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Moog CP-251 Control Processor

Moog CP-251
Moog CP-251
List Price: $399.00
Our Price: $385.00

Availability: Currently Unavailable
Product Code: 9999-08717


Moog CP-251 Control Processor

The award-winning Moog CP-251 Control Processor is a collection of classic modular synthesizer circuits designed by Bob Moog.

Moog CP-251 Control Processor Details

The award-winning CP-251 Control Processor is a collection of classic modular synthesizer circuits designed by Bob Moog. With the Moogerfooger analog effects, minimoog Voyager analog synthesizer, or other voltage-controlled synthesis gear you can generate, modify, combine, and distribute control voltages for creating complex sound events with patch cords.

The CP-251 Control Processor can be used in connection with one or more Moogerfooger analog effects modules, the Minimoog Voyager, or other voltage-controlled gear. The CP-251 adds the same kind of power and versatility of the classic MOOG modular synthesizers.

There are two kinds of signals in a modular analog synthesizer: audio and control. As audio signals go through a system of synthesizer modules, they get shaped into the sounds that you hear. Control signals, on the other hand, correspond to the variations in the sound that are imparted by the synthesizer modules, like invisible hands that turn the knobs of the modules.

The CP-251 provides a dual waveform LFO, Noise Generator, Sample-and-Hold circuit, as well as two attenuators, a lag processor, a CV mixer and a 4-way mult. This gives you ways to modify, mix, and distribute control voltages to produce the incredible variety of sounds and effects that analog synthesizers are famous for.

Power Supply is included for use with 110 VAC.

Moog CP-251 Control Processor Features

  • FOUR INPUT MIXER - Enables you to combine control signals to create complex effects.
  • LAG PROCESSOR - Reshapes control signals by slowing down abrupt changes, used to produce glides and swoops.
  • LOW FREQUENCY OSCILLATOR (LFO) - Makes periodic control signals over the range of one cycle every five seconds to 50 cycles per second. The LFO is itself voltage-controlled so you can vary its rate with an expression pedal or other control signal to create effects such as vibrato, warbles, and sirens.
  • Two ATTENUATORS - To reduce the strength of control signals, enabling you to adjust the strength of an effect.
  • FOUR-WAY MULTIPLE - Enables you to send one control signal to as many as three destinations.
  • NOISE SOURCE - Provides pure noise for use as an audio or control signal.
  • SAMPLE AND HOLD - Produces stepwise control signals by sampling the voltage of any signal at rate of the LFO to produce classic sample-and-hold effects. This circuit also has a second output which is a smoothed version of the stepwise output.

Control Voltage

In electronic music terms, a control voltage is an electric signal that you route to a destination such as a voltage-controlled oscillator, amplifier, or filter (VCO, VCA, or VCF, respectively). You might think of voltage as electrical pressure, which is used to control--or modulate--some aspect in the destination device. When you apply different voltages to a VCO, the oscillator's pitch will vary. Route a control voltage into the frequency cutoff of a lowpass VCF and you can modulate the brightness of the audio signal traveling through the filter. Audio signals passing through a VCA will come out louder the greater the control voltage you pump into the amplifier; lower the control voltage and the signal will get quieter. Even the audio signal itself is an analog voltage.

A control voltage is an analog signal. What's the main difference between analog and digital? While an analog signal is capable of continuous fluctuations, digital data is quantized into discrete steps.

In an analog audio system, fluctuations in voltage are analogous to changes in air pressure in a wind instrument. Parameters such as oscillator pitch and LFO speed are modulated by analog control voltages in an analog synthesizer. Conversely, digital music equipment uses microprocessors to store, retrieve, and manipulate information about sound in the form of numbers, and typically divides potentially continuous fluctuations in value (such as amplitude or pitch) into discrete quantized steps.

The types of control-voltage sources and the destinations to which CV signals can be applied depend on the system you're making music with. If you have any of the Moogerfooger products, you get a good selection of both--and the possibilities increase exponentially when you combine multiple Moogerfoogers. Such a combination makes for an effects-processing system with which you have realtime dynamic control. Include an MF-101 Lowpass Filter or MF-102 Ring Modulator--either of which can serve as an audio source--and you have a functional modular synthesizer.

Let's take a look at the sources and destinations found in a typical modular system, as well as those inherent in all five of the Moogerfoogers, then discuss what the heck you can do with all this fun stuff.

Generic CV Sources and Destinations

Devices that generate control voltages come in numerous shapes and sizes. Prior to the introduction of MIDI, keyboards were designed to output discrete stepped voltages to trigger specific pitches in a VCO. Analog sequencers worked the same way. Play a note on a CV keyboard or advance an analog sequencer by one step, and either device will output a specific, steady-state voltage.

Two of the most creative CV sources in a synthesizer are the envelope generator and low-frequency oscillator (EG and LFO for short). An EG outputs a continuously variable voltage that changes over time. This voltage is typically applied to a VCA or VCF to shape the volume or timbre of a sound; VCO pitch is another potent destination, so you can get programmed pitchbends. EGs range in complexity from a two-stage attack-decay envelope to a multi-stage envelope with independent rate and level parameters for each step and flexible envelope-looping options.

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