[sdiy] [OT] LM13700 spotted in commercial product of big Manufacturer

mskala at northcoastsynthesis.com mskala at northcoastsynthesis.com
Sun May 15 22:45:42 CEST 2022

On Sun, 15 May 2022, Brian Willoughby wrote:

> What about the Analog Devices SSM2018 and SSM2164?
> ... or is a VCA (OVCE) not always interchangeable with an OTA? I realize that an OTA is flexible enough to be used in many ways, but it seems that a VCA is the most useful.

Both obsolete according to Analog Devices' Web site - you can get clones
and equivalents from other manufacturers but we're in the same space as
the OTAs there.

As for interchangeability, it depends how interchangeable you want it to
be.  I don't think anything but an OTA has the specific distortion profile
that an OTA has, so if you want it to sound like an OTA, you'll have a
hard time replacing the OTA with anything else.  On the other hand, the
unique features of OTAs may be mostly *disadvantages*.  Other designs are
going to be cleaner and simpler.  I think it was David Dixon (he can
correct if I'm misremembering) who commented on this list about how after
trying the 2164 he was never going back to OTAs.

I've gotten some good use out of the differential inputs on the
LM13700 in a couple of my designs, and the 2164 doesn't have those.  But
that may not be a dealbreaker; I can use, um, a TL074H to do subtraction.

It's like saying, why use a Vactrol when you could use a VCA?  On the one
hand, yes; but on the other, there is no drop-in replacement, and no easy
exact simulation.

Matthew Skala
North Coast Synthesis Ltd.

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