AMP1-DA
User Manual P/N
821530
Rev-
C
© 2006 Wohler Technologies Inc. ALL rights reserved
18
Section 3: Technical Information
Series II Level Meter Rear Panel DIP Settings
Line Level (Auto) Calibration, Reference Level, and Display Mode
This 6-section DIP switch sets the
Line Level Calibration
,
Reference Level
, and
PPM/VU Display Mode
. See below.
Line Level (Auto) Calibration:
The unit is calibrated at the factory. To recalibrate:
1)
Turn on the power.
2)
Apply the desired reference level (nominal 0) signal to all channels.
3)
Make sure the
Reference Level
DIP sections (
2
and
3
) are set to the nearest level of the input signal being applied for calibration
(i.e., 0, +4, +6 or +8). The user should make sure that the signal applied to all four channels is within +/- 4 dB of the reference
level selected by DIP switch sections
2
and
3
.
4)
Place DIP section
1
in the
DOWN
position.
5)
Wait 10 seconds. The unit will remove the previous calibration and the
new
calibration will be applied.
6)
Place DIP section
1
in the
UP
position and return unit to service.
7)
Only ONE auto-calibration attempt may be made for each cycling of AC power to the unit. Once the
Line Level Calibration
DIP switch has been placed in the
CAL
position, it is necessary to cycle the power before that DIP switch will be functional again,
EVEN if a calibration attempt was unsuccessful.
If one wishes to calibrate again, turn off the power to the unit and repeat steps 1 through 6.
Reference Level:
DIP switch sections
2
and
3
determine the
Reference Level
, which adjusts the level of the input signal and the resultant level
displayed on the LED bargraphs. Factory setting is
+4 dB
. See DIP switch diagram below for settings.
Bargraph Display Mode:
DIP switch sections
4
and
5
determine how peak levels are displayed for the associated meters on the front panel. There are four
possible settings;
VU Only
,
VU-PPM Floating Segment
,
PPM Only
, and
PPM-PPM Floating Segment
. The
VU Only
selection has a
VU
floating segment when a
Peak Hold
value is selected using the
Internal 10-Position DIP Switch Module
(see
page
19
). The factory default setting is
VU-PPM Floating Segment
. See diagram below for DIP settings.
Meter Calibration NOTE:
For more accurate indication of signal levels, meters are tuned to effect a “rounding” function, which occurs BETWEEN the
thresholds of any two bargraph segments. This means the level meter zero LED segment will turn on at one-half the smallest
spacing between LED segments (mid-scale resolution)
before
that segment's scale indication. Below are the offset amounts for
each of the two types of meter.
26-Segment Meters:
The "rounding offset" is
0.5 dB
for the
Analog
(
extended VU
),
Digital
,
Nordic
,
BBC
, and
DIN
scales. It is
0.25 dB
for the
VU
scale.
Example:
Using the
Analog (extended VU)
scale, a meter calibrated for a
+4 dBu
nominal level will actually turn the zero
LED segment of the level meter on at
+3.5 dBu
(and so
all
segments will turn on at
0.5 dBu
before
that segment’s silk-
screened scale indication).
Calibrate
Operate
+6
dB
+8
dB
1 2 3 4 5 6
Meter Calibration
Reference Level
Display Mode
1
2
Note:
Position-6 of DIP switch is NOT used.
AMP Series Level Meter Rear Panel DIP Switch Settings
3
3
1 2
6
5
4
+4
dB
0
dB
x
x
VU
-
PPM
Floating Segment
2
1
PPM-PPM
Floating Segment
5
3 4
6
VU
Only
PPM
Only
5
4
x
See the "
AMP Series Level Meter Internal 10-Position DIP Switch Settings
" diagram on page
19
for separately setting the
Peak Hold
and
PPM Ballistics
characteristics.