How to create a polyphonic FM/Subtractive synth

[rrooyyccee]

Hi folks,

I've been trying to figure out how to create a 4 voice fm synth with analogue filters for each voice (to go into something like an Studio Electronics Omega).
In theory, something like the tx802 should be capable of doing this, as it has 8 indiv. outputs. But it doesn't quite work, as it pairs up each of the 16 voices, so you would have 2 voices in each output. Darn.
A way around this would be to create a performance with 8 sepearate 2 voice modules, and have some kind of midi processor turn a polyphonic message into a series of 8 (or 4) monophonic messages. Lots of midi-cv convertors seem to be able to do this (motu volta, encore expressioninst) but I have not yet found a midi processor able to do this.
The final idea would be to see if something like a tx81z could be modified to have individual outputs. . . but I'm guessing that there is not a DA for each voice.
Any ideas would be welcome. Seems like it should be a tractable problem.



     

[Matthew Ritenburg]

Nord G2 Engine has 4 independent outs.  Run a DX Operator/Router combo in each slot.  Set each slot to mono.  Route each slot to one of the outs respectively.  Of course you can just create a poly FM/Subtractive synth in the G2.

--- On Tue, 11/3/09, royce <rrooyyccee@...> wrote:
> Any ideas would be welcome. Seems like it should be a
> tractable problem.

[rrooyyccee]

I don't have a TX802, but I don't think so. The monopatches will just be multitimbral. I see that there are some Os9 and Windows midi utilities that can split up a "midi chord" into monophonic midi messages. It looks like Cockos Reaper may have this built into its midi plugin library. Digital Performer does not, nor have I found anything for Ableton Live.

The Nord G2 seems like the only working (non-software) option out there, but I don't have a Nord G2 and it is a bit pricey just to get a 4 voice, 4 op synth. The complexity of the G2 disturbs me: I'm trying to minimize modular madness as it seems to decrease my productivity already, which is odd but seems to be the overall trend for me.

I very much like how the Studio Electronics filters saturate with external input, and am finding wonderful sounds using the Tx81z + analogue filters. It is possible that the polyphonic approach will not be as fun (perhaps there is something good about grinding up a chord and shoving it through a monophonic filter) but am interested in exploring the polyphonic route. To bring this on topic, one could also process the indvidual voices with effects, enabling some polyphonic analogue physical modelling.

Modding a tx81z to have individual outputs is way beyond anything I would even consider. IF anybody wants to give it a shot, let me know.




     

[Jason Proctor]

>I don't have a TX802, but I don't think so. The monopatches will
>just be multitimbral.

ISTR a flag in a DX7 patch that makes it monophonic, actually i just
checked and it's in the "function" memory for the patch rather than
the patch itself.

if i remember i'll give this a go with my TX rack + (analogue!)
modular tonight.

i'd still need the funky poly voice assignment trick, though the 802
could trigger the parts of a performance memory in round-robin
fashion IIRC.

[optical]

Have you played with the older nord modular? The micromods can be had fairly
inexpensively. On the other hand, when I've played around a little bit with
FM on the micromod I found it unsatisfying, though I didn't dig deep enough
that I could say exactly why.

mike

[Jason Proctor]

>On Wed, Nov 4, 2009 at 17:53, Mike Perkowitz <mike@...> wrote:
>>
>>  Have you played with the older nord modular? The micromods can be had fairly
>>  inexpensively. On the other hand, when I've played around a little bit with
>>  FM on the micromod I found it unsatisfying, though I didn't dig deep enough
>>  that I could say exactly why.
>>
>
>It might not be through-zero; but not sure of that.
>
>Royce: with regards to polyphony:
>buy 8 FB01's, they can be had really cheaply.
>
>You can send the midi from your keyboard to the computer, do magic
>there using either Cakewalk midi scripts (CAL), Logic, or Cubase, and
>then spit out stuff through midi on separate midi channels. I also
>think it could be especially easy in something like Max/MSP. Then set
>up each FB01 to accept a separate midi channel. Each FB01 then goes to
>a filter on your omega. Your omega is also split into single-voice
>modules and accepts the same midi channels as the FB01. I'm sure Greg
>St Regis from SE can tell you how you can do this.
>
>D.

i'm going to try this tonight with a TX816 (in 8-channel mono mode),
analogue modular, and some custom Arduino software. i'll report with
findings and recordings. in fact it's going to sound a bit weird
because i no longer have dups of filters!

[Jason Proctor]

i have an allocator i wrote a while back for something else, i'll
just use that on the Mac, or port it to Ard for fun and see what
happens.

it's at times like this when i wish my Ard module had more than two
"gate" outputs. happily the "production" version will have 4, i
think. gates == polyphony.



At 10:02 PM +0000 11/4/09, cheater cheater wrote:

>I could sure use that for my 816. If you find out anything
>interesting, share the code. There's some pseudocode in one of my
>posts on the Tom Oberheim SEM MIDI from this or last week that you
>might be able to use to ease up your work.
>
>D.
>
>On Wed, Nov 4, 2009 at 19:14, Jason Proctor <jason@...> wrote:
>>>  On Wed, Nov 4, 2009 at 17:53, Mike Perkowitz <mike@...> wrote:
>>>>
>>>>   Have you played with the older nord modular? The micromods can be had
>>>>  fairly
>>>>   inexpensively. On the other hand, when I've played around a little bit
>>>>  with
>>>>   FM on the micromod I found it unsatisfying, though I didn't dig deep
>>>>  enough
>>>>   that I could say exactly why.
>>>>
>>>
>>>  It might not be through-zero; but not sure of that.
>>>
>>>  Royce: with regards to polyphony:
>>>  buy 8 FB01's, they can be had really cheaply.
>>>
>>>  You can send the midi from your keyboard to the computer, do magic
>>>  there using either Cakewalk midi scripts (CAL), Logic, or Cubase, and
>>>  then spit out stuff through midi on separate midi channels. I also
>>>  think it could be especially easy in something like Max/MSP. Then set
>>>  up each FB01 to accept a separate midi channel. Each FB01 then goes to
>>>  a filter on your omega. Your omega is also split into single-voice
>>>  modules and accepts the same midi channels as the FB01. I'm sure Greg
>>>  St Regis from SE can tell you how you can do this.
>>>
>>>  D.
>>
>>  i'm going to try this tonight with a TX816 (in 8-channel mono mode),
>>  analogue modular, and some custom Arduino software. i'll report with
>>  findings and recordings. in fact it's going to sound a bit weird because i
>>  no longer have dups of filters!
>>
>>

[Jason Proctor]

well i just did this, the setup is --

DX7 -> Arduino
Arduino -> TX816

Arduino gate out 1 -> EG 1 -> VCA 1
Arduino gate out 2 -> EG 2 -> VCA 2

EG 1 -> VCF 1
EG 2 -> VCF 2

TX816 audio out 1 -> VCF 1 -> VCA 1
TX816 audio out 2 -> VCF 2 -> VCA 2

the Arduino is running a straightforward allocator which steals the
earliest played note when the polyphony (only 2 voices, in this
rather sad configuration) is exhausted. it spits out MIDI on channels
1 and 2, and sets the relevant analogue gate outputs to follow the
corresponding MIDI channel.

it works fine, and the envelopes duly sweep the filters nicely. i am
seeing some pitch hiccuping before some notes, this might be a timing
issue between the Arduino gate outputs going high and the MIDI packet
getting to the TX and sound eventually emerging. but i don't know for
sure. one other suboptimal part of this setup is that i couldn't be
bothered to set the TX modules to mono mode. it shouldn't be an issue
as each only plays one note, but some release tails etc might get in
the way.

i'm not going to post audio as i have other synthy tasks to get to
tonight and it's nothing to write home about anyway.

but the idea principally works, i'd say.

hth
j

[rrooyyccee]

Hmmm. I wonder if something like the Encore Expressionist could spit out the equivalent midi signal, as it already has this kind of program in it and has a midi thru. I hope Tony reads this :)

I think there are some midi VSTs etc., but so many of those things are only good for 4 -5 years, which seems to be the shelf-life of software solutions.

Thanks Jason for boldly going where nobody else seems to want to go!

There are great monophonic solutions to the FM+filter sound (modcan vcdo) but no polyphonic solutions. This is too bad, as things like the TX81z are basically sold at negative cost (80$ is basically like GIVING a synth addict money).

And I'm pretty convinced that the current software approaches (fm7, fs1r) really aren't fm + subtractive. They are really FM + digital filter without personality + VCA without personality. In most of these, the filter is just a tone control and is best left wide open.

royce (broke and trying to make a new synth out of old ones)



--- On Thu, 11/5/09, Jason Proctor <jason@...> wrote:

> From: Jason Proctor <jason@...>
> Subject: Re: [AH] How to create a polyphonic FM/Subtractive synth
> To: "Analogue Heaven" <analogue@...>
> Date: Thursday, November 5, 2009, 12:38 AM
> well i just did this, the setup is
> --
>
> DX7 -> Arduino
> Arduino -> TX816
>
> Arduino gate out 1 -> EG 1 -> VCA 1
> Arduino gate out 2 -> EG 2 -> VCA 2
>
> EG 1 -> VCF 1
> EG 2 -> VCF 2
>
> TX816 audio out 1 -> VCF 1 -> VCA 1
> TX816 audio out 2 -> VCF 2 -> VCA 2
>
> the Arduino is running a straightforward allocator which
> steals the earliest played note when the polyphony (only 2
> voices, in this rather sad configuration) is exhausted. it
> spits out MIDI on channels 1 and 2, and sets the relevant
> analogue gate outputs to follow the corresponding MIDI
> channel.
>
> it works fine, and the envelopes duly sweep the filters
> nicely. i am seeing some pitch hiccuping before some notes,
> this might be a timing issue between the Arduino gate
> outputs going high and the MIDI packet getting to the TX and
> sound eventually emerging. but i don't know for sure. one
> other suboptimal part of this setup is that i couldn't be
> bothered to set the TX modules to mono mode. it shouldn't be
> an issue as each only plays one note, but some release tails
> etc might get in the way.
>
> i'm not going to post audio as i have other synthy tasks to
> get to tonight and it's nothing to write home about anyway.
>
> but the idea principally works, i'd say.
>
> hth
> j
>
>
>