1.5 Front Panel
1.5.1 LED VU and Peak Meter
The VU Meter for the Mic Pre 4T is a true VU Meter with
300ms averaging ballistics. The main difference between
this meter and a mechanical VU meter is that this meter
extends to +25dB, while a mechanical meter only goes
up to +3dB. This feature allows the engineer to see level
with much greater accuracy and detail above +3dB.
The highest point on the meter is labeled with an
asterisk (*) which is the peak indicator. When this LED is
lit, the signal has reached or exceeded 26dBu. Most
audio interfaces will clip at +18dBu, while most
professional mixing consoles will clip b24dBu to
+30dBu. VU Meters measure the
RMS
(Root Mean
Square) of an audio signal. Often the RMS is considered
to be the “continuous” level of the signal. A
PPM
(Peak
Program Meter) measures the signal much more quickly
and keeps track of the absolute value of the greatest
voltage in the audio signal. This is why the Peak
Indicator (*) can be lit when the VU meter is showing a
much lower signal. The peaks of an audio signal are
much higher than the RMS of the audio signal.
NOTE:
While most VU meters are calibrated to 0dB VU
= +4dBu, this meter is in fact a true dBu meter where
0dB on the meter is in fact 0dBu. This means that when
the Mic Pre 4T VU meter is reading 0dB and you patch
into another standard VU meter directly from the mic pre,
you will show a reading of -4dB.
