User manual CREST AUDIO PRO SERIES

[. . . ] PROFESSIONAL POWER AMPLIFIERS Clip/Limit Signal Temp/DC -6 -10 -15 -30 -80 -1 0dB -3 7301 Professional Power Amplifier 10004 Professional Power Amplifier Active -10 -15 -30 -80 -6 -3 -1 0dB LOWS HIGHS Clip/Limit Signal Temp/DC Clip/Limit Signal Temp/DC Active -6 -6 -3 -10 -15 -1 0dB -30 -80 -1 0dB -3 -10 -15 -30 -80 -1 0dB -6 -3 Clip/Limit Signal Temp/DC -6 -10 -15 -30 -80 -1 0dB -3 7001 Professional Power Amplifier -6 -10 -15 -3 Active -10 -15 -1 0dB -30 -80 Active -10 -15 -30 -80 -6 -3 -30 -80 Ch A -1 0dB Ch B Ch C Ch D Ch A Ch B 10001 Professional Power Amplifier Clip/Limit Signal Temp/DC -6 -10 -15 -30 -80 -1 0dB -3 6001 Professional Power Amplifier Active -10 -15 -30 -80 -6 -3 Clip/Limit -1 Clip/Limit Signal Temp/DC Active -6 -10 -15 -3 Signal 0dB Ch A Ch B Temp/DC Active Clip/Limit Signal Temp/DC -6 -10 -15 -30 -80 -1 0dB -3 4801 Professional Power Amplifier -6 -10 -15 -30 -80 -1 0dB -3 -30 -80 -1 0dB Active -10 -15 -30 -80 Ch A -6 -3 Ch B -1 0dB Ch A Ch B 9001 Professional Power Amplifier Clip/Limit Clip/Limit Signal Temp/DC -6 -10 -15 -30 -80 -1 0dB -3 4601 Professional Power Amplifier Signal Temp/DC Active Active -10 -15 -30 -80 -6 -3 -10 -15 -6 -3 -10 -15 -1 0dB -30 -80 -6 -3 -1 0dB -30 -80 -1 0dB Ch A Ch B Ch A Ch B Clip/Limit Signal Temp/DC -6 -10 -15 -30 -80 -1 0dB -3 3301 Professional Power Amplifier 8001 Professional Power Amplifier Clip/Limit -3 Active -10 -15 -30 -80 -6 Signal -1 0dB Temp/DC Active -6 -10 -3 -10 -15 -1 0dB -30 -80 -1 0dB -6 -3 Ch A Ch B Clip/Limit Signal Temp/DC -6 -10 -15 -30 -80 -1 0dB -3 MA7120 Professional Power Amplifier -15 -30 -80 Ch A -6 -10 -3 Ch B Active -15 -30 -80 -1 0dB MA9130 Clip/Limit Professional Power Amplifier Ch A Ch B Signal Temp/DC Active -6 -6 -3 -10 -15 -1 0dB -30 -80 -1 0dB -3 -10 Clip/Limit Signal Temp/DC -6 -10 -15 -30 -80 -1 0dB -3 MA5850 Professional Power Amplifier Active -10 -15 -30 -80 -6 -3 -15 -30 -1 0dB -80 Ch A Ch B Ch A Ch B OWNER'S MANUAL Including MA Series Amplifiers Important Precautions This symbol is used to alert the operator to follow important operating procedures and precautions detailed in documentation. 10. Power down & disconnect units from mains voltage before making connections. Never hold a power switch in the "ON" position if it won't stay there itself!Do not use the unit near stoves, heat registers, radiators, or other heat producing devices. [. . . ] Active LED The Active LED indicates that its channel's output relay is closed and the channel is operational. It lights under normal operation and remains on even when the channel is in clip limiting or IGM gain reduction. These are protection features which leave the output relay closed. If the Active LED goes off, there is no signal at the module output point. Protection Features Professional Series amplifiers incorporate several circuits to protect both themselves and loudspeakers under virtually any situation. Crest Audio has attempted to make the amplifiers as foolproof as possible by making them immune to short and open circuits, mismatched loads, DC voltage, and overheating. If a channel goes into the clip limiting or IGM gain reduction mode, the speaker load remains connected, but clipping percentage or output power are instantly reduced. When a problem occurs that causes a channel to go into a protection mode, the Temp/DC LED for that channel will glow. DC voltage on the output, excessive subsonic frequencies, or thermal overload will cause the channel's output relay to disconnect the speaker load until the problem is corrected or the amplifier cools down. Clip Limiting Any time a channel is driven into hard, continuous clipping, the clip limiter circuit will automatically reduce the channel gain to a level just slightly into clipping, guarding the speakers against the damaging high power continuous square waves that may be produced. Situations that may activate the clip limiter include uncontrolled feedback, oscillations, or an improper equipment setting or malfunction upstream from the amplifier. Normal program transients will not trigger the clip limiter; only steady, excessive clipping will. The Clip/Limit LED will glow brightly and continuously when limiting occurs. IGM Impedance Sensing Professional Series amplifiers feature innovative circuitry that allows safe operation into any load. When an amplifier sees a load that overstresses the output stage, the Instantaneous Gain Modulation (IGM) circuit adjusts the channel gain to a safe level. This method of output stage protection is far superior to conventional, brute force type limiting found on other amplifiers. Like the clip limiter, the IGM circuit is sonically transparent in normal use and unobtrusive when activated. Crest Audio Pro Series Power Amplifiers Page 13 Thermal Protection The internal fan(s) will keep the amplifier operating well within its intended temperature range under all normal conditions. If a channel's heat sink temperature reaches 75°C, (85°C for Models 7001 and 8001) which may indicate an obstructed air supply, clogged air filter, etc. , that channel will independently protect itself by disconnecting its load and shutting down until it has cooled to 72°C ( 82°C for Models 7001 and 8001). During this time, the channel's DC/Temp LED will light. If the power transformer gets too hot, its thermal sensing circuit will disconnect both channel outputs. Normal operation will resume automatically once the transformer cools to a safe level. During this time, the Active LED will extinguish, the Temp/DC and Clip/Limit LED's will stay lit, and the cooling fan will stay running. Short Circuit If an output is shorted, the IGM and thermal circuits will automatically protect the amplifier. [. . . ] Power figures are watts per channel, both channels driven. Crest Audio reserves the right to make improvements in manufacturing or design which may affect specifications. Crest Audio specification literature is available in down- Appendix D Crest Audio Pro Series Power Amplifiers MA7120 8 Bridged Mono Power 4 Bridged Mono Power Max RMS Output Voltage (bridged) Peak Output Voltage (bridged) Frequency Response (+0 / -0. 3dB, 1W/8) Power Bandwidth (rated power at 4, 1% THD+N) Protection Circuitry THD+N (rated power, 1kHz) SMPTE IMD (rated power at 8, 60Hz & 7kHz) Damping Factor (10-400Hz at 8) Input CMRR (1kHz) Input Sensitivity (rated power at 4 bridged ) Voltage Gain Input Impedance (balanced) Hum and Noise ("A" weighted, full power, 4) Crosstalk ("A" weighted, full power, 4) Class Input Connectors (per channel) Output Connectors (per channel) Filter Storage Power Supply (factory configured) Idle Current Draw (120V) 1/8 Power Curr. Draw (typical music, 120V/4) 1/3 Power Curr. [. . . ]