FM Systems Audio Level Master Audio AGC.(Single Channel)

The ALM771 AUDIO LEVEL MASTER regulates audio program level so that the sound volume as perceived by the human ear will be consistent even when the source program material differs in amplitude by as much as 25dB. This 300:1 input power variation is corrected to within 0.5dB of the desired audio level.

Each ALM771 regulates the audio power level of one monaural channel. Two ALM771 modules can be connected together with a control jumper wire to enable them to be operated in synchronism to control the level of a Stereo signal.

The ALM771 AUDIO LEVEL MASTER incorporates a Program- Dependent Gating System to insure that a background sound remains at a constant level even during pauses in foreground speech. Program-Dependant Loudness Control Time Constants insure that sudden short term sound impulses such as gun-shots or door-slams do not affect background sound levels. The dual Frequency Band Control systems also insure that pulses of low frequency sound do not cause pumping of higher frequency program material. In short, the ALM771 will establish a consistent audio output level even when the input from various program sources changes by as much as 25dB. All this without noise pumping, program pumping, ducking or any other artifact resulting from level control being exerted by the AUDIO LEVEL MASTER.

The ALM771 does not occupy any front panel rack space. The module is fully shielded against RF interference and is only 1-1/2" x 3-1/2" x 4-1/2" in size. The ALM771 is supplied with a bracket that enables attachment to the mounting rails at the rear of an equipment rack so that the ALM771 may be retro-fitted into otherwise fully occupied equipment racks.