[damcleanParticipant]

I figured out a work around – use Dante.

It will add 10-20ms latency. For most that’s fine especially since it’s for audio streams outside of the room (although may be in ear shot).

So we’d get the SQ and get a Dante expansion card. Then connect a Dante enables computer to the QU usb and send the Dante channel through the usb.

With USB the qu gain long controls trim.

This also gives you Dante for anyone else on the network, which is a nice benifit. Gotta love network solutions.

Daniel

[damcleanParticipant]

@volounteer

They did not. The documentation on page 29 seems pretty clear to me about the preamp gain setting with dsnake devices though. If you dont pay close attention to their being a digital trim in each channel processing cohort you likely wouldnt think anything of it.

The thing is, there is not QU based documentation that talks about the ability to connect to the SQ or any other mixer for that matter. Rather, there is only SQ documentation that talks about how to connect to the QU. The QU was not designed with this connection feature in mind. The SQ mixer came much later, and this particular feature came even later than that. They simply found a way to enable it by reusing the dsnake capability, hence we run into this particular issue as the dsnake feature bypassed the trim and forwarded preamp control signals.

I asked about potential future firmware updates… he just responded by saying essentially what I just wrote, that the SQ came much later and this feature was not considered when they did the initial QU hardware and software architecture. Although it may seem like a simple adjustment based on the block diagram, my guess is under the hood it would be a substantial change. Also I think they are end-of-lifeing the QU at some point in the near future, so it wouldn’t make sense for them to make further feature enhancements. Oh well.

We will want to upgrade to a 32 channel unit anyway at some point, so we may still do this which will still give us better control of our stream, and then maybe eventually we will get an additional SQ mixer just to give us this trim control, depending on how much of an issue it actually is for us.

Thank you everyone who engaged with me on this, and hopefully other people find this post helpful in future.

[damcleanParticipant]

Hey all, I got confirmation from Allen and heath. As I feared, the qu treats the sq as if it were any other dsnake source (I.e. an audio rack) and sends control signals to change the SQ gain. However these control signals are ignored, so it does nothing. There is no way to control the trim in this way, here’s the email:

Hi Daniel,

With the SQ SLink port connected to the Qu dSnake port, the Qu will see this as if a dSnake expander is connected, so a gain control will be available on the Qu but it does not control the preamp on the SQ, the control messages are ignored. A trim control isn’t available on the Qu as there is no way for the Qu to know that there is an SQ connected and to change the gain control to a trim.

Sending the Qu Preamps to the SQ means that the gain control on the Qu does work, and there is a trim control available on the SQ. So if both gain/level controls are needed, this would be the best way to route it.

Thanks

Alex

[damcleanParticipant]

BTW I’ve emailed support to see if they can confirm what the behavior will be, I hope you are right.

[damcleanParticipant]

Yes, Your description of the block diagram is what I have been describing this whole time, and your conclusion is the behavior I would want. I am writing this forum post precisely to confirm if your conclusion is true.
I have given an explanation on how the QU might not behave in that way. To be honest, what I am expecting that the gain knob in the QU would do nothing OR that the QU would try and set the analog gain of the SQ but it would have no effect… meaning the gain knob in this mode would try to do something but in effect it would just do nothing. Either way, anything other than your conclusion is undesirable to me.

This is an important part, if your conclusion is true than I am happy and would proceed with writing up a proposal of buying the SQ and using the QU as an auxiliary mixer… but it doesn’t sound like you are able to confirm that it’s true?

[damcleanParticipant]

@mfk0815: From what I understand on those other series board you have the ability to specifically control gain and trim separately. The QU series is annoying in that it sort of automatically selects what you are adjusting. You don’t get the choice to control trim and gain independently. Depending on your source you either control 1) the preamp gain (if you are using an xlr port at the rear)
2) the trim (if you are using USB as a source)
3) the remote preamp gain (if you are using an audio rack over dsnake).

It’s this third option that has be worried, as the qu-sq connection setup is virtually identical to an audio rack setup. Dsnake device source selection makes the gain setting change the remote gain, so it stands to reason that if it’s another console is connected using the dsnake path than the gain setting would change the connected consoles preamp gain.

[damcleanParticipant]

Take a look at the block diagram. This is the info path: From XLR input you first have a preamp gain, which is an analog gain which sets the voltage level for the adc. It then goes through some digital routing and gets to the channel processing cluster. Then the first element in the channel processing is a trim, this acts as a course gain adjustment in the digital domain. Than after some eqs and other processing you have the fader, which is more fine tune as you suggested. It can then be sent to various mixes ect and finally outputted.

If we were to connect two boards together, the connection would be a digital one. The path would go through the preamp of one board and then be split after digitization, one leg going into the trim on one board and the other into the trim of the second board.

Ideally we would have these boards act independently. To act independently we need the gain to remain constant as the gain is the only setting that effects both boards. We don’t want someone to adjust this gain unless the absolutely need to, as if they do it will effect the other board.
However you sometimes need this coarse
adjustment when the faders arent enough. In most cases the trim would be adequate, you don’t need to modify the preamp gain. Since each channel has a trim as the first digital element each board can most of the time function independently. However, unlike the SQ, the QU doesn’t give you the ability to modify the trim specifically. It automatically decides if your “gain” is changing the preamp or the trim, depending on what the source is.

I hope that clears it up.

To explain my other concern. One handy accessory you can buy is an audio rack which allows you to have a set of XLR ports in a box connected to the QU via Ethernet. What you do is you have your xlr cables connect to thjs box under the stage, and then you only need one cable running from the stage to the mixer, and this cable is an Ethernet cable which can travel a long ways without any analog degradation as it’s already digitized. This connects using the dsnake port. Now, I know for a fact that when you do this, and you change the gain knob on the QU for one of the channels going to the audio rack, what you are doing is changing the preamp gain in the audiorack, you aren’t changing the preamp gain on your board, nor are you changing the trim. This is what page 29 is talking about.

If I were the engineers at A&H and I was trying to find an easy way to enable this board to board connnection I would
Just reuse this audio rack functionality. That would suggest that changing the gain knob would change the preamp gain of the connected mixer just as it changes the preamp gain of the audio rack.

[damcleanParticipant]

Thanks for the responses guys.

@volounteer, I am not talking about output trim, I am talking about input trim. Yes, you will fine the output has eq, compression, ect. ect, but those are settings for the entire mix. If I get a second sound board, each channel will take one channel as a source from the first soundboard via dsnake (or slink from the SQ perspective). It will be grabbed right before the TRIM and send to the second board. That way the second board has full control, it can set per channel EQ, FX, the works. However, will it have control of the trim? Thats the question.

It matters to have trim control, it helps you set the volume range of your faders. I dont want one sound board to change the trim and have it effect the other. The documentation for the QU suggests strongly that you dont get to chose if you are changing the preamp or if you are changing the trim, it is done automatically. See page 29 https://www.allen-heath.com/media/Qu-Mixer-Reference-Guide-AP9372_10.pdf

The SQ gives you the ability to change gain and trim seperately, but the QU doesnt seem to allow you.

@mfk0815: How are you so sure? Have you tried this?

[damcleanParticipant]

Right now we also feed the stream with a mix. I would double check what you said… for us the gain does change everything… as it should when you look at the block diagram. Even if the knob changed the trim and not the gain.

The mix has its own fader for each input to the mix, but that’s all it has, it doesn’t have its own trim or eq ect. We are getting by right now, but it is a bit arduous at times.

With regards to the remote gain control: I read somewhere that when connected to dsnake the gain setting controls the remote preamp. Which would make sense. But I can’t find it in the reference manual, maybe it’s written in some other supporting document. But it needs to be done this way. The audio rack converts the signal to digital. You need a way to control the preamp gain to set the voltage range before the adc. It would have been a design requirement for A&H otherwise the value of the audioracks feature is severely impaired. You can also control things like phantom power and I think polarity as well. All the source analogue settings need to be forwarded to the audio rack. I just want the ability to also change the local trim :p

[damcleanParticipant]

Quick followup. From my understanding, when the QU24 is connected to an audiorack and set to source inputs from the rack, the gain knob will control the preamp gain on the audio rack. The connection to the SQ console, from my understanding, reuses this feature in the QU console. That is to say that I dont think the QU console has any understanding that it is connected to an SQ console, it will treat the SQ console as if it is an audio rack. Ergo my suspicion that the gain knob would try and change the SQ preamp when really I would want it to control the trim.

What I want is to beable to set the GAIN on the mixer which has the mic connections, and then leave the gain constant at a good but safe level. The channel will then be split, one going to the primary mixer and the other going to the secondary mixer. I then want each board to have the ability to change the trim, as if it were the gain, without effecting the other board. If the SQ is the source, then I need the QU gain knob to control the QU trim and not try and control the SQ gain. If the QU is the source, I want to beable to adjust its GAIN and TRIM seperately. I know the SQ has a way to control gain an trim seperately, but I dont see if the QU has a method.

[damcleanParticipant]

Thanks for the response!

So the connection to SQ6 would be over the DSNAKE ethernet port, not USB.

Looking at the block diagram, each channel processing cluster has a trim. https://www.allen-heath.com/media/Qu-24and32-block-diagram_V1.8_1.pdf
It would be nice to have separate control of the preamp gain, and the trim. However it seems you can only control this trim for USB sources.

The documentation seems to suggest that when the channel source is “local”, meaning rear panel, then gain knob will control the preamp gain. When it is set to dsnake, it will remotely control the preamp gain on the connected device. When the source is USB, the knob will control the trim.

I have not seen documentation on what this knob does when the source is another console – i.e. the SQ6. I am wondering if the gain knob in this case will control the remote premamp gain as it does with a typical dsnake device. I would prefer it to control the trim. I am also wondering if I can get manual control of TRIM in anycase.

Not sure if this cleared that up.

Here is a copy paste of the text from the reference guide. The photos aide in how I arrived at my understanding as well (Page 29) https://www.allen-heath.com/media/Qu-Mixer-Reference-Guide-AP9372_10.pdf:

Source lets you choose one of four sources as the
input to the channel. Press the Fn key to open the
Source screen.

…

Channel Preamp source
Local (red Gain) – Rear panel Mic/Line sockets
feeding the internal Qu mixer preamps. These are a
pad-less design featuring wide gain range.

dSNAKE (yellow Gain) – Remote preamps located in
an AudioRack on stage or other remote location and
connected to the Qu dSNAKE port via a Cat5 cable.
The AudioRack preamps include 20dB Pad switching.

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