The SP75 Speech Processor is designed to provide an increase in average power and readability of a single sideband voice signal during weak signal or high interference conditions. The SP75 is connected between the microphone and microphone input of the single sideband transmitter, thus requiring no modification of the existing transmitter or transceiver. A front panel switch allows the processor to be switched in or bypassed as conditions warrant. Two additional inputs, such as a tape player or phone patch, may be front panel selected in place of the normal microphone input. The amount of RF envelope clipping is adjustable between zero and twenty decibels by a front panel control. A LED indicates proper audio input level. Because of the pre-clipping audio compression, small changes in voice levels do not widely affect the clipping level. Muting circuitry reduces gain during speech pauses, thus reducing undesirable background noise pickup and allowing VOX operation with the processor on. The SP75 was designed for optimum performance using the Drake model 7077 microphone and the Drake TR7 transceiver or Drake 4-line transmitters. However, excellent performance can be obtained with most other transmitters which have a microphone input impedance of approximately 50 K ohm or greater. Microphones other than the Drake 7077 may be used successfully. However, microphones with a more sharply rising frequency response may produce a less pleasant response than a microphone with a flatter response.