Standalone MediaPort 200
Output Tab
On the
Output
tab, levels are set relative to the destination device. In most cases, the
default setting of 0 dB is proper (no adjustment), which is why the
Output
tab is the last
audio control tab in the
Audio Config
section. If using the available output DSP, see
on page 57 for more information.
Adjusting the Output Levels
Since the USB output and the analog Line output contain mixes of different audio signals, it
is important here to test the system and monitor these outputs to ensure that the signal level
approaches 0 dBFS with enough headroom to avoid clipping. If the meters show clipping,
the fader control on the output can be lowered to bring the signal down below
0 dBFS. If clipping occurs at the input and lowering the output fader control does not
eliminate the clipping, the input gain must be lowered.
If the output meter shows clipping and there is no clipping occurring at the input, then
lowering the output fader control will eliminate the clipping in most cases. Within the
MediaPort digital signal path, there is a certain amount of headroom, such that a signal or
mix of signals that is too hot at the output can be lowered at the output fader control to
eliminate clipping.
If lowering the output fader control prevents clipping at the output meter, but clipping is still
audible (and there is no clipping present at the input meters), then levels must be lowered in
the
Mix
tab to eliminate clipping. The
Room Volume
in the
Near End
section (and the
Mic
and
Program
controls in the
Mix to Far End
section) are all master controls that include
soft limit controls. Setting the soft limit so that the fader cannot go above a level that causes
clipping is a method of controlling clipping from the
Mix
tab (see
Otherwise, it will be necessary to lower faders in either the
Program Mix
section, the
USB
Communications
fader, or both. Check the output meter often to verify that clipping does
not appear on the meter.
Connecting to an Amplifier
When the line output is connected to a sound reinforcement system, the amplifier of the
sound system must be set to accommodate the output level of the MediaPort. If adjusting
the amplifier input sensitivity instead of the MediaPort line output level, the Line output
attenuation control set to 0 dB will give the best signal-to-noise results. See Sound
Reinforcement System below for additional information.
Sound Reinforcement System
A typical sound reinforcement system includes a power amplifier and speakers. In most
cases, the input sensitivity of an amplifier has a maximum of +4 dBu. The max output of
the MediaPort is +21 dBu, so attenuation of the amplifier input sensitivity is recommended.
An input sensitivity of −12 to −17 dB on the amplifier should work well, but this may require
testing the system and fine-tuning the settings. The target SPL level for the application must
also be taken into consideration.
The gain structure article referenced earlier in this section suggests an amplifier input setting
of 12 o’clock, which usually falls in the aforementioned range. The 12 o’clock setting is
convenient and easily repeatable, making it a recommended best practice.
MediaPort 200 • Standalone Application Setup
88
