Gain control device for high fidelity audio systems

Claim 1

IN A HIGH FIDELITY AUDIO SYSTEM HAVING AN AUDIO SIGNAL SOURCE AND AN AMPLIFIER FOR AMPLIFYING THE AUDIO SIGNALS FROM SAID SOURCE, A GAIN CONTROL DEVICE FOR CONTROLLING THE DYNAMIC RANGE OF THE AUDIO SIGNALS IN SAID SYSTEM, SAID DEVICE COMPRISING A VOLTAGE DIVIDER CIRCUIT COUPLED BETWEEN THE OUTPUT OF SAID AUDIO SIGNAL SOURCE AND THE INPUT OF SAID AMPLIFIER FOR CONTROLLING THE VOLTAGE LEVEL OF THE AUDIO SIGNALS APPLIED TO SAID AMPLIFIER FROM SAID SOURCE, SAID CIRCUIT COMPRISING A RESISTOR SERIALLY COUPLED BETWEEN THE OUTPUT OF SAID SIGNAL SOURCE AND THE INPUT OF SAID AMPLIFIER, A LIGHT-DEPENDENT RESISTOR, AND SWITCH MEANS HAVING A FIRST SWITCH POSITION FOR CONNECTING SAID LIGHT-DEPENDENT RESISTOR TO SHUNT SAID FIRST-NAMED RESISTOR AND A SECOND SWITCH POSITION FOR CONNECTING SAID LIGHTDEPENDENT RESISTOR TO SHUNT THE INPUT TO SAID AMPLIFIER; A GASEOUS GLOW CONTROL LAMP OF THE TYPE ADAPTED TO RECTIFY AUDIO SIGNALS APPLIED THERETO; A LIGHTPROOF ENCLOSURE ENCLOSING SAID LIGHT-DEPENDENT RESISTOR AND SAID CONTROL LAMP; AND COUPLING CIRCUIT MEANS FOR COUPLING SAID CONTROL LAMP ACROSS THE OUTPUT OF SAID AMPLIFIER FOR ENERGIZATION THEREBY, WHEREBY WITH SAID SWITCH MEANS IN SAID FIRST SWITCH POSITION AN INCREASE IN THE AVERAGE SIGNAL LEVEL OF THE AUDIO SIGNALS AT THE AMPLIFIER OUTPUT CAUSES AN INCREASE IN THE VOLTAGE LEVEL OF THE AUDIO SIGNALS APPLIED TO THE AMPLIFIER INPUT, TO THEREBY INCREASE THE GAIN OF THE SYSTEM AND EXPAND THE DYNAMIC RANGE OF THE AUDIO SIGNALS, AND WITH SAID SWITCH MEANS IN SAID SECOND POSITION AN INCREASE IN THE AVERAGE SIGNAL LEVEL OF THE AUDIO SIGNALS AT THE AMPLIFIER OUTPUT CAUSES A DECREASE IN THE VOLTAGE LEVEL OF THE AUDIO SIGNALS APPLIED TO THE AMPLIFIER INPUT, TO THEREBY DECREASE THE GAIN OF THE SYSTEM AND COMPRESS THE DYNAMIC RANGE OF THE AUDIO SIGNALS.