[sdiy] [AH] Buchla 192 design [was: Buchla used for Silver Apples of the Moon]

[cheater cheater]

> Putting some "thing" in the negative feedback loop kind of undoes the effect of that "thing" - there's good discussion of this notion in Horowitz and Hill.

ah ok, makes sense. Just to be 100% sure, we're talking about the HPF
being in the negative input feedback loop, right? I've seen designs
which use both positive and negative feedback.

If I have an HPF in the negative feedback of an op amp with no
positive feedback (like the hammond filter I assume), will the
resonance be "normal" in that case, or will it be "wrong"/"out of
phase" like when you mix an inverted HPF output with the original
signal in order to create an "LPF"?

Cheers,
D.

On Sat, Jun 26, 2010 at 22:15, Aaron Lanterman <lanterma at ece.gatech.edu> wrote:
> On Jun 26, 2010, at 4:06 PM, cheater cheater wrote:
>
>> ah right, ok makes sense. i wonder if you ever ended up trying that
>> hammond filter with another high pass filter, to see what happens?
>
> No, just getting it working was enough trouble.
>
>> can i just put any HPF in an op amp's feedback loop to get an lpf?
>
> Putting some "thing" in the negative feedback loop kind of undoes the effect of that "thing" - there's good discussion of this notion in Horowitz and Hill.
>
> - Aaron
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