The RCA Type 77-B Uni-Directional Microphone MI-4042
Hear the sound of the Type 77-B voiced by Tom Booth.
Blue-background photos are courtesy of Trevor Cousineau
Mr. Cousineau observes:
This microphone’s elegant, dramatic black-and-chrome art deco style was the first of the iconic pill-shaped designs that followed the artillery-shell-shaped monster that was the original Type 77-A. The Type 77-B and its descendants (the 77-B1, 77-C, 77-C1, 77-D and the 77-DX) have become the universal icon for classic microphone design recognized throughout the world.
The original Type 77-B was significantly smaller than previous RCA designs due to improvements in the magnetic materials used for the large permanent magnets required by all ribbon microphone designs.
The RCA 77-B was introduced in 1937. Only a few were manufactured until it was replaced by the Type 77-B1.
Like its predecessor the Type 77-A, the 77-B was unusual in that it featured two different types of ribbons in series with each other: One was a velocity ribbon, and the other was a pressure ribbon. RCA claimed that the combination of the two types of ribbons resulted in a perfect cardioid pattern and more uniform frequency response. The next version in the series, the Type 77-C, featured a switch that allowed selecting between one or the other or both ribbons.
“The RCA Uni-Directional Microphone of entirely new design. Uses the exclusive RCA principle of two ribbons (one pressure activated, one velocity activated) in series, to obtain a nearly perfect cardioid pattern and uniform frequency response. This is an excellent microphone that assures good pick-ups under high reverberatory conditions. Particularly good for stage use. Picks up all sounds from the stage, excluding audience and house noises. $130.”
Quoted from a 1938 RCA advertisement. There are no microphones for sale on this site.
Download the specification sheet for this mic. Price is shown for historic purposes only. Microphones on this site are not for sale.
