Abstract: A cartridge box which holds a plurality of cartridges in spaced apart relation to each other and prevents them from rattling while entirely enclosed in the box. A cover for the box can be partially opened for exposing a predetermined number of the cartridges and novel means is provided for moving the exposed cartridges into a position where they can be readily removed from the box without disturbing the remaining cartridges. The novel cartridge moving means includes a cartridge carrier that has a plurality of spaced apart openings that are inclined from the vertical so as to incline the cartridges and make them more readily accessible for removal.

Abstract: A method of determining the physical location of undesired resonance zones induced by acoustic feedback in a spring reverberation unit and damping the vibration of these resonance zones. The improved spring reverberation unit with damping material located at the resonance points of the unit produces a reverberated audio signal which is substantially free from the screeching and howling caused by acoustic feedback.

Abstract: A variable resistance control comprising a variable resistance control portion and a stabilizer assembly portion. The variable resistance control portion is provided with a housing, a resistance element and a contactor supported within the housing with the contactor wipably engaging the resistance element, and an adjustment member operatively connected to the contactor and exposed on the exterior of the housing. The stabilizer assembly portion comprises a stabilizer having weight greater than the weight of the variable resistance portion and having a threaded bushing. An aperture extends through the stabilizer and the bushing and an extension shaft is rotatably received in the aperture with one end extending outwardly from the aperture cooperatively engaging the adjustable member. A U-shaped plate having a bight portion and a pair of arms secures the stabilizer to the housing.