Hey Igor,
You can think of a frequency shifter as a ring modulator with TWO
outputs: the upshift output has only the sum of the two input
frequencies, the downshift output has only the difference frequencies.
Serge has two FS's in their catalog, the internal carrier model, which
has an onboard sinewave oscillator, and the external carrier, which lets
you use your own sinewave or some other waveform or complex source.
Please note that since it is ring modulator based, a frequency shifter
is NOT a pitch shifter! A frequency shifter will add the carrier
frequency to all the harmonics of the sound you want to shift. The
greater the carrier frequency, the more pronounced the harmonic
distortion. This is suitable for, well, distortion effects like
robot/computer/alien voices, etc. At very low carrier frequencies the
FS will simply impart vibrato, mild doppler effects, leslie effects etc
since the harmonic distortion is more subtle and harder to notice.
A pitch shifter on the other hand will multiply by the harmonic
frequencies, keeping the original sound's harmonic structure intact, so
you can *transpose* the original sound by an octave, fifth, or some
other arbitrary interval. You can't do this with a frequency shifter as
far as I know.
Make sense??
John P.
dahlia13@... wrote:
You can think of a frequency shifter as a ring modulator with TWO
outputs: the upshift output has only the sum of the two input
frequencies, the downshift output has only the difference frequencies.
Serge has two FS's in their catalog, the internal carrier model, which
has an onboard sinewave oscillator, and the external carrier, which lets
you use your own sinewave or some other waveform or complex source.
Please note that since it is ring modulator based, a frequency shifter
is NOT a pitch shifter! A frequency shifter will add the carrier
frequency to all the harmonics of the sound you want to shift. The
greater the carrier frequency, the more pronounced the harmonic
distortion. This is suitable for, well, distortion effects like
robot/computer/alien voices, etc. At very low carrier frequencies the
FS will simply impart vibrato, mild doppler effects, leslie effects etc
since the harmonic distortion is more subtle and harder to notice.
A pitch shifter on the other hand will multiply by the harmonic
frequencies, keeping the original sound's harmonic structure intact, so
you can *transpose* the original sound by an octave, fifth, or some
other arbitrary interval. You can't do this with a frequency shifter as
far as I know.
Make sense??
John P.
dahlia13@... wrote:
> I got a catalog from Serge/STS a few months ago and one of the modules that's causing me alot of confusion is the Frequency Shifter. What the hell is this thing? I've never heard of it before. After some web searches, I discovered a few other manufacturers who have built FS's - Moog (Bode), Buchla, EMS - but the information is scant and I'm nowhere closer to understanding what this thing actually does. The catalog informing me that I can do vibrato effects, robot voices, or Leslie simulations isn't much help either, since I could accomplish those using delays, phasers, ring mods, etc. And it's the most expensive module in the catalog, to boot!
>
> Is this device related to: A vocoder? A ring modulator? An octave divider (i.e. where an oscillator tracks the input frequency)?
>
> Can anyone offer a (simplified) explanation of what's happening inside a frequency shifter circuit? Or put up some .mp3's of a frequency shifter in action?
>
> Thanks!
>
> Igor.
> http://www.geocities.com/charnel_whorehouse/
>
>
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