QSC CX Series User Manual
Cx series
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- Service manual (90 pages) ,
- Technical & service manual (78 pages) ,
- Owner's manual (1 page)
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Summary of Contents for QSC CX Series
- Page 1 CX Series U S E R M A N U A L CX4T CX6T CX12 CX12T Rev. B *TD-000057-00* *TD-000057-00* *TD-000057-00* *TD-000057-00* *TD-000057-00* *TD-000057-00*...
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Page 2: Table Of Contents
Table of Contents PART 1—CX SERIES USER MANUAL Warning Notices ... 2 Speaker Damage ... 3 Speaker Output Shock Hazard ... 3 Rack Mounting Precautions ... 3 II. Overall Description ... 4 III. Inputs ... 6 Input Sensitivities ... 6 IV. - Page 3 EXPLANATION OF GRAPHICAL SYMBOLS The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to alert the user to the presence of uninsulated “dangerous voltage” within the product’s enclo- sure that may be of sufficient magni- tude to constitute a risk of electric shock to humans.
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Page 4: Warning Notices
I. Warning Notices SPEAKER DAMAGE The CX Series amplifiers are among the most powerful professional amplifiers available and are capable of producing much more power than many loudspeakers can handle. It is the user’s responsibility to use suitable speakers with the amplifier and to use them in a sensible way that will not cause damage. -
Page 5: Overall Description
This mounting technique also helps support the weight of the upper amplifiers. The CX Series derives much of its design from our award-winning MXa Series amplifiers. They are engineered for stability and exceptional reliability, with protection for open or short circuits and mismatched loads. To protect your loudspeakers, the outputs mute during turn-on and turn-off, and also in the event of a DC fault. -
Page 6: Rear View
Front features of CX4 or CX4T amplifier Rear features of amplifier Rear features of CX4T amplifier Front features of CX6, CX6T, CX12 or CX12T amplifier 1 — Power Switch 2 — Power Indicators (Ch1, Ch2) 3 — Signal Indicators (Ch1, Ch2) 4 —... -
Page 7: Inputs
If you need XLR or 1/4” RTS inputs on your CX6, CX6T, CX12, CX12T, use the optional MX-1 input expander (available through QSC’s Technical Services Department). Typical of QSC amplifiers, the input impedance of a CX Series amplifier is 20 kilohms balanced and 10 kilohms unbalanced. - Page 8 If your application calls for connecting an 8-ohm speaker and a distributed line to the same amplifier channel, the CX4T, CX6T and CX12T can do that. However, since most of the audio power is drawn by the direct-connected speaker, you must derate the distributed line; the distributed line should have a total power load of no more than one-fourth the amplifier’s normal distributed line power rating.
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Page 9: Controls & Displays
V. Controls & Displays CX4 AND CX4T The channel attenuator controls, labeled in dB of attenuation , are located on the rear panel. They have 11 detents, adjustable from 0 dB (full gain) to × (full attenuation). The LED displays for each channel function as shown at right. -
Page 10: Troubleshooting
CX6, CX6T, CX12 and CX12T When the amplifier is first turned on, the red “PROTECT” LED on each channel will light for about two or three seconds, during which the output relays will stay open to mute the speakers. After the turn-on muting interval, the “PROTECT”... -
Page 11: Open Input Architecture Level I
PROBLEM: Overheating • The thermal management system on a CX Series amplifier features a two-speed fan that modulates the cooling air flow over the heatsinks in response to the cooling needs. If the air flow is blocked, however, or if the amplifier is overdriven into very low impedance loads, the amplifier could overheat even though the fan is running at full speed. -
Page 12: Parallel, Stereo, Or Bridged Operation
The standard input panel installed on the CX Series amplifier has balanced Euro-style detachable header inputs, gain controls, and the Parallel-Stereo-Bridge switch. The panel’s circuit board has solder footprints for passive roll-off circuit components, input isolation transformers, and other special customizations. - Page 13 MODE BRIDGÉ MONO: BRIDGED-MONO MODE ATTENTION CAUTION: TOUT LES MODÈLES— ALL MODELS—Output Des tensions de sorties voltages as high as 160 aussi élevée que 160 volts rms are available be- tween the CX amplifier’s volts rms sont disponible aux bornes bridged terminals (200 du amplificateur CX en volts at isolated outputs).
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Page 14: Maximum Long-Term Output Power
Except for an occasional flash, keep the “CLIP” indicator dark to avoid overheating the amplifier channel. AC CURRENT CONSUMPTION A major objective in the design of the CX Series amplifiers-even the higher-powered models-is to permit their operation from readily available, standard AC power sources. -
Page 15: Heat Emissions
HEAT EMISSIONS Essentially, a power amplifier draws electrical energy from the AC mains, converts it to DC, and then converts it again into an analog of the input signal to send out to the loudspeakers. Any AC power that enters the amplifier through the power cord and does not exit through the speaker outputs turns into heat, which the amplifier must rid itself of by exhausting it to the outside. -
Page 16: Protection Circuits
PROTECTION CIRCUITS The design goal in high-efficiency amplifiers such as the CX Series is to increase the amplifier’s ability to deliver peak power without increasing its size, weight, and cost. However, the higher power flow through the output components makes effective, responsive protection circuitry absolutely vital. To this end, the design of the CX series takes a comprehensive approach to protection. -
Page 17: Specifications
VII. Specifications POWER OUTPUT Direct output, watts per channel, both channels driven 8 , 20 Hz–20 kHz, 0.1% THD 8 , 45 Hz–20 kHz, 0.1% THD** 8 , 1 kHz, 1% THD 4 , 20 Hz–20 kHz, 0.1% THD 4 , 45 Hz–20 kHz, 0.1% THD** 4 , 1 kHz, 1% THD 2 , 1 kHz, 1% THD* Isolated outputs, watts per channel,... - Page 18 VII. Specifications (cont.) VOLTAGE GAIN @ direct outputs: 35× (31 dB) 35× (31 dB) 40× (32 dB) 40× (32 dB) 56.5× (35 dB) 56.5× (35 dB) INPUT SENSITIVITY, VRMS for rated power, 8 ohms 0.98 INPUT IMPEDANCE 10K unbalanced, 20K balanced CONTROLS Front: AC Switch Rear: Parallel/Stereo/Bridge Switch (except CX4, CX4T)
- Page 19 VII. Specifications (cont.) POWER CONSUMPTION (see chart on page 13) Normal operation: 1/8 power @ 4 per channel Worst case continuous program: 1/3 power @ 2 per channel Maximum: full power @ 2 per channel Multiply current times 0.5 for 220-240 VAC operation Model Channel Load AC Current, Full Power...
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Page 20: Part 2-Cx Application Guide
Part 2—CX Series Application Guide ith the helpful advice and input from contractors and consultants around the world, engineers at QSC designed the CX Series amplifiers to be a versatile and reliable foundation for high-quality installed sound systems. This applications guide will help you design your sound system properly and utilize your CX amplifier(s) effectively. -
Page 21: Designing The Distributed Sound System
IX. Designing the Distributed Sound System There are several main steps in designing a distributed sound system: • Determining loudspeaker coverage and placement • Determining power levels for each loudspeaker • Choosing the right amplifier LOUDSPEAKER COVERAGE AND PLACEMENT The goal in placing the loudspeakers in a distributed system is to acoustically cover the required area effectively but economically. - Page 22 reflective surfaces—wood floors and ceiling, concrete and plaster walls, etc., the type of room that tends to make speech unintelligible—might benefit from using many low-powered loudspeakers placed throughout the room and close to the listeners, instead of using a couple high-powered, centrally-located loudspeakers. With ceiling-mounted loudspeakers, one general rule of thumb is to make the center-to-center distance between them no greater than twice the floor-to-ceiling distance.
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Page 23: Determining Power Levels
DETERMINING POWER LEVELS After you’ve determined where to place the loudspeakers, you need to calculate the power each one requires. If the installation is in an existing facility already in use, use an SPL meter, set for slow response, to measure the A weighted ambient noise at the listener’s ear position. -
Page 24: Selecting The Amplifier
EXAMPLE A loudspeaker (sensitivity: 94 dB @ 1W, 1 meter) in a busy office covers an area with an ambient noise of 72 dBA, measured at a seated person’s ear position at the desks. The client wants superb intelligibility, so your goal is to provide an SPL of 97 dB (72 plus 25) to the intended listeners. The ceiling- mounted speaker is about 6 feet, or 1.8 meters, above the listeners’... -
Page 25: Using Components With Different Voltages
USING COMPONENTS WITH DIFFERENT VOLTAGES Sometimes it may be practical to use a transformer or loudspeaker/transformer combination with a different voltage system from what it was originally intended. For example, a 70-volt transformer could be used in a 25- volt system, although you would have to derate the power taps similarly. Never use a transformer with a higher voltage than what it is designed for, though;... -
Page 26: How Many Speakers
X. How Many Speakers? How many loudspeakers can you connect to the distributed line? The amplifier itself determines the amount of audio power available to the line, and from that figure you must compensate for insertion loss in the speaker 1.56 watts …+25% for headroom. -
Page 27: Other Design Considerations
XI. Other Design Considerations SPEAKER TRANSFORMER SATURATION Speaker transformers tend to be fairly small, and some vary widely in quality. They tend, therefore, to be prone to core saturation at low frequencies. Saturation occurs when the magnetic field induced in the transformer’s iron core by the audio signal waveform has built up as high as the core can handle. -
Page 28: Wire Loss
speaker, it will affect the sound level from the distributed line’s speakers also, possibly altering them from your intended levels. An alternate method is to attach an 8-ohm speaker across the 25-volt outputs. This provides up to approximately 80 watts to the speaker and makes more power available to the 70V or 100V connections: up to 75 watts for the CX4T, up to 150 watts for the CX6T;... -
Page 30: Ac Current Consumption
AC CURRENT CONSUMPTION A major objective in the design of the CX Series amplifiers—even the higher-powered models—is to permit their operation from readily available, standard AC power sources. “Normal conditions” in power amplifier rating means operating with a random program source (pink noise), using pink noise as a source, at an average power level equal to one-eighth of maximum power. -
Page 31: Address & Telephone Information
XII. Address & Telephone Information Address: QSC Audio Products, Inc. 1675 MacArthur Boulevard Costa Mesa, CA 92626-1468 USA Telephone Numbers: Main Number Sales Direct Line Sales & Marketing (800) 854-4079 (toll-free in U.S.A. only) Technical Services (714) 957-7150 (800) 772-2834 (toll-free in U.S.A. - Page 32 1675 MacArthur Boulevard Costa Mesa, California 92626 USA PH: (714) 754-6175 FAX: (714) 754-6174 “QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office...