RME Audio DSP Multiface, User Manual

Page: 56 / 80

56
User's Guide HDSP System Multiface II
© RME
25.15 Level Meter
The Multiface II calculates all the display values Peak, Over and RMS in hardware, in order to
be capable of using them independent of the software in use, and to significantly reduce the
CPU load.
Tip: This feature, the Hardware Level Meter , is used by DIGICheck (see chapter 12/19) to
display Peak/RMS level meters of all channels, nearly without any CPU load.
The level meters integrated in TotalMix - considering their size - cannot be compared with
DIGICheck. Nevertheless they already include many useful functions.
Peak and RMS is displayed for every channel. 'Level Meter Setup' (menu Options or F2) and
direct keyboard entry (
hotkeys ) make various options available:
•
Display range 40 or 60 dB ( hotkey 4 or 6 )
•
Release time of the Peak display (Fast/Medium/Slow)
•
Numerical display selectable either Peak or RMS ( Hotkey E or R )
•
Number of consecutive samples for Overload display (1 to 15)
•
RMS display absolute or relative to 0 dBFS ( Hotkey 3 or 0 )
The latter is a point often overlooked, but
nonetheless important. A RMS measurement
shows 3 dB less for sine signals. While this is
mathematically correct, it is not very
reasonable for a level meter. Therefore the
RMS readout is usually corrected by 3 dB, so
that a full scale sine signal shows 0 dBFS on
both Peak and RMS meters.
This setting also yields directly readable
signal-to-noise values. Otherwise the value
shown with noise is 3 dB better than it actually
is (because the reference is not 0 dB, but -3
dB).
The value displayed in the text field is
independent of the setting 40/60 dB, it
represents the full 24 bit range of the RMS
measurement An example: An
RME ADI-8 DS
connected to the Multiface's ADAT port will
show around -113 dBFS on all eight channel's
input level meters.
This level display of TotalMix also provides means for a constant monitoring of the signal qual-
ity. Thus it can be a valuable tool for sound optimization and error removal in the studio.
Measuring SNR (Signal to Noise) requires to press R (for RMS) and 0 (for referring to 0
dBFS, a full scale signal). The text display will then show the same value as an expensive
measurement system, when measuring ‘RMS unweighted’.
Note: There is no RMS calculation for the third row, the physical outputs. Therefore the green
bars show the peak value only.