RCA BK-11A Ribbon Microphone #VK01971 (Vintage)

Product Description

The RCA BK-11A is a classic ribbon microphone. Great on horns, guitars, vocals. Rich lows, silky smooth mids and highs. A must have for every mic locker - from RCA, the inventors of the ribbon mic.

History

A ribbon mic works by suspending a thin piece of corrugated aluminum, (the 'ribbon'), between two poles of a magnet. The compression and rarefaction of air vibrates this ribbon in the magnetic field, which creates voltage changes that are run through an output transformer to the external amplifier of your choice. Like a dynamic mic, a ribbon requires no tubes, batteries or power supply of any kind. In the case of the RCA BK-11A, the chassis is built to absorb mechanical shocks, the output transformer is shielded against magnetic fields, and the capsule is resistant to changes in humidity and temperature.

The BK-11A was the final production ribbon microphone from RCA. As such, it distills all the quality and expertise that RCA gained from decades of ribbon mic production. From the original brochure:

"The BK-11A is intended primarily for AM, FM, and TV studio use where a microphone of highest quality reproduction is desired. It is a dependable, bi-directional microphone free of the effects of cavity resonance, diaphragm resonance and pressure doubling. The BK-11A is well shielded against stray magnetic fields and can perform satisfactorily in high hum fields. Acoustically designed, sturdy stainless steel screens protect the microphone from mechanical injury. Internal shock and vibration isolation is provided between the case and the element. The microphone is supported by a swivel mounting which permits a 45 degree forward or backward tilt."

The frequency response of the BK-11A is from 30 Hz to 15 kHz, with an output impedance of either 30, 150 or 250 Ohms. A three-position switch allows for recording voice or music, with an accompanying bass roll-off in the 'Voice' position to diminish the proximity effect.