JBL CSMA 240 8-Channel 40W Commercial Mixer Amplifier

The JBL CSMA 240 8-Channel 40W Commercial Mixer Amplifier is can get the job done!  Whether you run a restaurant, store or office, this Mixer/Amp can meet your needs. 8 input channels allow for great background music options, while still saving mic connections on 2. . The JBL CSMA 240 Mixer-Amplifier allows you to page customers or employees, and make announcments with absolute clarity. The JBL CSMA 240 8-Channel 40W Commercial Mixer Amplifier even includes signal sensing lights for convenience if the system is stored in a dark area. CSMA is compatible with a remote control to adjust volume levels.  Remote must be purchased separately. The JBL csma 240 Mixer Amp will help you create the system you need. Recommendations: For wire runs of 25 feet or less, JBL recommends 16-gauge speaker wire. For longer runs, 14-gauge or better is recommended.


 The JBL CSMA 240 2-Channel 40W Commercial Mixer Amplifier utilizesuses DriveCore technology.  This allows for the reduction in volume and mass.  Less space, less energy used!

Harman GreenEdge

JBL Commercial mixer amplifer's are manufactured under Harman's GreenEdge environmental initiative. These products are created using recycled materials to establiSHan environmentally-conscious manufacturing processes. The result is an 80% improvement in efficiency over previous models.,JBL CSMA 240 8-Channel 40W Commercial Mixer Amplifier is EnergyStar certified.

Front Panel

The front panel of the JBL CSMA 240 8-Channel 40W Commercial Mixer Amplifier was built with eight independent input level controls. Each level control has a ring which lights green to indicate presence of an input signal. Two volume controls (Master 1 and Master 2) allow you to control the output of the two amplifiers. These 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 on each output channel. A flat or Phillips screwdriver is needed to adjust bass and treble.


 The JBL CSMA 240 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 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.


The JBL CSMA 240 comes with 2 powered outputs 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 we suggest you use a wire. 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.

Aux 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 zero effect on the aux output signal. The Aux 1 and Aux 2 outputs each have 3-pin Euro-block connectors.

Input Routing DIP Switches

The JBL CSMA 240 8-Channel 40W Commercial Mixer Amplifier 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 correct 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 on its own as you choose.

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.

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 JBL CSMA 240 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 standard use of the VOX function would be to automatically lower the background music in the room while making an announcement over the sound system. After the announcement is made, the background music returns to its previously set level.  

JBL CSMA 240 Product Highlights:

  • amplified mixer for commercial audio distribution features 8 input channels and 2 output channels of 40 watts each
  • supports 70-volt and 100-volt distributed audio systems without the need for a separate transformer
  • stable from 2-16 ohms
  • uses Crown's high-efficiency DriveCore™ technology to provide excellent audio performance
  • independent bass and treble controls for each output channel
  • dip switches for input routing, phantom power, and 70/100V operation
  • illuminated rings around buttons and dials for easy operation in darkened environments
  • fanless, space-saving single rack space (1U) design
  • rack mounting kit included
  • Energy Star® certified

In the Box:

  • JBL CSMA 240 mixer/amplifier
  • 3' AC power cord (3-prong plug/IEC 3-prong)
  • 4 Self-adhesive rubber feet
  • 2 Front angle brackets
  • 2 Rear flat brackets
  • 2 Rear angle brackets
  • Eight 3-conductor Euro-block connectors
  • Four 5-conductor Euro-block connectors
  • 10 M4 x 20mm Phillips-head rack-mounting screws (each with a flat washer)
  • Three 3/16" screws
  • 3 Flat washers
  • 3 Split lock washers
  • 12 M3 x 5mm flat-head screws
  • Operation Manual


Maximum Output Power 40 W per channel into 4 ? or 8 ?, 1 kHz, ? 0.5% THD
Insertion Loss 1 dB maximum
Continuous Power 5 W per channel
Number of Channels Input: 8 Output: 2
Line Output Level 5.0 V RMS into 10 k?
Input Sensitivity Mic Input: 3 mV RMS Line Input: 775 mV RMS RCA Input: 300 mV RMS 1
Please Note:
To obtain full rated power at 8 ? (or 5 VRMS to line output) close
Frequency Response 4/8 ? Output: 20 Hz - 20 kHz, ±2 dB 70 V/100 V Outputs: 80 Hz - 15 kHz ±2 dB Line Output: 20 Hz - 20 kHz, ±1 dB 2
Please Note:
Measured at 2.83 V RMS into rated load impedance at any output close
Total Harmonic Distortion (THD) Power Amplifier Output: <0.5%, 20 Hz - 20 kHz Line Output: 0.05% typical 3
Please Note:
Measured at 2.83 V RMS into rated load impedance at any output close
Signal to Noise Ratio > 90 dB
Nominal Input Impedance Mic: 400 ? Line: 20 k? (balanced) RCA: 50 k?
Minimum Load Impedance Low Impedance Output: 4 ? 70 V Output: 120 ? 100 V Output: 240 ?
Crosstalk -70 dB @ 1 kHz
Operating Temperature / Humidity 32 to 95°F (0 to 35°C), 95% RH (non-condensing)
Storage Temperature -4 to 185°F (-20 to 85°C)
Phantom Power 27 VDC
AC Input 100-240 VAC, 50/60 Hz
Dimensions (W x D x H) 17.2 x 11.9 x 1.7" (43.7 x 30.3 x 4.3 cm)
Weight Approximately 10.6 lb (4.8 kg)