Deep noise by FM synthesis

Question

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?

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.