Polyphony in Eurorack

I’ve poked around in the Eurorack and Polysynths threads, but there doesn’t seem to be a thread specifically devoted to this topic (mods, please correct me if I’m wrong!).

I have been debating the possibility of building a little polyphonic eurorack system built around a set of 4 Castor & Pollux modules and an Ansible + Grid. The idea is to have 4 voices (two oscillators per voice) with sequencing or live playing via Grid. I’ve currently got 2 C&Ps and the Ansible & Grid. Beyond that there are a few related options that pique my interest - Instruō’s Harmonaig and Verbos’ Polyphonic Envelope come to mind for their intentional focus on polyphony. And extending this to be semi stereo, I’d like to include a stereo filter in this setup, so something like Blades (which I have) or QPAS might work well. So, in my head the setup would be something like this:

Grid & Ansible > C&Ps > VCAs > Filter > VCA
Grid & Ansible > Envelopes ^ and ^

The round-robin nature of handling envelopes is the most confusing thing to me.

I’m curious, what are some strategies you use to accomplish polyphony in eurorack? I’m aware of recent poly-additions to eurorack like the Knobula’s Poly Cinematic and its MIDI partner Chord Pilot, but they seem somewhat limited in terms of patching and control goes.

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I made a “strumm” script for crow. Where it acts the same as the rings polyphony.
Then i have a custom midi controller (to yarns) which can handle multiple key presses as once and converts it to a strumming stroke with 3ms inbetween (on changing the cv value and giving a new trigger). I can’t hear it and alway hear a full chord strucked at once so for me it’s good. This setup worked out for me as i can use the same setup on both just friends and rings at the same time (to layer the two synth voices)

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My poly experience is largely focused on the Sinfonion, a Doepfer A111-4 and a handful of other oscillators and mono filters. I haven’t gone as far as a stereo or poly filters yet, but if I do I may keep to the Doepfer line for one nice chord chain. I loved the Harmonaig when I had it, and like you I have Ansible + Grid as well which all paired very nicely. If you’re curious, this series Enter the Polyverse is immense - there are some great tips of how an ambitious poly system comes together (mostly Doepfer. I think there are 9 videos in the whole series)

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Not clear what you mean by polyphony. When I hear that word in the synth context, my first association is the meaning that was established by slab synths in the 1970s that contained an array of monophonic synths that were all basically identical, and notes were doled out to them through a hocketing circuit. That’s where a module like Intellijel Shifty comes in and gives you your round robin. I have one and it works well. (Of course, the 2–4 voices don’t have to be identical—that’s a nice creative opportunity made possible by modular.)

As you’ve noted, there’s a small-but-growing collection of digital modules that take MIDI and dole out the note events to their own virtual synths, but those tend to be black boxes: MIDI goes in and an audio mix comes out.

Modules like Harmonaig and Polyphonic Envelope aren’t necessarily polyphonic in the above sense, although they can be employed in some polyphonic patches.

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This series is pretty great - I wasn’t aware of all these poly focused Doepfer units!

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Yeah, but even with Doepfer’s generally reasonable prices, a set of modules to comprise four voices adds up pretty fast. For example:

  • quad VCO $450
  • quad VCF $300
  • quad VCADSR $200 (clever module)

That’s basically $1k. You still need a voice management front end. Doepfer has the $300 MIDI unit and there are various non-Doepfer alternatives. But now we’re up around $1300 and all we have is a rather rudimentary and cumbersome four voice synth. That only starts to make sense if you have a great strategy to augment it into territories no non-modular synth can go, which of course implies more investment.

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:100: I learned a lot… of course that system is a bit OTT for what it is, the principles apply nicely for a smaller poly setup… The Intellijel Shifty also appears, as @mdoudoroff pointed out. I also used one for the round robin on the quad oscillator.

I like the idea of using Shifty for this, though how would you configure Ansible to this situation if you, say, play a 4 note chord at once on Grid?

I have an Acid Rain Chainsaw, and an nb mode for Norns/crow that does paraphonic voice allocation on it. Unused voices are unison with used voices, and crow outputs v/8 x3 and one envelope.

There’s also good ol JF, and a few modules with Rings-style poly…

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hmm a bit of mental gymnastics there. I haven’t quite used it to that effect with Ansible grid yet, but you’ve given me some fun homework :+1: I would either use the Shifty cv/gate as a sequential switch with each step triggering a different oscillator+env+filter+vca, and each preceding note ringing out to hold the chord, as such. (simillar to @bloc strumming script I gather). To have all four notes from Ansible play at once with Shifty, it’s still only allowing one note CV / gate pair… you’d probably need to use another series of switches like Trees / Boss Bow Two. I’ll experiment though and update this thread in time

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A while ago I went through those same calculations and ended up taking the shortcut of a Vernona Perfourmer. No regrets!

True poly, round robin, four monos… it can do a lot.

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That of course is a very sensible (out of case) option. Still weighing that one up!

It wasn’t my intent to have multiple voices/oscillators but things keep changing unexpectedly.

I’m gonna lurk here because i am rethinking everything about my system lately

Nice bit of kit. Of course, you could have 3 minilogues or a Peak or Take 5 for the same or less investment. The essential question is what you’re trying to do and how.

Just a quick reminder - the intention of this thread is to explore the hows and whys of polyphony in eurorack, not to argue why it is a dumb, expensive enterprise - lol.

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In that spirit, I did some poking around, and while I’m not 100% positive, it sure seems like Shifty is still (2023) the only voice hocketing Eurorack module entirely within the CV domain (i.e., not MIDI). I’m a little surprised! It’s pretty darn difficult to roll your own from general purpose utilities.

Shifty has an important limitation that a note gate has to end before the next one can begin—MIDI doesn’t share that limitation. (In other words, Shifty gets you notes that can overlap during the release phase of their envelopes, but it doesn’t really get you pads, because only one note can be active—ON—at a time.)

It’s only duophonic (though perhaps there is a way to chain them), but there is also:

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For chordal playing, I don’t really think modular brings you much benefit, and it engenders a lot of hassle. If you want to play a handful of notes at the same time, a more normal poly synth is almost certainly a better idea.

That said, I love hocketing and other shift register games that can be played with modular. Buchla had the first module I know of that did this sort of thing, in the 264 Quad Sample-And-Hold / Polyphonic Adaptor. In Eurorack the Intellijel Shifty is a modern take on this concept, and can do a very similar job.

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i don’t have an ansible, but doesn’t it already support polyphony and round robin behavior without any extra modules? earthsea?

edit: a quick glance at the documentation (under voice allocation), tells me indeed it can.

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I am finding myself doing polyphony most of the time in my sets these days, with Teletype doing the duty of sending out to the various voices. Modules like the Disting EX which can do eight voice polyphony in some of its modes, which can be controlled over CV or i2c.