Casella CEL CEL-206 - Manual (Page 4)

Casella USA
17 Old Nashua Rd #15
Amherst, NH 03031 USA
CEL-206 DISCO NOISE LEVEL LIMITER
INTRODUCTION
The problems of entertainment noise are now well established both in terms of the
nuisance element in respect of nearby residents and the health hazard to employees
and patrons alike. It is to eliminate problems in these areas that the CEL-206 has
been introduced. A comprehensive design study has been undertaken to ensure that the
system is practical and accurate in a wide range of installations.
The basic approach is to monitor the noise level in the required noise sensitive
area, which can be either indoors or outside the premises, and display the measured
level on a wide dynamic range sound level meter. This level is continually compared
against a preset threshold level which will, if exceeded, light a warning indicator.
If after a short period the levels have not been reduced a trigger is latched that
will introduce attenuation into the signal leads for a period of approximately 20
seconds. If necessary, this trigger can be used to cut the main supply to the audio
power amplifiers thereby completely shutting off the noise source for a short
period. The object of these arrangements is to discipline performers to keep within
agreed sound levels.
1 TECHNICAL DESCRIPTION
The CEL-206 system is provided as standard with a 0.5 inch microphone and integral
pre-amplifier assembly complete with a 10 metre cable. A mounting bracket is
provided to enable the microphone to be located in the required monitoring position
and extension cables of any length up to 100 metres are available under the part
number CEL-3381. A security link is wired throughout the microphone cable such that
the threshold level will be triggered if the microphone is disconnected for any
reason. The main electronics package is housed within a robust steel enclosure that
may be mounted onto a wall and directly wired into the mains electricity supply. It
comprises a wide range sound level meter that covers 60-110dB; however, for special
applications this may be offset during field calibration to cover levels between 45-
115dB. This calibration is performed by the supervising authority using a CEL-184
Acoustic Calibrator and at the same time the threshold level is set the unit is then
closed and, if necessary, a seal attached via the link provided. The threshold level
may be set anywhere within the instrument's dynamic range and may be in terms of a
dB(A) level where airborne sound is the prime consideration or dB Flat (Linear)
where the main nuisance is in respect, of structure borne noise.
During the performance it is obviously difficult to keep an eye on the meter and
limit lamp mounted on the CEL-206 so facilities are provided for a power outlet to
be activated in parallel with the warning indicator and this can be connected to a
lamp on stage that can be sited so as to be clearly visible to the performers.
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www.casellausa.com 2 Mar 2009 Fax: (603) 672-8053