CX168 8-Channel Installed Sound Professional Audio Amplifier User Manual *TD-000095-00* TD-000095-00 rev.
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. NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL.
TABLE OF CONTENTS INTRODUCTION: CX168 Overview .......................................................................................4 Front Panel Illustration .........................................................................................4 Rear Panel Illustration ........................................................................................5 Mounting Dimensions .........................................................................5 INSTALLATION: What is Included.....................
INTRODUCTION Congratulations on your purchase of the CX168 power amplifier. To help you obtain the best results from your purchase, we encourage you to carefully review this manual. With information including connections, configuration and operation, it offers many useful guidelines.
INTRODUCTION REAR PANEL DIMENSIONS AND MOUNTING POINTS 5
INSTALLATION: UNPACKING & RACK MOUNTING What is Included Your CX168 shipping container, as shipped from the factory, includes: - CX168 eight channel audio power amplifier - this user’s manual - security cover (plate) for gain controls - self-adhesive rubber feet (use for non-rack mount applications) - eight 3-pin terminal block input connectors - two 8-pin terminal block output connectors - #14AWG IEC-type detachable power cord Save the container and packing material so the amplifier may be shipped without
INSTALLATION: COOLING & AC MAINS REQUIREMENTS Fan Cooling The CX168 amplifier draws cool air into the rear of the amplifier and exhausts hot air from the front. This is done so the equipment in the rack stays as cool as possible. This method of cooling gives the operator “direct” air temperature feedback at the front of the rack, where it is the most convenient. The front panel’s temperature indicates “how hard” the amplifier is working.
SETUP: SETTING THE MODE CONFIGURATION DIP SWITCHES Setup By using the mode switches and connecting to the amplifier properly, the CX168 amplifier can be configured as a 1 to 8 channel amplifier. This flexibility enables the CX168 to be used for most any multichannel application. The CX168 can be thought of as four separate 2-channel amplifiers on one chassis. Each of the four amplifier sections may be operated in Stereo, Parallel, or Bridge mode independently of the others.
SETUP: SETTING THE MODE: STEREO, PARALLEL, OR BRIDGE Modes The following descriptions apply to a channel pair (such as Ch. 1 & 2 or Ch. 7 & 8). It is possible to set each channel pair’s mode differently and customize the system configuration. All possible combinations will not be shown.
SETUP: MODE SWITCHES: CLIP LIMITER AND LOW FREQUENCY FILTERS Clip Limiter The CX168 amplifier has separate clip limiters for each of the 8 channels. These clip limiters respond only to actual amplifier clipping. Amplifier clipping generates internal error signals which cause the clip limiter to quickly reduce gain and minimize the overdrive. To preserve as much of the program dynamics as possible, limiting occurs only during actual clipping.
SETUP: MODE SWITCHES: CLIP LIMITER AND LOW FREQUENCY FILTERS Low Frequency Filtering Tips: The OFF position should be used only for subwoofer systems with rated frequency response below 33 Hz. or if low frequency filtering is provided by other devices. Know the specification of the speaker cabinet you are driving. Match the low frequency roll off setting to the specified low frequency capability of the speaker cabinet. Do not drive the speaker with frequencies below its rating.
CONNECTIONS: INPUTS- Using the Terminal Block Inputs Each channel has an active balanced "Euro-style" terminal block input jack. These terminal blocks allow the input wiring to be terminated using simple hand tools and allows for quick reconfiguration when needed. The input impedance is 20k ohm balanced or 10k ohm unbalanced. Balanced connection is recommended for all audio inputs. Balanced signals are less prone to AC hum and other electrical noise.
CONNECTIONS: INPUTS- Using the DataPorts If used, the DataPort must be connected to a QSC DataPort product using a QSC DataPort cable. Do not use computer cables; they look similar but can cause operational problems with your amplifier and/or DataPort accessories. DATAPORT CONNECTORS The CX168 amplifier is equipped with four QSC DataPort connections that may be used for connecting to accessory QSC DataPort devices. Each DataPort services a specific channel pair; the channels are paired as: Ch. 1 and Ch.
CONNECTIONS: OUTPUTS Outputs Refer to the label on the rear panel of the amplifier for proper wiring connections. The output connection for STEREO and PARALLEL modes is on the left side of the label , while the output connection for BRIDGE mode is shown to the right side of the label. Note: Polarity changes from channel to channel and is different for bridge mode. Be certain of polarity of connections before applying power. Reversed polarity may degrade audio frequency response.
CONNECTIONS: OUTPUTS- USING THE TERMINAL BLOCK CONNECTORS OUTPUT TERMINAL SAFETY WARNING! Do not touch output terminals while amplifier power is on. Make all connections with amplifier turned off. Risk of hazardous energy! When selecting speaker cable (wire), always use the largest wire size and shortest length of wire practical for an installation. Larger wire sizes and shorter lengths minimize power loss and degradation of damping factor. Do not place speaker cables next to input wiring.
OPERATION: POWER SWITCH and GAIN CONTROLS Power Switch The power switch is a rocker-type switch. It is located on the left side of the front panel. To turn the amplifier on, push in on the top of the switch. To turn the amplifier off, push in on the bottom of the switch. The green power LED should light up when the switch is in the on position. When the power is switched off, the LED may takes several seconds to go out; this is normal.
OPERATION: LED INDICATORS LED Indicators The LED indicators provide basic operation information to the operator. The ‘normal’ indications of the LED’s are shown, below. NOTE! The BRDG and PAR mode indicator LED’s are discussed on page 9. POWER: The power ‘on’ indicator LED is located at the upper-left of the gain control cluster. It is green and illuminates when the power switch is set to the on position and AC power is present at the IEC cord receptacle.
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).
OPERATION: GAIN CONTROL SECURITY PLATE Gain Control Security Plate After final gain adjustments have been made, the gain controls can be covered with a security plate. This easy-to-use security plate makes it difficult for others to adjust the gain. This may be desirable in instances where the gain controls should not be tampered with. To install the security plate: 3. Line up the tabs with the keyed portion of the 1. Use a 9/64” or 3.
OPERATION: USING THE QSC DATAPORT CONNECTIONS DataPort Connectors QSC’s DataPort equipped amplifiers offer operators of larger audio systems a high degree of system monitoring and operation from remote locations. A system operator in a sports complex might be located hundreds of yards (meters) from the actual amplifiers, making ‘normal’ control and monitoring of the system difficult, at best.
OPERATION: USING THE QSC DATAPORT CONNECTIONS What Can I Connect to the DataPort? Consult your QSC representative for up-to-date accessory compatibility. QSC has several DataPort-based accessories available like the: CM16a Amplifier Controller & Monitor DSP-3 Digital Signal Processing Module DSP -30 Digital Signal Processor XC-3 Crossover SF-3 Subwoofer Filter LF-3 Low Frequency Filter DCM Crossovers & Monitors General Guidelines to using the DataPorts on the CX168 1. Each channel pair ( Ch.1-2, Ch.
APPLICATIONS: TYPICAL APPLICATION EXAMPLES Four Room Stereo Feed A simple application of the CX168 would be an installation with 4 rooms of coverage; each room to be provided with a stereo audio feed. All speakers are 4 ohm or greater impedance and have a frequency response rated down to 45 Hz., making them suitable for the 70 Hz. low frequency setting. Clip limiting will be used with these full-range speakers.
APPLICATIONS: TYPICAL APPLICATION EXAMPLES Tri-Amp’d Stereo Cabinets with Subwoofer Driven by Bridged Channel Pair (continued) Routing is a function of ‘easiest wiring’ order and is: LF Driver Left: Ch. 4 Mid Driver Left Ch. 3 HF Driver Left Ch. 2 HF Driver Right Ch. 1 Mid Driver Right Ch. 5 LF Driver Right Ch. 6 Subwoofer Bridge Ch. 7 & 8 MODE switch configuration: Ch.1/Ch.2 Mode: Ch.1 Clip Limiter: Ch.1 LF Filter: Ch. 2 Clip Limiter Ch. 2 LF filter Stereo ON OFF ON OFF Ch.3/Ch.4 Mode: Ch.
APPENDIX: DESCRIPTION OF STEREO & PARALLEL OPERATING MODES NOTE! In the following diagrams, channels 1 and 2 are shown as examples only. Any channel pair can be configured as shown here. The channels pairs on the CX168 are : Channels 1 and 2, Channels 3 and 4, Channels 5 and 6, and Channels 7 and 8. Therefore, in any example below, replace channel 1 and 2 with the channel pair numbers you are setting up. Stereo Mode: Each input signal is sent to its respective channel.
APPENDIX: DESCRIPTION OF BRIDGE OPERATING MODE Bridge Mode Bridge mode combines both output channels into one output. This mode is for driving a single, high-power-rated load with twice the “normal” voltage swing. This results in about 4 times the peak power and about three times the sustained power of a single channel. It is also common to call this bridge mono mode. When to use BRIDGE mode: Use BRIDGE mode when you need to deliver the power of two channels to a single 8 ohm load, such as a subwoofer.
APPENDIX: MULTIPLE SPEAKER LOADS IN SERIES Multiple Lo-Z Loads in Series: Series connection is where the same signal current flows through each of the speaker loads. The signal goes into one terminal of the first speaker and out its other terminal; then the signal goes into one terminal of the next load, and so on. If any of the speakers in a series-connected branch of a system fails, the signal is prevented from flowing through any of the loads (no sound).
APPENDIX: MULTIPLE SPEAKER LOADS IN PARALLEL Multiple Lo-Z Loads in Parallel: If each speaker load is connected across the same signal source (the output of the amplifier), then the loads are in parallel with one another. If one of the speakers fails in a parallel-connected system branch, the remaining speakers will continue to operate.
TROUBLESHOOTING: NO SOUND Problem: NO SOUND • INDICATION: POWER LED INDICATOR NOT ILLUMINATED • Check both ends of the AC line cord for proper connection. Both ends should be fully seated in their connectors. • Check that the AC outlet works by plugging in a known-good device or by testing with a voltmeter. If too many amplifiers are used on one outlet, the building's circuit breaker may trip and shut off power.
TROUBLESHOOTING: DISTORTION, NO CHANNEL SEPARATION, HUM, HISS, FEEDBACK 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, then that cable or speaker is shorted. Try another cable and speaker to locate and/or remove the fault.
SPECIFICATIONS CX168 OUTPUT POWER in watts FTC: 8 ohms per channel (20 Hz.-20 kHz., 0.05% THD) 90 EIA: 4 ohms per channel (20 Hz.-20 kHz., 0.1% THD) 130 8 ohms (1 kHz, 0.1% THD, 1 channel driven) 120 (100 watts, all channels driven) 4 ohms (1 kHz, 0.1% THD, 1 channel driven) 180 (140 watts, all channels driven) Bridged Mono: 30 16 ohms, 20 Hz.-20 kHz., 0.1% THD 180 8 ohms, 20 Hz.-20 kHz., 0.1% THD 260 DYNAMIC HEADROOM 2 dB at 4 ohms DISTORTION SMPTE-IM Less than 0.02% Typical 20 Hz.
SPECIFICATIONS CX168 AMPLIFIER PROTECTION Full short circuit, open circuit, thermal, ultrasonic and RF protection. Stable into reactive or mismatched loads.
WARRANTY INFORMATION & HOW TO CONTACT QSC WARRANTY (USA only; other countries, see your dealer or distributor) Disclaimer QSC Audio Products, Inc. is not liable for any damage to speakers, amplifiers, or any other equipment that is caused by negligence or improper installation and/or use of the ISA amplifier.
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QSC Audio Products, Inc. 1675 MacArthur Boulevard Costa Mesa, California 92626 USA “QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office. ©2000 QSC Audio Products, Inc.
