I’m a big fan of Gotharman’s stuff, and I like that he offers a choice of analogue filter boards. Being that SSM & CEM reproductions now exist, a thought occurred to me about an analogue board for Zynthian. I often have lots of ideas but no technical/engineering knowledge so I class these as fun thought experiments or “what if” scenarios.
I imagine it would work like this: 4/6/8 analogue filters on a board that could be controlled by the Pi.
A custom Zynthian filter plugin could offer flexible audio and MIDI trigger routing, some envelopes and LFO’s.
Then you’d load up multiple instances of a synth plugin, and route each to a different filter voice. I assume it would have to work this way because plugins, I’m guessing, sum their voices to stereo? I guess being open source, some could be hacked to have multiple outputs, though.
Anyhow, the tricky thing would be the initial setup - maybe an option would exist to replicate all the options across the filter boards. You could have presets in the filter plugin that you could save for various synth patches. I imagine with time, more integration could exist, with plugins aware of the filter board that generated the control data itself.
In another thought experiment I imagined a set of CV/Gate outputs for the device, I think this would be cool for modular integration.
Outboard routing to a zynth is a certainly possible. You need a zynth with enough outputs to allow your signals out for the final sounds and a feed to your external audio kit. You will also need an input to return the external send to the zynth. USB offers some solutions, the Behringer 1820 allows you 8 outs and 8 inputs, so it would certainly accommodate the idea. And I have done it using a Electro Harmonix Mel Nine Pedal, because I’ve not seen an lv2 that does anything like that pedal does ( corrections, obviously joyously submitted, I’m not even sure I know how it actually does what it does, but someone will know).
But then you get onto the subject of levels with the curtis chips and their friends where you are on a modular synth so you can expect audio levels of plus and minus 10 volts compared with the audio line level of about 0.775V that the Behringer would be expecting, so your curtis circuit is going to be doing some matching on the input and output to get it into the same zone as the chips. And you have to power it… Another wall wart for the collection…?
You also have the problem of latency 2 chunks of USB audio processing is certainly getting faster but it’s still a fair oold chunk of delay to throw into the signal path, for what is ultimately an attempt to produce a specific filter effect.
The zynthian mini audio in one of our development dungeons has been making some interesting noises recently and it is likely they will reduce the time it takes to AtoD & Dto A but ultimately i’ts still got to go on. A Pure DSP device like theNord Modular ( here he goes again) could do this sort of thing with very finely defined audio in’s and outs, which is what I would prefer to use, at the moment, if I needed the Mel9 in the audio chain. It’s got a horrible wall wart as well . . .
There has been discussion in the MiDI-D thread about filter emulations at the chip level so perhaps that might be an engine that could offer what you are considering.
So, yep, it can be done, but there are approaches that keep as much of the audio processing in the zynthian world, which on this forum is perhaps understandale.
The Tascam device that @riban believes he’s getting for xmas (*) , has some DSP on it, and the possibilities this offer in the future might allow a purely software emulation at the chip level, but as with much, it’s knowing how close a particular future is.
But f someone is doing something like this , then please tell us all about it.
