User manual AUSTRALIAN MONITOR AM1200

[. . . ] AM1200 Operation Manual IMPORTANT! Please read carefully. This operation manual contains important information regarding safety precautions, installation, performance, operation and maintenance of your AM1200 power amplifier. You should familiarize yourself with the contents of this manual before operating your amplifier. Safety Precautions and Labelling The rear panel of the unit has a number of markings and internationally recognized symbols related to the hazards and precautions that should be taken when operating MAINS connected equipment. The presence of a LIGHTNING FLASH with an arrowhead contained within the boundaries of an equilateral triangle is intended to alert the user that dangerous uninsulated voltages may exist within the unit's enclosure. These voltages may be of a sufficient magnitude as to constitute the risk of an electrical shock. [. . . ] When you power up your amplifier, your amplifier goes through an establishment period before it will accept signal. The Inrush Current Suppression (ICS) circuit is in operation for the first 0. 5 seconds. This limits the mains current to prevent "nuisance tripping" of circuit breakers. During this period the THERMAL LED will flash red whilst the mains voltage gradually charges up the power supply. You will then hear a relay "click", indicating mains is now directly applied to the amplifier. While the ICS circuit operates there is also a 30dB mute on the signal input. After two seconds this mute will release, allowing any applied signal to pass unattenuated. When switching the amplifier off, wait a couple of seconds before switching the unit on again. This allows the ICS circuit to reset. Level Matching The normal operating position for the attenuator is the "0 dB" position (fully clockwise, no attenuation). Turning the attenuator back (anticlockwise) reduces the input sensitivity by the amount marked on the attenuator scale (dial). NOTE: If full power output is required you should operate your amplifier with the front panel attenuator above the -15dB position, otherwise clipping of the input circuitry and its resultant distortion will occur before full output power is achieved. Very Important Due to the high power ability of the AM1200 you need to be aware that certain precautions need to be followed to ensure longevity of your amplifier: Sensitivity Your amplifier is a linear device operating with a fixed input to output voltage gain (less attenuation). The maximum output voltage swing is determined by the applied mains voltage, load, load type and the duty cycle of the applied signal. The input sensitivity for your amplifier when the attenuator is at the "0" dB attenuation position (fully clockwise) is nominally: +3. 0dBu (1. 10volts in) for rated power into a 8 ohm load. +1. 6dBu (0. 93 volt in) for rated power into a 4 ohm load. - Never turn your amplifier on unless all connections (inputs and speakers) have been made! - Never plug in a signal lead after the amplifier has been turned on!- Never drive the output into clipping if the load is open circuit or there is no speaker load connected! Powering Up REMEMBER The amplifier should be the last piece of equipment that you turn on and the first piece of equipment that you turn off. We recommend turning the attenuators on your 14 Operation Each channel of your amplifier has a nominal balanced input impedance of 18k Ohms (@1kHz) and should not present a difficult load for any signal source. the equipment feeding the amplifier) should have an output impedance of 600 Ohms or lower to avoid unwanted high frequency loss in the cabling. This voltage difference between the amp earth and source equipment earth appears to the amplifier's input as a signal and is amplified as hum. Ensure your mains power for the audio system is "quiet" i. e. without equipment on it such as airconditioning, refrigeration or lighting which may generate noise in the earth circuit. Ensure all equipment within the system shares a common ground/ safety earth point. This will reduce the possibility of circulating earth currents as the equipment will be referenced to the same ground potential. [. . . ] The fan blades are accessible once the lids are removed and can be easily cleaned. You need only hold the fan rotor still and wipe the dust off the blades. Many users stall the fan and use Fuses There are eight (8) rail fuses provided on the back panel of the unit. These rail fuses are in series with the positive and negative output supply to each amplifier channel and provide overall protection for the output stage. [. . . ]