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M Series Electronics M Series Brochure
(Adobe Acrobat, 369kb)


Both the M552 and M553 Electronic Crossovers give you "constant directivity horn pre-emphasis," a special equalization curve that optimizes the audio signal for JBL Bi-Radial® horns. The result is a system that delivers balanced power response across both the horizontal and vertical planes for superb coverage.

The M644 Noise Gate has four discrete channels of gating with user-adjustable Threshold, Attack, and Release.

The M712 Gating Compressor/Limiter features "Soft-Knee" compression characteristics for transparent gain control.

All four devices incorporate Servo-Balanced outputs for proper gain matching and elimination of extemporaneous noise.


M552 2-Way Stereo/3-Way Mono Electronic Crossover
M553 3-Way Stereo/4-Way Mono Electronic Crossover

Key Features:

  • Constant-Directivity horn pre-emphasis allows for smooth, flat frequency response from JBL 2360 Series and 2380 Series Flat-Front Bi-Radial® horns, or other CD horns.
  • 24 dB Linkwitz-Riley filters generate seamless transitions between loudspeaker components for improved high frequency driver protection as well as reduced lobing and phase distortion.
  • LF summing combines both channels for subwoofer applications where only one mono channel is needed.
  • Servo-balanced outputs provide automatic output level adjustment to accommodate either balanced or unbalanced feeds.
  • Outstanding 117 dB dynamic range for lowest noise and greater headroom, resulting in superb transient response.
  • Extremely low distortion: THD 0.004%.
  • Wide bandwidth, flat response; 10 Hz to 75 kHz.
  • Subsonic filtering for protection of low frequency transducers from over excursion.
  • RF filtering to defeat extraneous noise and ultrasonic oscillations.
  • External ground link terminals for independent access to signal and chassis grounds, permitting greater flexibility in system grounding.
  • XLR input and output connectors.
SPECIFICATIONS:
Crossover Frequencies:
Stereo Mode: M552: Low/High: 180 Hz to 2 kHz, (18 to 200 Hz) (switchable from back panel)
M553: Low/Mid: 180 Hz to 2 kHz, (18 to 200 Hz) (switchable from back panel), Mid/High: 450 Hz to 5 kHz
Mono Mode: M552: Low/Mid: 180 Hz to 2 kHz (18 to 200 Hz), Mid/High: 800 Hz to 9 kHz
M553: Low/LoMid: 180 Hz to 2 kHz (18 to 200 Hz), LoMid/HiMid: 450 Hz to 5 kHz, HiMid/High: 800 Hz to 9 kHz
Maximum Input Level: +24 dBu, XLR balanced
Maximum Output Level: +27 dBu (+25 dBm), XLR balanced
Input Impedance:  
Balanced: 10 kOhms
Unbalanced: 20 kOhms
Noise: Less than -90 dBu (LF), Less than -88 dBu (HF)
THD + Noise: Less than 0.004% (in-band)
Frequency Response: 10 Hz (-0.5dB) to 75 kHz (-3 dB)
Dimensions (HxWxD): 44mm x 483mm x 144mm (1 3/4in x 19in x 5 5/8in)
Accessory: Model SC8 Security Cover
note:  0 dBu = .775V; 0 dBm = 1 mW

 M644 Four Channel Noise Gate

Key Features:

  • Combines four independent channels of noise gate in a compact one rack space chassis.
  • User adjustment of Threshold, Attenuation, Attack and Release controls.
  • Increased versatility through extremely broad Threshold control range (-60 to +20 dBu).
  • Servo balanced outputs provide automatic output level adjustment to accommodate either balanced or unbalanced feeds.
  • External key inputs on each channel allows gate triggering from external sources.
  • Outstanding 115 dB dynamic range for lower noise, greater headroom, and unparalleled transient response.
  • Extremely low distortion; THD 0.03%.
  • Wide bandwidth, flat response; 10 Hz to 40 kHz.
  • Subsonic filtering for protection of low frequency transducers from over excursion.
  • External ground link terminals for independent access to signal and chassis grounds, permitting greater flexibility in system grounding.
SPECIFICATIONS
Frequency Response: 10 Hz (-0.5 dB) to 40 kHz (-3 dB)
THD + Noise: Less than 0.03% @ +4 dBm, (20 Hz to 20 kHz, unweighted)
Noise: -105 dBu, gate closed, with 90 dB attenuations, (20 Hz to 20 kHz, unweighted)
-94 dBu, gate open, with 90 dB attenuations, (20 Hz to 20 kHz, unweighted)
Crosstalk Between Channels: Immeasurable (lower than noise floor)
Maximum Input Level: +24 dBu (XLR balanced)
Maximum Output Level: +27 dBu; +25 dBm (XLR balanced)
Dynamic Range: 115 dB from maximum signal to noise floor
Input Impedance:  
Balanced: 20 kOhms differential
Unbalanced: 10 kOhms
Key Input: 10 kOhms
Output Impedance:  
Balanced: 102 Ohms
Unbalanced: 51 Ohms
Control Ranges:  
Threshold: -60 dBu (open) to +20 dBu
Attenuation: 0 dB (open) to 90 dB
Attack Time: 50 microseconds to 25 msec
Release Time: 50 msec to 5 seconds
Dimensions: (HxWxD) 44mm x 483mm x 144mm (1 3/4in x 19in x 5 5/8 in)
Accessory: Model SC8 Security Cover
note:  0 dBu = .775V; 0 dBm = 1 mW

M712 Two Channel Gating Compressor/Limiter

Key Features:

  • Complete user control over Threshold, Attenuation, Attack and Release controls.
  • Gate function with independent Threshold control for each channel.
  • Stereo linkable.
  • High visibility 8-element LED metering.
  • Outstanding 115 dB dynamic range for lower noise, greater headroom, resulting in unparalleled transient response.
  • Extremely low distortion; THD 0.03%.
  • Wide bandwidth, flat response; 10 Hz to 50 kHz.
  • Subsonic filtering for protection of low frequency transducers from over excursion.
  • External ground link terminals for independent access to signal and chassis grounds, permitting greater flexibility in system grounding.
  • XLR and 1/4 inch TRS connectors for convenient patching.
  • Servo balanced outputs provide automatic output level adjustment to accommodate either balanced or unbalanced feeds.
SPECIFICATIONS
Frequency Response: 10 Hz (-0.5 dB) to 50 kHz (-3 dB)
THD + Noise: Less than 0.03%
Noise: Better than -90 dB unweighted
Maximum Input Level: +24 dBu (XLR balanced)
Maximum Output Level: +27 dBu (XLR balanced)
Input Impedance:  
Balanced: 20 kOhms differential
Unbalanced: 10 kOhms
Side-chain Input: 10 kOhms
Output Impedance:  
Balanced: 51 Ohms
Unbalanced: 102 kOhms
Side-chain Input: 10 kOhms
Noise Gate Control Ranges:  
Threshold: -60 dBu (open) to +10 dBu
Attenuation: 54 dB
Attack Time: 470 microseconds
Hold Time: 200 microseconds
Release Time: 95 msec
Compressor Control Ranges:  
Threshold: -40 dBu to +20 dBu
Ratio: 1:1 to :1 (165:1)
Attack Time: 1 msec to 100 msec
Release Time: 100 msec to 1.5 seconds
Output Gain: -20 dBu to +20 dBu
Dimensions: (HxWxD) 44mm x 483mm x 144mm (1 3/4in x 19in x 5 5/8 in)
Accessory: Model SC8 Security Cover

note:  0 dBu = .775V; 0 dBm = 1 mW


Copyright © 2001 JBL Professional.
All rights reserved.