Pre, Post and Mix group

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This topic contains 15 replies, has 6 voices, and was last updated by Profile photo of MarkPAman MarkPAman 4 years, 2 months ago.

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  • #61289
    Profile photo of necos
    necos
    Participant

    I recently got qu32 and would like to describe an issue i have faced.
    I switched from analog MIDAS Venice 32 and when i being using AUX, either PRE or POST gain was not an issue, my master aux knob was always on 12pm and it was easy to push more volume to my floor monitors.

    On Qu 32 in PRE mode situation is somewhat similar, but mix depend on GAIN(preamp) knob of each channel. Its very weird i assume that PRE signal would not have any dependency on GAIN knob, at least it doesn’t on MIDAS

    in POST mode it’s different situation. i have to push fader always up to get some volume from the floor monitor.
    and if it wasn’t enough than i started playing with the fader channel and master balances to get some result.
    Did anyone else experienced the same thing ?

    Would appreciate any advise.

    Another thing if anyone knows. is it possible to assign general EQ to MIX groups, same way like to LR master.
    I mean to get rid of external EQ for floor monitors.

    #61292
    Profile photo of Andreas
    Andreas
    Moderator

    Just have a look at the block diagrams at the end of The Manual. While you may globally select the point, where the mixes are fed from, the gain is always before that point (and that’s exactly the same on the Venice F32, check out the block diagram on page 75: Venice Manual).
    Pre/Post setting only states, if the mix feed follows (POST) the LR fader or not (PRE).

    And on Qu32 you already do have PEQ+GEQ+Compressor+Delay on each Mix, Group and Matrix, no need to assign anything. Just select the mix and go to the processing screen.

    #61293
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    Sound like you had something the like the sound craft ‘DOGS’ system (Direct out gain stabilisation) which manipulates the gain sent to each mix to counter any changes made to input gain…

    I’d find that useful occasionally – go to channel page, hold a softkey and spin the gain up/down a bit according to the whims of the musician who has turned their instrument up/down…

    #61294
    Profile photo of Dick Rees
    Dick Rees
    Participant

    “Pre” and “post” most often refer to the faders: pre-fader and post-fader. You want your monitors to be pre-fader so the levels don’t change when you’re doing the main mix.

    The basic difference between your analog console and the Qu IN THIS CASE is that instead of knobs feeding your channels to the monitor aux (“Mix” on the Qu instead of “Aux”) you have “Sends on Faders”. Otherwise the function is exactly the same…with ONE very significant difference:

    In digital world you can select the “pick-off point” in the signal chain at several different points whereas in analog world you had to open the console and physically re-jigger some jumpers. I’ll try to post a link to illustrate.

    There are different versions of the manual out there, but in the PDF copy I have it is on page 38: “Mix Routing”. When you press the Mix button for Mix 1 while on the “Routing” screen, you’ll find your options menu including “Assign”, “Pre/Post” and “Channel Source”. Look at the “channel source” options for your pick-off point. You can use post-preamp and other options as to how much channel processing you want to be reflected in your Aux/Mix.

    Once you dig into it a bit with an eye as to how these paryicular features can work for you I think you’ll find just how flexible you can be in “digi-world”. You’ll have more options. Now you just need to spend the time to see of what benefit they can be. Eventually you’ll get the hang of “virtual cabling” on your digital console.

    Good luck, have fun.

    #61304
    Profile photo of Giga
    Giga
    Participant

    On Qu 32 in PRE mode situation is somewhat similar, but mix depend on GAIN(preamp) knob of each channel. Its very weird i assume that PRE signal would not have any dependency on GAIN knob, at least it doesn’t on MIDAS

    I don’t want to bet my life on it but I’m pretty sure you’re mistaken here; the Midas -as well as any other analog mixer for that matter- takes it’s signal after the preamp. The only thing out of the ordinary with the Midas is that in auxes 1 + 2 you can choose between pre- or post eq.

    As Dick said, the pre or post setting usually refers to whether the aux takes it’s signal before the channelfader or after it.

    Set the gain for each channel (with a healthy bit of margin to cater for the one’s that can’t help themselves and turn up halfway the first song) once during soundcheck and then don’t touch it anymore or you’re forced to compensate everywhere else as a result.

    Good luck !

    Giga

    #61305
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    Giga – I agree, but one desks (the Soundcraft ones I’ve been looking at) do something that has often been requested as a feature on these boards…

    It’s a process that requires a digital desk of course…
    When ‘DOGS’ is enabled on a SC desk changing the gain by +3dB drops those 3dB off all the sends. The makes it *look* like the sends are ‘unaffected by the gain’

    #61317
    Profile photo of Giga
    Giga
    Participant

    Ah, that’s a new one to me (and a pretty clever one I might add). So, how does this work ? Does one have to engage that feature after setting the gain ?

    Giga

    #61320
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    I’d have to go back and check the manual – but I believe that it is set globally on the SC desk, and yes – you’d do that after soundcheck – AND have to remember to disable it for the next soundcheck.

    PS – I tried to type ‘some desks’, not ‘one desks’

    #61447
    Profile photo of necos
    necos
    Participant

    Thanks everyone for feedback , but i suspect that i did not express my self correctly.
    So here is step by step.
    Connect power monitor with volume 60% on to Mix1
    Bring up Mix1 channel 1 fader to 0 or 5 db. Do same thing on Mix1 master fader to route signal to monitor.
    Connect microphone to channel 1 and push channel 1 fader to 0 or 5
    Now: when you are in PRE, output volume from monitor will be pretty much OK (means enough loud), when in POST it will be at least 20 DB less.
    That’s what my post is about. On MIDAS i had enough room to push up volume in POST mode, not on QU.

    regards.

    #61448
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    So there is a difference between post fade and pre fade level that isn’t accounted for by the fader position?

    I would have to go and check that myself, but it would surprise me…
    Is there a DCA in effect maybe?

    #61449
    Profile photo of Giga
    Giga
    Participant

    when in POST it will be at least 20 DB less.

    Which is only possible if the fader which determines how much of the “pre” signal actually is send to mix 1 is *at least* 20 dB UNDER the 0 dB mark.

    Giga

    #61452
    Profile photo of Dick Rees
    Dick Rees
    Participant

    This is a result of the way you’re running the board, not the board itself. There are a few things that could possibly cause this behaviour, but you’d have to have done something such as having a compressor engaged, an assignment to a DCA, extreme EQ cuts or ???? Who knows?

    Since this is your first digital desk, chances are you may even be suffering from “analog lag” or the like, expecting the new desk to behave like the old one. This is not necessarily the case. You’ll have to let go of the past, I’m afraid.

    If you’re working strictly within the Mix, you may be missing this:

    Remember when I said that “sends on faders” replaces the aux send knobs of your analog console with the faders when you’ve selected Mix 1 as your working layer? Well, you’re raising the level of the channel from a point just AFTER the pre-amp and BEFORE the various channel control options (comp, gate, EQ, etc). This is the PRE scenario. However…

    In POST, your level can follow the fader position on the MAIN L/R LAYER, so you may well have your main mix fader 20dB down.

    PRE and POST are just terms, not singular states of routing. These terms can be applied to several things: pick-off point for signal routing, insert point likewise OR…and this is where I think your confusion arises…faders. You have to ask yourself pre- or post- WHAT?

    So if you are working on just the MIX faders, POST in this case can mean that the channel fader on the Main L/R layer is also in the loop. I know it seems odd right now, but once you take the time to understand the control/routing options in digital world it will make perfect sense. Heck, you’ll probably even be able to see how it relates to your previous analog experience.

    But for now you need to learn the digital mode of operation and let go of the expectation that it’s just like analog with the addition of A/D conversion.
    It’s a it more than that…

    Perhaps if you post your location, someone who has a Qu and can be reached by telephone will contact you and you can get some real-time help.

    Good luck. Be patient…

    #61453
    Profile photo of Dick Rees
    Dick Rees
    Participant

    Pardon the length of the poost above. Here’s a quick check you can do which may help you make sense of what I wrote:

    Set things up exactly as you described, but this time when you switch to POST, exit the Mix 1 layer and raise the channel fader on the Main L/R layer.

    What happens now???

    #61454
    Profile photo of necos
    necos
    Participant

    As i said previously all faders involved in position 0(-5) db, including master
    When in mode PRE it will be pretty much loud in POST situation is drastically different. All effects are off.
    it`s a simple test. The only way to balance it is to play with gain on the channel.
    Dick, thanks for your post. Of cause i fully realize that digital world is different and now i have to implement different mindset.For the last 4 days i have Qu i really really love it,… except this issue yet. 🙂

    Thanks everyone for feedback

    #61455
    Profile photo of Dick Rees
    Dick Rees
    Participant

    OK. One more time…

    Remember that when you select Mix 1, your faders are now “virtual aux send knobs”.

    PRE- and POST- refer to the faders on the main layer, not the “virtual aux send knobs”.

    So when in POST- you have to exit Mix 1 and return to Main L/R and use the channel fader which is now the fader referred to in the term POST-FADER. It is no longer operating as a “virtual aux send knob”.

    The faders serve two functions, you see.

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