No trim on SQ tie lines

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This topic contains 2 replies, has 2 voices, and was last updated by Profile photo of JakeW JakeW 1 year, 8 months ago.

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    Profile photo of JakeW

    We have recently upgraded to digital. We have 2 AB168 on the stage fed by ethercon via Dsnake protocol to an SQ 7 at FOH. We then have imputs tie-lined to a QU-24 in our Broadcast room. We have the SQ clocked to the QU. Both boards are running most recent firmware version. We have gain control at foh, but only fader control on broadcast (no trim, or pad). Sq audio sync is clocked to the QU. Everything functions normally on the FOH board. We have an ambient mic for broadcast connected locally to the QU and we have full function of that channel. No matter which channel we plug it in, so all channels function properly when connected local. Our problem is all signals to channel on the QU via Dsnake are recognized and can apply fx, comp, etc…But no trim or pad control. We do have fader…but thats all. We did have trim control on the QU but lost it. I have gone through all of the settings on the SQ and can’t find anything that would cause the issue. Any ideas what to try?

    Profile photo of KeithJ A&H
    KeithJ A&H


    The reason for this takes a little bit to explain properly, so bear with!

    ‘Gain’ is often used to refer to ‘Preamp Gain’ and in our digital consoles this is a digitally controlled analogue preamp that exists either locally (in the console) or remotely as with your AB168’s.
    The physical preamp has the preamp and gain, a pad (you’ll be able to hear relays switching in and out if you listen to your AB168’s) and 48V phantom power.
    With all our A&H protocol expanders (i.e. everything non-Dante), you will only have preamp control on the console you have expanded and the console plus any expanders should be thought of as a single system.
    When connecting two consoles, you are connecting two systems with an audio only connection (no messaging) – an SQ, Avantis or dLive will just see a bunch of incoming digital signals and available output sockets on a port which you can then freely patch from/to.

    The Qu however, was never intended to be connected to another system, the dSnake port was only designed to work with AR2412/AB168/AR84 and ME systems.
    With the launch of SQ however, we realised we could make the Qu discoverable to the SQ and have the SQ receive signals back from the Qu too.
    So we decided to do it and it can obviously be really useful, but because we never saw it happening there are a couple of points to note:

    • The Qu has to be clock leader as it has no way to clock to an external source. This is also why you cannot connect two Qu’s, as they both want to be leader! (Note that when clocking 96kHz consoles to the Qu, they still run at 96kHz internally and all I/O is up/down sampled).
    • Patching outputs on the Qu is like patching to physical outputs (1-20 at SQ) as well as to a non-existent ME system (21-60 at SQ).
    • Patching inputs on the Qu – the Qu thinks there is a 40 input expander connected.

    The last point is the reason you have no trim, as the Qu thinks the SQ is an expander and therefore displays preamp controls which do nothing because there isn’t actually a physical preamp there.
    The only time you will see trim control on the Qu is when channels are sourced from USB.

    So with regards to what you can do – we’d recommend looking at it the other way around, ensuring the preamps are set correctly (good practice anyway) and then if required use the trim on the SQ.
    If you want to avoid adjustments to preamp gain on the SQ (which will affect both consoles), you could also turn ‘Preamp On Surface’ ‘Off’ in the SQ Surface Prefs – you’ll still be able to adjust preamp settings from the ‘Processing > Preamp’ and ‘I/O’ screens, but the dedicated gain rotary on the surface will control trim instead.

    Hope this helps 🙂

    Profile photo of JakeW

    Thanks for the explanation.

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