[sdiy] OTA performance (was SSM chip reissue)

[Neil Johnson]

Tom Wiltshire wrote:
> In this case, we *know* that the 2164's matching is good enough, because we've tried it. It can howl.

Except you were the one going on about larger differences:

> What's the smallest decibel difference people can detect? About 3dB, isn't it? Quite a bit more than 0.25dB.
>
> To be honest, if it were 1dB out by -60dB, who's really going to notice? 2dB out at -80dB? And that's a lot worse than the spec'd figures suggest is likely.

0.25dB is about 3% error.  1dB is about 12% error - an SVF would have
quite a poor Q with that kind of gain error.

And quite honestly, making a circuit howl is easy - circuits will
quite happily do that all by themselves, even when you don't want them
to.  Making it howl nicely, or precisely, is much harder.

Neil
-- 
http://www.njohnson.co.uk