[sdiy] Problems with linearized SSI2164 ?
neil.johnson71 at gmail.com
Thu Feb 7 00:30:40 CET 2019
> 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
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
The SSI2164 has
- higher control pin input resistance (10k vs 5k)
- higher input headroom
- lower noise and distortion
- larger gain cell transistors
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.
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