Duophony ?

[k brown]

Anyone know if Duophony as implimented in the ARP Odyssey and a few others (two-osc synth, when two notes played, the lower note sounds the first osc and the higher note sounds the second) is doable in FS? Perhaps it would require one of trogg's MIDI tools?

[wlangfor@uoguelph.ca]

Anyone know if Duophony as implimented in the ARP Odyssey and a few others (two-osc synth, when two notes played, the lower note sounds the first osc and the higher note sounds the second) is doable in FS? Perhaps it would require one of trogg's MIDI tools?

Well, I should look at Trogg's midi tools, never have.

I was thinking initially that it should be as simple as making it use int so as to be able to interpret those commands in asm, but I dunno, that would also require a float array.

Kind of involved, but it would ensure it could potentially be simpler.

In the case of ds code I think you can do this:

Code: Select all

((arg1=1)|(arg2=2))&dothis


potentially that simple, if arguably that code works.

[adamszabo]

Should be pretty simple, just make the voice 2 polyphony, then in dsp split the pitch two way. You can write a simple code something like:

osc1 pitch = (pitch < 60) & pitch //only send pitch to osc1 if its smaller than pitch 60
osc2 pitch = (pitch >= 60) & pitch //only send pitch to osc2 if its higher or equal to 60

Ofcourse you have to find where the pitch split is, I just put 60 there for no reason

[trogluddite]

It could also be done with strict highest/lowest note rather than a keyboard split point. The MIDI tools include a module for listing which notes are playing, and the list can be sorted in note-number order. In principle that could be used by taking the first and last notes in the list, and using (list_length > 0) as the 'gate' signal.

However, you would have to implement the synth in 'blue' for this method to work. If it were done in poly, notes would retrigger whenever you switched between one note played and two notes played.

[k brown]

Damn - I was afraid it would have to be done in blue; I assumed that wasn't the case because I thought only one note at a time was possible in blue.

Yes, you're right - traditional duophony works with any two notes played anywhere on the keyboard.

[trogluddite]

...traditional duphony works with any two notes played anywhere on the keyboard.

Also, for a strictly correct emulation of most of those synths, the filter and modulators would be shared between the oscillators. So, even if poly were used to generate the oscillators, you'd need a 'blue' modulator/filter section. It would be easier to do the whole thing in 'blue' in that case, as you'd also need shared 'gate' and 'trigger' signals for driving the mono envelopes.

[k brown]

I'm kind of surprised that apparently nobody's gone down this road yet - duophony results in some interesting playing styles that a polysynth can't do. But of course most synth players these days let the sequencer do the 'playing'.

[trogluddite]

I suspect that it's having to use a custom "voice manager" and blue processing that has put people off doing it. As you say, it's quite a unique sound - I remember a long time ago having a play with a mate's OSCar synth that could do a similar trick by sending the keyboard and internal sequencer to separate oscillators; so the sequenced notes could change character depending how you played the lead-line (I assume this was a standard feature - he was known as a bit of a "circuit-bender"). Even the shared modulator section on some of the divide-down string synths has it's own particular charm once you get used to it, I think.

[k brown]

Obviously such a custom manager would be needed for what most of the 'ensemble' synths could do, which was have a split keyboard where left of the split it was mono and right of it was poly. ARP Quadra, etc.

Yeah, I hadn't thought of that aspect of duphony - that a sequencer could drive on osc and the other 'played'.

We're clearly getting onto what my lego blocks abilities with FS is incapable of!

[deraudrl]

Anyone know if Duophony as implimented in the ARP Odyssey and a few others (two-osc synth, when two notes played, the lower note sounds the first osc and the higher note sounds the second) is doable in FS? Perhaps it would require one of trogg's MIDI tools?

I'm almost afraid to ask what happens when the low/high order changes on a held note. E.g. hold C4 (osc1) and E4 (osc2), release C4 and play G4, so E4 is now the lower note...does it retrigger on osc1?