[sdiy] Problems with linearized SSI2164 ?

Neil Johnson neil.johnson71 at gmail.com
Thu Feb 14 00:53:37 CET 2019


Hi David,

> The datasheet says (in large boldface type):
>
> "FEATURES: Improved Direct Replacement for SSM2164/V2164"
>
> So, the datasheet is literally screaming that it is a direct replacement.
> In my book, that means a drop-in replacement.

You can drop an SSI2164 into a properly designed circuit, and it will
likely work as-is, or with minimal tweaks.  But this is analogue
electronics, not Lego.

> In any case, I believe that the circuit Dan was using it in is exactly the
> one given by Phillip Gallo in the datasheet, and it ain't working.  That
> tells me that the ICs are defective.

In this case, no - the circuit as built by Intellijel was not as Irwin or
Gallo designed, as the loop compensation capacitor was wrong but a factor
of 5ish (22p vs. 100p).

> 2) If the SSI2164 is NOT a drop in replacement for the SSM2164 (or it's
true
> drop-in replacement, the Coolaudio V2164), then I would submit that it is
> the most facking useless IC in the history of ICs.  There are hundreds (if
> not thousands) of designs using the 2164, and if these all have to be
> changed, that's an enormous cost and a major headache for all involved.

That is rather harsh and unfair when the circuit as built by Intellijel was
not the one published by Irwin or Gallo.  Details matter, and when you get
the details wrong, you don't get the results you wanted.  To blame the chip
vendor is churlish.

> I suspect that this thread alone will cost SSI a major chunk of business,
at
> least in the short term.  If it were me and I were reading this thread, I
> wouldn't touch these shitty ICs with a ten-foot pole.  Good job SSI!

Really, David, is that language necessary in a public forum?  The SSI2164
is a great chip, packs a lot of useful functionality, is actively supported
by the manufacturer (including a very detailed datasheet), who is actively
engaging in the analogue synth community, and is a definite improvement
over the SSM2164.

But you're right about one thing:  *Good job SSI!*

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