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I. DESCRIPTION
The UF-3 is an embedded dual-channel universal filter accessory for use with select QSC power amplifiers. Compatible amplifier models and lines,
both current and discontinued, include:
• All PLX, two-channel CX, and two-channel DCA models (with a BSC-3 or BSC-5 BusCard installed)
• All four-channel CX and DCA models (with a BSC-7 BusCard installed)
• PowerLight models PL 1.0, PL 1.0
HV
, PL 1.4, PL 1.5
X
, PL 1.6
HVX
, PL 1.8, and PL 2.0
HV
(with a BSC-2 or BSC-4 BusCard installed)
• PowerLight models PL 3.4, PL 3.8
X
, and PL 4.0 (with a BSC-6 BusCard installed)
• All MXa models (MX 1000a, MX 1500a, MX 2000a, and MX 3000a;
Note: does not include MX 700
), which use Level 1 Open Input
Architecture
• All EX models (EX 800, EX 1250, EX 2500, and EX 4000), which use Level 2 Open Input Architecture
• Legacy CX models CX6, CX6T, CX12, and CX12T, which use Level 1 Open Input Architecture
Using the UF-3 as a default crossover or EQ is ideal for rental sound systems, since it virtually eliminates the possibility of unauthorized tampering
with settings or other such user errors.
Physically, the UF-3 is a small circuit card that mounts inside the amplifier. Older amplifier models that use Open Input Architecture have a two-
section row of 22 solder holes called a “Mini Slot” on their input boards. This is where the UF-3 is installed. The input board is part of the
removeable input module, so the UF-3 can be installed without opening the amplifier chassis or even without removing the amplifier from an
equipment rack.
The UF-3 performs the same functions as the older UF-2 accessory does, but on a smaller, more compact circuit board that can fit in more amplifier
models, such as the PowerLight 3.4, 3.8
X
, or 4.0. To fit in these models, the circuit board has a pre-scored breakaway section.
Newer models such as the PowerLight, PLX, DCA and CX series require the installation of an appropriate BusCard in order to provide a slot for
the UF-3. Depending on the amplifier model, a BusCard can provide as many as four slots for accessory cards. Each slot is equivalent to the “Mini
Slot” of the older amplifiers’ Open Input Architecture. For ease of installation, it is best to mount the UF-3 to the BusCard before installing the
BusCard itself inside the amplifier.
The installation process involves soldering, so only qualified technical persons should attempt to install the UF-3; ideally, you should enlist QSC’s
Technical Services department or an authorized service center to perform the task. The installation section of this manual offers more information
about installing the UF-3.
II. FEATURES
The UF-3 allows independent filtering of the two audio channels. You can select high-pass, low-pass, or bandpass filtering, as well as the
frequencies of the filtering.
Either channel’s circuitry contains electronically balanced input circuitry and bypassable low-pass and high-pass circuitry. Each filter circuit has
a four-pole (24 dB/
octave) Linkwitz-Riley
alignment. Figure 1
shows a block dia-
gram of the UF-3.
UF-3 UNIVERSAL FILTER
(+) Input
(-) Input
Input
Differential
Amplifier
Programmable
Linkwitz-Riley
Low-Pass Filter
Optional
CD Horn
Boost
Programmable
Linkwitz-Riley
High-Pass Filter
Low-Pass Filter Bypass High-Pass Filter Bypass
Channel
Output
3-pin
jumper block
3-pin
jumper block
1
2
3
1
2
3
Figure 1—Block diagram of UF-3 (1 of 2 channels shown)