User manual AUSTRALIAN MONITOR AMIS CL2

[. . . ] Caution: To prevent electric shock do not use this (polarised) plug with an extension cord, receptacle or other outlet unless the blades can be fully inserted to prevent blade exposure. To prevent electric shock, match wide blade of plug to wide slot, fully insert. AMISCL2 INSTALLATION & OPERATION MANUAL PAGE 3 FRONT PANEL 1 3 2 14 1 POWER SWITCH This switches the mains power "on" to the unit. 2 COMPRESSOR/LIMITER SECTION Refer to inset box immediately opposite. 3 EXPANDER/GATE THRESHOLD This control adjusts the threshold level of the expander/gate within a range from off (bypass) to +10dB. The Red LED glows when expansion occurs. ENHANCER 4 5 6 8 7 9 10 12 11 13 COMPRESSOR LIMITER SECTION 4 THRESHOLD This controls threshold at which compression will start to occur. [. . . ] Note that the ring of the insert point is the send and the tip is the receive. AMISCL2 INSTALLATION & OPERATION MANUAL PAGE 5 SET UP AND OPERATION the threshold, the signal is reduced in level, relative to the amount the signal exceeds this point. This gain reduction is set by the ratio control. Generally, threshold levels for compressors are set below the normal operating level to allow for the upper dynamics to be musically compressed. For limiters, the threshold point is set above the normal operating level ini order to provide reliable signal limiting and thus protect subsequent equipment. EXPANDERS/NOISEGATES Audio, in general, is only as good as the source from which it was derived. The dynamic range of signals will often be restricted by noise. Synthesisers, effects devices, guitar pickups, amplifiers etc generally produce a high level of noise, hum or other ambient background hiss, which can disturb the quality of the program material. Normally these noises are inaudible if the level of the desired signal lies significantly above the level of the noise. This perception by the ear is based on the "masking" effect: noise will be masked and thus becomes inaudible as soon as considerably louder sound signals in the same frequency band are added. Nevertheless, the more the level that the desired signal decreases, the more the noise floor becomes a disturbing factor. Expanders or noisegates offer a solution for this problem: these devices attenuate signals when their amplitudes drop, thereby fading out the background noise. Reliant on this method, gain controlling amplifiers, like expanders, can extend the dynamic range of a signal and are therefore the opposite of a compressor. In practice, it is shown that an expansion over the entire dynamic range is not desired. With an expansion ratio of 5:1 and a processed dynamic range of 30dB, an output dynamic range of 150dB will be the result, exceeding all subsequent signal processors, as well as human hearing. Therefore, the amplitude control is restricted to signals whose levels are below a certain threshold. Signals above this threshold pass through the unit unchanged. Due to continuous attenuation of the signals below this threshold, this kind of expansion is termed "downward" expansion. The noisegate is the simplest form of an expander: in contrast to the expander, which continuously attenuates a signal below the threshold, the noise-gate cuts off the signal abruptly. In most applications this method is not very useful, since the on/off transition is too drastic. The onset of a simple gate function appears very obvious and unnatural. [. . . ] A limiter continuously monitors the signal and intervenes as soon as an adjustable level is exceeded. Any signal exceeding this threshold will be immediately reduced back to the adjusted threshold level. A compressor also monitors the program material continuously and has a certain threshold level. However, in contrast to the limiter, signals exceeding the threshold are not reduced abruptly but gradually. [. . . ]