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Regular price $299.00 USD
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  • Studio-grade DBX Compression circuit in a pedal
  • Variable 1:1 to ∞:1 compression Ratio
  • +30 dB maximum Gain boost (use as clean booster)
  • 18-volt operation for more headroom and full-frequency response
  • Reduction status LED
  • True Bypass Switching

The CP-9 Pro+ is that rarity of rarities – a compressor with tons of squash that does not color your guitar tone or create excessive noise.

The CP-9 circuit provides a very smooth, transparent, almost “glassy” compression with an extremely low noise floor, even at maximum settings.  Your guitar sounds like your guitar, only with a smoother, more balanced dynamic response - Notes jump off the fretboard with stunning clarity and limitless yet controlled sustain.

The CP-9’s internal voltage doubler provides massive headroom with full-range frequency reproduction.  It can be used with any instrument and for a variety of applications – send into an amp’s front end, place in a loop, or use as an outboard processor for home recordings.

With up to +30 dB of clean Gain, the CP-9 Pro+ can also be used as a straight clean booster or as a volume attenuator to clean up an already dirty amp by reducing input level.

The CP-9 Pro+ provides studio-grade compression in a portable stompbox format – you’ll wonder how you ever played without it!


When re-designing the CP-9, Maxon looked at every type of compressor on the market and came to one conclusion – standard-grade components and traditional guitar compressor designs simply would not do.

The CP-9 Pro+ runs off of a dual power supply (converted from a single 9V+) giving the pedal twice the headroom and ability to handle compressing/expanding a signal without clipping.

The pedal starts by splitting the input signal into 2 circuits - control and effected.  The control stream makes its way into a THAT2252 chip, a precision RMS level detector (by the “THAT Corporation,” a Silicon Valley manufacturer of high-end precision analog chips) which measures the input signal and provides a precise trigger signal for the VCA.

After the RMS chip we head into a series of 4 Op Amps that are used to control the Threshold, Shape, and Gain of the trigger signal. The affected trigger signal is then routed into a THAT2150 VCA which follows the unity gain amplifier in the effected circuit.

The THAT2150 is a Voltage Controlled Amplifier based on the “Blackmer Gain Cell” developed by David Blackmer, the founder of DBX - This VCA structure is the granddaddy of them all and was instrumental in the early DBX designs.  After the 2150 VCA the signal is amplified again by another Op Amp and then out through the true bypass switch.

The CP-9 Pro+ features Mechanical True Bypass switching using a Fujisoku 4PDT switch.

NOTE ON POWERING THE CP-9 Pro+ - this pedal’s voltage regulator IC requires a high inrush current of approximately 2000 mA upon startup.  When using with a Power Brick such as the Voodoo Labs Pedal Power 2+, this pedal should be connected to a high current power jack when possible.

If it is not possible to connect to a high current jack, you can power the CP-9 Pro+ by leaving a battery in the pedal.  Upon initial start-up, unplug the external DC power input cable, engage the pedal, and then plug the DC power input cable back in – the pedal will now power up normally off the external power supply until you power down your pedalboard.

Input Impedance: 500K Ohms

Input Jack: 1/4 inch standard phone jack

Output Impedance: 10K Ohms or less

Output Jack: 1/4 inch standard phone jack

Output: 1

Switch: Normal/Effect (true bypass configuration)

Maximum Output Level: +18 dBu (1 KHz)

THRESHOLD: 0 dBu TO -40 dBu
RATIO: 1:1 to ?:1
GAIN: 0 dB to +30 dB

Distortion Ratio: 0.01% (1 kHz) at 0 dB output

Residual Noise: 95 dBu (input shorted, IHF-A weighted)

Indicator: Normal/Effect LED, Reduction LED (when reduction LED lights, Compression is more than 3 dB)

Internal Circuit Voltage: Stabilized +/-9V DC-DC converter

Power Supply: 9V Manganese dry cell battery (6F22) or special AC adaptor

Power Voltage: DC9 V (Battery) / DC10 V (AC-adaptor)

Current Consumption: 25 mA (9 V) / 23 mA (10 V) at 18 volts

Battery Life:
Panasonic NEO battery 6F22NB
Approximately 5.1 Hours @ 77 deg F / 25 Deg C
Panasonic Alkaline battery 6LF61G
Approximately 12.4 hours @ 77 deg F / 25 deg C

AC Adaptor: AC210N (option) Input: AC120V Output: DC9V/200 mA Center - / Sleeve +)

Dimensions (whole): 74 mm (W) x 124 mm (D) x 54 mm (H)

Weight: 580 g

Accessories: 9V Manganese dry cell battery (S-006P) x 1

Warranty Card: x 1

User's Manual: x 1

* All specifications are subject to change for improvement without notice or obligation.All brand names and product names are trademarks or registered trademarks of their respective companies.

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