Casella CEL CEL-393 - Manual (Page 42)

When using the auxiliary input on the B version, attention is drawn to the
overall frequency response of the instrument, as described in Section
5.2.2.
4.6 Alternative Microphones & Preamplifiers
Warning
The CEL-393 is designed to operate with air con-
denser microphones. If electret types are to be used,
the polarisation voltage must be suppressed.
Seek advice from the CEL calibration centre.
As an alternative to the CEL-299 Preamplifier provided as standard, the
instrument may also be used with the CEL-2980 which is a direct
equivalent.
For outdoor applications, the CEL-298/2 Preamplifier is available. This
is an electrical equivalent that has been repackaged to suit the CEL-
194/2 Outdoor Microphone Enclosure. It should be noted however that
this preamplifier does not include any heating elements so it will be
necessary to take other precautions to prevent condensation damage to
the microphone capsule.
When the instrument is supplied to the US market, the CEL-186/F free
field microphone normally provided is replaced by the random incidence
version, designated CEL-186/R. The instrument then conforms to the
ANSI S.1.4 standard type 1.
The CEL-186 series of microphones are manufactured to industry stand-
ard dimensions, and therefore there are many other types that are
mechanically compatible. It must be borne in mind that the CEL-186
series has a nominal sensitivity of 35mV/Pa, so care must be taken when
fitting alternatives which can be obtained with a sensitivity range from 10
to 50mV/Pa. It may not be possible to calibrate these directly, so a k
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