[sdiy] VCO tuning philosophy re-visited

[David]

Thanks Oren.

I bought the Electro-Notes, but they are a bit daunting to search. Does anyone have an index or can point me to the issue?

Thanks

David

-- -----Original Message-----
-- From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-
-- bounces at dropmix.xs4all.nl] On Behalf Of Oren Leavitt
-- Sent: Sunday, February 06, 2011 9:52 PM
-- To: synth-diy at dropmix.xs4all.nl
-- Subject: Re: [sdiy] VCO tuning philosophy re-visited
-- 
-- 
-- 
-- On 2/6/2011 9:44 PM, David wrote:
-- > I know we have hashed this before, but as I’ve now had some time to actually dig into
-- the Steiner VCO (schematics here:
-- http://www.xmission.com/~dingebre/spvco_main_1.4.pdf) and compare it to my Blacet
-- VCO, JH Living VCO, and MOTM Ultra 300 VCO, I’ve noticed a difference in high
-- frequency tracking. Nyle did not have a high frequency adjustment and I’ve noticed that
-- most who do include them typically say they didn’t adjust them (notably JH) or when I’ve
-- tried to adjust them, they tend to mess up mid frequency tracking or have had very little
-- effect. (Ian, I know your VCO tracks over 15 octaves so don’t rub it in  ).
-- >
-- > Where can I learn more about high frequency compensation and how it works?
-- > Where can I learn more about why high frequencies droop?
-- >
-- > Philosophy:
-- > Do you tune a VCO for mid range tracking, like over one octave around middle C, and
-- then let the low and high ends fall where they may?
-- > Do you tune a VCO for wide range tracking, like over 5 octaves and let the middle range
-- fall where it may?
-- > Do you use/adjust/design in to a VCO a high frequency tracking trimmer?
-- > If so, does it affect the mid frequency tracking?
-- >
-- > Finally, where is the best place to compromise, low end, middle, high, and what percent
-- error is OK musically? To me, even when I measure an exact doubling of frequency from
-- 8kHz to 16kHz, the 16kHz still sounds flat. I’ve tuned the Steiner VCO a dozen different
-- ways, and none sound any better to me.
-- >
-- > Have I finally gone over the SDIY insanity cliff… What’s that ringing in my ears?  Stop
-- the noise…. PLEASE STOP THE NOISE………….. ok, that’s better. Now where’s my
-- trimmer adjustment tool, oh there it is, stuck in my ear…
-- >
-- > David
-- 
-- Hi David,
-- 
-- In the early issues of Electronotes there's a very nice explanation of
-- how the various schemes for analog VCO HF tracking compensation work.
-- Nice to hear you've got the Steiner VCO and other stuff working nicely.
-- 
-- - Oren
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