Opposite of noise gate? + Lame question...

[gstopp at fibermux.com]

     The standard type of exponential VCO used in synthesizers will double 
     its frequency of oscillation for each increase of one volt on any of 
     its exponential CV inputs. This means that every volt added to the sum 
     of the CV inputs will increase the VCO pitch by an octave.
     
     So - as the voltage at the input goes 1 volt, 2 volts, 3 volts, etc., 
     the output frequency goes 440 hertz, 880 hertz, 1760 hertz, etc. and 
     the pitch goes A3, A4, A5, etc. The frequencies in this example are 
     arbitrary and may be anything, but the relationship holds.
     
     A CV applied to a linear VCO (or to a linear FM input of an 
     exponential VCO) will cause the frequency to go 440 hertz, 540 hertz, 
     640 hertz, etc. as the input goes 1 volt, 2 volts, 3 volts, etc. 
     (assuming a 100 hertz/volt scale factor). As you can see these are not 
     octaves, and in fact are not even musical intervals in the traditional 
     equally-tempered 12-tone intonation system.
     
     Linear FM is usually used to modulate a VCO at an audio frequency with 
     another VCO (tracking the first VCO), to produce bell-like tones. When 
     the exponential FM inputs are used for this the modulated VCO tends to 
     "stretch" its pitch as you go up the keyboard and sounds out of tune. 
     Using the linear FM input lessens this effect.
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: Re[2]: Opposite of noise gate? + Lame question...
Author:  abowyerlowe at mindscape.com at ccrelayout
Date:    5/20/96 11:58 AM
     
On another point entirely, what is the difference between the linear and 
exponential inputs on VCOs? Is it that (assuming a 1v/octave vco), putting twice
the voltage into the exponential fm input will result in a one octave increase, 
whereas in the linear fm input doubling the voltage will have results depending 
on the base voltage? In that case, what use is the linear fm input?
     
(As you can tell, I'm not too hot with electronic-thinking in the mornings).