Introduction and setup

MIDI (Musical Instrument Digital Interface) is a standardised communication protocol that enables digital devices to communicate and allows one piece of equipment to control another.

The SQ+ sends and receives MIDI over USB (via the USB-B port) as well as over ethernet (using MIDI over TCP/IP via the network port).

These can be broken down into two sets of bi-directional messages. Those that are used with SQ+ mixing parameters (e.g. level control of SQ+ audio channels), and those used to control external software or equipment (e.g. to control a DAW).

Connection

When connected to a computer or other host using the USB-B port, the SQ+ will appear as a MIDI input and output device. This can be used with software directly or through use of the Allen & Heath MIDI Control application.

To connect a computer to the SQ+ over a network, the Allen & Heath MIDI Control app can be used.

All other clients used for network communication should be configured to send messages to the SQ+’s IP address and use port 51325.

ⓘ With an option card fitted that supports network messaging (e.g. Dante or Waves) and the Control Network Bridge turned On, it is also possible to send and receive network MIDI messages via the option card.

MIDI channels

There are 16 MIDI channels available, and the SQ+ can use up to 6 of these, one for the mixer itself, one for the MIDI channel strips which can be used with Allen & Heath MIDI Control to emulate a DAW control surface and up to 4 for control of RackUltra FX.

Press the ‘UTILITY’ screen key on the SQ+, then touch the ‘General’ tab followed by the ‘MIDI’ tab to view and adjust the MIDI channel settings.

This screen also displays MMC (MIDI Machine Control) buttons for control of computer sequencers and DAW’s.

• Touch the ‘MIDI Channel’ or a 'RackUltra FX Unit MIDI Channels' value and use the touchscreen rotary to adjust.
• Touch the ‘NRPN Fader Law’ value to switch NRPN level control (to and from the SQ+ core) between Linear Taper or Audio Taper.
• Touch the ‘Apply’ or ‘Cancel’ buttons to apply or disregard changes.

The channel used for MIDI DAW control (and therefore all MIDI fader strips) is always one higher than the MIDI Channel the SQ+ itself is set to.

ⓘ To use MIDI channel 1 for DAW control purposes, set the main SQ+ MIDI channel to 16.

The NRPN Fader Law selects whether Linear or Audio Taper is used for control of levels in the mixer. The audio taper option allows the SQ+ level control to be used with external linear controls such as MIDI faders or pots and have them behave in the same way as SQ+ faders.

ⓘ See the Levels section for more information on Fader Laws.

Touching any of the 'MMC Controls' sends standard MMC transport messages to all channels. These are also used when using the SQ+ for DAW control to send transport messages for the control surface emulation being used.

Types of message

MIDI messages can be presented in different ways in various hardware and software, including as plain text, binary, decimal or hexadecimal.

As an example, here are four representations of the same message:

This document uses the representations you are most likely to come across for each kind of message when communicating with the SQ+.

Note On/Off

The SQ+ uses a note on followed by a note off for MIDI strip keys and MIDI triggering of the SQ+ SoftKeys.

MMC

MIDI Machine Control is used to send transport control messages from the SQ+.

ⓘ MMC messages are ‘Real Time Universal System Exclusive’ messages and are sent to all connected devices rather than being assigned to a single MIDI channel.

CC (Continuous Controller)

For each MIDI channel there are 128 continuous controllers, each of which can have a value between 0 and 127 (128 steps). These are used by MIDI strip faders, MIDI on Soft Rotaries and other parameters with more than just an on/off state.

NRPN (Non-Registered Parameter Number)

For high-resolution control (16384 steps) and access to many more parameters, NRPN messages are used to communicate with SQ+ to control levels, panning, mutes and assignments.

NRPN messages can be thought of as a specific string of CC messages, with MSB (Most Significant Byte) and LSB (Least Significant Byte) representing a parameter number, and a further one or two messages representing parameter value.

NRPNs can be used to set the absolute value of a parameter, or to increment/decrement a parameter value.

These are displayed as hexadecimal values in this document and it should be noted that the ‘0x’ prefix has been removed for brevity.

Allen & Heath MIDI Control and DAW Control

The Allen & Heath MIDI Control app works by creating virtual MIDI ports in Mac OS or Windows and then facilitating a MIDI connection between these virtual ports and the SQ+, either with or without translation.

This enables MIDI channel strips and SoftKey options on the SQ+ to control DAW software on Mac OS or Windows by emulating popular HUI or Mackie Control protocols.

It can be used to send and receive MIDI control messages directly to and from the SQ+ core for remote control of mixing parameters, scene changes and other functions (as detailed in this document).

Simplified control of the most common mixing parameters using MIDI CC and Note On/Off messages from the computer is also made possible with the ‘CC Translator’ options.

Visit https://www.allen-heath.com/hardware/controllers/midi-control/resources/ to download the latest version of Allen & Heath MIDI Control and refer to the Help document for information on setup and configuration.

MIDI Faders and Soft Controls

MIDI faders

The SQ+ has 32 freely assignable MIDI fader strips. Refer to the SQ+ Firmware Reference Guide for information on strip assignments.

Each strip sends and responds to the following messages sent on the ‘MIDI DAW Control Channel’:

SoftKeys and Foot switch

The SQ5+ features 8 assignable Soft Keys, while the SQ6+ and SQ7+ both feature 16 assignable Soft Keys. All SQ+ models feature a dual foot switch input. Any of these can be assigned the following MIDI functions:

ⓘ Refer to the SQ+ Firmware Reference Guide for information on assigning Soft Key and foot switch functions.

Soft Rotaries

The SQ6+ and SQ7+ feature 4 and 8 Soft Rotaries respectively, with options for these to send the following MIDI messages:

ⓘ Refer to the SQ+ Firmware Reference Guide for information on assigning Soft Rotary functions.

Control to and from the Mixer

Scene change (All Scenes)

A scene change when using ‘All Scenes’ uses a bank change followed by a program change.

Where: N= MIDI Channel, BK = Bank, PG = Program

The bank change (BK) selects between three ranges of scenes:

Scenes 1 to 128 = Bank 1 = 00
Scenes 129 to 256 = Bank 2 = 01
Scenes 257 to 300 = Bank 3 = 02

The program change (PG) is then a value between 00 and 7F (decimal 0-127), which selects a scene in that range.

ⓘ Note that there is an offset of -1 between the SQ+ values and the MIDI values due to the SQ+ counting from 1 to 128 and MIDI counting from 0 to 127.

So scene 96 is bank change 00 (1) and program change 5F (95), and scene 264 is bank change 02 (3) and program change 07 (8).

The scene being recalled must exist as a saved scene in the SQ+, blank scenes cannot be recalled.

ⓘ When recalling a Scene on the SQ+, the same message is sent.

Scene Recall Examples:

Scene change (Cue List)

When Scene Manager is in 'Cue List‘ mode (Cue List is selected), scenes can still be recalled directly from the ‘All Scenes’ list using a bank change followed by a program change as detailed in the previous section.

Where: N= MIDI Channel, BK = Bank, PG = Program

To instead recall scenes based on their position in the Cue List (Cues), different bank change (BK) messages should be used:

Cue Position 1 to 128 = Bank 1 = 0A
Cue Position 129 to 256 = Bank 2 = 0B
Cue Position 257 to 300 = Bank 3 = 0C

Cue List Recall Examples:

Cue List MIDI Show Control (MSC)

The Cue List also supports the following MIDI Show Control messaging:

GO - Recall currently selected Cue, using the mixers’ Cross Fade time.

Timed GO - Recall currently selected Cue, using the MSC defined Cross Fade time (20 second max).

GO + CueNumber - Recall a specific cue, using the mixers’ Cross Fade time.

Timed GO + CueNumber - Recall currently selected Cue, using the MSC defined Cross Fade time. (20 second max).

LOAD - Set selected Cue but does not recall, awaiting GO message.

RESET - Return to the first item in the Cue List.

Soft Keys

The SQ+ Soft Keys can be controlled using standard MIDI Note On/Off messages, allowing the control of many more internal functions of the SQ+ by proxy.

ⓘ The SQ+ does not send note on/off messages when a Soft Key is pressed unless the Soft Key is set to a MIDI note on/off function. See the Soft Keys and Foot switch section above for more details.

A key press is triggered with note on and a release is triggered separately with a note off, making it possible to replicate a held key (e.g. for use with the talkback function).

Each Soft Key is controlled with a different sequential note starting at C3 (30) as follows:

ⓘ The HEX values shown here are accurate, but some applications and hardware use different octave designations. So if C3 is not controlling SoftKey 1, try C2 or C4 instead.

Note On (Soft Key press)

Note Off (Soft Key release)

Both where: N= MIDI Channel, SK = Soft Key Note

ⓘ The SQ+ will respond to both MIDI note off standards, i.e. a specific note off message or a note on message with zero velocity.

SoftKey Examples:

Mutes

The SQ+ sends and receives absolute On or Off mute messages. It will also toggle the mute state when either an increment or decrement message is received.

MSB and LSB are a parameter number for the channel you wish to mute or unmute.

ⓘ MSB/LSB parameter numbers are shown in the reference tables section.

The last byte of the full message then represents a mute on or off.

Mute On

Mute Off

Both where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number

When either a data increment or decrement message is received, the SQ+ will toggle between states, in the same way as pressing a mute key on the SQ+ does.

Mute Toggle (increment)

Where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number

Mute Examples:

Levels

Levels can be set using either absolute values or in relative 1dB increments/decrements.

MSB and LSB are a parameter number showing where the signal is being sent from and where it is being sent to.

ⓘ MSB/LSB parameter numbers are shown in the reference tables section.

An absolute level is represented with a combination of course and fine values.

Where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number, VC/VF = Value

NRPN Fader Law

The way the SQ+ responds to and sends level messages can be switched between two modes.

Press the ‘UTILITY’ screen key, then touch the ‘General’ tab followed by the ‘MIDI’ tab to view and adjust this setting.

• 'Linear Taper' offers high resolution control with 16384 possible values.
• 'Audio taper' has a lower resolution, with 256 possible values, but allows mapped external linear controls (e.g. MIDI faders or pots, typically with only 128 possible values) to work in a similar way to the SQ+ faders, with more control about the unity gain (0dB) position.

ⓘ See ‘Example Linear Taper Level Values’ and ‘Approximate Audio Taper Level Values’ in the reference tables section.

Level Examples (Linear Taper):

Level Examples (Audio Taper):

A relative level message uses the same parameter number, but with an increment or decrement byte.

This raises or lowers a level in 1dB steps.

ⓘ The NRPN Fader Law setting has no effect on relative control.

+1dB (increment)

-1dB (decrement)

Both where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number

Increment/Decrement Level Examples:

Panning/Balance

Panning (mono sources) or balance (stereo sources) can be set using either absolute values or in relative increments/decrements.

MSB and LSB represent a parameter number showing where the signal is being sent from and where it is being sent to.

ⓘ MSB/LSB parameter numbers are shown in the reference tables section.

Absolute values are set with a combination of coarse and fine values. Ranging from 00 00 (full left) to 7F 7F (full right), with centre being 3F 7F.

ⓘ See ‘Example Pan/Balance Values’ in the reference tables section.

Where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number, VC/VF = Value

Pan/Balance Examples:

A relative pan/balance message uses the same parameter number, but with an increment or decrement byte. Incrementing moves to the right and decrementing moves to the left.

Right one step (increment)

Left one step (decrement)

Both where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number

Increment/Decrement Pan/Balance Examples:

Mix Assignments

The SQ+ sends and receives absolute On or Off assign messages. It will also toggle the assign state when either an increment or decrement message is received.

MSB and LSB represent a parameter number showing where the signal is being sent from and where it is being sent to.

ⓘ MSB/LSB parameter numbers are shown in the reference tables section.

The last byte of the full message then represents assignment on or off.

Assign On

Assign Off

Both where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number

When either a data increment or decrement message is received, the SQ+ will toggle between assign states, in the same way as holding the Assign key and pressing a Sel key on the SQ+ does.

Assign Toggle (increment)

Where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number

Assignment Examples:

Getting values

A ‘get’ command can be sent to the SQ+ in order to return the current value of any mute, level, pan/balance or assignment parameter listed in this document.

MSB and LSB represent the parameter number of the value being requested, followed by a data increment with value 7F (i.e. the same as a standard increment message but with a value of 7F instead of 00).

ⓘ All MSB/LSB parameter numbers are shown in the reference tables section, be sure to use the correct parameter number for either mute, level, panning/balance or assignments.

Where: N= MIDI Channel, MB/LB = MSB/LSB Parameter number

Get Value Examples:

RackUltra FX

Three types of MIDI messages are used for RackUltra FX control; MIDI CC messages can be used to control the parameters for some FX types and the global key/scale, Note messages can be sent to the Vocal Tuner, and NRPN messaging is used for control of send and return levels, panning/balance and assignments for each unit.

Aside from the Global Key/Scale, which use the SQ+'s main MIDI channel, these messages use the MIDI channels assigned to each RackUltra FX unit.

Each of the 4 units should have a different MIDI channel assigned, and these should also be different to the base MIDI channel for the unit and MIDI DAW Control Channel being used.

Press the ‘UTILITY’ screen key, then navigate to the ‘General’ tab followed by the ‘MIDI’ tab to view and adjust all MIDI Channels in one place.

Alternatively, the MIDI channel for each RackUltra FX Unit can be changed in the MIDI Setup pop-up, accessed from the back panel of every RackUltra FX unit.

RackUltra FX Parameter Control

Some RackUltra FX units have parameters which can be adjusted by sending standard MIDI CC messages to the SQ+.

Where: N= RackUltra FX unit MIDI Channel, CC = CC Number, VA = Value

The RackUltra FX unit being controlled is determined by MIDI channel, i.e. the MIDI channel used for the message needs to match the MIDI channel set for the unit.

Then the parameter being controlled depends on the RackUltra FX model currently loaded into that unit:

ⓘ The controllable parameters and associated MIDI CC Numbers can be seen at any time by recalling a RackUltra FX model, then pressing the MIDI Setup button on the Back Panel of the RackUltra FX unit.

RackUltra FX Parameter Control Examples:

Other RackUltra FX Tuning Controls

Global Key and Scale

The global key and scale can be set using standard MIDI CC messages sent to the SQ+'s main MIDI Channel (not one of the RackUltra FX MIDI channels, which are for control of individual units).

Note that unlike the Key and Scale of individual units, which is treated as a parameter mapped across the full value range of a controller (0-127), Global controls use discrete values.

Global Key

Where: N= MIDI Channel, VA = Value

Global Key Values

Global Scale

Where: N= MIDI Channel, VA = Value

Global Key Values

Global Key/Scale Examples:

Vocal Tuner Note Control

Sending standard Note On MIDI messages to the RackUltra FX Vocal Tuner will force the tuning to the received note. This overrides automatic correction, key, scale and note settings and allows vocal tuning to be synchronised to backing tracks with a vocal melody programmed on a separate MIDI track.

• Only a single note can be used, so the last MIDI Note On message received is used.
• Tuning will fall back to automatic once the MIDI Note Off message for the currently used note is received (i.e. any note that was held previously is ignored).
• Received octave information is ignored, correction is to the received note closest to the detected pitch of the source.
• Pitch bend information is ignored.

RackUltra FX Level, Panning/Balance and Assignments

NRPN messaging is the same for each RackUltra FX unit, aside from the MIDI channel used.

Most of the NRPN parameter numbers also match those used to control levels, panning and assignments to the main LR mix when sent to the mixer's main MIDI channel.

For these reasons, it is very important that RackUltra FX units all have different MIDI channels assigned, which are also different to the SQ+'s main MIDI channel (and DAW Control MIDI channel).

The available controls for each unit include all sends and returns relating to it, using exactly the same messaging formats as the rest of the mixer, and detailed previously.

Mutes

• Mute On
• Mute Off
• Mute Toggle

Levels

• Absolute Send/Return Levels
• Relative (Increment/Decrement) Levels

Panning/Balance

• Absolute Send/Return Panning/Balance
• Relative (Increment/Decrement) Panning/Balance

Assignments

• Assign On
• Assign Off
• Assign Toggle

Getting Values

• 'Get' any value for an NRPN

ⓘ MSB/LSB parameter numbers are shown in the reference tables section.

Reference Tables

MIDI channels 1 to 16 Decimal/Hexadecimal (N)

Value to Note to Hexadecimal (PG and other values from 1-128)

Soft Key Note and Hexadecimal Values (SK)

Example Linear Taper Level Values (VC/VF)

Approximate Audio Taper Level Values (VC/VF)

Example Pan/Balance Values (VC/VF)

Example RackUltra FX Key/Scale Parameter Values (VA)

NRPN's (Non-Registered Parameter Numbers)

In the following tables, the source is shown on the left and the destination is shown at the top.

Each NRPN includes an MSB (MB) and an LSB (LB).

Mute Parameter Numbers – Inputs to LR/Aux (MB/LB)

Level Parameter Numbers – Inputs to LR (+Groups) and Aux (MB/LB)

Level Parameter Numbers – Groups to LR/Aux (MB/LB)

Level Parameter Numbers – FX Returns to LR/Aux (MB/LB)

Level Parameter Numbers – FX Sends (MB/LB)

Level Parameter Numbers – Mix Sends (MB/LB)

Level Parameter Numbers – RackUltra FX (MB/LB)

Panning/Balance Parameter Numbers – Inputs to LR (+Groups) and Aux (MB/LB)

Balance Parameter Numbers – Groups to LR/Aux (MB/LB)

Balance Parameter Numbers – FX Returns to LR/Aux (MB/LB)

Balance Parameter Numbers – Mix Sends (MB/LB)

Panning/Balance Parameter Numbers – RackUltra FX (MB/LB)

Assignment Parameter Numbers – Inputs to LR/Aux (MB/LB)

Assignment Parameter Numbers – Inputs to Groups (MB/LB)

Assignment Parameter Numbers – Groups to LR/Aux (MB/LB)

Assignment Parameter Numbers – FX Returns to LR/Aux (MB/LB)

Assignment Parameter Numbers – FX Returns to Groups (MB/LB)

Assignment Parameter Numbers – FX Sends (MB/LB)

Assignment Parameter Numbers – Matrix Sends (MB/LB)

Assignment Parameter Numbers – RackUltra FX (MB/LB)