1-8
Model 820 Components
Model 820 Technical Reference Manual
As can be seen, the standard Model 820 includes the
following:
• Model PRM828 is a 5 1/2 inch precision preamplifier
using a standard 5 pin SwitchCraft™ connector and may
be extended up to 20 feet with EXCXXX microphone
cable. The preamplifier is removed by depressing the small
black latch button with a fingertip, while gently pulling it
away from the mating connector.
• A two-line, 32-character, high-contrast LCD display.
• One of the 1
⁄
2 inch precision air condenser microphones in
Table 1-1, “Microphones for use with 820,” on page 1-8.
The microphones are rugged and reliable but should be
kept in their protective case when not in use. Avoid unnec-
essary shock (Although an Larson Davis microphone can
usually survive being dropped, it is a delicate, precise
transducer that should be handled with care).
Keep clean and protect from con-
densing moisture and water. The
microphone’s ultra-thin diaphragm
is covered by a protective grid
which should not be removed in
normal use. Rain droplets or other
foreign matter on the diaphragm
may alter the microphones’s
Microphone
Type
Sensitivity
mV/Pa
Bias
2540
Free-field
14.5
Voltage Required
2541, 377B41
Free-field
44.5
Voltage Required
377B02
Free-field
50.0
Prepolarized
377A20
Random
50.0
Prepolarized
2559
Random
12.9
Voltage Required
2560, 377A60
Random
45.2
Voltage Required
Table 1-1
Microphones for use with 820
