Figure 5 - Input sensitivity screen
For most installations where 0 VU = +4 dBu, the recommended setting is +14 dBu = 0 dBFS.
Note: Don't confuse dBu with dBFS!
dBu - an analog measurement - is a comparison to an arbitrary voltage. When a console's VU
meter reads 0, the output is typically +4 dBu, or 1.228 volts when using a sine wave. However,
actual audio levels are typically much higher due to audio peaks in the waveform. Analog audio is
very forgiving of such peaks, but digital audio is not.
A digital level of 0 dBFS (decibels in reference to full scale) is an absolute ceiling, and audio that
exceeds that level will result in audible distortion. PDM II has a built-in limiter to prevent levels
from exceeding 0 dBFS, but the recommended setting of 14 dBU = 0 dBFS provides 10dB of
headroom while still maintaining an 84dB signal-to-noise ratio. Lower settings can be used when
dealing with heavily processed input content, while higher settings may be necessary for content
with very wide dynamic range.
The Analog Output Level screen displays how the analog output level reflects digital audio levels within
PDM II's processor. With the setting as shown below, 0 dBFS within PDM II will yield a +14 dBu analog
output. The output levels should generally be set to match the Input Sensitivity level, though levels can be
adjusted to create a gain or loss at the analog outputs. Note that in Bypass mode, any such gain changes
are also bypassed and the output levels will equal the input levels.
Figure 6 - Output level screen
The default sample rate of the AES3 output can be set to 32, 44.1, or 48kHz.
Figure 7 - AES output rate screen
The sample rate of the AES3 output can be locked to the sample rate of the AES3 input, even if the unit is
not configured for an AES3 input. If there is no valid clock at the AES3 input, the output will revert to the rate
set in the AES3 Default Output Rate screen above.
