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CL44
Quad Compressor/Limiter/Compander with DSP Sidechain
The PreSonus CL44 sets a new standard in multi-channel dynamics processing. PreSonus Audio
Electronics has been an innovative leader in dynamics processing since its inception. This line of
quad dynamics processors shows our commitment to the market and to the creative audio
professionals we work with everyday. We’ve listened to what our customers have said and given
the industry what it has asked for. The CL44 presents itself as an attractively styled analog
compressor/limiter. But beauty is not skin deep with the CL44, it goes down into every circuit on
the surface mount boards and DSP code. The CL44 is a hybrid VCA, analog dynamics processor
under digital control with DSP flexibility. Digital sidechain processing allows PreSonus to program
multiple functions that can be applied simultaneously such as filtering, vintage compressor
emulation, and other special function processing.
The CL44 control set provides standard dynamics processing functions such as Threshold, Ratio,
Attack and Release. An Auto function monitors audio over three separate time constants and
provides a program dependent attack and release for quick set up and easy operation. Based on
demands from professional FOH engineers, PreSonus has included an extended feature set that
includes a filter that allows for frequency dependent compression, separate peak limiter threshold
and a Compander circuit that provides AGC (Automatic Gain Control). The Compander raises the
signal when it falls below a desired threshold. Used in conjunction with the compressor the CL44
can keep an audio signal within a very restricted dynamic range with out losing any information.
A special ‘optical’ mode emulates a vintage optical transfer curve found in the world’s most sought
after vintage compressors. Adjacent channels are stereo linkable. The rear panel of the CL44 is
well thought out with external sidechain insert on every channel. The unbalanced I/O is on a single
TRS jack, which facilitates a single cable for getting into and out of the CL44. A ‘flip’ button is
provided that ‘flips’ the ‘tip and the ‘ring’ on the 1/4” jack to match the wiring preference of your
console’s manufacturer. Balanced Input and Output are XLR. Internal power supply, +4/-10dBv
selector, lighted function buttons, 10 segment gain reduction meters, all steel chassis, one rack
space.
• Fully Featured Compressor with variable Attack, Release, Ratio and Release
• Separate Peak Stop Limiter
• Variable Frequency Filter Allows you to pinpoint the frequency range in which the compressor
operates
• Compander circuit for maximum control over dynamic range
• Vintage Optical Transfer Curve emulation
• Digital Sidechain Processor
• Flexible and comprehensive I/O: Balanced XLR, 1/4” TRS, Insert for external sidechain
• 10 Segment Gain/Reduction LED
• Backlit Function Buttons
• Internal Power Supply
Call Today: 1-800-750-0323
PreSonus Audio Electronics, Inc.
7257 Florida Blvd. | Baton Rouge, LA 70806
Phone: 225-216-7887 | Fax: 225-926-8347
[email protected] | www.presonus.com
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CL44
Technicial Specifications
Input
XLR ..........................................................................................................10K Ohms (Balanced)
1/4” TRS .................................................10K Ohms (Unbalanced) Ring or Tip Based on Flip Switch
Output
XLR............................................................................................................51 Ohms (Balanced)
1/4” TRS ...................................................51 Ohms (Unbalanced) Ring or Tip Based on Flip Switch
Insert/Sidechain (+4/-10 Based on Switch)
Tip = Return ..........................................................................................10K Ohms (Unbalanced)
Ring = Send.............................................................................................51 Ohms (Unbalanced)
Sleeve = Ground
Panel Controls
Low Cut Filter............................................................................................................20Hz-8kHz
Threshold......................................................................................................+15dBu to –40dBu
Ratio.......................................................................................................................1:1 to 20:1
Gain .................................................................................................................-20dB to +20dB
Compand ...............................................................................................................0% to 100%
Attack ..............................................................................................................01mS to 500mS
Release .....................................................................................................................01S to 3S
Limit........................................................................................................-10dBu to 24dBu (Off)
Optical Mode Switch
Link 1-2 and 3-4 Switch
Auto Switch
Bypass Switch
Performance
THD + Noise ..............................................................................................0.01% (0dBu output)
Signal To Noise...............................................................................................................>90dB
Gain Reduction Meters
LED...................................................................................................................-0.5dB to-24dB
Physical
Weight............................................................................................................................10lbs.
Dimensions..............................................................................................19” W x 7” H x 1.75” D
Chassis ............................................................................................................................Steel
Panel .............................................................................................................Painted Aluminum
Power Supply
Type...................................................................................................................Internal Linear
Input ..........................................................................100/120/220/240VAC (Factory Configured)
Power.........................................................................................................................24 Watts
What is DSP doing in the side-chain?
In modern compression, gating, limiting and dynamics processing technology, a copy of the audio signal is
processed to compute a precise amount of gain reduction or gain expansion of the original waveform (the sidechain of the audio signal). This computation can be very complex as it involves frequency, time and amplitude
signal analysis. Traditionally, this process is performed using analog electronic functions such as rms/peak
detectors, rc time constant generators and general mathematical analog operations. However, once the sidechain circuit is placed on the circuit board, it is fixed and cannot be easily changed or updated. This is where
digital signal processing (DSP) of the side-chain signal creates an enormous advantage over traditional systems.
Being software based, the DSP side-chain can be programmed to apply multiple functions simultaneously such
as filtering, vintage compressor emulation, and special function processing. Of course every common function
of dynamics processing; threshold, ratio, attack, release, etc. is part of the software.
(DSP in the side-chain is not to be confused with inserting an outboard EQ or other device into the side-chain
of a traditional setup to achieve frequency dependent compression or gating. Having DSP in the side-chain
allows for this to be accomplished on-board with out the need for external devices.)
In the PreSonus DSP side-chain products, the audible audio signal is controlled using a very warm, wide dynamic
range (>130dB) analog VCA. The VCA is adjusted using the output of the DSP side-chain computations. This
creates a warm yet very fast dynamics control system that is unparalleled in the industry.
Audio In Audio Out
Analog VCA Output BufferInput Buffer
DSP Sidechain
Processor
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