Ashly nX1504 Operating Manual page 40

Operating Manual - nX, nXe, and nXp 150W/75W Power Amplifiers
Global Automixer Response - Controls the response time constant of all output automixers. The automixer response
time is the speed in which the automixer makes gain changes in response to the input signal RMS levels. This value is shared
among all automixers.
Enable Ducking At Mixer - Checkbox allows selecting the ducking action to be applied at the mixer's summing point
rather than in the signal path prior to the mixer. This allows some output mixer zones to have ducking action applied while other
output mixer zones do not have ducking applied.
Auto Mixer
Practical use of the auto-mixer on nX amplifiers is limited, since there are only two or four input channels and external mic
preamps are required. The automixer is used to automate the mixing of multiple speech microphones to follow the dynamic
nature of the speech dialog and attenuate idle microphones. The automixer may also be used in conjunction with the autoleveler,
compressor, or gate on the input signal paths. This gives the user more advanced control of varied input signal levels produced
by different talkers. A feedback suppressor function may also be used on the inputs to further help control feedback problems.
Ashly Auto Mixer Technology
The automixer function is a "gain-sharing" type which automatically makes smooth gain transitions on all automixer
input channels to achieve a constant total system gain. This gain-sharing method of automixing has been found to be superior
to gating automixers due to the following characteristics:
1) The automatic gain action has a smooth transparent sound as though a person were mixing the inputs to follow
the audio program rather than rapid gating on-and-off of channels.
2) Properly designed gain-sharing automixers correctly adjust for mixing of coherent versus non-coherent signals
for a more consistent final mix level without feedback as channel gains are automatically changing.
3) A gain-sharing automixer is easier to setup and adjust without the need for threshold, attack, release, depth,
and number-of-open-mics (NOM) controls.
Mixer input channels can be individually selected as auto-mixed or manual mixed, all summed together to the same mixer output.
Channels which are selected as auto will participate in the automix in that they will contribute to the automatic adjustment of
other automix channel gains. Likewise, their channel gain will be affected by the signal level present on other automix channels.
Manual mixer channels (not selected as auto) will mix independently of the automixer channels into the output, only controlled
by their fader setting. The fader on auto channels still controls the input level before automatic mixing takes place so that more
of the system gain can be applied to one channel versus another.
Automixer Setup
Setting-up the Ashly gain-sharing automixer is quite simple compared to other gating-type automixers. The following
procedure is recommended for most multi-microphone speech applications.
1) Start with all mixer faders off and the automixer response time set to 0.1 seconds.
2) Select the input channel routes as desired in the matrix mixer and select <Auto> on the channels to be automixed.
3) Start with one of the main speech channels, or one which is centrally located. Slowly increase the fader for this one
channel just until feedback starts, then lower the fader approximately 3 dB to stay comfortably below feedback. This sets the
total mixer system gain.
4) Now increase the other routed input channel faders to approximately the same position as the first channel used
in step 3. The system will not feedback because the automixer will slowly attenuate the active channels as more channels are
turned-on to maintain a constant total system gain as set in step 3.
5) During the program, individual channel faders may be raised or lowered to adjust for the weakness or strength of
the respective talkers while the automixer is active.
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