so isn’t always done for basics.
  8. Add FX.

Sometimes I program in sequencer notes to help in the design process, while other times I tap the keyboard…but always make sure to give my ears rest every few moments so they don’t get fatigued or magically adjust to thinking a sound is better than it really is.


In addition to that: the x/y mix on the DT is pretty unique for FM. you can use an lfo to morph between the two outputs allowing for some nice movements in the sound


Movement is key for me, may be rapid or smooth and slow. DN allows for some really nice modulations through velocity and aftertouch (those are the ones i use) which maken playing sounds on it via a good midikeyboard real fun. Sounds really come alive that way and the same patch transforms from sweet and deep to roaring fuzz goodness. Such a shame is hasn’t got a sustain pedal control.

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Just stumbled across this YouTube video:


I’ve been spending the past several weeks strictly focused on learning how to make various sounds with the DN. It almost feels unproductive as I’m not really writing any music, but my ability to dial in sounds I’m after is speeding up.

It’s such an interesting instrument. Sometimes I will start to hit a road block after exhausting (in my mind) a particular technique, shortly to find a new approach to something I didn’t think of earlier and the inspiration starts all over again.

For example, I was messing around with creating snare patches the other day and noticed one of the presets used side X of the mix to create a plunk sound, then a quick exponential LFO to Y to add some noisy shimmer.

In the past I have modulated the mix, but usually in slow gradual ways for pads. It didn’t really click with me that I could use it this way, which opened up ideas for a plethora of other sounds. To accomplish similar sounds, I would’ve thrown an exponential LFO on the particular attribute, which wouldn’t always give me the sonic range I could accomplish using that technique on the mix.


looks great but I dont have a kindle, any knowledge of how to get it as as pdf or other format? thx!

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I’ve just ordered mine. Im thinking of making a standard word or power point template where I will take notes on patches/presets/sounds to see what each parameter is in each sound for purposes of seeing how those interactions sound in a “total sound” context meaning if there is a high ratio (or a type of movement of it) in a certain operator for example I look at that algorithm and the rest of the synth settings and see if that is more or less the “key” to a particular sound or if it is other sounds in conjunction… this is something I used to do with my blofeld… So basically I will be writing up and printing out diagrams for every synth setting and just making little “patch sheets” for particular sounds to learn them from the ground up…

If you go to that Amazon link, you’ll see a Read with Our Free App link and it looks like you can read it on other devices without having a Kindle.


cool, will do thanks!

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I’ve found that even harmonics (especially at lower mod depths) produce sawtoothish and odd harmonic squarish waves.

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Absolutely :+1:

My absolute favorite article on crafting FM patches… from the June 1985 issue of Keyboard magazine, “How to Program the DX7