Qu-series: confusion about Buss/Matrix/Groups

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This topic contains 16 replies, has 7 voices, and was last updated by Profile photo of gravyface gravyface 5 years, 12 months ago.

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  • #52567
    Profile photo of gravyface
    gravyface
    Participant

    I’m interested in using the Qu-24 (or 32, more on that below) to get away from mixing in-the-box. I’ll still likely be using some console channel/tape sim plugins (Slate VCC and VTM) for colour, but for hands-on mixing, my plan was to use the DAW (Reaper) as more of a tape machine than anything, as I record mostly live-off-the-floor with minimal overdubs.

    One thing that I’m slightly confused on is the Matrix vs. Bus vs. Groups.

    On the comparison page (http://www.allen-heath.com/key-series/qu-series/), the Qu-16 has “16 Busses”. What is a buss as it pertains to the Qu-16 (or series in general)?

    The Matrix appears to correlate to the stereo outs, with 2 Stereo Matrices for the Qu-24, and 4 for the Qu-32. Then there’s Groups, which I believe are the same as the Matrices? DCAs cannot be processed with FX, etc. as I understand it.

    To put this into context, if I were to want to smash a parallel drum buss, I’d want to first route all the drum channels to stereo buss #1 then in turn route that to a second stereo buss #2 for heavy compression.

    How would you accomplish this entirely within the Qu-24, for example?

    #52571
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    10 mixes, 2 FX mixes and L/R?

    #52572
    Profile photo of gravyface
    gravyface
    Participant

    Not sure I’m following what you’re saying here. Is that the total number of busses you’re tallying up?

    #52575
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    That’s the things on a QU16 which could easily be defined as busses, and since there are 16 I guess the tally applies…

    #52583
    Profile photo of gravyface
    gravyface
    Participant

    Ok. Any comment re: setting up parallel busses (2 x stereo busses) that would only be routed internally and streamed via USB B-Port to DAW?

    #52584
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    You can easily route any of the mixes out to the DAW, so run 7/8,9/10

    #52585
    Profile photo of cornelius78
    cornelius78
    Participant

    A bus is an audio path that sums multiple signals together. In some cases a bus can have some degree of DSP applied (eg eq and compression.) TBH I’m not sure where the Qu16 gets it’s 16x busses, as I count mix1-10 +2x FX + LR = 14 busses. Perhaps they’re including the stereo PAFL to make 16.

    The Qu16 has 10x “mixes.” 4 of these are fixed as mono, the other 6 are fixed as 3x stereo pairs. You can send any or all of your input channels (16x mono +3x stereo +4x stereo FX returns) channels pre or post fader (configured on a channel-by-channel basis) to these mixes. These mixes could be used to feed monitors so the band can hear themselves, they could be used to feed the internal FX engines, they could be used to feed external FX engines or recording devices, or they can be used as subgroups if you go out and come back in on a stereo pair.

    The Qu16 also has 2x dedicated FX sends. These are used for feeding the internal FX engines (2 of the 4 anyway. The other 2x FX engines can be feed from mix1-10, or used as inserts on a channel/mix/LR, or used in a channel-return config.) These dedicated FX sends don’t have physical output sockets.

    LR is obviously the mains bus.

    In addition to the above, the Qu24 and Qu32 (and Qu-Pac) have an extra 2x FX engines, for a total of 4: one for each FX engine.

    They also have stereo “groups” (2x on the Qu24, 4x on the Qu32.) A group is essentially a bus with the sends from whichever combination of inputs you assign (24/32 mono + 3x stereo + 4x stereo FX returns) locked at unity, post fader, and follows the contributing channels’ pan settings. These groups can also have DSP or FX inserted across them. Unlike the 10x mixes, the groups can be routed directly (digitally, without having to go out of the desk and come back in) to LR. As of firmware 1.8, A&H allowed these groups to be changed from groups (post fader fixed at unity, routed to LR) to act as additional stereo mixes like mix5-10, allowing for a total of 4x mono and 5x/7x stereo mixes on the Qu24/Qu32.

    The matrices found on the Qu24/32 are like extra mixes, but instead of summing the signals from individual channels, they sum the inputs of buses (mix1-10, StGroups1-4 and LR.) Like the mixes they can also have their own peq, geq, comp, delay and inserts applied. I’ve heard them described as “buses for your buses.” They’re useful for things like setting up delay fills, having extra outputs for a vision feed, overflow rooms, recording etc.

    DCAs are essentially remote controls for your faders (whichever inputs/mixes/groups/mains you assign to the DCA master.) They’re not an audio path, so they can’t have processing applied, but they are useful for level control, and they affect the post-fade level from the channels/mixes too, which can be quite handy. Unlike a mono group, they allow the channels to retain their pan settings. eg if you used a group for level control over a group of stereo drum channels, you’d need to burn 2x mono groups and then pan those groups in LR to maintain the stereo image. You could instead use a single DCA and not burn any groups at all, and still maintain the stereo image.

    In some cases you want to use groups. In other cases you want to use a DCA. In some cases you want to use a DCA to control a group.

    As [XAP]Bob said, p75 (sec 11.18) of the v.18 manual describes pressing the “Setup” button, navigating to the “I/O Patch” tab, selecting the “USB Audio” tab and selecting which 32x streams are going out to your DAW via the USB socket. By default it’ll be the 32x inputs (if you get a Qu32,) but you can change them to be anything you want: fx returns, mixes, mains or your groups.

    #52586
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    [XAP]Bob
    Participant

    Ok, apologies – I can’t count…

    #52590
    Profile photo of NZdave
    NZdave
    Participant

    Bring your drum tracks into their respective channels on the QU 24/32 [from Reaper]- USB-B
    Assign them to a group [within QU] & then to FOH [in QU] being main left and Right out of the desk. [or tape out]
    In Reaper make a stem track and return that stem track using the Reaper matrix to a stereo channel in the QU
    Be-aware of phasing issues or time alignment.

    The Reaper matrix can asign nearly any data anywhere.

    #52601
    Profile photo of gravyface
    gravyface
    Participant

    Thanks so much, Cornelius78.

    Sounds like I’d burn two of the groups with the Qu-24 (and a DCA to control all the drums, post-processing) unless I wanted to physically route out a Mix and back in again, which would be really tempting to slap a real 1176 or Distressor pair out there.

    NZdave: yup, could certainly do that, but trying to avoid round trips/latency, and have a self-contained mix platform: would love to even mix down all channels to the Qu-Drive so I could be completely screen-free (well, the 5″ doesn’t count).

    How are the compressors? I’ve seen complaints online that the lowest release setting is only 100ms, which doesn’t seem adequate.

    #52602
    Profile photo of Dick Rees
    Dick Rees
    Participant


    How are the compressors? I’ve seen complaints online that the lowest release setting is only 100ms, which doesn’t seem adequate.

    This and other information is easily available in the PDF user manual.

    It’s 10ms, BTW, not 100.

    #52603
    Profile photo of GCumbee
    GCumbee
    Participant

    Dick. I have complained about the slow release times to no avail. The GLD has 50. As an old recording engineer I typically like faster for vocals.

    #52604
    Profile photo of Dick Rees
    Dick Rees
    Participant

    George…

    The specs are attack/hold/release @ 50 micro seconds / 10 milli seconds / 10 milli seconds. So as I read it the maximum “open time” would add up to 20 ms.

    I hadn’t noticed anything unworkable, but for me…I’m still waiting for a downward expansion option.

    #52605
    Profile photo of GCumbee
    GCumbee
    Participant

    If that’s the case why does the dial on the compressor only go down to 100? It defaults to 150. Am I missing something?

    #52607
    Profile photo of Andreas
    Andreas
    Moderator

    George and Dick, you’re referring to two different units. Gate has shorter times, Compressor is slower (100mSec minimum release instead 10mSec we have on Gate).

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