[sdiy] New here

[Gene Stopp]

I can say that flute makes for a good source for a PV converter, at least
the one I built some years back.

It's a 3080-based exponential VCO core (Electonotes workhorse VCO) with a
home-built phase locked loop detector I made out of a quad NAND gate. The
VCO tracks the mic signal, and the CV that's driving the VCO is brought out
as the recovered pitch CV. My wife plays the flute, so one day I had her
play into the converter and drove a Minimoog with it. It tracked perfectly
and the response was plenty fast. The only thing that needed possible work
was when the signal went away, the pitch CV dropped to minimum so the
Minimoog pitch went sub-audio.

Question - what *should* a PV converter do when the input goes away? Should
you latch the last stable CV with a sample and hold? If so, I found that you
need to delay the CV by some amount (some kind of DC delay, like a cascaded
S/H). The sample command is triggered by the lack of input, and by that time
the CV has already dropped.

Or, let the CV drop, and turn off the gate when the input falls below some
threshold, which is higher than the lost phase-lock point.

I was going to take the latter approach, since I did not want to add
latency. I never did add the envelope follower to make the gate...
someday...

Best Regards,

- Gene



-----Original Message-----
From: Harry Bissell Jr [mailto:harrybissell at prodigy.net]
Sent: Tuesday, January 27, 2004 11:08 AM
To: Thomas Dunker; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] New here


Hi Thomas

for a good envelope follower design, see the Design
Ideas submission for DEC 25, 2002 in EDN Magazine

"Envelope Follower combines fast response, lowest
ripple" by Harry Bissell Jr (me)

I have some experience with P/V conversionn as well,
but not for flute.  Most of my experiments have been
with guitar, and I do not find it to be very
satisfying.

My current work is using the actual waves produced by
the strings as the sound source, warped, modified etc
and fed to filters etc.

The PV-1 pitch to voltage converter was based on the
Etherwave (theremin) P/V converter designed by Bob
Moog
and used with permission.  Many people have used it
with
theremins (which have a continuous wave, no pauses) as
well as with analog keyboards to get a CV out.  I've
played a little with guitar and microphone with it,
and am not too pleased with the result (I'm fussy -
the low-fi people might actually like it !).

The boards (from EFM) are sold out but probably if you
asked on list, someone would prlly offer you a blank
board for some price (they can't ALL have been built
or I'd get MORE e-mail).  I can provide the
documentation.

enjoy

H^) harry