I’m trying to make a patch uses an LFO to modulate the cutoff for each individual voice of a polyphonic channel. It doesn’t seem like there are any filters/lfos that have this functionality built into them. So what I’m thinking is:
Say I have a 4 note chord going running into a filter (like POLY LPG from NYSTHI). If I split the chord into 4 mono signals and run each through its own filter with modulated cutoff, then pair them back together with a merge. From the animations in Bitwig’s LFO modulator it seems like each voice might be running through at different intervals? If so, then maybe something like Bog Audio’s 4FO would be necessary to offset the phase of each note’s modulation.
Is this the idea behind “per voice” modulation or is there more to it that I’m missing?
Surely most VCV filters are polyphonic and have polyphonic modulation inputs? No need to emulate anything.
In Bitwig the modulator is not applied in a uniform time to each voice. So maybe all I need is a 4FO → merge → cutoff? I’ll try that later when I don’t have to do work stuff
Thanks for helping me not overthink it!
It sounds like you need a polyphonic LFO where they outputs are not “uniform”. That is the missing “secret sauce”? I don’t know of one, but I’m sure plenty of ppl here do.
I think that some of the bogaudio LFOs are polyphonic if you send a polyphonic CV to the v/Oct input.
I’ll bet the fundamental modules do, too. But are there any that automatically generate un-correlated outputs without a lot of patching? Like a single “spread” knob for all LFOs?
No I don’t know of any, it would be cool though.
It seems to work with bogaudio 4LFO. That outputs 4 phase offset signals. Merge them together and you should have a non-uniform modulation per voice. It’s not random at all, but it seems to work for me so far.
EDIT: I guess the problem here is that each phase output from 4FO has modulation for all the voices, so I’d have to split 4 times (once for each output) to get each individual channel, merge those back together and then run that into my filter. Is there an easier way I’m not seeing?
Not a single spread knob - but ShapeMaster gives you 8 LFOs where you can set the phase for each (to whatever you want). The LFOs can of course be any shape you want and you can have them all running at the same or different speeds.
This is as minimal as I can get it:
Although if you want each note to change the LFO speed you can do this:
BTW, this works nicely for vibrato, to get that Boards of Canada vibe:
Brilliant! Going to try that. I’m trying to recreate Taches Teaches video on modulating modulators in Bitwig but in Rack. This was the key component that I was missing, but I think I have what I need to make it work. Thanks all!
Here’s what I’m trying to recreate:
Another solution that doesn’t require a Chord-Key (using one here to get pitches, but not necessary). It’s more modules overall, but I find it to be more intuitive.
EDIT 1: Cloner has a spread knob, but it only spreads the voices vertically (amplitude) not horizontally (phase). Not useful here.
EDIT 2: I’ve figured out that with the poly delay module you can change the time to offset voices uniformly and feedback to change the amplitude. Turning the poly knob spreads out the voices phases.
Oh I see now what you want to achieve. The LFOs must be in phase but you must be able to control the phase of each LFO.
The surge LFO is polyphonic and triggers its envelope per voice. You can emulate the bitwig per voice modulators with it i bet.
You can do this with my module
VCV Library - RPJ Grendel (vcvrack.com)
Put it in phase mode and you have 4 lfo’s available where you can control the phase.
Pretty much any polyphonic LFO with a poly reset or sync input should work.
The VCV Fundamental LFOs have that ability.
I did look at that one but couldn’t figure out how to modify the poly spread to make it work the way I wanted.
Wow, very easy! Nice module, thanks for putting it out there and also for sharing on this thread You have a new fan.
To be honest, I’ve never really thought about polyphonic LFOs. This thread made me try it out (see above). I always just stack a bunch of monophonic LFOs in my patch for movement. I’m sure it will free up alot of CPU.
Depends a lot on the LFO. In some LFOs 4 channels takes the same CPU as one, but those LFOs tend to be pretty efficient already (like Fundamental LFO). Some LFOs are truly terrible with CPU. An LFO is by definition pretty slow, so there is absolutely no need to make it inefficient.
So, like with all modules, use the CPU meters and see how much it’s using. Avoid modules that use a ton of CPU is there is one “just as good” that doesn’t do this (if you care about CPU usage).