Each of the LD-3's two channels consists of a master input section, a dedicated subwoofer output, and three outputs to control the array. Three sends and four returns provide the control you need, via insert switches, to route the signal and incorporate additional signal processing, such as parametric equalization.

The master input section provides individual channel gain adjustment from -12 to +6 dB, mute, signal/clip/mute indicators, and a switchable high-pass filter (0, 80, or 160 Hz) for boundary correction or optimizing crossover to subwoofers. Master environmental controls include temperature (0° to 45° C), altitude (switchable in three ranges: 0-800, 800-2200, and 2200+ m) and relative humidity (10 to 100%).

Individual outputs provide gain trim from -6 to +6 dB (-6 to -3 and +3 to +6 settings not recommended to preserve array behavior), signal/clip/mute indicators, send/return insert switches, and distance controls to define the throw from each sound system branch to its audience coverage area up to 150 meters (492 feet).

The LD-3's dedicated subwoofer control sections feature polarity switches, gain trim from -6 to +6 dB, mute, signal/clip/mute indicators, and send/return insert switches.

In addition to its sophisticated environmental and array control functions, the LD-3 integrates different types of Meyer Sound self-powered speakers into a full-range main system, while maintaining signal integrity for long cable paths.

The LD-3 occupies two standard 19-inch relay rack spaces. Flash memory for future expansion is built in, and all input and outputs are electronically balanced and utilize XLR (A-3) type connectors. The AC inlet is an IEC standard male connector, protected with a 250 mA 250 V fuse, and switchable in the ranges of 105 to 125 V AC and 210 to 250 V AC.

Features & Benefits

• Compensates for low to mid-low frequency build-up in line arrays to provide ultra-flat frequency response
• Up to three separate array outputs per channel to control the correction according to the distance of the array section’s coverage, and dedicated sub output controls
• Input gain from -12 to +6 dB, mute, signal/clip/mute indicators, and a switchable high-pass filter for boundary correction or crossover optimization
• Total control of an array with mute and optimized filters to integrate subwoofers into the array
• Compensates for high frequency absorption of air based on temperature, relative humidity, altitude, and throw, enabling your system to work consistently under virtually any weather conditions
• Male and Female XLR Send/Insert Returns allows flexible routing of the signal and allows the insertion of signal processing such as parametric equalization
• Corrects frequency response up to 16 kHz at a resolution down to 1 dB
• Integrates different M Series self-powered speakers for maximum flexibilityHigh-quality, wide dynamic range, digitally-controlled analog filtersMaintains signal integrity for long cable paths

More info from Meyer Sound site:
LD-3 : Line Driver
LD-3 Datasheet