Hi everybody,
I need help building my first rack to act like a MIDI controlled poly synth for live & studio use.

I understand a poly with VCOs is a very expensive thing to consider, so I am considering wavetable.
Specifically considering the Flame 4osc which actually sounds really nice imo.

MIDI control would come from an Elektron sequencer but I'm not sure if, for example, I'd be needing a VCA or midi note length would take care of that. Yet, a VCF would be triggered from what?

I'm stuck with just the Flame module in my digital rack and don't know if I should just go for a Waldorf Microwave. But that would mean that maybe next time will be too late for eurorack.

I hope this all makes sense, thx to anyone that could provide some insight.


It's not that doing it with VCOs is costly...it's the whole concept itself. Full polyphony means that you have a fully-independent synth under the control of each voice signal, so you have to replicate the VCOs, VCF, VCAs, EGs, LFOs and so on over and over until you arrive at your final output mixer, where you'll mix the different voice signals together for a single mono or stereo output.

The next step down from this isn't actual polyphony. It's something referred to as 'paraphony'; each set of sound generators is controlled by a single voice signal, but instead of replicating the rest of the audio and control chains per voice, the mixdown to a single signal happens after the VCOs, then this goes through a single VCF, etc etc chain to the output. This method actually makes more sense in a modular context, since you can branch and recombine all sorts of paths along that post-VCO chain for sonic variation and arrive at a more controllable (and affordable!) system as a result. This is what I'd recommend as an approach, as a true polyphonic modular is, by default, going to be very spendy and also hell to patch and control. Think something along the lines of Junkie XL's MU 'wall' or Hans Zimmer's monster wall rig of Moog, PPG and Roland modules.


What's really the difference sound wise to create a paraphonic synth by running multiple VCO's all into the same VCF, VCA, EG versus "true" polyphony though? With some affordable VCO/DCOs and a MIDI to CV converter capable of routing the various CV inputs to the VCO/DCOs; it seems very doable in modular, especially compared to the massive rigs with expensive digital modules people put together without complaining too much of the cost and complex patching.

I would think tuning / calibrating it might be a pain, kind of akin to playing that guitar you keep lying around but can never quite get in tune with itself 100%.


Yeah, part of the problem does lie in patching and programming a beast like that. It's pretty daunting. Even a simple poly setup on my Digisound (basically, one VCO into one VCF into one VCA, same individual EG per voice for timbral and amplitude envelope, same LFO per voice for modulation), while it's fairly simple to patch, usually involves quite a bit of tweaking to get the balances and tunings right.

As for the difference, it sort of depends on how the VCF is being used, and how the voicings work. If the polyphony is very tight, and the VCF isn't doing anything really high-Q, it can sound much the same as normal polyphony. But when the VCF settings per voice start to get critical, as in something at near-breakthrough in resonance, then the drawbacks start to become apparent. Also, if the polyphony is spread widely, this too will be noticeable.

Really, this works better in actual polysynths, where everything can be under microprocessor control, and where everything is all chip-based. That way, the hardware costs get minimized, programming is less of a pain, and everything behaves more tractably. An example of one polysynth where this doesn't exactly happen is in the SEM-based Oberheims, where you technically have several individual synths under one master programmer's control, and once again, you can quickly find yourself in knob-tweaking hell trying to get the several SEMs to match up exactly. There are ways around that, though, but the SEM Oberheim polys are such an esoteric thing that that example's almost moot (even though Oberheim reissued them in recent years).


What's really the difference sound wise to create a paraphonic synth by running multiple VCO's all into the same VCF, VCA, EG versus "true" polyphony?
-- goodbyebluesky82

If you want a setting for each note, like a filter sweep, there is a huge difference. In polyphony you get a sweep for each note, in no way affected by the trigger of a new note. In paraphony the sweep of the first note will restart when you trigger a new note.


What's really the difference sound wise to create a paraphonic synth by running multiple VCO's all into the same VCF, VCA, EG versus "true" polyphony?
-- goodbyebluesky82

If you want a setting for each note, like a filter sweep, there is a huge difference. In polyphony you get a sweep for each note, in no way affected by the trigger of a new note. In paraphony the sweep of the first not will restart when you trigger a new note.

-- sislte

I'm primarily a guitarist / drummer who started dabbling in synth, not a keyboard player, and therefore play very basic things, so that didn't occur to me but makes sense now. For very simple chords / pads, I still don't think it would be an issue, but I could see that being a problem for bigger chords / pads where you are adding and releasing notes while keeping some notes sustained simultaneously.


Exactly...when you're dealing with an instrument that works on discrete note-on/note-off behavior, then the point of actual discrete polyphony enters into things. A good parallel in guitar would be the various complex picking styles of Doc Watson, or the techniques found in a lot of classical guitar repertoire, flamenco/Andalucian style music, etc. Paraphony is more akin to strumming chords and the like, where a single attack occurs more or less simultaneously for all notes, and the result is more of a single sound without internal attacks, modulation characteristics, etc on single notes within the chord.


It's not that doing it with VCOs is costly...it's the whole concept itself. Full polyphony means that you have a fully-independent synth under the control of each voice signal, so you have to replicate the VCOs, VCF, VCAs, EGs, LFOs and so on over and over until you arrive at your final output mixer, where you'll mix the different voice signals together for a single mono or stereo output.

The next step down from this isn't actual polyphony. It's something referred to as 'paraphony'; each set of sound generators is controlled by a single voice signal, but instead of replicating the rest of the audio and control chains per voice, the mixdown to a single signal happens after the VCOs, then this goes through a single VCF, etc etc chain to the output. This method actually makes more sense in a modular context, since you can branch and recombine all sorts of paths along that post-VCO chain for sonic variation and arrive at a more controllable (and affordable!) system as a result. This is what I'd recommend as an approach, as a true polyphonic modular is, by default, going to be very spendy and also hell to patch and control. Think something along the lines of Junkie XL's MU 'wall' or Hans Zimmer's monster wall rig of Moog, PPG and Roland modules.
-- Lugia

Thank you for answering and sorry for the late reply.
Yes, a paraphonic instrument is what I need for starters. I've done a lot of research and concluded I'll start with a wavetable module that does chords too (leaning towards Shapeshifter).
This way I will have a patch for chord duties along with external sources for my live needs, and I guess will be a good starting point overall..
I've decided to invest in a 14u/96HP flight case with lots of clean power and low noise and start with 10 or modules, already above budget but functional enough. After that I guess I'll try and fill it slowly and wisely.
Except if I win the lottery. Then it will be sth like 6 Bateleurs for a chord drone and a monster rack for modulation only
Wish me luck