Synth with LFO Crossfading
Posted: Mon Sep 23, 2019 7:22 am
So here's the synth for which I inquired about shelving filters (thanks Martin!)
Based on/inspired by the rather obscure 1979 Crumar DS-2 monosynth. Only remarkable for two rather unusual features. It had something called a 'Poly' section which was fully 44-note polyphonic (divide down) and produced only sawtooth wave. The output of this went through what it called HIgh Pass and Low Pass filters that were actually just high and low shelf filters. A switch allowed it to route to the VCF or to it's own rear panel output jack. The other (much more) remarkable feature was it's "LFO's Mixer" section that allowed each of six targets to receive mod from either of two LFOs or an equal mixture of the two (1, 2, 1+2 or 'Out'), as well as it's own level control.
Always a fan of the Moog Sonic Six's Wave Gen X/Y control (crossfader between the two LFOs), I gave the LFO's Mixer section crossfaders in place of the switches. I also moved LFO waveform selection from the LFO sections themselves, to each of the target sections of the LFO's Mixer. So, each mod target can crossfade between any of LFO 1's waves and any of LFO 2's waves. A quick web search suggests that very few non-modular synths, old or new, soft or 'hard' had this capability - can be done with most modulars, but requires some fairly extensive patching. The Crumar Spirit (designed by Bob Moog) had two LFOs that could interact in a few ways but no simple, single knob to crossfade between them, and certainly not a dedicated crossfader for each mod target (I've even added the ability to control the crossfade with the mod wheel instead of the panel controls).
As to the 'Poly' section, since the whole synth can be Mono or Poly, I made it instead a third full-featured oscillator (thus, the name 'DS-3'), gave it the low and high shelf filters Martin supplied and a switch to disconnect it from the VCF. There is also a switch to have the VCF output sent to both stereo outs, or the VCF to the Left and Osc3 to the Right. Thus in DAWs that allow for it (or using a separate plugin to split the L and R), one can process the two outputs separately. It would be cool to have the option (like on the hardware) to have Oscs 1 and 2 play mono and Osc3 poly - anyone know how to do this, I couldn't figure it out.
Thanks also to Spogg - I used a couple of your wave 'shapers' and the VCA EG 'snap' you made for
minDy S.
The Crumar had no mod wheel, so I added lots of wheel functionality - the 'emulation' has been 'plussed' in a whole host of other ways too numerous to go into here, but I tried to keep the GUI as uncluttered as possible (most of the added functions are 'hot' labels along the bottom (some are 'hidden'; a read of the 'Info' pane is a must on this one) - this turned out to be a real fun little beast, especially for LFO fans.
P.S. - let me know if anyone's computer doesn't render the font as shown in these screenshots. If too few people have Eurostar Black Extended installed, I may have to render the panel as one big image that includes the text so it looks the same on everyone's computer.
Based on/inspired by the rather obscure 1979 Crumar DS-2 monosynth. Only remarkable for two rather unusual features. It had something called a 'Poly' section which was fully 44-note polyphonic (divide down) and produced only sawtooth wave. The output of this went through what it called HIgh Pass and Low Pass filters that were actually just high and low shelf filters. A switch allowed it to route to the VCF or to it's own rear panel output jack. The other (much more) remarkable feature was it's "LFO's Mixer" section that allowed each of six targets to receive mod from either of two LFOs or an equal mixture of the two (1, 2, 1+2 or 'Out'), as well as it's own level control.
Always a fan of the Moog Sonic Six's Wave Gen X/Y control (crossfader between the two LFOs), I gave the LFO's Mixer section crossfaders in place of the switches. I also moved LFO waveform selection from the LFO sections themselves, to each of the target sections of the LFO's Mixer. So, each mod target can crossfade between any of LFO 1's waves and any of LFO 2's waves. A quick web search suggests that very few non-modular synths, old or new, soft or 'hard' had this capability - can be done with most modulars, but requires some fairly extensive patching. The Crumar Spirit (designed by Bob Moog) had two LFOs that could interact in a few ways but no simple, single knob to crossfade between them, and certainly not a dedicated crossfader for each mod target (I've even added the ability to control the crossfade with the mod wheel instead of the panel controls).
As to the 'Poly' section, since the whole synth can be Mono or Poly, I made it instead a third full-featured oscillator (thus, the name 'DS-3'), gave it the low and high shelf filters Martin supplied and a switch to disconnect it from the VCF. There is also a switch to have the VCF output sent to both stereo outs, or the VCF to the Left and Osc3 to the Right. Thus in DAWs that allow for it (or using a separate plugin to split the L and R), one can process the two outputs separately. It would be cool to have the option (like on the hardware) to have Oscs 1 and 2 play mono and Osc3 poly - anyone know how to do this, I couldn't figure it out.
Thanks also to Spogg - I used a couple of your wave 'shapers' and the VCA EG 'snap' you made for
minDy S.
The Crumar had no mod wheel, so I added lots of wheel functionality - the 'emulation' has been 'plussed' in a whole host of other ways too numerous to go into here, but I tried to keep the GUI as uncluttered as possible (most of the added functions are 'hot' labels along the bottom (some are 'hidden'; a read of the 'Info' pane is a must on this one) - this turned out to be a real fun little beast, especially for LFO fans.
P.S. - let me know if anyone's computer doesn't render the font as shown in these screenshots. If too few people have Eurostar Black Extended installed, I may have to render the panel as one big image that includes the text so it looks the same on everyone's computer.