envelope follower followup

[Magnus Danielson]

>>>>> "KD" == Kevin Day <kday at netcom.com> writes:

 KD> Thanks, everybody, for the EF info.  I was very surprised by the amount
 KD> of response.
 KD> (maybe it was an easy question? :)

 KD> Thanks especially to Magnus for explaining the concept behind it.

Anytime!

 KD> I am thinking that I will try the Polyfusion circuit on Synthfool.  I am
 KD> curious if it would be worthwhile to replace the 3-way response filter
 KD> with a continuously variable filter.  Would it likely improve the
 KD> usability of it, or just be a waste of effort?  I'm not a 'set and
 KD> forget' type of person, if you know what I mean, so having only three
 KD> options sounds a little limiting.  Opinions?

The Polyfusion cursuit (which I just saw for the first time BTW) is a
fairly straigth implementation. On thing is that the current-summer
cuirsuit of the precision full-wave rectifier is also acting as the
post processing filter. The cap's will slow down the op-amp, thus
making it a LP filter. By separating this out to a more traditional RC
cursuit you may use a standard potentiometer instead of a variable
capacitance to vary the delay. This would require another op-amp to
act as a buffer, but it's no big deal.

I think that the pot should be a logarithmic one, but that's just a
gut feeling.

 KD> For what it's worth, I don't necessarily intend to run a guitar through
 KD> this thing, but rather more bizarre sounds to effect drone patches.  And
 KD> drums, too, of course.

That's the spirit!

Cheers,
Magnus