--- In Doepfer_a100@yahoogroups.com , "omegaattraktor"
<omegaattraktor@...> wrote:

>
> --- In Doepfer_a100@yahoogroups.com , "Monroe Eskew"

<monroe.eskew@>

> wrote:
> >
> > That sounds like thru-zero amplitude modulation, which is

nothing new,

> > though it is a nice feature to put within one module. But thru-

zero

> > frequency modulation Still confused.
>
>
> negative frequencies has nothing to do with inverted phase. it

means

> that the signal is going its way back. but of course the time

continuum

> will not be affected. this can happen at any amplitude of the

signal,

> therefore it doesn't invert the phase.
>
> negative frequencies do occur with large amount of fm. imaginge

the

> frequency of an osc with 1kHz is modulated by another osc. if the
> amount of modulation is increased there is a point when the

frequency

> is modulated between 0kHz and 2 khZ. if you increase the

modulation

> further the frequency finally goes to negative. thru-zero fm just

means

> that an osc can handle this.
>
> regards,
> oliver
>
> http://www.namshub.ch/

exactly. a standard vco will stop oscillating at 0 hz,
it even cannot reach 0 hz at all because of technical issues
within the vco design. a standard vco can never have more
than 100% linear fm.

a thru-zero vco can handle more than 1000% linear fm, because
it can go "through" that 0 hz barrier into "negative" frequencies,
which means that the waveform reverses direction, not it's phase.
it's a bit like driving a car in reverse gear.

example, a vco sinewave cycles between +5 and -5. lets say that at
one given point the waveform has an amplitude of +1 volts
and is on its way down, towards -5 volts. when the thru-zero vco
reverses direction at that given point then the waveform will
continue at +1 volts amplitude, but going up towards +5 volts.
while the facts are quite boring, the sonic differences are huge.

best wishes

ingo