Phonitor
21
VU Meter
The VU meter displays the input level for each channel. The gauge in-
dicates levels from -20 dB to +5 dB. If necessary you can lower the sen-
sitivity by 6 dB so that the gauge goes up to +11 dB output level (see
“Meter Cal.“ on page 22).
The VU meter is custom made to meet SPL specifications and assures a
balanced optical perception thanks to it’s optimized ballistics.
An especially interesting feature is the option to switch between two
display modes: VU mode and PPM mode. The VU mode (VU=Volume
Unit) displays average levels to provide information on the overall
loudness. The PPM mode (PPM=Peak Program Meter) displays the
peak levels.
The integration time of the display complies with BBC requirements.
In VU mode the rise time up to 0 dB is approximately 300 ms. In PPM
mode the rise time up to 0 dB is about 2 ms and the release time down
to -20 dB is at a “slow” 1,5 seconds. This calibration ensures to display
even short peaks up to about +5 dB since the needle does not have to
travel the entire distance of the gauge every time.
Meter Mode
The Meter Mode switch allows to switch the VU metering characteris-
tics from VU display mode to PPM display mode. In PPM mode, peak
levels are displayed – comparable for example to A/D converter dis-
plays. Monitoring peak levels is for example most important to avoid
overloading and to prevent audible distortion. Peak levels are always
above the average levels. It may make sense to choose the Meter Cal.
+6 dB switch position to extend the metering range.
Meter Cal.
With this switch you can change the sensitivity of the VU display. If you
choose the +6 dB position, the range of the display is extended by 6 dB.
With the +6 dB switch activated and the needle at 0 dB, a value of +6 dB
input level is displayed.
Control Elements
VU Meter, Signal LED, Overload LED
METER MODE
VU
PPM
METER CAL.
+ 6
0
