User Manual

User's Guide HDSPe AES © RME

25.15 Level Meter

The HDSPe AES 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 15/21) 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: A RME ADI-8 QS

connected to the HDSPe AES via the AES

inputs will show around -114 dBFS on all eight

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) is best done with RME’s free software DIGICheck. The

function Bit Statistic includes three different RMS meters for exactly this purpose (RMS un-

weighted, A-weighted and DC).