linuxaudio.org

On Tue, Aug 21, 2012 at 06:29:22PM -0400, David Robillard wrote:
> What is this signal?  It either means some absolute frequency, or it is

quoted text
> useless.  This is what I mean by: in reality/practice, signals that

> represent absolute frequencies *do* exist here, whether anyone likes it

> or not.  They must exist, since the ability to make an oscillator play

> the appropriate frequency is obviously something you must be able to do

> in order to build a synth.

>

> In AMS, this is true.

> In actual analogue modular synthesizers, this is true.

> In every modular synthesizer ever, this is true.

>

> It has to be true, because otherwise you can't build synths.

It doesn't have to be true... you can always see the

absolute part as a property of whatever receives the

signal.
Suppose you have a VCO with two 1/octave control ports.

One is used by a GUI element, say a slider which could

have a scale in Hz, note names, or octaves. The second

is the 'voltage' from a keyboard.
The actual frequency of the VCO would be
 F = exp2(V1 + V2 + C)        (1)
where C is some constant, e.g. log2(440).
Each of these two ports can be used without the other,

that depends just one what you are doing. In case you

use only V1, you could say that C is a property of the

port that delivers V1. Same for V2.
But if you use both, which one, keyboard or calibrated

slider, is the absolute one and which one is the offset ?

That, I'd say, is just 'in the eyes of the beholder'. 
That's why I'd say that both are offsets, and C is a

property of the VCO.
Ask yourself this: in what way would (1) be different

if you'd consider either port to be 'absolute' ?
Even if you'd move C 'into a port', the net result

would still be the same sum, in which all terms have

equal status.
Ciao,
--

FA
A world of exhaustive, reliable metadata would be an utopia.

It's also a pipe-dream, founded on self-delusion, nerd hubris

and hysterically inflated market opportunities. (Cory Doctorow)
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