QSC LF3
Low Frequency Filter for QSC Amplifiers

LF3

The LF-3 Low-Frequency filter, when used with the XC-3 two-way crossover, provides the low-frequency crossover to create a three-way active system. The unit mounts to the rear panel of a two-channel DCA or CX amplifiers to save cost and rack space. The output signal andthe operating power for the unit are conducted through the amplifier’s DataPort, eliminating added external wiring or power transformers.

The LF-3 features two discrete channels with 4th-order Linkwitz- Riley low-pass filters with 24 dB/octave slopes. Each channel has an all-pass filter providing delay for time alignment of lowfrequency drivers with mid- or high-frequency drivers, as well as a trim control providing 0 to 20 dB of attenuation for matching levels among the various frequency bands. Frequency and delay parameters for both channels are set individually. One LF-3 mounted on an amplifier will support two other amplifiers with XC-3 accessories installed, even in stereo.

Features:

• Compatible with 2-channel DCA series or CX series amps
• Designed for tri-amp cinema or installed sound systems
• Adds crossover and time alignment functions without requiring additional rack space, cabling, or AC outlets
• Selectable low-pass frequencies from 80 to 500 Hz
• Selectable time-alignment delays from 0.3 to 1.8 millisecond
• Mounts directly to back of amplifier via DataPort interface
• Precision components for accurate performance
• Active balanced XLR inputs

Specifications:

• Low-pass frequency: Selectable using SIP resistor networks: 80, 150, 200, 250, 300, 400 & 500 Hz
• Time alignment (all-pass) delay: Selectable using SIP resistor networks: 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 1.0, 1.3, 1.4 & 1.8 miliseconds
• Low frequency delay: Bypass or engage using DIP switch
• Gain adjustment: Trim potentiometer 0–20 dB attenuation
• Input: Female 3-pin XLR, one per channel
• Output to amplifier: Male HD-15 connector to amplifier DataPort
• Accessory’s operating power: Male HD-15 connector to amplifier DataPort
• Input stage type: Electronically balanced differential
• Output stage type: 3Balanced
• Dynamic range: 118 dB nominal
• Total harmonic distortion: Less than 0.1%
• Signal to noise ratio: Min. 103 dB
• Low-pass filter type: 4th-order Linkwitz-Riley alignment; -6 dB at crossover frequency
• Low-pass roll-off type: 24 dB/octave rolloff
• Supply Voltage (no load): +15 volts provided by amplifier, -15 volts provided by internal charge-pump converter
• Supply Current Requirements: Less than 50 mA
• Operating Temperature: 0–70 degrees Celsius
• Input type, each channel: Electronically balanced differential
• Input impedance: 22.6 kohm balanced; 11.3 kohm unbalanced

Our Part #  LF3