User manual QSC AUDIO CX 168

[. . . ] CX168 8-Channel Installed Sound Professional Audio Amplifier User Manual *TD-000095-00* TD-000095-00 rev. C 1 IMPORTANT SAFETY PRECAUTIONS & EXPLANATION OF SYMBOLS CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE THE COVER. REFER SERVICING TO QUALIFIED PERSONNEL. 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 enclosure that may be of sufficient magnitude to constitute a risk of electric shock to humans. The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance (servicing) instructions in this manual. The lightning flashes printed next to the OUTPUT terminals of the CX168 amplifier are intended to alert the user to the risk of hazardous energy. Output connectors that could pose a risk are marked with the lightning flash. Do not touch output terminals while amplifier power is on. [. . . ] Continuous operation at high power may trigger the thermal protection circuitry, shutting down the amplifier and fully illuminating the clip LED. Illuminated most of the time: Not normal; for cleaner sound, reduce the output of the amplifier and/or input signal to avoid thermal shutdown of the amplifier and possible speaker damage. If clipping persists at normal levels, check for shorted or abnormal load impedances. Normal indication: illuminates briefly at extreme output power peaks. Occasional clipping at high power levels may be normal. At power-on, the clip LEDs may briefly flash during turn-on muting. Continuous operation at high power may trigger thermal protection circuitry, shutting down the channel pair concerned. The CLIP LEDs for the channel pair will fully illuminate to indicate thermal protection activation. 8 17 OPERATION: GAIN CONTROLS Gain Controls The gain controls are located on the right side of the front panel. They are operated by rotating the control clockwise to increase gain or counterclockwise to decrease gain. When turned fully counterclockwise, gain is fully reduced and no output signal will be present. When turned fully clockwise, the voltage gain of the amplifier is +26dB and the output signal will potentially be full strength (provided the input is fully driven). The gain controls are detented in 21 steps for repeatable adjustment. Surrounding the Gain control, the power attenuation level is shown in dB. Each detent is approximately 1dB change in amplifier gain. To operate the gain control, rotate the control's knob so that the desired level is achieved. A small, flat-tipped screwdriver (#1 blade size) is typically used. Be sure not to use large screwdrivers as it is possible to damage the gain control by applying excessive torque. Gain controls are sensitive, electronic components and should be treated with care. Location of gain controls on the front panel of the CX168 Each channel pair's gain controls and indicator LED's are grouped together as shown, right. The channels are paired in the following manner: Channel Pair #1Channel Pair #2Channel Pair #3Channel Pair #4Ch. 8 As detailed in the `Setup' section of this manual, channels can only be paralleled and bridged within their channel pair. Example- Channel 3 can be bridged with channel 4 only; it can not be bridged with any other channel. Typical channel-pair control and indicator group on the CX168 The dB markings around the gain controls are attenuation. At 0db attenuation, the voltage gain of the amplifier is 26dB. If the gain control is set at the 7dB attenuation position, then the voltage gain of the amplifier is 19dB (26dB - 7 dB). Typical gain control showing attenuation level markings and LED's for the channel. [. . . ] If hum is a problem, try relocating cabling so that is away from power supplies, transformers and other magnetic field producing devices. 29 SPECIFICATIONS OUTPUT POWER in watts FTC: 8 ohms per channel (20 Hz. -20 kHz. , 0. 05% THD) 4 ohms per channel (20 Hz. -20 kHz. , 0. 1% THD) CX168 90 130 120 180 (100 watts, all channels driven) (140 watts, all channels driven) EIA: 8 ohms (1 kHz, 0. 1% THD, 1 channel driven) 4 ohms (1 kHz, 0. 1% THD, 1 channel driven) Bridged Mono: 16 ohms, 20 Hz. -20 kHz. , 0. 1% THD 8 ohms, 20 Hz. -20 kHz. , 0. 1% THD DYNAMIC HEADROOM 180 260 2 dB at 4 ohms DISTORTION SMPTE-IM Typical 20 Hz. -20 kHz. , 10 dB below rated power Typical 1 kHz. and below, full rated power Less than 0. 02% Less than 0. 05% Less than 0. 02% FREQUENCY RESPONSE +0. 0, -3. 0 dB: 8 Hz. ±0. 2 dB: 20 Hz. -20 kHz. DAMPING FACTOR >200 for 8 ohm load (5 kHz. and below) SIGNAL to NOISE (unweighted, 20 Hz. -20 kHz. ) -107 dB VOLTAGE GAIN (gain control set to 0 dB attenuation) 26 dB (20 X) INPUT SENSITIVITY for rated power into 8 ohms 1. 35 Vrms INPUT CLIPPING, Vrms 10 Vrms (+22 dBu) INPUT IMPEDANCE 10k ohms unbalanced , 20k ohms balanced 30 SPECIFICATIONS AMPLIFIER PROTECTION CX168 Full short circuit, open circuit, thermal, ultrasonic and RF protection. [. . . ]