Analog tuner idea (try show)

Don Tillman don at
Fri Mar 14 09:22:10 CET 1997

   From: Synthfool at
   Date: Fri, 14 Mar 1997 02:40:49 -0500 (EST)

   I'm talking about tuning VCO scaling trimmers.
   The V/oct response of them.


   A little box that has a rotary switch that puts out 1volt
   increments along with a corresponding audio xtal derived tone of
   "what it should be".

Okay.  The way I handle this situation is to calibrate my CV source
(keyboard for me, but possibly a MIDI->CV converter, whatever floats
your boat) with a voltmeter, and then connect a Korg tuner to the
synth output and tune the 0volt frequency of the VCO, then play C's at
one octave above the lowest note and one octave below the highest note
and tweak the v/oct to those.  Iterate a couple times.

The problem with calibrating your VCOs to your custom-built voltage
source is that you're probably not going to be playing a solo on your
custom-built voltage source.  Any nonlinearities or offsets in the CV
source you'll actually be playing ought to be accounted for.

   And yes, I AM talking about tuning VCO's by ear! 
   (I don't tune them visually and never have.)
   If you can't hear it, does it make a difference???

If there are other musicians tuning up or making ghastly noises
nearby, tuning visually becomes vitally important.  For me anyway.  

Surprisingly, I've found that with a tuner I tend to tune VCOs a
little *too* accurately.  (ie., no beat!)

  -- Don

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