[sdiy] RE: [AH] Parametric EQ

[Tim Parkhurst]

On Sun, Feb 21, 2010 at 9:58 AM, David G. Dixon
<dixon at interchange.ubc.ca> wrote:
>>
>> http://www.electricdruid.com/VCResonator.jpg
>
> One thing that strikes me about this schematic is that the Res CV will have
> an exponential effect on the degree of resonance feedback.  Of course, an
> exponential response is desired on the variable resistors and the output
> level.  However, I would have thought that a linear response would be more
> appropriate on the Res CV.  Of course, that would require two 2164 VCAs (a
> la Mike Irwin), thus raising the total number to five, which is pretty
> darned inconvenient unless the output one is sacrificed, or moved to a
> dedicated four-input mixer.

So we've all seen that the normal method for linearizing the response
of the 2164 is to use another section as a converter for the CV (in
essence, expo voltage to an expo response curcuit give a linear
response). What I'm wondering is, could a 'standard' expo converter be
used for the same purpose? Instead of using another 2164 section
(which, if you're already using all four sections of the chip,
requires you to use a second 2164), could you just use a couple of
transistors and an op-amp? Sounds like it could work, but I had Chai
Tea instead of coffee this morning, so my caffeine count could be low.
;)

Tim (start this man on a caffeine iv, stat!) Servo
-- 
"Sire, the church of God is an anvil that has worn out many hammers."
- H.L. Hastings