The 1986 is designed to
permit checking nearly all the characteristics of a sound-level
meter as specified by IEC and ANSI standards. With its supplied
and optional microphone cavity adaptors, it can be used with all
types and sizes of commonly used measurement microphones.
The calibrator includes tones at six different frequencies,
from 125 Hz to 4000 Hz in octave steps, and five different sound-pressure
levels, from 74 to 114 dB in 10 dB steps. This allows a sensitivity
check of an acoustic instrument near the specific frequency and
level of each measurement being made.
The frequency response of an overall sound-measuring
system, weighing network or filter may also be checked. The two
sources of linearity error in a sound-measuring instrument are
easily checked with the 1986. One source is the indicator scale
(meter or digital display) and the other the level-range control.
The multi-level output of the 1986 allows selection of different
levels on a sound-measuring system and a check of the instrument's
response at each level.
Standards require that Fast detector response be
tested by applying a sinusoidal signal having a frequency of 1000
Hz and a duration of 200 ms. Slow detector response is tested
by applying a sinusoidal signal having a frequency of 1000 Hz
and a duration of 500 ms. The 1986's tone burst mode allows checking
to the above requirements by automatically presenting a 1000-Hz
sinusoidal signal of either 200-ms or 500-ms duration.
The 1986 permits a check of rms accuracy and crest-factor
capability by presenting repeated tone bursts with a high crest
factor.
The transducer on the 1986 is resiliently mounted
to protect against damage from the accidental bumps and drops
often encountered in field calibration simulations. The entire
assembly, except for the test cavity, is enclosed in a molded
plastic case that is tightly sealed against dust and moisture.
The cavity of the 1986 is designed to fit GenRad
1-inch microphones, the WE640AA and Tokyo Riko MR130. An adaptor
is included to accommodate GenRad ½-inch microphones. An
optional adaptor set allows you to use the 1986 on instruments
with Bruel & Kjaer 1-inch, ½-inch and ¼-inch microphones,
the Shure Brothers 1 1/8-inch microphone, and the 3/8-inch microphone
on GenRad's 1954 Noise Dosimeter. |