@SPH1X
Salut Laurent,
It is not possible to connect 2x mixers to 1x expander, except in the special case of Dante/DT units.
All expanders using A&H protocols are used to increase the number of input and output sockets available to the mixer they are connected to. Together, the mixer and expanders can be thought of as a system.
Another type of connection is system to system, which is connection of 2x mixers to share audio in both directions. This is possible using third party protocols like Dante, Waves or MADI, but also with most of our ranges using gigaACE/GX (via the SLink port for SQ to SQ connections) or dSnake (if connecting a Qu to an SQ).
So as Tobi says, you can connect a GX4816 to an SQ and then also connect a Qu to the same SQ with the addition of an SLink card.
The SQ<->GX4816 connection is an expansion of the sockets for the SQ using the 96kHz gigaACE/GX protocol, and the SQ<->Qu connection is a system to system connection using the 48kHz dSnake protocol.
You could then use tie lines in the SQ to route signals directly between the Qu and the GX4816, allowing for independent processing on the SQ at FOH and Qu on monitors.
Things to note:
- The SQ must sync/clock to the connection with the Qu. The SQ will still be running at 96kHz, but the Qu cannot sync to an external clock, so everything must sync to the Qu.
- You will need to run two cables to FOH from the stage (as Tobi says)
There is more information on SLink and examples of setups in this document – https://www.allen-heath.com/media/SLinkConnections_V1_5_0.pdf
As the built-in SLink port and an SLink option card port are independent, you can use any two of these examples at the same time on an SQ with an SLink option card fitted.
Hope this helps!
Keith.