QSC Audio CX Series manuale d’uso

31 CX Series USER MANUAL ▼ ▼ ▼ ▼ ▼ CX4 ▼ ▼ ▼ ▼ ▼ CX4T ▼ ▼ ▼ ▼ ▼ CX6 ▼ ▼ ▼ ▼ ▼ CX6T ▼ ▼ ▼ ▼ ▼ CX12 ▼ ▼ ▼ ▼ ▼ CX12T Rev. B *TD-000057-00* *TD-000057-00* *TD-000057-00* *TD-000057-00* *TD-000057-00* *TD-000057-00*[...]

1 T able of Contents P ART 1—CX SERIES USER MANUAL I. Warning Notices ....................................................................................................................................... 2 Speaker Damage ................................................................................................................. ...........[...]

2 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. The exclamation point within an [...]

3 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. QSC wil[...]

4 II. Overall Description The CX Series from QSC comprises six high-efficiency professional power amplifier models, each with two independent channels. The table below lists the range’s audio power ratings. Each channel has its own power transformer secondary. The CX4, CX4T, CX6 and CX6T utilize complementary Class AB linear output circuitry. For[...]

5 2 4 1 12 Front features of CX6, CX6T, CX12 or CX12T amplifier 2345 1 12 10 9 7 7 8 14 6 11 10 11 13 10 9 7 7 8 6 14 13 Front features of CX4 or CX4T amplifier 1 — Power Switch 2 — Power Indicators (Ch1, Ch2) 3 — Signal Indicators (Ch1, Ch2) 4 — Clip Indicators (Ch1, Ch2) 5 — Protect Indicators (Ch1, Ch2) 6 — Accessory Slot Cover 7 —[...]

6 Channel 2+ Channel 2- Ground Ground Ground Channel 1- Channel 1+ Loosen screw, insert wire here, then tighten screw. III. Inputs CX amplifiers feature balanced inputs, connected via a Euro-style 7-terminal detachable header. Attach input signal wires as shown. If you are connecting an unbalanced signal to an input, use the non-inverting (+) input[...]

7 Output connections for CXT, bridged mono mode, 200 volt line. Output connections for CXT, bridged mono mode, 140 volt line. 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 sp[...]

8 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. CX6, CX6T, CX12, AND CX12T The channel attenuator controls, labeled i[...]

9 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 ” LEDs turn off, the green “ POWER ” LEDs light, and the output relays [...]

10 • If the fan is not running at full speed, or the channel does not reset to normal after a cool-down period, the muting is probably because of a DC fault or other amplifier failure, especially if the “ SIGNAL ” or “ CLIP ” indicators are lit even with the attenuator turned all the way down. PROBLEM: Overheating • The thermal manageme[...]

11 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. The MX-1 Input Expander [...]

12 Instructions for bridged operation CX4 and CX4T 1. To engage the bridged mono mode, jumper the barrier strip inputs on the rear, in accordance with the diagram printed under the barrier strip inputs. Connect the amplifier input to channel 1 only, with the jumpers as shown to channel 2. Channel 1 and channel 2 gains must be matched. A 4, 8, or 16[...]

13 MAXIMUM LONG-TERM OUTPUT POWER In a properly designed sound system, you can obtain the desired sound level without using the full output power of the amplifier; if the “ CLIP ” indicators flash once in a while, that is perfectly normal. If the amplifier is operated at extremely high power levels, it may overheat or may even damage the speake[...]

14 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[...]

15 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 de[...]

16 VII. Specifications CX4 CX4T CX6 CX6T CX12 CX12T POWER OUTPUT Direct output, watts per channel, both channels driven 8 Ω , 20 Hz – 20 kHz, 0.1% THD 1 5 0 2 0 0 4 0 0 8 Ω , 45 Hz – 20 kHz, 0.1% THD** 1 5 0 20 0 4 0 0 8 Ω , 1 kHz, 1% THD 1 7 0 1 7 0 22 0 2 2 0 4 7 5 4 75 4 Ω , 20 Hz – 20 kHz, 0.1% THD 2 2 5 3 0 0 6 0 0 4 Ω , 45 Hz [...]

17 VII. Specifications (cont.) CX4 CX4T C X6 CX6T CX12 CX12T 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 0.98 1.03 1.03 1.043 1.043 INPUT IMPEDANCE 10K unbalanced, 20K balanced CONTROLS Front: AC Switch Rear: Parallel/Ster[...]

18 VII. Specifications (cont.) POWER CONSUMPTION (see chart on page 13) Normal operation: 1/8 power @ 4 Ω per channel Worst case continuous program: 1/3 power @ 2 Ω per channel Maximum: full power @ 2 Ω per channel Multiply current times 0.5 for 220-240 VAC operation Model Channel Load AC Current, Full Power AC Current, 1/3 Power AC Current, [...]

19 Part 2 — CX Series Application Guide W 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 you[...]

20 1watt in 1 meter 2 meters 3 meters 92 dB SPL 86 dB SPL 82.5 dB SPL 80 dB SPL 4 meters sensitivity = 92 dB, 1 watt@1m 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[...]

21 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[...]

22 -10.0 -8.0 -6.0 -4.0 2.0 4.0 6.0 8.0 0.5 10.0 12.0 14.0 16.0 18.0 20.0 0.1 1 0.2 10 100 5 20 50 2 0.0 dB(ref1watt) Power(Watts) -2.0 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[...]

23 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 [...]

24 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 tra[...]

25 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 transformers and for headroom when you determine how much power is available for the speakers. For example[...]

26 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 hi[...]

27 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 wa[...]

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29 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 a[...]

30 XII. Address & T elephone Information Address: QSC Audio Products, Inc. 1675 MacArthur Boulevard Costa Mesa, CA 92626-1468 USA Telephone Numbers: Main Number (714) 754-6175 Sales Direct Line (714) 957-7100 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. onl[...]

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[...]