[sdiy] Problems with linearized SSI2164 ?

[Neil Johnson]

> Unfortunately we just built a ton of modules with the SSI2164 and our factory did not tell me they had switched to the new chip (from the v2164).   We can re-work these by replacing the three 30k resistors with 100k but I would still like to understand this better.  It also unfortunately means the SSI2164 is not a blind drop in replacement for the V2164 and I am going to have to test out the rest of our circuits very carefully before any more manufacturing.

At $DAYJOB this situation would be cause for serious shouting at the
factory, because
a) A factory should NEVER change anything without approval from
engineering, even seemingly trivial component swaps can be fatal,
b) There is no such thing as a "drop in replacement", even for things
like capacitors.

The SSI2164 has
- higher control pin input resistance (10k vs 5k)
- higher input headroom
- lower noise and distortion
- larger gain cell transistors
- etc..

That lot together is a screaming "not drop in replacement" sign!

And yes, been there, but fortunately things were caught in the
pre-production stages so we only scrapped a few hundred units.

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