The Radial Engineering StageBug SB-7 Earmuff Headphone Silencer is especially useful for overdubbing applications such as when scoring a film with an orchestra. Typically, recording an orchestral musical score involves sending a pre-recorded track via headphones to each musician which they then overdub. In order to hear both the pre-recorded track and the sound of their live instruments, such as a violin, the musician will often remove one of the headphones. As the volume of the headphone is increased, bleed from the headphone that is removed gets picked up by the microphone and contaminates the recording.

This entirely passive device allows the musician to push a switch and sum the left and right headphone channels to a mono signal output on the right headphone. It also provides a passive attenuation knob for the headphone mix. For inputs the unit features a stereo 1/4" input. For outputs it offers the option of both a 1/4" headphone as well as an 1/8" earbud output.

The device is constructed from 14 gauge steel to help reduce the detrimental effects of electromagnetic interference. The double-sided circuit board is military grade with steel stand-offs and through-hole solder points for improved durability, and the switches are rated to over 20,000 cycles. The insulated connectors are made from glass-filled nylon with tarnish-free nickel contacts to reduce noise.