Synth with LFO Crossfading

[k brown]

So here's the synth for which I inquired about shelving filters (thanks Martin!)

Krumar DS-3 + copy.jpg (133.41 KiB) Viewed 18448 times

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).

Krumar DS-3 +_lfos mixer.jpg (67.72 KiB) Viewed 18462 times

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.

Krumar DS-3 +.fsm

(1.6 MiB) Downloaded 1011 times

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.

[Duckett]

Looks great, Kevin! I was able to find the Eurostar Black Extended font for free- but thanks to Laci (GyL Synths)'s testing feedback, for Combellish I did end up using ScreenshotCaptor's "Grab selected region" to turn the Techno28 ( a free Data 70 lookalike font) section titles into bitmaps- that was actually easier for me (if a bit more fiddly) than trying to do one big image.

[k brown]

Yeah, you're probably right - I'll try it that way if it comes down to it.

[Halon]

Thanks Kevin

[Spogg]

This is yet another lovely synth Kevin. You really have a good eye for GUI design. Can I have it please?

I really like the sound, but only 3 presets?

I know I often mention this but it just seems so odd to me that you put all that time and effort into a great design but don’t go the extra few yards to show off more of what it can do. This is more of a plea than criticism of course. When I get to play with a new synth I immediately like to run through the presets to get some idea of the range of the instrument. Maybe I’m in a minority in that respect, I don’t know, but if I hear an unusual or unexpected sound I often get drawn in to see how it was made and that encourages me to dive in and explore.
I sometimes get criticised, quite justifiably, for not putting more effort into my GUIs. But in my case it’s a missing skill and talent. Maybe you consider yourself bad at sound design in a similar way, but I somehow doubt that because what you do provide is good.

Anyway, as always, thank you for sharing your excellent work.

Cheers

Spogg

[Phil Thalasso]

Hello Kevin, hello you all,

I*ve been quiet for a time as I had nothing to contribute. But here's an instance in which I might add a tip for value-added. There's this wonderful free utility on the market that really helps testing a synth for it's abilities:

https://vst-preset-generator.org/

It only outputs fxp / fxb files, but those might be of use to anyone who makes use of a DAW.

Wishing that you all are doing well.
Best regards
Phil

fxb files: https://fileinfo.com/extension/fxb

[k brown]

Thanks for that PT - I'll check it out; could provide some useful starting points from which to fine-tune some useful presets.

To Spogg - all you say is true. It's really just laziness and a time thing. I occasionally use my FS cobbling as brain-flush time away from painting; I find it necessary to use my brain in a completely different way for a while, but by the time I get a project pretty much finished, guilt sets in about how much time I've spent away from painting and can't force myself to spend the extra time building presets. What I really should do is next time I need some FS time, spend it making some presets for an existing synth instead of working on another one. Hadn't occurred to me till now - thanks for the mind-jog!

[k brown]

Been tweaked and refined a bit since the initial post, so if you grabbed it that day or the following one, get the latest.

[Spogg]

I know exactly what you mean about building presets. I once confided to a dear friend here that I find it a real chore. By the time I get to the end I’ve already explored most of the sounds while I developed and tweaked. So, to me, nothing sounds new and exciting or interesting.

In my case I came to realise, eventually, that giving away a synth is really only half a gift, if that. That helped spur me on. Then I started to make videos, so I needed good sounds to provide more of an impact.

I don’t see the need to provide a hundred variations of a filter sweep. But I do think it’s good to provide maybe 10-20 distinctive presets as launch pads for tweaking.

What I’ve started to do recently is make some presets before the synth is finally ready. This means I can find limitations or get ideas for improvements or additions. The down side is that I often have to re-do those existing presets as I change stuff, but I find the experience for me is better overall because the early presets are then more a part of the development process, which is the part I enjoy most.

Cheers

Spogg

[k brown]

What I’ve started to do recently is make some presets before the synth is finally ready. This means I can find limitations or get ideas for improvements or additions. The down side is that I often have to re-do those existing presets as I change stuff, but I find the experience for me is better overall because the early presets are then more a part of the development process, which is the part I enjoy most.

This is a great idea.

I know it was probably a dumb-a** question, but any idea if what I asked about in my OP regarding osc1 and 2 being mono and osc 3 poly - is that possible?