Gain Assistant

Gain Assistant can be used on any Input processing channel which is sourced from either a Local or SLink analogue input socket with a digitally controlled preamp.

It carries out two functions to speed up setup and prevent issues with gain staging during use;

Auto Set – Automatically sets preamp gain to an optimal level for the incoming signal.

Auto Gain – Monitors the incoming signal level and reduce preamp gain to prevent clipping.

Both functions are available in the PROCESSING > Source screen of an input channel, when the channel is sourced from a Local or SLink preamp socket.

|| PROCESSING | Source (Input Channel)

Alternatively, these functions can be actioned on multiple channels at the same time from the UTILITY > Gain Assist screen.

|| UTILITY | Gain Assist

Selecting Multiple channels in the Gain Assist screen

• Touch any channel sourced from a Local or SLink socket with a preamp to toggle selection. Selected channels are highlighted. Channels sourced from input sockets without a preamp cannot be selected.
• Use the Select All or None buttons at the top right to quickly select all possible channels or deselect any selected channels.

Auto Set Process

• Connect the input source and turn on 48V phantom power or activate any Pad as required.
• Generate signal at the expected level e.g. make noise into a microphone or DI box.
• Press the Auto Set button to begin the process
• Gain Assistant will start with the preamp gain set to 0dB and gradually raise it until the optimum amount of gain has been applied and the input signal sits at around 0dB on the meters.
• Success or failure of the process is displayed per channel.

Auto Gain On/Off

This can be used independently of Auto Set and turned on or off at any time. Auto Gain constantly checks the input signal level in the background and if the preamp gain is set too high (e.g. an instrument or voice get louder than they were during sound check), it will automatically and gradually reduce the preamp gain.

Feedback Assistant

The Feedback Assistant (FBA) is available for use on any Mix processing channel. It detects the prominent and persistent frequencies caused by feedback, then precisely applies narrow filters to reduce the levels of those frequencies whilst changing the overall sound as little as possible.

It can be used in any situation where the input source can ‘hear’ an output it is being sent to. Most commonly, a microphone being used in the same space as monitor speakers and PA system.

The FBA is intended to be used during setup to apply Fixed Filters and then to look out for feedback during the show or event and apply Live Filters. For best results always run through the setup steps again whenever the setup or venue is changed.

ⓘ See the Mix > Switching between FBA and GEQ section in this guide for information on how to load the Feedback Assistant into a Mix channel.

False Positives and best practices

False positives can occur with any feedback-like sound being played (e.g. guitar feedback, keyboard and synth sounds, flute, operatic vocals etc…). The FBA cannot know if this is a desired feedback-like sound or not. The FBA on any Mix will always boot with Detection Off to prevent unnecessary filters being added. It is best not to leave any FBA actively detecting and adding fixed filters. Instead, if being left unattended, it is best to leave Auto Apply set to Live Filters, which will recover and then simply be re-applied if the feedback returns.

Number of simultaneous detectors

FBA can be used on any or all Mix channels, but there are 8 available detectors in the Qu, meaning detection can only be active, and automatically applying filters on up to 8 Mix channels at once. Touch the Config button in the FBA to view and select where detectors are in use.

Before using the FBA

Some Feedback must occur for the FBA to detect and filter it. Therefore, before doing anything, ensure that:

• All microphones to be used are connected and have preamp gain set.
• All Input processing has been set to an approximate starting point.
• All outputs have been connected and any speakers powered on.
• A rough mix should be set for monitors and other outputs (though with the output level lower than needed if feedback is already an issue).
• FBA has been recalled in the FBA/GEQ processing ‘block’ for any Mix channel where it’s needed.

Apply Fixed filters during setup/soundcheck

This is the most important stage to prevent feedback during a show or event. Feedback can also be detected more accurately and quickly during setup/soundcheck and there is less chance of false positives.

|| PROCESSING | FBA | Detect (Mix Channel)

1. Select the Mix to ‘ring out’ using a blue MIX key on the surface.
2. Select the Mix channel itself with the green SEL key on the main MIX channel strip.
3. Navigate to the PROCESSING > FBA/GEQ screen.
4. At the bottom left of the screen, select the Detect tab (if not already selected)
5. Set Auto Apply to Fixed Filters. This will mean any detected feedback frequencies will have a fixed filter applied which will remain in place until manually deleted.
6. Turn Detection On in the Find Feedback section. Turn it Off at any time to pause detection.
7. Gently raise the Mix level fader (the MIX channel strip fader). As the output level increases, feedback will occur, and the FBA will be able to detect this and add fixed filters. Raise the fader to a higher level that it will be used at during the show or event to generate and detect as much potential feedback as possible and allow for changes to the mix (e.g. extra vocal being added later).
8. When feedback no longer occurs, lower the level again.
9. With setup detection complete, turn Detection Off or switch filter Mode to Live.
10. Repeat for any other outputs as required.

Apply Live filters during a show or event

Live filters are intended to temporarily filter out feedback frequencies, for example a wireless microphone may usually be positioned behind speakers where there is less chance of feedback but might be occasionally moved in front of speakers where feedback is far more likely.

Add Fixed Filters during setup whenever possible. This gives the best starting point for the system and avoids persistent feedback issues due to the system or space.

1. Select the Mix where feedback may occur using a blue MIX key on the surface.
2. Select the Mix channel itself with the green SEL key on the main MIX channel strip.
3. Navigate to the PROCESSING > FBA/GEQ screen.
4. At the bottom left of the screen, select the Detect tab (if not already selected)
5. Set Auto Apply to Live Filters. This will mean any detected feedback frequencies will have a live filter applied, which will recover over time.
6. Set the Response for the Live Filters. A faster response will mean filters are applied faster but the FBA is more prone to false positives. A slower response means the detector is less likely to be triggered by false positives, but it takes longer for filters to be applied.
7. Set the Recovery rate for all Live Filters. This can be adjusted at any time to speed up, slow down or even pause the recovery of all Live Filters. It does not affect fixed filters.
8. Turn Detection On in the Find Feedback section. Turn it Off at any time to pause detection.
9. Repeat for any other Mixes as required.

AMM (Automatic Mic Mixer)

|| UTILITIES | AMM

Qu’s Automatic Microphone Mixer uses a gain sharing algorithm, designed for use in multi-microphone speech applications like conferences, meetings, broadcasting and podcasts. It can be used on every mono input channel of the Qu.

The AMM algorithm looks at the incoming signal level, the priority setting and the fader level, then adds gain (level) to any channel in use, while reducing gain on the other channels. This reduces background noise and the chance of feedback while improving intelligibility.

• Touch and drag the blue navigation box in the overview at the top to view and adjust all channels.

In/Out – Switch the whole AMM on or off.

On/Off – Enable or disable AMM on each channel individually.

Priority Faders – Adjust priority of each channel in the calculation.

ⓘ Only mono channels will be displayed.