The RCA Type 77-B
Blue-background photos are courtesy of Trevor Cousineau
Mr. Cousineau observes:
This microphone’s elegant and dramatic black-and-chrome art deco design 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 first introduced in 1937 and 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.
Four small photos are courtesy of Allen Boaz
- Frequency Range: 40 to 10,000 cycles
- Output Level: –63 dB (10-bar open circuit)
- Output Impedance: 50 and 250 ohms
- Cable: 30 feet (less plug)
- Finish: Chromium and black
- Fitting: ½-inch pipe thread
- Net Weight: 2 pounds
- Dimensions: 8″ long, 2½″ diameter, 3¾″ wide (at mount)
“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.
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