[sdiy] Problems with linearized SSI2164 ?
ijfritz at comcast.net
Thu Feb 14 03:27:34 CET 2019
There is an old saying hereabouts: "Weirdness is caused by hf
oscillations." This is obviously one of the first things to consider in
a situation like this. Especially when a change has been made that
reduces the stability by a factor of 5.
If you make a change in a design and it doesn't work reliably, then
guess what? You should change it back.
On 2/13/2019 4:53 PM, Neil Johnson wrote:
> 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!/
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