AW: VC Phaser using the LM13600

[Haible Juergen]

	>> phase(degrees) = -2*arctan(2*pi*f*RC) for a lagging type filter
and
	>
	>>phase(degrees)= -180-2*arctan(2*pi*f*RC) for a leading type
filter.
	>
	>Well, I suppose my question should have been: Which of the
commercial >phasers use lagging and which use leading filters? Can the
Hammond scanning >vibrato be considered leading or lagging?
	>
	>I suppose my phaser (and the Small Stone) would be of the leading
type, as the >frequency shift gets lower at higher frequencies (if f=0 then
phase is -180 >degrees). But if you look at the oscilloscope, the signal
moves left when the >phase shift is increased. Because the oscilloscope
trace moves from left to right, >it must mean the signal is delayed and
therefore lagging! Right?

I have a stupid question: Does this leading / lagging distinction
make any sense at all ? I mean, you only can *delay* a signal
anyway, and the phase shift is just the delay normalized to an
angle for a certain frequency. I'd say the 180 degree difference
in the above equation is just a signal inversion. (I know there
are cases where it's useful to speak of lead and lag, but I doubt
it is when you build delay units like phasers.)

JH.