Processing Overview

|| PROCESSING | Source (Input Channel)

Each Input and Mix channel in the Qu has independent processing and routing options.

One channel can be selected at any time by using the green Sel key on each channel fader strip.

That channel can then be controlled using dedicated surface controls, and the PROCESSING and ROUTING screens display all possible processing and routing options for that channel.

Navigation

There are multiple processing stages for each channel, and the available processing is slightly different for input and mix channels.

The top of the PROCESSING screen has tabs for each processing stage in the order signal is processed from left to right (with the exception of the Input High Pass Filter, shown in the EQ tab for convenience).

• Touch any processing stage in the top section of the screen to display and adjust all parameters for it in the lower section of the screen.

Input > Source

|| PROCESSING | Source (Input Channel)

Source Select –The current source for this input channel is displayed. Touch to select a different source for the channel. See Input Patching for more information.

Stereo Image – This section is visible only when a stereo input channel is selected. Touch the mode to select from the following options:

L/R - standard left/right.

R/L - switched left/right.

L-Pol/R - standard left/right with switched polarity on left.

R-Pol/L - switched left/right with switched polarity on right.

Mono - left and right fed to both channels.

L/L - left fed to both channels.

R/R - right fed to both channels.

M/S - for decoding a mid/side array (outputs M+S/M-S).

ⓘ For normal M/S use, the mid signal/microphone should be patched to the odd channel and the side signal/microphone should be patched to the even channel.

The width control can be adjusted in 1% increments from Mono (0%) to Stereo (100%).

48V - Touch and hold to activate phantom power on the XLR input (required for condenser microphones and active DI boxes).

ⓘ Phantom Power is only provided via an XLR connection. It is not sent to the ¼” TRS Jack connection of a Combi socket.

Pad - Switch the socket pad on or off. This reduces the incoming level of signal by a set amount before it reaches the preamp and is used to prevent overloading.

ⓘ Qu has a fixed -20dB pad on the TRS connection of the local combi input sockets.

Gain - Adjust preamp gain manually for the incoming signal.

Auto Set – Starts the Gain Assistant Auto Set process to set optimum preamp gain for the source/socket based on the level of signal detected at the input.

Auto Gain – When turned On, the Gain Assistant automatically reduces the preamp gain if high levels are detected to prevent clipping.

ⓘ Gain Assistant functions are only available when the input channel is sourced from a local or SLink socket with a preamp available to control.

ⓘ Gain Assistant features can be used on a per-channel basis or on multiple channels at once. See the Gain Assistant section for more information.

Trim – Digital ±24dB level adjustment.

Pol – Invert the polarity of the signal. Often used where multiple microphones are used on the same source (e.g. snare top and snare bottom).

Tube Stage

|| PROCESSING | Source (Input Channel)

Preamps in the Qu itself and those in Remote Audio Units are accurate and transparent, with fast transients and low THD. However, there are situations where the harmonic distortion, frequency and dynamics response of vintage preamps are desirable. Using a DEEP preamp model like Tube Stage allows you to add these characteristics with complete control, and none of the associated limitations or reliability concerns of esoteric equipment.

Note that, just like the units it is modelled on, Tube Stage reacts differently depending on the incoming signal level. So it’s important to setup the preamp before making any adjustments to Tube Stage.

• When in the channel Preamp screen, touch +Tube Stage or press the LIBRARY key and recall Tube Stage from the Factory Preamp Library.
• Tube Stage settings can also be stored and recalled from the User Preamp Library.

ⓘ Tube Stage is a Qu Add-on available from shop.allen-heath.com

On/Off - Switch Tube Stage on or off.

Mode – Select from different valve/tube preamp topologies.

Fine Adj. – Adjusts different parameters depending on the selected mode.

Level – A trim control to be used for attenuation or makeup gain.

Input > Gate

|| PROCESSING | Gate (Input Channel)

The Gate allows wanted signal through and attenuates unwanted signal. It has many uses including removal of hum from an idle instrument or avoiding hearing the snare drum through a tom microphone when only the snare is being played.

Attack – Adjust time it takes for the Gate to open once signal has reached threshold.

Hold – Adjust time the Gate remains open after signal has dropped below threshold.

Release – Adjust time it takes for the Gate to fully close once signal has fallen under the

threshold and hold time has expired.

Threshold – Adjust the level at which the Gate is triggered to open.

Depth – Adjust the amount the signal is reduced by when the gate is fully closed.

In/Out – Enable or disable the Gate.

Side Chain

• Select either Self Keyed or select another channel to trigger the gate.
• Touch the filter type to switch between Off/HPF/BPF/LPF modes.
• Touch the frequency value to select it, then adjust with the touchscreen rotary.

Input > Insert

|| PROCESSING | Insert (Input Channel)

The Insert point allows the post-Gate signal to be processed before being returned directly into the channel before the PEQ. It is commonly used for EQ or dynamics processing but can also be used to insert FX.

Send – Select a destination for the signal. This can be any available output socket or FX unit.

Return – Select a source for the returning signal. This can be any available input socket or FX unit.

ⓘ Send and Return will always automatically match when inserting an FX unit.

Operating Level – Select from line level options to match insert socket being used.

Digital - Uncompensated, for use with digital I/O.

Analogue - For use with +4dBu outboard equipment.

-10 dBV - For use with -10dBV outboard equipment.

Unassign – Unassign and clear Send and Return socket selections.

In/Out – Switch the insert in or out, without affecting the assigned sockets.

ⓘ If the socket is in use elsewhere in the system, this is noted. A + symbol is shown when a Return socket is being used in multiple places.

Input > EQ

|| PROCESSING | EQ (Input Channel)

The 4-band Parametric Equaliser enables adjustments to the tone of the signal by cutting or boosting around different frequencies.

• Touch one of the bands on the graph to display settings and values at the bottom of the screen.
• Adjust using dedicated surface controls, by touching and dragging on the graph or by selecting a parameter and using the touchscreen rotary.

Type – LF and HF bands include options for Shelf, Bell or HPF/LPF.

Width – Adjust the amount that frequencies around the centre frequency are affected.

Freq – Select the centre frequency for adjustment.

Gain – Cut or boost the selected centre frequency by up to +/- 15dB.

RTA – Display Real Time Analyser behind PEQ.

In/Out – Enable or disable the PEQ.

HPF

The High Pass Filter lets audio above a set frequency pass, whilst cutting out lower frequencies. It’s commonly used wherever the low frequencies are undesirable (e.g. microphone handling noise, traffic rumble or low background humming) or when it is not adding anything to the mix (e.g. on predominantly mid or high frequency sources like voice, guitar or cymbals).

Note that the High Pass Filter is shown in this screen for convenience but is actually applied before the Gate in the channel signal path.

Freq – Adjust the High Pass Filter frequency. When HPF is In, all frequencies above this setting will pass whilst those below will be attenuated.

In/Out – Switch the HPF In or Out.

Input > Compressor

|| PROCESSING | Comp (Input Channel)

The Compressor is used to control and reduce the dynamic range of the signal.

RMS/Peak – Compression is either triggered by RMS (short average) or Peak (instant) signal level.

Hard/Soft Knee – With a hard knee, compression begins to take effect only when the threshold is reached. With a soft knee, the compression begins to take effect earlier but in a more gradual way.

Attack – Adjust the time it takes for compression to take effect once the signal has reached the threshold. Set a longer time to allow transients through and compress only the body of the sound, set a shorter time to flatten the signal and tame peaks.

Release – Adjust the time that it takes for the compressor to stop compressing after signal has fallen below the threshold.

Ratio – The ratio of the incoming signal to compressed signal when compression is active. E.g. when set to 3:1 and when compressing, every 3dB increase in level at the input will result in only a 1dB increase of level at the output.

Threshold – Adjust the input level at which compression will be active.

Gain – Use to compensate for the resulting attenuation of the signal.

In/Out – Enable or disable the compressor.

Side Chain

• Select either Self Keyed or select another channel to trigger the compression.
• Touch the filter type to switch between Off/HPF/BPF/LPF modes.
• Touch the frequency value to select it, then adjust with the touchscreen rotary.

Parallel Path

This allows you to blend the compressed signal with the uncompressed signal. Due to the XCVI core, these signals are coherent, and no comb filtering is introduced.

• Touch the Parallel Path button to switch in or out.
• Touch the Dry/Wet values and adjust using the touchscreen rotary.

DEEP Compressors

DEEP compressors are available as optional Add-ons for the Qu mixer.

Modelled on classic hardware units with unique tonal and behavioural characteristics, they can be used in place of the standard compressor on every input and mix processing channel without adding latency.

• Press the LIBRARY key to see the Compressor Library.
• Different DEEP Compressor models can be recalled from the Factory library.

|| PROCESSING | DEEP Compressor (Input Channel)

Input > Delay

|| PROCESSING | Delay (Input Channel)

The Input channel Delay can be used to time align channels that may be offset, when using multiple microphones at different distances from a source for example.

Delay – Set the amount of delay by the selected delay unit.

Delay Units – Select how the delay should be displayed and adjusted.

ms - Millisecond

m - Meters

ft - Feet

Samples – Processing samples (Qu runs at 96,000 samples per second)

As the speed of sound through air depends on the temperature of the air, the Temperature value should be set to match ambient temperature for accurate calculation of delay shown as distance.

Temperature -

-20°C to +40°C

-4°F to +104°F

ⓘ Note that these values extend outside the operating temperature range of the Qu.

Mix > Insert

|| PROCESSING | Insert (Mix Channel)

The Mix Insert point allows the summed signal to be processed before being returned directly into the channel before the FBA/GEQ. It is commonly used for EQ or dynamics processing but can also be used to insert FX.

Send – Select a destination for the signal. This can be any available output socket or FX unit.

Return – Select a source for the returning signal. This can be any available input socket or FX unit.

ⓘ Send and Return will always automatically match when inserting an FX unit.

Operating Level – Select from line level options to match insert socket being used.

Digital - Uncompensated, for use with digital I/O.

Analogue - For use with +4dBu outboard equipment.

-10 dBV - For use with -10dBV outboard equipment.

Unassign – Unassign and clear Send and Return socket selections.

In/Out – Switch the insert in or out, without affecting the assigned sockets.

ⓘ If the socket is in use elsewhere in the system, this is noted. A + symbol is shown when a Return socket is being used in multiple places.

Mix > Switching between FBA and GEQ

|| PROCESSING | FBA/GEQ Library (Mix Channel, pop-up)

Every Mix channel has the option of using either the Feedback Assistant (FBA) or a Graphic Equaliser (GEQ). These use the same processing ‘block’ in different ways.

To choose which is in use on any individual Mix:

• Press the LIBRARY key while viewing the FBA/GEQ for the selected Mix channel in the PROCESSING screen.
• Select a GEQ type from the Factory library to recall a flat/reset GEQ.
• Select FBA Reset from the Factory library to recall the default Feedback Assistant state with no filters in use.
• Select any GEQ or FBA data which has been stored in the User library.
• Press Recall to recall, or close the library pop-up to cancel.

Alternatively, the SETUP > Config > FBA/GEQ screen displays whether FBA or GEQ is being used on every Mix channel and allows toggling between the two.

ⓘ Note that switching from FBA to GEQ may cause instant feedback if FBA filters have been applied.

Mix > FBA

Detect

|| PROCESSING | FBA | Detect (Mix Channel)

The Feedback Assistant detects feedback and automatically applies narrow filters to prevent it.

Detection On/Off – When turned on, feedback frequencies will be detected, and filters will be automatically applied.

ⓘ Detection can be active on up to 8 FBA instances at once.

Config – Opens a pop-up showing all mixes and allows detectors to be turned on and off per-FBA instance.

Auto Apply – Select whether the next filter to be added (when feedback is detected) will be Fixed or Live.

Live Response – Adjust the speed at which Live filters are applied.

Live Recovery – Adjust the speed at which Live filters are currently recovering. Can be set to Off to pause live filter recovery.

RTA – Enable this option to see a Real Time Analyser in the FBA graph.

In/Out – Select to enable or disable the Feedback Assistant.

Adjust

|| PROCESSING | FBA | Adjust (Mix Channel)

Touch the Adjust tab at the bottom left to make adjustments to individual or all filters. Each numbered box at the lower left of the screen represents one of the 16 available filters.

Blue – Fixed mode filters.

Green – Live mode filters.

Orange – Currently selected filter.

Touch a box or a point on the graph to select a single filter for adjustment.

(Adjust Filter) Width – Adjust the width of the selected filter.

(Adjust Filter) Cut – Adjust the cut of the selected filter.

Filter Type – Toggle the mode of the filter between Fixed and Live.

Remove Filter - Remove the filter completely and make it available for use again.

(All Filters) Width – Adjust relative width of all active filters at once.

(All Filters) Cut - Adjust relative cut of all active filters at once.

ⓘ To reset all filters, recall FBA Reset from the Library, or hold the Reset key and press the GEQ Fader Flip key.

Number of Feedback Detectors

Feedback detection can be active on up to 8 instances of the FBA at once.

Filter Modes

Fixed filters - Remain in place until they are manually deleted, the FBA is completely reset, or if the Feedback Assistant ‘steals’ them. These are designed to be used during setup to ‘ring out’ the system and notch out problematic frequencies that are due to the frequency response of the microphones, speakers and environment.

Live filters - Recover over time and once fully recovered, will switch back to being unused filters. They can be deleted individually or with a complete FBA reset. These are intended for use during a performance, where temporary changes in the system may cause feedback (e.g. position of microphones relative to speakers), meaning filters need only be applied temporarily.

Automatic re-use of filters

When all filters are already in use, but a new feedback frequency is detected, the Feedback Assistant can re-use or ‘steal’ an existing filter, using logic to decide the best possible outcome i.e. the least amount of feedback.

Note that Live filters can only ‘steal’ other Live filters, but Fixed filters can steal any filters.

On power up

Every time the Qu is powered on or restarted; all Feedback Assistant instances are set to a ‘pre-show’ state. Fixed filters, the Live Response and Recovery settings, All Filters settings and In/Out state are recalled from last power down. Any Live filters will have been removed, and detection will be turned off.

Copy/Paste and Library Store/Recall

Copying and pasting of the FBA can be carried out by holding COPY or PASTE keys and pressing the GEQ FADER FLIP key. It is also possible to store and recall FBA states using the FBA/GEQ library. Note that Fixed filters and settings (including Live Filter settings) are copied, but Live filters are ignored.

Scene changes

By default, the FBA/GEQ Global Filter is set to Block, preventing changes to the FBA/GEQ when changing scenes.

Mix > GEQ

|| PROCESSING | GEQ (Mix Channel)

The GEQ is used to cut or boost specific frequencies in the signal.

Fader – Touch and drag or select a band and use the touchscreen rotary to cut or boost by ±12dB.

RTA – Enable this option to see a Real Time Analyser on the GEQ. The most prominent frequency is displayed red.

In/Out – Enable or disable the GEQ.

DEEP GEQ’s

DEEP GEQ models are available as optional Add-ons for the Qu mixer.

These offer different bandwidth/Q options to the standard Constant-Q GEQ and can be used in place of the FBA/GEQ on any mix processing channel without adding latency.

• Press the LIBRARY key to see the GEQ Library.
• Different DEEP GEQ models can be recalled from the Factory library.

Mix > PEQ

|| PROCESSING | PEQ (Mix Channel)

The 4-band Parametric Equaliser enables adjustments to the tone of the mix by cutting or boosting around different frequencies.

• Touch one of the bands on the graph to display settings and values at the bottom of the screen.
• Adjust using dedicated surface controls, by touching and dragging on the graph or by selecting a parameter and using the touchscreen rotary.

Type – LF and HF bands include options for Shelf, Bell or HPF/LPF.

Width – Adjust the amount that frequencies around the centre frequency are affected.

Freq – Select the centre frequency for adjustment.

Gain – Cut or boost the selected centre frequency by up to +/- 15dB.

RTA – Display Real Time Analyser behind PEQ.

In/Out – Enable or disable the PEQ.

Mix > Compressor

|| PROCESSING | Comp (Mix Channel)

The Compressor is used to control and reduce the dynamic range of the signal.

RMS/Peak – Compression is either triggered by RMS (short average) or Peak (instant) signal level.

Hard/Soft Knee – With hard knee, compression begins to take effect only when the threshold is reached. With soft knee, the compression begins to take effect earlier but in a more gradual way.

Attack – Adjust the time it takes for compression to take effect once the signal has reached the threshold. Set a longer time to allow transients through and compress only the body of the sound, set a shorter time to flatten the signal and tame peaks.

Release – Adjust the time that it takes for the compressor to stop compressing after signal has fallen below the threshold.

Ratio – The ratio of the incoming signal to compressed signal when compression is active. E.g. when set to 3:1 and when compressing, every 3dB increase in level at the input will result in only a 1dB increase of level at the output.

Threshold – Adjust the input level at which compression will be active.

Gain – Use to compensate for the resulting attenuation of the signal.

In/Out – Enable or disable the compressor.

Side Chain

• Select either Self Keyed or select another channel to trigger the compression.
• Touch the filter type to switch between Off/HPF/BPF/LPF modes.
• Touch the frequency value to select it, then adjust with the touchscreen rotary.

Parallel Path

This allows you to blend the compressed signal with the uncompressed signal. Due to the XCVI core, these signals are coherent, and no comb filtering is introduced.

• Touch the Parallel Path button to switch in or out.
• Touch the Dry/Wet values and adjust using the touchscreen rotary.

DEEP Compressors

DEEP compressors are available as optional Add-ons for the Qu mixer.

Modelled on classic hardware units with unique tonal and behavioural characteristics, they can be used in place of the standard compressor on every Input and Mix processing channel without adding latency.

• Press the LIBRARY key to see the Compressor Library.
• Different DEEP Compressor models can be recalled from the Factory library.

|| PROCESSING | DEEP Compressor (Mix Channel)

Mix > Delay

|| PROCESSING | Delay (Mix Channel)

The Mix channel Delay can be used to time align outputs, when synchronising audio to video for example. Another common use is when feeding fill or delay speakers that should be time aligned to main speakers, so the sound from all speakers reaches the listener at the same time.

Delay – Set the amount of delay by the selected delay unit.

Delay Units – Select how the delay should be displayed and adjusted.

ms - Millisecond

m - Meters

ft - Feet

Samples – Processing samples (Qu runs at 96,000 samples per second)

As the speed of sound through air depends on the temperature of the air, the Temperature value should be set to match ambient temperature for accurate calculation of delay shown as distance.

Temperature -

-20°C to +40°C

-4°F to +104°F

ⓘ Note that these values extend outside the operating temperature range of the Qu.