Overview: The JBL CSMA 280 is a two-channel commercial mixer-amplifier
with eight input channels. The CSMA series mixer-amps are designed and built for
commercial sound applications, such as restaurants and coffee shops, or
educational applications. The CSMA 280 is rack-mountable in a 1U rack space, and
includes a rack-mount kit.
DriveCore Technology: The JBL CSMA series utilizes DriveCore
technology developed by Crown, another Harman brand. DriveCore technology
integrates the amplifier drive stage into the power output stage, and fuses
everything into a chip the size of a dime. This significantly reduces the size
and weight of the mixer-amps into a 1U rack space.
Harman GreenEdge: JBL Commercial mixer-amps are manufactured under
Harman's GreenEdge environmental initiative, utilizing recycled copper, aluminum
and steel, an energy-saving powder coat finishing process, and conforming to
lead-free RoHS standards and other environmentally-conscious manufacturing
processes. The result is an 80% improvement in efficiency over previous models.
In addition, the CSMA mixer-amplifiers are EnergyStar certified.
Front Panel: The front panel of the CSMA 280 includes eight
independent input level controls. Each level control has a ring which
illuminates green to indicate presence of an input signal. Two volume controls
(Master 1 and Master 2) let you independently control the output of the two
amplifiers. The illuminated rings surrounding the volume controls will light
green with the presence of a signal. If the signal reaches the threshold of
clipping or audible distortion, the ring will glow red. Bass and treble tone
control potentiometers are provided on each output channel. A flat or Phillips
screwdriver is needed to adjust bass and treble.
Input Configuration: The CSMA 280 has 8 inputs which will accept 3-pin
or 5-pin Euro-block mic/line connectors. These are designed for pre-built or
professionally-wired balanced line 22-24 gauge cables. Six of the inputs also
have RCA mono sum connectors for connecting audio devices, such as CD/DVD
players. The remaining two inputs (Ch1 and Ch5) are capable of being used for
Voice-activated Ducking (VOX function) and Priority Muting, and utilize the
supplied 5-pin Euro-block connectors. Each of the 8 inputs has a Line/Mic switch
for selecting the input gain, according to the source used.
Output Configuration: The CSMA 280 has two powered outputs that are
designed for low impedance or constant-voltage systems. These outputs will
accept 5-pin Euro-block connectors. Pre-built or professionally-wired,
high-quality two-conductor, heavy gauge speaker wire is recommended. At
distances of up to 25 feet, 16-gauge wire is recommended. From 26-40 feet, you
should use 14-gauge speaker wire. To drive distributed speaker systems designed
to operate at 70V or 100V, the 5-pin Euro-block connectors have designated
terminals for 70V, 100V and Common. For 8-ohm speakers, the + and - terminals
should be used.
Auxiliary Outputs: Two Auxiliary outputs are available for connecting
additional amplifiers. The audio signal is the mix of the input channels, and
the output is at a fixed level. The master volume control and tone controls have
no effect on the aux output signal. The Aux 1 and Aux 2 outputs each have 3-pin
Input Routing DIP Switches: The CSMA 280 has a default routing of
input channels 1-4 to amplifier 1 and input channels 5-8 to amplifier 2. Six DIP
switches for each channel are provided to send the signals to the appropriate
amplifiers. Switches 1-4 allow channels 1-4 respectively to be sent to Amp 2 (in
addition to Amp 1), and switches 7-10 allow channels 5-8 respectively to be sent
to Amp 1 (in addition to Amp 2). Each channel can be configured independently as
Phantom Power: Phantom power (27V) can be applied to all microphone
inputs by turning on the Phantom Power switch (one of the unit's DIP switches).
Hi-Z Switch: By default, the CSMA 280 is configured to drive low
impedance speakers (4 Ohms, minimum). The unit has two DIP switches, one for
each amp, that will configure the unit to drive 70V or 100V speaker systems
independently and directly. When driving these high impedance speakers, the
amplifier automatically inserts a 70Hz high-pass filter.
VOX Function: Voice-activated ducking, or the VOX function,
is available on input channels 1 and 5. This function causes attenuation of the
overall output level of the amplifier when the input levels on channels 1 and/or
5 reach a set threshold. A designated trim pot is provided on the two channels
for setting the audio input level required to activate ducking. A typical usage
of the VOX function is to automatically lower the background music in the room
while making announcements over the audio system. After the announcement is
made, the background music returns to its previously set level.
Sleep Mode: To save energy, the unit is designed to go into sleep mode
when no signal is present for approximately 30 minutes. When the input signal
returns, the amp will wake up and return to normal operating mode.
Remote Volume Control: Two RJ-45 ports are provided on the back panel
for plugging in up to 2 CSR-V remote volume controllers via Ethernet cables. One
RJ-45 port is provided to control the volume for Amp 1, and one port is provided
for Amp 2.
- Maximum Output Power: 80 watts per channel (into 4Ω or 8Ω, 1kHz,
≤ 0.5% THD)
- Line Output Level: 5.0V RMS into 10 kΩ
- Frequency Response:
- 4/8Ω Output: 20 Hz - 20 kHz (+/- 2dB)
- 70V/100V Outputs: 80 Hz - 15 kHz (+/- 2dB)
- Line Out: 20 Hz - 20 kHz (+/- 1dB)
- Total Harmonic Distortion (THD):
- Power Amp Output: <0.5%, 20Hz-20kHz
- Line Output: 0.05% typical
- Signal-to-Noise Ratio: >90 dB
- Phantom Power: 27 VDC
- Minimum Load Impedance:
- Low Impedance Output: 4Ω
- 70V Output: 60Ω
- 100V Output: 120Ω
- Net Weight: 11.9 lbs