QSC Audio Stereo Amplifier CMX 300V User Guide

CMX Series  
User Manual  
CMX 300V  
CMX 500V  
CMX 800V  
TD-000322-00-B  
*TD-000322-00*  
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Warranty (USA only; other countries, see your dealer or distributor)  
Disclaimer  
QSC Audio Products, LLC is not liable for any damage to amplifiers, or any other equipment that is caused by negligence or improper installation and/  
or use of this loudspeaker product.  
QSC Audio Products 6-Year Limited Warranty  
QSC Audio Products, LLC (“QSC”) guarantees its products to be free from defective material and / or workmanship for a period of six (6) years from date  
of sale, and will replace defective parts and repair malfunctioning products under this warranty when the defect occurs under normal installation and use  
- provided the unit is returned to our factory or one of our authorized service stations via prepaid transportation with a copy of proof of purchase (i.e.,  
sales receipt). This warranty provides that the examination of the return product must indicate, in our judgment, a manufacturing defect. This warranty  
does not extend to any product which has been subjected to misuse, neglect, accident, improper installation, or where the date code has been removed  
or defaced. QSC shall not be liable for incidental and/or consequential damages. This warranty gives you specific legal rights. This limited warranty is  
freely transferable during the term of the warranty period. Customer may have additional rights, which vary from state to state.  
In the event that this product was manufactured for export and sale outside of the United States or its territories, then this limited warranty shall not apply.  
Removal of the serial number on this product, or purchase of this product from an unauthorized dealer, will void this limited warranty.  
© Copyright 2010, QSC Audio Products, LLC  
QSC is a registered trademark of QSC Audio Products, LLC  
“QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office  
All trademarks are the property of their respective owners.  
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Introduction  
These rugged, fan-cooled, 2-channel, 2RU amplifiers provide high-value performance and power in a strong, compact chassis. The series comprises  
four models: the CMX 300V, CMX 500V, CMX 800V and CMX 2000V. The CMX 2000V is covered in a separate manual.  
Features  
Independent, user-defeatable clip limiters  
Fully selectable low-frequency filtering; choice of 30 or 50 Hz roll-off  
Stereo (dual-channel), parallel-input, or Bridge Mono operating modes  
Balanced inputs — XLR, ¼" (6.3 mm) TRS, and barrier strip  
Pluggable terminal block and Speakon™ outputs  
21 detent gain knobs  
Front panel LED indicators for signal and clip and power  
Attenuation control security plate  
CMX  
300V  
CMX  
500V  
CMX  
800V  
Stereo mode, both channels driven  
8Ω / FTC 20 Hz –20 kHz / 0.1% THD  
8Ω /EIA 1 kHz / 0.1% THD  
185 W  
200 W  
280 W  
300 W  
430 W  
-
260 W  
300 W  
400 W  
500 W  
700 W  
-
450 W  
500 W  
650 W  
800 W  
1200 W  
400 W  
4Ω / FTC 20 Hz – 20 kHz / 0.1% THD  
4Ω /EIA 1 kHz / 0.5% THD  
2Ω /EIA 1 kHz / 1% THD  
70V Direct Drive /EIA 1 kHz / 1% THD  
– Table 1 –  
Front Panel  
5. Attenuation control (Channel 1)  
1. Power switch  
6. Clip and Signal indicator LEDs, (Channel 2)  
7. Attenuation control (Channel 2)  
8. Lockout plate retention screw  
2. Power indicator LED  
3. Cooling vents  
4. Clip and Signal indicator LEDs, (Channel 1)  
8
7
5
1
2
3
4
6
– Figure 1 –  
3
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Back Panel  
7. Terminal block connector outputs, Channels 1 and 2  
8. Circuit Breaker  
1. Barrier strip input  
2. XLR inputs, Channels 1 and 2  
3. Configuration dip switches  
4. TRS inputs, Channels 1 & 2  
5. Fan  
9. Serial number label  
10. Configuration switch chart  
11. IEC power inlet (power cord connector)  
6. Speakon™ output, Channel 1 and 2  
2
4
6
7
3
9
10 11  
1
5
8
– Figure 2 –  
Features and setup  
Clip Limiter  
What it is  
When the audio signal drives the amplifier's output circuit beyond its power capability, it clips, flattening the peaks of the waveform. The clip limiter  
detects this and reduces the gain to minimize the amount of overdrive. To preserve as much of the program dynamics as possible, limiting reduces the  
average program level until peaks barely clip.  
Each channel has its own clip limiter, and you can switch it on or off independently, as shown in (Figure 3).  
When to use it (or not)  
When driving full-range speakers, clip limiting reduces high-frequency distortion caused by bass overloads. It also protects higher frequency drivers  
from excess overdrive and harsh clipping harmonics.  
When driving subwoofers, some users let the amplifier clip without limiting because it gives extra “punch” to kick drums and similar sounds.  
CAUTION: In bi-amp systems, excessive limiting will affect the frequency balance.  
– Figure 3 –  
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Input Filter  
What it is  
The low-frequency (LF) filter rolls off signals below either 30 Hz or 50 Hz (Figure 6 and 7). This improves bass performance by limiting sub-audio  
cone motion, making more power available for the speakers' rated frequency range.  
The filter settings for each channel are controlled individually through the DIP switch settings shown in (Figure 4). When the filter is turned off  
(Figure 5), a 5 Hz roll off protects against DC or deep sub-audio inputs.  
When to use it (or not)  
As a rule, your speakers will sound better with proper filtering. Unless you already have filtering in a preceding device, match the setting to the low  
frequency rating of your speakers. Vented (bass reflex, ported, etc.) speakers are especially sensitive to cone over-excursion at frequencies below their  
rated limit.  
The 50 Hz filter works well with most compact full-range speakers, and has a slight boost at 100 Hz for greater fullness. The 30 Hz filter is intended for  
subwoofers and large full-range cabinets. The “off” position should be used only for applications such as studio playback monitoring, where you need  
to know if there are unwanted sub-audio signals present in your mix.  
– Figure 5 –  
– Figure 4 –  
– Figure 6 –  
– Figure 7 –  
5
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Parallel Input Mode  
What it is  
The Parallel Input switches let you operate the amplifier in Parallel mode, delivering the same signal to both channels without using a Y cable. Each  
channel drives its own speaker load, with independent gain, filtering, and clip limiting.  
Set switch positions 4 and 5 to "PARALLEL INPUTS" to couple the inputs together (Figure 8). Turn the switches to "STEREO" for stereo, bi-amping, or  
other 2-channel modes.  
With the inputs in parallel, you can use the other set of input connectors to carry the signal to other amps (Figure 9). This is often called  
a “daisy-chain.”  
When to use it  
Use the Parallel mode when driving two speakers with one input signal (Parallel mode) while keeping separate control of both channels' gain, filtering,  
and limiting. Use Parallel mode and Bridge Mono mode to patch the signal to additional amplifiers through the extra input jacks.  
Note: If you're using a balanced signal, use only balanced patch cables; even one unbalanced cable will unbalance the entire signal chain, possibly  
causing hum.  
Note: Turn off the “Parallel Inputs” switches when feeding the amp two separate signals.  
– Figure 8 –  
– Figure 9 –  
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Bridge Mono Mode  
What it is  
Bridge Mono mode combines the power of both amp channels into one speaker, resulting in twice the voltage swing, four times the peak power, and  
approximately three times the sustained power of a single channel. This mode uses Channel 1's input, attenuation control, input filter, and clip limiter;  
Channel 2's dip switch settings should be in the OFF position, the attenuation control should be at maximum attenuation (Figure 10 and 11).  
When to use it (or not)  
Use Bridge Mono mode to deliver the power of both channels to a single 8 or 4Ω load. Set switch positions 6 and 7 to BRIDGE MONO ON  
(Figure 10). Use Channel 1's inputs, and connect the speaker as shown in (Figure 12 and 13).  
Bridge Mono Precautions  
This mode puts a high demand on the amplifier and speaker, Excessive clipping may cause protective muting or speaker damage. Be sure the speaker  
has a sufficient power rating.  
Output voltages greater than 100 volts RMS are available between the bridged terminals of the CMX 800V. CLASS 3 wiring methods (NEC 1999), as  
specified in accordance with national and local codes, must be used to connect the speaker.  
– Figure 10 –  
– Figure 11 –  
Channel 2 settings, switches 8, and 10 are  
set to off.  
To patch the signal to additional amplifiers, use  
the parallel input switches described under  
Parallel Input Mode.  
To speaker  
– Figure 12 –  
– Figure 13 –  
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The Difference Between Modes  
Stereo Mode  
Stereo mode is the typical way of using the amplifier. Each channel is fully independent. Separate signals connect at the inputs, the attenuation  
knobs control their respective channels, and separate speakers connect to each output. The dip switches are set as shown in (Figure 14), a schematic  
illustration in (Figure 15).  
Examples:  
Two-channel (stereo) playback.  
Two independent mono signals, such as main and monitor mixes.  
Bi-amped operation, with the low frequencies in Channel 1 and the highs in Channel 2.  
– Figure 15 –  
– Figure 14 –  
Parallel Input Mode  
This mode is similar to the Stereo mode, except that the inputs for Channel 1 and Channel 2 are internally connected together. A signal into  
Channel 1 jack drives both channels directly (Figure 16). Use Channel 1 Input, do not connect different sources to both channels. Each channel's  
attenuation control still functions as usual, and each channel feeds its own speaker load. The dip switches are set as shown in (Figure 17).  
In Parallel mode, you can patch the input signal on to additional amplifiers by using any of the remaining input jacks. See Ch. 2 in (Figure 16).  
Example:  
One mono signal driving both channels, with independent attenuation control for each speaker system.  
signal input  
NO INPUT!  
Can be used to Daisy-chain  
additional amplifiers  
– Figure 17 –  
Amplifier #2  
– Figure 16 –  
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Bridge Mono Mode  
This mode combines the full power capabilities of both channels into a single speaker system. The amplifier internally re-configures so that both  
channels operate as a unit. This delivers double the output voltage, resulting in four times the peak power and three times the sustained power into a  
single 8 or 4Ω speaker load. The Bridge Mono mode section on page 7 describes the special speaker connection used.  
Examples:  
Driving a single 8Ω speaker with the combined 4Ω power of both channels.  
Driving a single 4Ω speaker with the combined 2Ω power of both channels.  
Precautions:  
Bridge Mono mode makes it possible to drive thousands of watts into a single speaker. AC current consumption will usually be higher. Avoid  
excessive signal level, and make sure the wiring and speaker can handle the power.  
If the load is 4Ω or less and prolonged overloads occur, the amplifier will probably mute for several seconds during peaks, and the circuit breaker  
may trip.  
Do not use 2Ω loads.  
Ensure Channel 2 dip switches are set to off (Figure 18), and Channel 2 attenuation control is set to maximum attenuation.  
See the additional Bridge Mono precautions on page 7.  
– Figure 18 –  
Set Channel 2 dip switches, 8 and 10, to off.  
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Channel 1  
input  
Channel 2  
input  
not used  
Channel 1  
signal input  
Channel 2  
No input!  
Can be used to Daisy-chain  
additional amplifiers  
Amplifier #2 input  
– Figure 19 –  
Distributed Constant Voltage Outputs  
70 Volt Operation:  
CMX  
300V  
CMX  
500V  
CMX  
800V  
Specifications  
The CMX 300V and 500V must be configured for Bridge Mono mode for 70  
Volt operation. Please refer to the above section on Bridge Mono mode for  
proper setup configuration.  
Stereo Mode (Both Channels Driven)  
The CMX 800V can operate in 70 Volt operation in Stereo mode or Bridge  
Mono mode.  
70 Volt  
-
-
-
-
400 W  
-
100 Volt  
100 Volt Operation:  
Bridge Mono Mode  
70 Volt  
The CMX 500V and CMX 800V must be configured for Bridge Mono mode for  
100 Volt operation. Please refer to the Bridge Mono mode section for proper  
setup configuration.  
600 W  
-
1200 W  
600 W  
2000 W  
2300 W  
100 Volt  
– Table 2 –  
10  
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Installation  
Rack mounting of the amplifier is optional.  
Use four screws and washers when mounting the amplifier to the front rack rails.  
Support the amp at the rear also, especially in mobile and touring use; rear rack mounting ear kits are available from QSC’s technical services  
department or by special order from your dealer or distributor. Use the dimensions (Figure 20 and 21 ) for planning.  
Side view  
15.75" 400 mm  
15.60" 396 mm  
15.35" 390 mm  
15.23" 387 mm  
15.10" 384 mm  
3.0"  
76.2 mm  
– Figure 20 –  
17.3"  
440 mm  
14.65"  
372 mm  
15.75"  
400 mm  
3.5"  
88.9 mm  
– Figure 21 –  
11  
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Connections  
Inputs  
Each channel has active balanced XLR and ¼" (6.3 mm) inputs wired in parallel (Figure 22). The input impedance is 20 kΩ balanced,  
10 kΩ unbalanced.  
Balanced signals are less prone to AC hum, but unbalanced signals can be suitable for short cable runs. The signal source’s output impedance should  
be less than 600Ω to avoid high frequency loss in long cables.  
Balanced Inputs  
Use the XLR or ¼" (6.3 mm) TRS input jacks, or the barrier strip (Figure 25).  
Unbalanced Inputs:  
Connect the unused side (Pin 3) of the balanced input to ground (Pin 1), as shown in (Figure 23).  
A tip-sleeve ¼" (6.3 mm) connector will correctly terminate the unused side of the input ( Figure 26).  
For Stereo operation, use the inputs for both Channel 1 and Channel 2. For Parallel or Bridge Mono operation, use the Channel 1 input.  
See the section on operating modes for more information. To patch the audio signal to other amps (Parallel and Bridge Mono modes only), see the  
instructions for using Parallel Inputs on page 6.  
XLR unbalanced  
Jumper pin 1 to pin 3  
Or  
Pin 1 = Ground  
Pin 2 = +  
Pin 3 = -  
– Figure 23 –  
TRS unbalanced  
No modification needed  
– Figure 24 –  
– Figure 22 –  
Balanced  
Unbalance  
ground  
ground  
inverting Input  
non-inverting input  
non-inverting input  
– Figure 25 –  
– Figure 26 –  
12  
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Speakon™ Outputs  
CMX amplifiers offer a choice of output connections, with two Neutrik NL4MD Speakon™ jacks and a Terminal Block connector.  
The Speakon™ connector is designed specially for high-power speaker connections. It locks in place, prevents shock hazard, and assures the  
correct polarity.  
The upper Speakon™ jack has both Channel 1 and Channel 2 outputs, so it is especially useful for Parallel, bi-amp, or Bridge Mono mode operation  
(see Bridge Mono mode operating precautions on page 7). The other Speakon™ carries only the output from Channel 2.  
For easier insertion, use the newer-style NL4FC Speakon™ connectors with quick-lock thumb latches (Not shown).  
Speaker Cabling  
Larger wire sizes and shorter lengths minimize both loss of power and degradation of damping factor. Do not place speaker cables next to  
input wiring.  
WARNING: To prevent electric shock, do not operate the amplifier with any of the conductor portion of the speaker wire exposed.  
To Channel 1 speaker  
To Channel 2 speaker  
2 channels & 2 Speakon™ connectors  
(Stereo, bi-amp, or parallel mode)  
– Figure 27 –  
To Channel 1 speaker  
To Channel 2 speaker  
Channel 1  
Channel 2  
2 channels & 1 Speakon™ connectorss  
(Stereo, bi-amp, or parallel mode)  
– Figure 28 –  
To speaker  
Bridge Mono mode  
– Figure 29 –  
13  
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Terminal Block Connector  
The terminal block connector requires the following assembly.  
1. Strip the wires to 7 ~ 8 mm.  
2. Insert the wires into the male part of the connector according to the Mode you are using. See below.  
3. Use a flat-tip screwdriver to secure the wires. Tighten the screws to 6 in.-lbs.  
4. Insert the plug into the receptacle on the amplifier.  
5. Use a flat-tip screwdriver to secure the connector. Tighten the screws to 6 in.-lbs.  
Stereo and Parallel Mode: Wire as shown by loudspeaker symbols 1 and 2, and the solid wires in (Figure 30).  
Bridge Mode: Wire as shown by Bridge Mono loudspeaker symbol, and the dashed wires in (Figure 30).  
– Figure 30 –  
Terminal Block Connector Wiring  
Wire range  
UL  
IEC  
-
6 mm2  
Solid wire (AWG)  
Stranded wire (AWG/mm2 )  
Torque (lb.-in.)  
28 – 10  
28 – 10  
6
-
-
-
-
Wire strip length  
7 – 8 mm  
– Table 3 –  
14  
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Operating Voltage  
(AC Mains)  
Make sure you connect the amplifier to the correct AC line voltage, as shown on the serial number label. Connecting to the wrong line voltage is  
dangerous and may damage the amplifier (Figure 31).  
– Figure 31 –  
Operation  
AC Power Switch  
Before applying power, check all connections and turn the attenuation controls fully counter clockwise to maximum attenuation.  
One second of muting is normal when the amp is turned on or off (Figure 32).  
Attenuation Controls  
The controls are marked with a scale indicating attenuation. Maximum attenuation is fully counter clockwise, minimum attenuation is fully  
clockwise. (Figure 33).  
LED Indicators  
The green SIGNAL LED indicators light at approximately 0.1% of full power.  
The red CLIP LED indicator flashes during overload (clipping).  
If the amplifier's protection circuitry triggers protective muting, the signal and clip LEDs will not light. If this occurs during use, see the Troubleshooting  
section on pages 16 — 17.  
On  
– Figure 32 –  
– Figure 33 –  
Model Maximum Voltage Gain  
CMX 300V  
CMX 500V  
CMX 800V  
31.6 x (30 dB)  
40 x (32 dB)  
46 x (33 dB)  
– Table 4 –  
15  
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Fan cooling  
The fan speed varies automatically to maintain safe internal temperatures. Keep the front and rear vents clear to allow full air flow. Hot air exhausts out  
the front of the amp so it does not heat the interior of the rack. Make sure that plenty of cool air can enter the rack, especially if there are other units  
which exhaust hot air into it.  
Safe operating levels  
The amp's protective muting system guards against excessive internal temperatures. With normal ventilation and 4 - to 8Ω loads, the amplifier will  
handle any signal level including overdrive-but make sure that the speakers can handle the full power! However, lower load impedances and higher  
signal levels produce more internal heating. Into 2Ω loads, frequent or prolonged clipping (indicated by constant flashing of the red CLIP LED) may  
trigger protective muting. Bridged mono mode doubles the output impedance of the amp; 4Ω is the minimum load impedance. Heavy clipping may  
cause muting. If this happens, see the Troubleshooting section below through the following page.  
Warm air exits the amplifier  
and rack.  
Cool air enters the amplifier  
and rack.  
Rack  
– Figure 34 –  
Troubleshooting  
Problem: No Sound  
Indication: POWER indicator not lit  
Check the AC plug. Also check the circuit breaker on the rear panel.  
Confirm that the AC outlet works by plugging in another device. If too many  
amplifiers are used on one outlet, the building’s circuit breaker may trip and shut  
off power.  
An overload in Bridged Mono mode may cause the amplifier to click off  
for several seconds. Check the load impedance (4Ω minimum), or reduce  
signal level.  
An amplifier which keeps shutting off may have a serious internal fault. Turn it  
off, remove AC power, and have the amplifier serviced by a qualified technician.  
Indication: SIGNAL LED responding to signal level  
If the green SIGNAL indicators are lighting normally, the fault is somewhere  
between the amp and the speaker. Check the speaker wiring for breaks. Try  
another speaker and cable.  
Indication: SIGNAL LED not lit  
If the green POWER indicator LED is lit and the fan is running, yet the signal  
LEDs indicate no signal, check the input. Make sure the signal source is operating  
and try another input cable. Connect the source to another channel or amplifier  
to confirm its operation.  
16  
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Indication: CLIP LED flashing  
If the red CLIP indicator flashes when signal is applied, the amplifier output may be  
shorted. Check the speaker wiring for stray strands or breaks in the insulation.  
Indication: CLIP LEDs bright and steady  
The amplifier is in protective muting.  
One second of muting is normal when the amp is turned on or off.  
Overheating will cause protective muting. The fan will be running at full speed and the  
chassis will be hot to the touch; sound should resume within a minute as the amplifier  
cools to a safe operating temperature. Check for proper ventilation. If the fan isn’t running  
at all, the amplifier requires servicing.  
Problem: Distorted Sound  
Indication: CLIP LED flashing  
If the red CLIP indicator flashes before the signal indicator does, the load impedance is  
abnormally low or shorted. Unplug each speaker one-by-one at the amplifier. If the CLIP  
LED goes out when you disconnect a cable, that cable or speaker is shorted. Try another  
cable and speaker to locate the fault.  
Indication: CLIP LED not flashing  
This could be caused by a faulty speaker or loose connection. Check the wiring and try  
another speaker.  
The signal source may be clipping. Keep the amplifier attenuation controls at mid point so  
that the source does not have to be overdriven.  
Problem: No channel separation  
Check the switch settings on the back of the amplifier. Make sure the “Parallel Input” and  
“Bridge Mode” switches are OFF in dual-channel, bi-amp, or stereo use where different  
signals go to each channel.  
Make sure other equipment in the signal path, such as mixers, preamps, etc., are set for  
stereo, not mono.  
Problem: Hum  
Move cabling and signal sources to identify “hot spots” in the system. Cables with faulty  
shielding are a frequent entry point for hum.  
Problem: Hiss  
Unplug the amplifier input to confirm that the hiss is coming from the source or a device  
upstream; erratic or popping noises indicate an electronic fault in the offending unit.  
To keep the normal noise floor low, operate the primary signal source at full level, without  
clipping, and avoid boosting the signal further between the source and the amplifier.  
Problem: Squeals and feedback  
Microphone feedback should be controlled with mixer controls. If noise continues to build  
up with zero mic gain, there is a serious fault in the signal processors or cables. Working  
in succession from the signal source towards the amplifier, check each device in the signal  
path by reducing its gain or unplugging it.  
17  
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Specifications  
CMX 300V  
CMX 500V  
CMX 800V  
Stereo Mode (both channels driven)  
8Ω / FTC 20 Hz - 20 kHz / 0.1% THD  
8Ω / EIA 1 KHZ / 0.1% THD  
4Ω / FTC 20 HZ - 20 KHZ / 0.1% THD  
4Ω / EIA 1 KHZ / 0.5% THD  
185 W  
200 W  
280W  
300 W  
430 W  
-
260 W  
300 W  
400 W  
500 W  
700 W  
-
450 W  
500 W  
650 W  
800 W  
1200 W  
400 W  
2Ω / EIA 1 KHZ / 1% THD  
70 V - Direct drive / EIA 1 kHz / 1% THD  
Bridge Mono Mode  
8Ω / FTC 20 Hz - 20 kHz / 0.1%THD  
8Ω / EIA 1 kHz / 0.1%THD  
4Ω / EIA 1 kHz / 1%THD  
70 V - Direct drive / EIA 1 kHz / 1% THD  
100 V - Direct drive / EIA 1 kHz / 1% THD  
530 W  
600 W  
830 W  
600 W  
-
800 W  
900 W  
1400 W  
1200 W  
600 W  
1300 W  
1500 W  
2400 W  
2000 W  
2300 W  
Distortion (SMPTE-IM)  
Signal to Noise (20 Hz – 20 kHz) 8Ω  
Input Sensitivity 8Ω  
< 0.02%  
< 0.01%  
< 0.01%  
> -100 dB  
1.15 V (+3.4 dBu)  
30 dB  
1.15 V (+3.4 dBu)  
32 dB  
1.23 V (+4.0 dBu)  
33 dB  
Voltage Gain (8Ω)  
Output Circuitry  
Class AB  
Class AB  
2-tier Class H  
Power Requirements  
Typical, 1/8 power, pink noise at 4Ω  
120 VAC  
4.4 A  
2.2 A  
5.4 A  
2.7 A  
6.3 A  
3.2 A  
230 VAC  
Severe, 1/3 power pink noise at 4Ω  
120 VAC  
6.6 A  
3.3 A  
9.6 A  
4.8 A  
15.6 A  
7.8 A  
230 VAC  
Frequency Response  
20 Hz – 20 kHz, +0, -1 dB  
-3 dB points: 5 Hz and 50 kHz  
(LF filter bypassed / 8Ω)  
Damping Factor  
Input Impedance (Ω)  
Input Clipping  
> 300 at 8Ω  
10 kΩ unbalanced / 20 kΩ balanced  
10 Vrms (+22 dBu)  
Cooling  
Continuously variable speed fan, back-to-front air flow  
Connectors (each channel)  
Input: Active balanced; barrier strip, XLR and ¼" (6.3 mm) -  
TRS tip and XLR (pin 2 positive)  
Output: Detachable terminal block and Speakon™  
Controls  
Front: AC Switch, Channel 1 and Channel 2 gain knobs  
Rear: 10-position DIP switch  
Indicators  
Power-on: Green LED / Signal: Green LED (1 per channel) /  
Clip: Red LED (1 per channel)  
Amplifier Protection  
Load Protection  
Stable into reactive or mismatched loads  
On/off muting, AC Coupling (CMX 300V and CMX 500V), triac  
crowbar (CMX 800V on each channel)  
Dimensions (HWD)  
3.5" (2RU) x 19" x 15.9" (89 mm x 483 mm x 400 mm)  
Weight - Net / Shipping  
35 lb (15.9 kg) / 41 lb  
(18.6 kg)  
40 lb (18.2 kg) / 46 lb  
(20.9 kg)  
44.5 lb (20.2 kg) / 50.5 lb  
(23.0) kg)  
18  
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Mailing Address:  
QSC Audio Products, LLC  
1675 MacArthur Boulevard  
Costa Mesa, CA 92626-1468 USA  
Telephone Numbers:  
Main Number: (714) 754-6175  
Sales & Marketing: (714) 957-7100 or toll free (USA only) (800) 854-4079  
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