?
Did You Know ?
Capsule Backplates
The original K87 capsule on the U87 was
manufactured with electrically-isolated
backplates and since the capsule was a
dual-diaphragm design, it came with 4
terminals.
When the circuit design was changed to
the U87a version in 1986, the capsule was
switched to the K67 as used in the
famous U67 tube microphone
manufactured prior to the U87.
The K67 was also a dual-diaphragm
design but unlike the K87, the backplates
were not isolated from each other and
therefore came with only 3 terminals.
This difference in design affects the
polar pattern mechanism of the switch
circuit but the capacitance of both
capsules remains the same at 50pF per
diaphragm.
26
K87
K67
