3-4
Operation
Microphone Bias Voltage
The bias voltage should be set to
zero when using a prepolarized
(electret) microphone and 200 V
when using a traditional air
condenser microphone.
The microphone bias voltage is either On, providing a
highly stable level of 200 Vdc, or Off. Pressing the
MICROPHONE BIAS key
will toggle the state between these two, When the bias
voltage selection is changed, the MICROPHONE BIAS
LED will flash for 40 seconds while the bias voltage
stabilizes.
Frequency Weighting
The input signal frequency weighting is selected by pressing
the WEIGHT key
Repeated presses will move the selection in the sequence Z
(Flat), C and A as indicated by the illuminated LED to the
left of the key. The characteristics of these weightings are
described in the section “Frequency Response” on page A-2
Gain
The input gain is set using the up and down arrow keys in
the front panel section entitled GAIN. The selected value is
indicated by the illuminated LED to the right of the arrow
keys.
Vernier Adjustment
Very fine gain adjustments can be made using the 12 turn
potentiometer located on the front end of the case to the right
of the signal input connector. This can increase the gain by
up to 10 dB by turning it clockwise using the adjustment tool
provided.