Abstract: An audio processing system for maximizing the efficiency of transferring audio frequency signals. Signals to be processed are supplied to a bandpass input filter, then to a primary active frequency control. Its output drives a primary voltage compressor selectively limiting audio dynamics to a predetermined window, the latter being controllably preset and driven with different audio bands of amplitude determined by the primary frequency control to maximum compression levels indicated by a visual indicator. The output of the primary compressor is presented to a secondary active frequency control driving a secondary dynamic compressor with different audio bands. A second visual indicator indicates maximum compression levels of the latter. An automatic gain control (AGC) tied to the secondary compressor supplies feedback to the primary voltage compressor via AGC circuitry to control primary compression as a function of average, overall dynamic compression of the system.

Abstract: A chuck brake is secured to a hand-held reversibly rotatable drill of the variable speed type having a chuck. The chuck brake permits selective tightening or loosening of the chuck by operation of the drill. Brake shoes surround and are adapted to engage at least a portion of the peripheral surface of a housing of the chuck, being secured to the front of a drill on opposite sides of the chuck. The brake shoes are manually engageable by pinching action of the user for movement between a first position permitting free rotation of the chuck housing and a second position providing friction between the brake shoes and a first area of the chuck housing. In the second position, rotation of the chuck housing in one direction is impeded, as for tightening. The brake shoes are shiftable also toward the drill to a third position in which increased friction with the chuck housing is provided to impede rotation of the chuck housing in an opposite direction, as for loosening of the chuck.