Is there a bass sub harmonic generator block? Like the opposite end of "superbass")

Yes, but the algorithm needs to unwrap the phase to produce a subharmonic.

Hello,

You could try using a low pass filter then running that through the pitch transposer to shift it down an octave. This is a long way to shift so you will probably hear some distortion.

What DSP are you looking at using?

Dave T

Adau1701 connected to an es9023 via i2s for low frequencies.

Hello,

Actually there used to be a subharmonic synth block in SigmaStudio. I tested it and documented what it does here:

https://ez.analog.com/message/250522?commentID=250522#comment-250522

I can't find it in current versions of SigmaStudio, however.

It's rather difficult to derive a subharmonic directly, so here's an idea which takes a different approach. It senses 13 incoming bass frequency bands from 27 to 55 Hz in order to control the levels of fixed oscillators at half those frequencies. The result is forced into 1/12 octave intervals with random phase -- but likely neither matters because this sort of bass is more felt than heard. Here's what the SigmaStudio project looks like:

Playing some dance music through this thing, the top trace is dry, the lower trace is processed with the "subharmonics":

As for a listening test, well... I've got nothing that goes down this low. My 15" powered sub went through the motions (literally) but only rattles were audible. I've no idea what a rotary sub is, except likely I don't want to be anywhere near one. So you'll need to try it for yourself, to see if this is workable. Happy thundering!

Best regards,

Bob