Title: Audio compressor/limiter amplifier

Do you think this is a good invention? Vote now:

Votes so far: For:(0) Against:(0)
Claims: We claim:

1. An audio compressor amplifier comprising:

a. an audio amplifier circuit having an output and an input;

b. compressor means connected from the output to the input of said amplifier circuit for controlling the input of said amplifier circuit to compress signals at the output to a predetermined constant level in a predetermined attack time;

c. semiconductor means connected in said compressor means for decreasing the attack time when the output signal exceeds the predetermined constant level by a predetermined amount;

d. gain control feedback means connected from the output to the input of said amplifier circuit for controlling the gain thereof; and

e. semiconductor controlled circuitry connected to the output of said amplifier circuit and said gain control feedback means for controlling said gain control feedback means to reduce the gain of said amplifier circuit when a signal at the output exceeds a predetermined value in excess of the predetermined constant level.

2. An audio compressor amplifier as claimed in claim 1 wherein the audio amplifier circuit includes an operational amplifier.

3. An audio compressor amplifier as claimed in claim 2 wherein the gain control feedback means includes a first resistor.

4. An audio compressor amplifier as claimed in claim 3 wherein the semiconductor controlled circuitry includes a second resistor and a pair of diodes connected to be normally reverse biased and to be forward biased by a signal a predetermined value in excess of the predetermined constant level at the amplifier output, said diodes connecting said second resistor in parallel with said first resistor in the forward biased condition.

5. An audio compressor amplifier as claimed in claim 1 wherein the compressor means includes rectifying and filtering circuitry for converting an AC signal at the output of the amplifier circuit to a DC control signal and a transistor connected to the input of the amplifier circuit and controlled by the DC control signal for varying the amount of signal applied to the input of the amplifier circuit.

6. An audio compressor amplifier as claimed in claim 5 wherein the rectifying and filtering circuitry has a resistance in series therewith for providing a predetermined attack time in the compressor means and the semiconductor means includes a plurality of diodes connected in parallel with said resistance for bypassing said resistance with signals larger than a predetermined value in excess of the predetermined constant level.

7. An audio compressor amplifier as claimed in claim 6 wherein the plurality of diodes includes at least two diodes connected in series and the series circuit connected in parallel with the resistance in a first direction and at least two more diodes connected in series and the series circuit connected in parallel with the resistance in a second direction for bypassing signals of either polarity.

8. An audio compressor amplifier comprising:

a. an operational amplifier having an output and an input;

b. rectifying and filtering circuitry for converting an AC signal at the output of said operational amplifier to a DC control signal and a transistor connected to the input of said operational amplifier and controlled by the DC control signal for varying the amount of signal applied to the input of said operational amplifier to compress signals at the output to a predetermined constant level;

c. first resistance means in series with said rectifying and filtering circuitry for providing a predetermined attack time and a plurality of diodes connected in parallel with said first resistance means for bypassing said first resistance means with signals larger than a predetermined value in excess of the predetermined constant level;

d. second resistance means connected from the output to the input of said operational amplifier for controlling the gain thereof; and

e. semiconductor controlled circuitry including third resistance means connected to the output of said operational amplifier and to said second resistance means for connecting the third resistance means in parallel with said second resistance means to reduce the gain of said operational amplifier when a signal at the output exceeds a predetermined value in excess of the predetermined constant level.

Other info:

Inventors: Campbell, Whitney Robertson (Elk Grove Village, IL, US)
Fardoux, Raymond Maurice (Wilmette, IL, US)

Application Number: 591388
Filing Date: 1975-06-30
Publication_date: 1976-10-12
Assignee: Motorola, Inc. (Schaumburg, IL)
Primary Class(es): 333/14 327/309, 327/312, 327/330, 330/141, 330/145, 330/278
Other Classes:
US Patent Ref:

3021489	Feb, 1962	Nielsen	330/141.
3576451	Apr, 1971	Markow	307/237.
3790896	Feb, 1974	Shimizu et al.	330/29.

Other Refs:
Primary Examiner: Zazworsky, John
Assistant Examiner:
Attorney: Gillman; James W., Parsons; Eugene A., Lee; Sang Ki