Multi channel audio system with crossover network feeding separate amplifiers for each channel with direct coupling to low frequency loudspeaker

Claim 2

In an audio frequency reproduction system of the type which produces sound waves in three adjacent frequency ranges from three separate loudspeakers in response to an audio frequency signal the combination comprising a frequency dividing network connected to respond to said signal, said network including a capacitor and a resistor in a first series circuit connected to receive said signal and a capacitor and resistor in a second series circuit connected across the resistor of said first series circuit, a differential amplifier connected across the capacitor of said first series circuit to amplify the low frequency component signal for energizing the low frequency loudspeaker, another differential amplifier connected across the capacitor of said second series circuit to amplify the middle frequency component for energizing the mid-range loudspeaker, and an amplifier connected across at least a portion of the resistor of said second series circuit to amplify the high frequency component signal for energizing the high frequency loudspeaker.

Claim 3

An audio frequency reproduction system as set forth in claim 1 in which the differential amplifier connected to amplify the low frequency component signal is a direct coupled amplifier.

Claim 4

An audio frequency reproduction system as set forth in claim 1 in which all of said amplifiers are direct coupled differential amplifiers each having a d.c. feedback path connecting the output of the amplifier to its inverting input through a feedback resistor and the circuit of the inverting input of said amplifier includes an isolating resistor for isolating the feedback signal from the frequency dividing network.

Claim 5

An audio frequency reproduction system as set forth in claim 3 in which each of the output stages of said amplifiers includes a series connected current limiting resistance in its output current path which increases its resistance value as the output current exceeds that predetermined value which will tend to overload the output stage so that the distortion due to overload is reduced.

Claim 6

An audio frequency reproduction system as set forth in claim 3 in which the input circuit to the inverting input of the amplifier for the low frequency component signal includes resistive coupling to ground from its isolating resistor with the inverting input being obtained from an adjustable tap on said resistive coupling to provide the desired tonal balance between the loudspeaker outputs in the several frequency ranges.

Claim 7

An audio frequency reproduction system as set forth in claim 1 which includes a variable tap for modifying the portion of the resistor in said second series circuit across which the amplifier for amplifying the high frequency component signal is connected for selectively varying the signal level of the high frequency component with respect to the middle frequency component signal. and in which the connecting path of the differential amplifier across the capacitor of the first series circuit which supplies an input signal to the inverting input of the amplifier includes a. a resistor connecting said input to ground, b. a variable tap on said resistor, and c. means connecting said variable tap to the inverting input of said differential amplifier whereby adjustment of said tap varies the signal level of the low frequency component signal with respect to the middle frequency component signal.

Claim 8

In an audio system of the type which produces sound waves in adjacent frequency ranges from separate ones of a plurality of loudspeakers in response to an audio frequency signal, the combination comprising a frequency dividing network responsive to said audio frequency signal so as to divide the audio frequency signal into separate component signals in adjacent frequency ranges having complementary frequency characteristics in the overlapping frequency regions, said frequency dividing network including, a first series circuit including a first capacitor and a first resistor; and a second series circuit including a second capacitor and a second resistor with the second series circuit being connected across said first resistor; a loudspeaker for each of said component signals, and means connecting each of said component signals produced by the frequency dividing network to a corresponding loudspeaker, the connecting means for the low frequency loudspeaker being a differential amplifier connected across said first capacitor and having a non-reactive output circuit, the connecting means for the mid-range loudspeaker being a differential amplifier connected across said second capacitor, and the connecting means for the high frequency loudspeaker being an amplifier connected across said second resistor.

Claim 9

In an audio system of the type which produces sound waves in adjacent frequency ranges from separate ones of a plurality of loudspeakers in response to an audio frequency signal, the combination comprising a frequency dividing network responsive to said audio frequency signal so as to divide the audio frequency signal into separate component signals in adjacent frequency ranges having complementary frequency characteristics in the overlapping frequency regions, said frequency dividing network including, a first series circuit including a first capacitor and a first resistor; and a second series circuit including a second capacitor and a second resistor with the second series circuit being connected across said first resistor; a loudspeaker for each of said component signals, and means connecting each of said component signals produced by the frequency dividing network to a corresponding loudspeaker, the connecting means for the low frequency loudspeaker being a differential amplifier connected across said first capacitor and having a non-reactive output circuit, the connecting means for the mid-range loudspeaker being a differential amplifier connected across said second capacitor, and the connecting means for the high frequency loudspeaker being an amplifier connected across said second resistor.

Claim 10

In an audio system of the type which produces sound waves in adjacent frequency ranges from separate ones of a plurality of loudspeakers in response to an audio frequency signal, the combination comprising a frequency dividing network responsive to said audio frequency signal so as to divide the audio frequency signal into separate component signals in adjacent frequency ranges having complementary frequency characteristics in the overlapping frequency regions, said frequency dividing network including a series circuit having a first and second resistor with a capacitor connected therebetween to provide for two frequency ranges, a loudspeaker for each of said component signals, and amplifier means connecting each of said component signals produced by the frequency dividing network to a corresponding loudspeaker, the amplifier connecting the low frequency component signal to the low frequency loudspeaker having a non-reactive output circuit and being connected between the junction of said capacitor and said first resistor and the side of said second resistor away from said capacitor, and the amplifier connecting the high frequency component signal to the high frequency loudspeaker being connected across at least a portion of said second resistor with one connection being made to the side of said second resistor away from said capacitor.

Claim 11

In an audio system of the type which produces sound waves in adjacent frequency ranges from separate ones of a plurality of loudspeakers in response to an audio frequency signal, the combination comprising a frequency dividing network responsive to said audio frequency signal so as to divide the audio frequency signal into separate component signals in adjacent frequency ranges having complementary frequency characteristics in the overlapping frequency regions, said frequency dividing network including a series circuit having a first and second resistor with a capacitor connected therebetween to provide for two frequency ranges, a loudspeaker for each of said component signals, and amplifier means connecting each of said component signals produced by the frequency dividing network to a corresponding loudspeaker, the amplifier connecting the low frequency component signal to the low frequency loudspeaker having a non-reactive output circuit and being connected between the junction of said capacitor and said first resistor and the side of said second resistor away from said capacitor, and the amplifier connecting the high frequency component signal to the high frequency loudspeaker being connected across at least a portion of said second resistor with one connection being made to the side of said second resistor away from said capacitor.

Claim 12

An audio system for producing from an audio frequency signal a plurality of separate component signals in adjacent frequency ranges so that each signal is operable to energize a separate loudspeaker comprising, a series circuit having a resistor and a capacitor to form a frequency dividing network responsive to said audio frequency signal for dividing said audio frequency signal into component signals in adjacent frequency ranges, a differential amplifier having its differential inputs connected across said capacitor for connecting one component signal to a corresponding loudspeaker, said differential amplifier having a non-reactive output circuit, and an amplifier connected across at least a portion of said resistor for connecting another component signal to a corresponding loudspeaker.

Claim 13

An audio system for producing from an audio frequency signal a plurality of separate component signals in adjacent frequency ranges so that each signal is operable to energize a separate loudspeaker comprising, a series circuit having a resistor and a capacitor to form a frequency dividing network responsive to said audio frequency signal for dividing said audio frequency signal into component signals in adjacent frequency ranges, a differential amplifier having its differential inputs connected across said capacitor for connecting one component signal to a corresponding loudspeaker, said differential amplifier having a non-reactive output circuit, and an amplifier connected across at least a portion of said resistor for connecting another component signal to a corresponding loudspeaker.