CA3094 ---> LM13700

[StephenGiles]

CA3080--->CA3094

The more I look at this I see that a "drop in" replacement  for the CA3094 is not an option in many cases, and would call for redesign using LM13600. But "There Ain't Half Been Some Clever Bastards" so something may turn up.

[liquids]

In terms of the filter and most of the OTAs in the Microsynth, it seems pretty easy to use a 13700/13600 the more I learn.  The only one I see that seems to be difficult is the OTA/CA3094 that drives the 'sweep rate.'   One $10 or less 3094 is better than 7!  But I own one, and will sell it (PM me), but don't see why someone would buildone of these from scratch if you want an exact circuit clone - just buy one, not worth the time, IMO...

Anyhow, all I'm mostly interested in is the Microsynth's filter and sweeping it (which may be more easily done by other means than in the microsynth, I suspect).  I like the triggered filter rather than envelope.

I finally got OTA simulation working a bit in LTspice and simulated the filter wtih the 13700s.  Here's what I got if anyone is interested.







The microsynth is a state variable filter, and while it has only 2-poles and 12dB/oct, it's much more consistent in it's sweep and sharp in it's cuttoff.  I like that.  If you model something like the mutron or most other simple filters, the peak intensity and width varies with frequency, which can be charmingly 'eccentric' to some and for some effects, but also sound kind of crude.  I like this one.

[liquids]

Actually....I think this is 18/dB 3-pole...my mistake.  And it may or may not be state variable, but a HP response is available...

[thedefog]

You may be able to compare the early versions of the small stone with the later ones that used the LM13700 and see how they dealt with the switch. May or may not be helpful.

[nocentelli]

I'm mostly interested in the Microsynth's filter and sweeping it (which may be more easily done by other means than in the microsynth, I suspect).  I like the triggered filter rather than envelope....

The microsynth is a state variable filter, and while it has only 2-poles and 12dB/oct, it's much more consistent in it's sweep and sharp in it's cuttoff.  I like that.

+100

I love the filter in the the microsynth (i'm not to bothered about the different octave voices and square fuzz section), and would like to build a stripped-down version with just the resonance, start, stop, and attack delay controls. However, I'd really like to do it with a 13700 and a few trannies if this is possible.

[liquids]

I wish you luck!

I like the different voices in the microsynth...but I actually prefer my sub-octave and 'square wave' to be more aggressive when feeding said filter for filtered 'synth' tones, believe it or not.