[sdiy] cool modulations (was live vco)

[Barry Klein]

Hi Dan,
I was kind of being tongue in cheek....  There were discussions like this in 
this list or another where the poor supply regulation and perhaps noise was 
suggested as a contributor to the "goodness" of the oscillator sound.   I am 
mainly thinking or questioning if the effects are isolated to the oscillator 
or more of a complete system result - where the whole signal chain is 
necessary.  Early synth circuits were much more discrete in design and could 
be more sensitive/reactant to other circuits in the system and variances in 
the supplies attached to them. I am not so sure I am reading much about how 
people perceive one vco vs another - I bet most are comparing one system to 
another.  Amplifying supply noise etc. if there is any would probably create 
oscillations/instability to whatever it is added to.  Usually a bad thing. 
Our "best" approaches to VCO's have had design features to eliminate these 
aspects.
As things got more and more perfect they sounded more and more blah.  At 
least that seems the perception and general consensus.

To try and answer your question - try adding small inductors or very low 
value resistors (~.1 ohm) to the supply paths (where??)and use op amps to 
differentially sense the voltage drop across them.  Then use this directly 
and/or pass through a fullwave rectifier and filter circuit as a modulation 
voltage sources.  (envelope follower like on page 81 of my book).

Barry

----- Original Message ----- 
From: "Dan Snazelle" <subjectivity at hotmail.com>
To: <barry.l.klein at wdc.com>; "sdiy" <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, December 10, 2008 9:23 PM
Subject: [sdiy] cool modulations (was live vco)


>
> in reference to Barry's comment
>
> could someone explain how we might go about adding:
>
> supply noise modulation
> inputs -
> "soft" modulations like ripple amplification, 60Hz modulation, and soft 
> sync variations
>
> is this actually adding noise to the POWER supply???
>
> thanks
>
>
> --------------------------------------------
> check out various dan music at:
>
> http://www.myspace.com/lossnyc
>
>
> http://www.soundclick.com/lossnyc.htm
>
>
> http://www.indie911.com/dan-snazelle
> (or for techno) http://www.myspace.com/snazelle
>
>
>
>
>> Subject: RE: [sdiy] "Living VCOs" PCB in 2009 ?
>> Date: Wed, 10 Dec 2008 18:38:15 -0800
>> From: Barry.L.Klein at wdc.com
>> To: synth-diy at dropmix.xs4all.nl
>>
>> Hi all,
>> Obvious question:
>> Has someone tried replacing the Moog VCO design
>> with one of "our" alternatives - in the same Moog system?
>> I guess if you have a nice Moog modular
>> you could give it a go...
>> Sound "yucky"?
>> Then try "messing up" the VCO by adding supply noise modulation
>> inputs - "soft" modulations like ripple amplification, 60Hz modulation, 
>> and
>> soft sync variations...
>> Seems like the best way to get a match and an understanding...
>>
>> Barry
>>
>>
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