Is it possible to create a deep (eg. lower frequencies only) noise by the means of basic FM synthesis (like Yamahas DX system)? The usual procedure for noise is to raise the modulating operators output (and / or feedback) to a certain level where the additional harmonics blend into a chaotic broadband noise. This however claims the whole audio spectrum, beeing almost white noise. We cannot go with less modulation as this would pronounce simple harmonic parts. In fact, the sound spreads all over the spectrum before audible harmonics blur into noise.

So is there any way to do a low bandwith noise?

  • 1
    Does the FM synthesizer in question have a low pass filter? Mar 20, 2019 at 15:25
  • No, it doesn't. Otherwise the answer would be straight forward for me...
    – dronus
    Mar 21, 2019 at 14:40

1 Answer 1


OK so the basics of FM are that you need two oscillators - one being the carrier frequency and one being the modulating frequency. The process of combining these two together through the 'frequency modulation' function is what results in the harmonics.

If you start with a low carrier frequency and a modulating frequency that is close to the carrier frequency, then the resulting sideband harmonics should not veer too far away from the original carrier frequency.

The trick though, to getting a low frequency result, is to start with a low carrier frequency and a low ratio modulation frequency. Also, as Todd mentioned, a low pass filter will also help to constrain the output.

  • 1
    In terms of low frequency waves, OP could start with a carrier with a frequency that is below the normal audible range (if available in the synth), and then have the upper sideband be the only audible portion of the sound. Mar 21, 2019 at 14:43

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