FW: quadrature oscillator jazz
2005-12-04 by John P
In case any of you were reviewing John's Serge panel layouts and asking
yourself "what the hell would anyone do with EIGHT quadrature
oscillators?!?" please allow me to offer a brief commentary on the QUO,
which along with the Variable Bandwidth VCF2 is probably the most
overlooked/underrated module in the Serge catalog. For those of you
unfamiliar with this sweet module, it is a voltage controlled sine
oscillator with "0" & "90" degree (phase shifted) outputs, each of which
has its own associated VCA. You can view the module to the far right here:
http://www.serge-fans.com/newpics/panel_blue_cv2_150dpi.jpg
For starters, the QUOs are excellent for spatial modulation of Serge VC
mixer channels and perfect for driving audio or voltage cross-faders.
But their usefulness goes way beyond these basic applications
- they're a fantastic mod source for almost any destination.
The built-in VCAs can be used to dial in the precise amount of
pan modulation or cross-fade, and they are especially handy when routing
the QUO's outputs to modules without CV attenuators: Wave Multipliers,
Ring Mod, /N-COMP, etc. These allow you to control the modulation index,
and using the QUO's built-in VC GAIN inputs even permits dynamic
indexing... Xpander, anyone? These VCAs also have switches to cancel the
output on the fly. One trick I have used with my pair of QUOs is to
route the offset from an Active Processor or CV Mixer to all four VC
GAIN inputs, which gives you control of all four modulation depths with
one knob; this is nice for taking a patch from serene to obscene very
smoothly, regardless of whether the change is sudden or gradual.
Each QUO also has a HOLD input that "freezes" the sine sweep of both
outputs when the input is high. You can have a swirling chorus that
suddenly hangs in space, then resumes its course. Or you can use a pulse
divider to create "stutter" effects when sweeping VCFs or timbre
modulators. Think about all the pulse sources available on the Serge -
random pulses, comparators, TKB/SQP gate outputs - and the possibilities
come alive.
The quadrature relationship between the outputs allows the various
modulations in a patch to bear correlation to each other without sharing
a simultaneous parallel or inverted path. Filter sweeps can "follow"
each other, volume swells can precede pitch droops, whatever else you
can imagine. And of course the modulation RATE can be controlled from
any voltage source, so your sweeps and swells can accelerate and
decelerate under the control of an envelope or LFO, vary with each stage
of a sequencer, or even track a keyboard using the 1v/Oct input!
The QUO serves as an excellent audio-rate mod source for VCO/VCF FM or
as one input to a ring mod. The 1v/oct tracking works very well until it
reaches the top of the oscillator's range, which I would peg around
middle C. Finally, as an audio-rate *destination* the QUO will produce
its own heterodyne timbres. Cross-patching two QUOs generates some very
interesting (and surprisingly useful) results. I can only imagine what
one could do with eight of these!
Chris Sawyer
--
m/n/m/l
surreal electronic music, sound, noise
http://www.mnmlnoise.com
yourself "what the hell would anyone do with EIGHT quadrature
oscillators?!?" please allow me to offer a brief commentary on the QUO,
which along with the Variable Bandwidth VCF2 is probably the most
overlooked/underrated module in the Serge catalog. For those of you
unfamiliar with this sweet module, it is a voltage controlled sine
oscillator with "0" & "90" degree (phase shifted) outputs, each of which
has its own associated VCA. You can view the module to the far right here:
http://www.serge-fans.com/newpics/panel_blue_cv2_150dpi.jpg
For starters, the QUOs are excellent for spatial modulation of Serge VC
mixer channels and perfect for driving audio or voltage cross-faders.
But their usefulness goes way beyond these basic applications
- they're a fantastic mod source for almost any destination.
The built-in VCAs can be used to dial in the precise amount of
pan modulation or cross-fade, and they are especially handy when routing
the QUO's outputs to modules without CV attenuators: Wave Multipliers,
Ring Mod, /N-COMP, etc. These allow you to control the modulation index,
and using the QUO's built-in VC GAIN inputs even permits dynamic
indexing... Xpander, anyone? These VCAs also have switches to cancel the
output on the fly. One trick I have used with my pair of QUOs is to
route the offset from an Active Processor or CV Mixer to all four VC
GAIN inputs, which gives you control of all four modulation depths with
one knob; this is nice for taking a patch from serene to obscene very
smoothly, regardless of whether the change is sudden or gradual.
Each QUO also has a HOLD input that "freezes" the sine sweep of both
outputs when the input is high. You can have a swirling chorus that
suddenly hangs in space, then resumes its course. Or you can use a pulse
divider to create "stutter" effects when sweeping VCFs or timbre
modulators. Think about all the pulse sources available on the Serge -
random pulses, comparators, TKB/SQP gate outputs - and the possibilities
come alive.
The quadrature relationship between the outputs allows the various
modulations in a patch to bear correlation to each other without sharing
a simultaneous parallel or inverted path. Filter sweeps can "follow"
each other, volume swells can precede pitch droops, whatever else you
can imagine. And of course the modulation RATE can be controlled from
any voltage source, so your sweeps and swells can accelerate and
decelerate under the control of an envelope or LFO, vary with each stage
of a sequencer, or even track a keyboard using the 1v/Oct input!
The QUO serves as an excellent audio-rate mod source for VCO/VCF FM or
as one input to a ring mod. The 1v/oct tracking works very well until it
reaches the top of the oscillator's range, which I would peg around
middle C. Finally, as an audio-rate *destination* the QUO will produce
its own heterodyne timbres. Cross-patching two QUOs generates some very
interesting (and surprisingly useful) results. I can only imagine what
one could do with eight of these!
Chris Sawyer
--
m/n/m/l
surreal electronic music, sound, noise
http://www.mnmlnoise.com