[sdiy] Discrete OTA

[David G Dixon]

> Interesting.. I still use the LM13700 in my filter designs, 
> but have been looking into the 2164...  You stated that  the 
> 2164 "sounded
> better".. could you try to define what you heard?   Is it the
> exponential response that makes the difference?
> 
> I know the expo converter built in is nice for modular and CV 
> control, but that is not an issue for me, so I was wondering 
> what else would make me switch.. Sound quality would be the thing.

I would take my comments with a large grain of salt.  The simple answer is
that 2164 is a more convenient block for filter design than 13700, and it is
a little less noisy.  In some ways, the noise of 13700 is desirable because
it gives a more vintage sound.  Also, OTA + Cap + Buffer filters often need
internal AC coupling, while VCA + Integrator designs don't.