Specifications

9
C. CONTROL FUNCTIONS
1. Power
The power switch is a push-on, push-off type switch. It has a neon lamp indicator built
into its plastic button and should never need maintenance.
2. Noise Level
The output level of the internal pink noise generator may be selected via the push-pull
switch on the level potentiometer. The level knob is pushed in for low level (microphone
level) and is pulled out for high level (line level) noise signal. The level of the noise
signal may be set more precisely by adjustment of the level vernier.
3. Noise Output
The pink noise signal is made available through the XLR-3-32 connector immediately
adjacent to the noise level control. Pin 1 is the shield connection. Pins
2
and
3
are the
signal. The signal is coupled out by a transformer and either side may be grounded, or
may be left floating.
4. Microphone Input
A standard XLR-3-31 connector is used for input from any typical dynamic microphone.
The input impedance is 2000 ohms into a transformer. Pin
1
is shield, pins
2
and
3
are
balanced signal in.
5. Line Input
A high level, single-ended input with impedance of 20 kilohms is provided via a standard
stereo phone jack. The sleeve is circuit common and the tip is the signal input. The ring is
the output of the microphone preamplifier.
6. dB-SPL
The
dB-SPL
switch selects the range to be displayed. With a calibrated microphone, it
yields calibrated readings from 41dB-SPL to 110dB-SPL. The actual level displayed on
the
SPL
column of the display is the
dB-SPL
switch setting plus the reading indicated by
the display.