Attero Tech DialogBox - Manual (Page 11)

DialogBox 4/2
User Manual
 Attero Tech LLC 2013 Page 6 614-00011-04
3.4 – Audio/CobraNet Inputs
Each of the four local inputs and the four CobraNet inputs has their own input
controls. Figure 9 shows the controls for both the local analog audio inputs (left
image) and the CobraNet inputs (right image).
3.4.1 – Input Gain (Analog Inputs Only)
The input gain sections are only available for the analog inputs and control the
settings for the mic pre-amp. This allows the input to be switched between line
level (0dB gain) and two different mic input gain levels (+25dB and +40dB).
Either a mic gain or a line level can be selected per input. This control is only
available for the analog inputs.
3.4.2 – Phantom Power (Analog Inputs Only)
Phantom power is available from the DialogBox for powering microphones. This
can be turned on or off per input. This control is only available for the analog
inputs.
3.4.3 – Mute (Analog inputs only)
The mute indicator warns the user whether this audio has been muted by the
activation of an appropriately configured logic input. The indicator will turn red
when the mute is active.
3.4.4 – Gain
The gain control sets the overall maximum volume for a particular input. Up to
+12dB additional gain can be added. The input signal may also be attenuated.
At a level of -100dB, the input is considered muted.
3.4.5 – High Pass Filter
The DialogBox has a controllable High pass filter that can be enabled or disabled. The filters default frequency is set at
80Hz but can be change from 20 Hz to 300 Hz.
3.4.6 – Auto Mixer Settings
The DialogBox uses a gain-sharing approach to auto mixing, modeled on the original Dan Dugan auto mixing
algorithm. Though the Dugan algorithm was the first true auto mixer approach, it is still the most natural and effective
type of auto mixing. In essence, the algorithm transforms the instantaneous pattern of input levels on all the automatic
inputs to a pattern of attenuations applied to the inputs. Those inputs with higher signal levels receive proportionally
more gain than those with lower signal levels. The total attenuation applied to all automatic inputs guarantees that the
total attenuation applied to all inputs keeps the total gain equal to one open microphone (the NOM=1 function). Noise
that is common to all microphones, like room ambient noise, is ignored by the algorithm. This prevents so-called “false
triggering” of inputs with changes in background noise. False triggering on background noise is a common occurrence
with most other auto mixing algorithms.
There are two settings for the Dugan-style gain-sharing auto mixer. The first is the Mode. Selecting Auto mode makes
the channel part of the auto mixer function. All input channels in the Auto mode will have their gains managed by the
auto mixer algorithm to optimize gain before feedback in multi-mic installations. Selecting Dir (direct) mode means the
input channel is always open and is not affected by the auto mixing algorithm. The second setting is the Number of
Open Mics (NOM) Send option. This determines whether the audio from that input is sent to the auto mixing algorithm
to help determine gain distribution for inputs in the Auto mode.
In general, only inputs with microphones attached should be put in the Auto mode. Line inputs (for example PC audio,
an MP3 player, etc) usually are put in the direct mode, and their NOM Send is set to off.
3.4.7 – Equalization
Each input has a low and a high shelf filter. The low shelf has set a set frequency of 100Hz while the high shelf has a
set frequency of 1kHz. The filter gain can be altered and each filter has a range of -12dB to +12dB.
Figure 9 - Analog and CobraNet
Input Controls