Allen & Heath SQ6

Trace the signal from the input socket to its processing channel, then through the LR mix to the output socket. In I/O, assigning a socket to a channel and assigning LR to an output are different operations. A Direct Out carries one channel's signal; it does not combine the microphones and music into the LR mix.

1. Save the current show and images of the patch. Identify the source socket, intended channel, mix and physical output to the system. Agree on a test level and keep the destination under control before enabling audio.
2. Press Sel on the channel and open Processing > Preamp. Under Source Select, Unassigned means the channel has no source. For an onboard SQ6 input, check Local Socket and its number. For a rack or card, identify the device and its signal path. You can also check the crosspoint under I/O > Inputs > Input Channel.
3. Compare Meters > Input Meters with the source under test and note the metering point. If there is no signal, check source selection, socket, cable and preamp. If signal is present before processing but missing afterward, follow the channel blocks, including the gate and insert. Do not compensate for a broken path by raising every level.
4. Press LR to work on that mix. In the channel's Routing screen, check its assignment and send to Main/LR, mute, channel level and any DCA controls affecting it. The master controls the selected mix: when a monitor Mix is selected, you are not adjusting the LR master.
5. If LR has signal but the sound system does not, check I/O > Outputs > Mix Outs. LR must feed the sockets actually connected to the speakers or processor. Do not confuse this tab with Direct Outs or Tie Lines. Numbered outputs are assignable; a label or factory patch does not establish how a loaded show is configured.
6. Test one known working source at a time and compare the channel, LR and destination. If the LED meter is following PAFL, it shows that monitored signal, not proof of output to the PA. Record where the signal appears and disappears. Restore changes you ruled out and check microphones and music together.

Check what feeds both the mix and the output socket. Muting an input channel does not mute its physical input socket in every possible route. Mix Ext In sends a source straight into a mix, while a Tie Line connects an input to an output without passing through a mixing channel.

1. If there is feedback, silence the destination using its known output control and confirm that it has stopped before investigating. Do not reopen the monitors simply to reproduce feedback. Save the show and the initial assignments.
2. Under I/O > Inputs > Mix Ext In, look for crosspoints feeding the monitor aux. You can also check the external source in that mix's Processing screen, in the Ext In block. A socket assigned here bypasses the input-channel faders and mutes; it is not a channel send to the aux.
3. Under I/O > Tie Lines, trace the physical output socket connected to the monitor. If it is fed directly from an input, a channel or mix mute outside that route cannot cut it. Check with the system operator whether the crosspoint is intentional before changing it.
4. If the output receives a Direct Out, check Routing > Dir Out on the channel and whether direct outputs follow faders and mutes. The tap point and these options apply globally to direct outs, so a change can affect recording and other destinations. Review every output using that route before choosing a control.
5. During a controlled test, remove only an identified accidental crosspoint with the destination silenced, then compare the result when enabling it at the agreed level. If audio remains, follow other sources, FX returns and channels outside the visible fader layer. A pre-fader send alone does not explain why a channel mute is ignored: pre/post-fader describes which level the send follows. Record the route checked and any path still unresolved.