suboctave + filter fm

[signboy]

A sound I use frequently in Reason is to run one osc into a low pass filter,  then use a second osc 1 8ve down to modulate the filter frequency. I absolutely love how it alludes to a suboctave without actually adding crazy low frequencies that would be useless.

Is this even doable in a stompbox?

I'm fairly new to circuit design, but I can't find anything like this out there, so it's a project I'd like to tackle, even though it's probably way out of my league.

edit for clarity:
this is not to be a synth pedal, but an analogue bass guitar pedal, to add some glottal "vocal fry" kind of growl.

[Strategy]

There are some modular synth DIY circuits out there somewhere that will be a filter module with FM input. Look at Elby, CGS, see what there might be. A few issues - you'd need to adapt the module to be line-level ready. Also, you'd need to figure out a source of the FM and I'm not sure in a pedal format how you'd do that. You could have a 3rd FM source, even maybe a little simple 555 timer oscillator or something, unless you wanted your bass signal that is being filtered, to also be the source of the FM.

Strategy

[signboy]

hmm, good idea. I have no idea why synth modules weren't my first place to look. I guess I got zeroed in on the stompbox challenge. Going the module route,  I'd run a sub octave pedal into the FM source, and dry bass into the... is it "carrier"?
Good ideas though. Maybe the octaver and FM filter could be modded into one unit.

[Strategy]

On the CGS page look for the "stompbox adaptor" PCB's. There's one that converts a synth module circuit to be switchable and line level friendly. There's another one that's the reverse, allows you to pull your stompboxes into a modular system if you are a modular user, so be careful not to confuse the two. You can easily power (power's integrated) two modules off that same pcb and put them under one enclosure, if you wanted.

Strategy

[Strategy]

Another thought. You could use the CGS Stompbox Adaptor pcb along with some Music from Outer Space modules. They sell a standalone Envelope Follower PCB that is supposed to be very nice and smooth. you could have a filter circuit that has an FM input. have your bass amplitude influencing the envelope follower and hard wire the envelope follower's output voltage to the FM input of the filter circuit. So, envelope controlled FM. Could be pretty cool.

[slacker]

You can certainly do what you're suggesting, there's plenty of guitar envelope controlled filters where the envelope generator could be replaced by an FM input and there's various octave down pedals to get your lower octave to drive it. I'm not familiar with Reason but if you can it might be worth trying your idea in it using a guitar or a sample of a guitar. What sounds good with oscillators may not work well with the more complicated output from a guitar.

[signboy]

Good call on the test. Out of curiosity, is there any interest in an effect like this?  If there is, I'll put up some audio files of the test.

[slacker]

I'd certainly be interested to hear what it sounds like.