Multi-way Crossover System
The UF-3 allows you to set up 3- and even 4-way systems. Of course, this also requires that you use more than one amplifier and more than one UF-3. The other basic requirement of using the UF-3 as a crossover is that you must feed each amplifier with the same full-range signal and use the UF-3 to filter the signals in the individual channels.
Figure 9 depicts an example of a 4-way system. Because of the multitude of possible system configurations, the fundamentals of the technique used in the example will be explained below, with a few specifics. The actual crossover frequencies you should use will depend on your
speaker system.
Subwoofer
The subwoofer subsystem in the example is driven by a bridged amplifier. Channel 1 of the UF-3 in this amplifier is set with the high- pass filter at 20 Hz (for subsonic filtering) and the low-pass at 150 Hz, which is the crossover point to the woofers. Channel 2 of the UF-3 is bypassed.
Woofer
The woofers are driven by an amplifier operating in the parallel mode. Both channels of its UF-3 are set with the high-pass filter at 150 Hz (the crossover point from the subwoofers) and the low-pass filter at 1 kHz.
Midrange and High Frequencies
The remaining speakers are driven by the same amplifier: the mids by channel 1, and the highs by channel 2. The settings for channel 1 of the UF-3 are: high-pass at 1 kHz (the crossover from the woofers) and low-pass at 5 kHz (the crossover point to the high-frequency drivers).
Channel 2 of the UF-3 is set for high-pass at 5 kHz. For ultrasonic protection, the low-pass is set at 20 kHz.
UF-3: Mids & Highs
Ch. 1: LP @ 5 kHz; HP @ 1000 Hz
Ch. 2 LP @ 20 kHz; HP @ 5 kHz
BSC-2
BusCard
Ch. 2
UF-3
Ch. 1
PowerLight 1.6HVX
UF-3: Woofers
Ch. 1: LP @ 1000 Hz; HP @ 150 Hz
Ch. 2 LP @ 1000 Hz; HP @ 150 Hz
BSC-6
BusCard
Ch. 2
UF-3
Ch. 1
PowerLight 3.4 (parallel mode)
UF-3: Subwoofer
Ch. 1: LP @ 150 Hz; HP @ 20 Hz
Ch. 2 Bypassed
BSC-6
BusCard
Ch. 2
UF-3
Ch. 1
PowerLight 4.0 (bridged mode)
Figure 10—Multiple amplifiers with UF-3s, set up for 4-way crossover operation
V. INSTALLATION
Installating the UF-3 requires PC board soldering skills, so only qualified service technicians should attempt it. Any authorized QSC service center—or, for an additional installation fee, QSC Technical Services Group—can perform the installation.
The UF-3 installs on a BusCard, which mounts inside the amplifier. Make sure you have the right BusCard for the amplifier model.
The UF-3 also installs on the amplifier input PC board of any QSC EX, MXa, or legacy CX Series amplifier. Some older EX amplifiers may require an upgrade to the current input board. Contact the QSC Technical Services Group for details on compatibility with older EX amplifiers.
When installed, the UF-3 settings and adjustments are not externally adjustable; this can prevent tampering by unauthorized users.
