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<DIV dir=ltr align=left><SPAN class=280031021-14022019><FONT color=#0000ff
size=2 face=Arial>Increasing the resistors from 30k to 100k also fixed the
problem, with the same 22pF cap in place.</FONT></SPAN></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>Mattias
Rickardsson<BR><B>Sent:</B> Thursday, February 14, 2019 12:53 PM<BR><B>To:</B>
Dave<BR><B>Cc:</B> Synth DIY<BR><B>Subject:</B> Re: [sdiy] Problems with
linearized SSI2164 ?<BR></FONT><BR></DIV>
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<DIV class=gmail_quote>
<DIV dir=ltr>Den tors 14 feb. 2019 20:49 skrev Dave <<A
href="mailto:dlmanley@sonic.net">dlmanley@sonic.net</A>>:<BR></DIV>
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class=gmail_quote><BR>This is a GBW/ phase margin issue? Indicating
the SSI part has greater GBW so is less tolerant to a reduced cap
value?<BR></BLOCKQUOTE></DIV></DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>Maybe? Or is it the op-amp that matters?</DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>Anyway, the circuit had values outside the recommendation. We
shouldn't expect makers of drop-in replacements to specify how their product
behaves versus the original in an unrecommended application.</DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>Btw, we're actually touching one of the hidden advantages of the
SSI part:</DIV>
<DIV dir=auto>With the old 2164s in the ordinary VCA configuration with 30k
resistors, one might be tempted to use quite small feedback caps in order to
not introduce noticable HF roll-off under 20 kHz. With the doubled current
capacity of the SSI2164 the resistor values can be halved (for reaching the
lower noise specification), meaning that the cap value can be doubled for the
same roll-off. So in practice, perhaps even better tolerance for the needed
cap values. :-)<BR></DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>/mr</DIV>
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