Brands:

• AMX
• BSS Audio

Models:

• AVX Suite

Overview:

This article will explore the VIRTUAL view of AVX Architect and look at the Automixer Gain Sharing object.  

To see a video of this article, click HERE.

Description:

In addition to the features of a conventional mixer, Automixers allow hands-free multi-microphone mixing without the need for manual gain riding to keep background noise and feedback under control.

Operation:

These objects use and Adaptive Threshold Gain Sharing technique to control the attenuation of each input channel.  All inputs share the available gain, and an 'open' microphone will attract the most gain.  If more than one microphone is being used, the gain on the active channels is shared to give the same overall system gain.  When all inputs are idle, the shared gain keeps all channels slightly active to avoid 'pumping' of the background noise.  Downward expansion is available for further reducing the background noise contribution from idle microphones.  Aux, Group and Direct channel outputs can be enabled for additional routing and processing.

Properties:

In the PROPERTIES pane, is the object name, workspace location, and DSP allocation settings.

Options:

The OPTIONS section contains the channel count, which can be set from 2 to 512.

Number of groups and auxes, which can be set up to 4 of each.  Notice that adding groups or auxes will add the outputs to the object block.

Voice Band Filters, which will allow the automixer to favor frequencies in the human vocal range.  This helps the mixer distinguish between speech and noise, reducing the chance that noise signals will be boosted instead of a vocal signal.

Stereo, to enable a stereo output pair on the object.

Direct Outs, to enable additional outputs for each input channel.  These feeds are taken before the mix, but after any processing such as autogain, so they can be sent for further processing or mixing elsewhere.

Pan Law, which is attenuation applied to each channel at the central pan position.

Factory panel:

Much like the standard mixer object, for each channel there is a polarity button, fader for gain, mute and solo buttons, and pan control if the Stereo option is enabled.

These faders control the level of the input before the automix logic is applied.

This Auto switch will assign each channel to operate as either a conventional mixer channel or an automated channel.  Note that when the channel is set to manual, it will not contribute to the overall gain attenuation for channels that are set to Auto.

Off Gain determines what maximum attenuation will be applied to an idle channel.  When this is set to 0db, no downward expansion is applied.

The Override button forces this channel to be heard above all the others by adding an additional 3-6 db of gain.  This can be applied to multiple channels at the same time.  Useful for example if a chairperson needs to interrupt another speaker.

This On indicator will show the loudest active channel.  This could be useful in identifying the speaker in automated camera applications.

Slope controls how aggressive the gain sharing is.  A low slope setting will cause the object to behave like a conventional mixer.  The fully clockwise 2:1 setting will be appropriate for most applications, but lowering this control will cause the sources to be attenuated less aggressively.

Speed is how quickly a channel recovers from being open.  Fast settings will be needed if different microphones are being used in quick succession.  If this setting is too fast, the gain sharing could adjust the gain between spoken words for a single speaker.  In most applications, a setting somewhere in the middle will be suitable.​