SergeModular

Thanks to all who responded. It makes sense that a second
phase shift network would be used on the FRSX.

Steve Ridley suggested I look at the schematics for Buchla's 285
Frequency Shifter for further clarity. It has both a built in thru-zero
vco and a second input for audio signals. Neat module, actually.
Also has a ring mod that cv crossfades between dry and
processed signal.

Romeo

--- In SergeModular@yahoogroups.com, "metafoetus2002"
<jan-hinnerk.helms@t...> wrote:

> Hi,
>
> I'll try to have a shot at it,
>
> In a one-input frequency-shifter [FRS], the built-in signal is

supplied by a built-in

> sine-wave oscillator which outputs two sine waves of identical

frequencies, but one of

> this sine waves is 90 degrees out of phase compared to the

other. Serge has such a

> quadrature oscillator [QUO] as a separate module - also, the

[VCFX] can be patch-

> programmed to be used as such.
>
> The free input of the [FRS] has to pass thru a phase shifting

network that allows for a

> phase shift of 90 degrees. This phase shifting has to constant

throughout the whole

> frequency range. To build such a phase shifter is AFAIK what

makes a frequency

> shifter (from any brand) so costly.
>
> The [FRSX] needs two of those phase shifting networks, one

for each input. It drops

> the [QUO], but this seems not to make up for the money

needed for the second phase

> shifting network.
>
> I don't know if the [FRSX] also needs doubling the level

compensation curcuits (it

> might, if this treats the input signal and not the output signal on

the [FRS]).

>
> Two questions from me to all owners and users of the [FRS]

on SMOG: I could not find

> any note on how low the shift frequency from the internal

oscillator can go on the

> [FRS] by (a) manual control and (b) voltage control.
>
> Second one. From trying out different frequency shifters on

Musikmesse and NAMM, I

> found out that there two different frequency shifter designs out

there -- thru-zero-

> ones and not-thru-zero-ones. On a thru-zero (e.g. Modcan,

Bode, Analogue

> Solutions or Systems, I always confuse these two) one you can

turn the shifting

> frequency not only very low, to say like 0.1 Hz, but you can also

make it negative. If

> negative, the upshift output becomes the downshift output and

vice versa. As you can

> voltage control the shifting frequencies, you can voltage control

if downshift and

> upshift outputs exchange places. This should be useful for very

interesting stereo

> effects (connect upshift to left and downshift to right).
>
> How does the Serge [FRS] fit in here? Thru--zero or not?
>
> Thanks,
> Jan-Hinnerk
>
> --- In SergeModular@yahoogroups.com, John Papiewski
> <johnp299792@a...> wrote:
> > Yo,
> >
> > If you think of the FS as a souped-up ring modulator you

might get

> a
> > clearer idea. Now, some ring modulators have one signal

input and

> they
> > use a built-in oscillator to modulate your incoming signal.

That's

> like
> > the first frequency shifter. Built-in oscillator.
> >
> > But some ring modulators have two open inputs so you can

modulate

> > anything against anything. The Serge ring modulator has

two inputs.

> > The FRSX is like that two. It drops the internal oscillator and
> accepts
> > anything.
> >
> > Frequency shifting by a sine wave is 'simple' - the output is A

+ B

> > (upshift) and A - B (downshift). If your shifting a sine wave by

a

> sine
> > wave, that's simplest. 100 hz in A and 200 in b gives you 300
> upshift
> > and 100 downshift.
> >
> > Frequency shift a square wave by a sine wave, things get a

little

> > trickier. All the harmonics get shifted by the same absolute
> > difference. So the more you shift the more inharmonic the
> overtones
> > become. It sounds weird. Also, downshift by enough and

you get

> > 'harmonic inversion' - the fundamental is at the high

frequency,

> and the
> > overtones are fractions (not multiples) of the fundamental.
> >
> > NOW - shift a square by a square. You get lots of things

going on.

> I'm
> > not familiar enough with it to go into it, but there must be a lot
> of
> > frequencies flying around in there.
> >
> > I don't know why it would be so much more money - it might

have

> > something to do with level compensation.
> >
> > Anybody else care to comment?
> >
> > vtl5c3 wrote:
> > > Last night I was perusing my Serge catalog and noticed

that

> > > there were two versions of the Frequency Shifter. The

second

> > > version (FRSX) caught my attention.
> > >
> > > Here's what it says about the FRSX:
> > >
> > > "The basic unit features a built-in oscillator .... Available at
> a
> > > higher cost and on special request is a version which

accepts

> > > any external shifting signal. This version may be of interest

to

> > > musicians wanting to shift the sound of one instrument by
> > > another, say the flute by a tuba....."
> > >
> > > Does anyone know how the Carrier input is designed? Is

there

> > > a pitch to voltage converter that is used to convert an audio
> > > signal to drive the FS? The catalog is a bit vague as to how

the

> > > module works.
> > >
> > > Romeo
> > >
> > >
> > >
> > > To unsubscribe from this group, send an email to:
> > > SergeModular-unsubscribe@yahoogroups.com
> > >
> > > Keep on Patchin'!
> > >
> > >
> > > Your use of Yahoo! Groups is subject to http:/
> /docs.yahoo.com/info/terms/
> > >
> > >