IM Series Modules for MPA Series Amplifiers

Crossover modules in the IM Series include the IM10 MPA Crossover and the IM11 MPA Sub-Bass Crossover and the IM12 Cinema Crossover.

IM10 MPA Crossover Module
IM10 Specification Sheet (Adobe Acrobat, 72kb)

Key Features:

• Low cost system design
• Selectable crossover frequencies
• Transducer alignment delay
• Horn correction
• Highpass or lowpass XLR output assign

When a basic crossover function is desired, this module offers a very compact and cost-effective solution. Ten crossover frequencies, four transducer delays, and horn correction are all selectable via internal dip switches.

The XLR output connectors can be programmed to transmit either the highpass signal or the lowpass signal. the internal crossover to amplifier connection can also be programmed as either highpass or lowpass using a simple dip switch.

IM11 MPA Sub-Bass Crossover Module

Key Features:

• Low cost system design
• Selectable highpass crossover frequencies
• Selectable sub-sonic filter
• Mono summation select
• XLR highpass outputs

When a sub-bass speaker is used, this module divides the frequencies so that only low frequencies are fed into the "host" amplifier, while all other frequencies are fed to the external XLR connectors for use by another amplifier.

This module offers crossover frequencies of 80 Hz, 120 Hz, or 250 Hz, as well as the ability to eliminate sub-sonic frequencies if needed. A sub-sonic filter can be set to cut-off frequencies from either 30 Hz or 40 Hz.

IM12 Cinema Crossover Module
IM12 Specification Sheet (Adobe Acrobat, 198kb)

Key Features:

• Selectable crossover frequency
• Transducer alignment delay
• Subwoofer output
• Infrasonic filter
• Screen loss EQ
• CD horn EQ
• Selectable high frequency limiter
• Adjustable trimpots for high frequency and subwoofer output levels

The IM12 Cinema Crossover module is designed to work with JBL MPA-Series power amplifiers to provide signal processing for JBL cinema loudspeaker systems. The IM12 uses state-of-the-art electronic circuitry to provide the required cinema signal processing functions. The IM12 also provides addition valuable functions to those which are normally used in cinemas, such as transducer alignment delay and limiting to make the cinema sound system sound even better. The functions are configurable to match the exact requirements of the system. All settings are selectable via DIP switches and are protected from tampering once the IM12 is installed.

Functions:

• Selectable Crossover Frequency: Select between 500 Hz and 800 Hz crossover points. The crossover offers a choice of a steep 24 dB per octave Linkwitz-Riley slope to minimize interaction between the LF and HF components at the crossover region, or a specialized dual-slope cinema rolloff.
• Transducer Alignment Delay: Transducer alignment allows more coherent summation around the crossover frequency. A 1.9 mS setting is provided for JBL "large-horn" systems. A 0.7 mS setting is provided for JBl "small-horn" systems.
• High-Pass Filter: A high-pass filter protects the speaker from damage due to overexcursion at very low frequencies. It allows the speaker to provide a cleaner sound by eliminating unneeded cone motion at these frquencies. The filter is switchable between 30 Hz and 80 Hz.
• Subwoofer Output: The high-pass filter circuitry can be utilized instead for an 80 Hz subwoofer low-pass output. The IM12 includes this subwoofer output for systems without a cinema processor, or where no subwoofer output is available. A subwoofer level control is accessible from the back panel.
• CD Horn Equalization: The IM12 provides constant directivity horn equalization that compensates for the high-frequency rolloff inherent in all constant directivity horns. Settings are matched to JBL horns, or can be bypassed for use with older multi-cell or radial horns.
• Screen-Loss Equalization: Projecting sound through perforated screens filters out substantial high frequency content. The IM12 compensates for the screen loss via a special equalization circuit. This function can be bypassed for speakers that are not behind the screen, or for smaller auditoriums were high frequency rolloff is negligible.
• Protection Limiting: A limiter provides protection for the screen system's high frequency components. The limiter threshold is adjustable and a chart provided with the IM12 assists in setting the threshold for a variety of threshold levels and for various MPA amplifier models.
• HF Level Balance: A control accessible from the back panel adjusts the gain of the high-frequency channel so it can be matched to that of the low-frequency channel.