TRS I/O vs XLR I/O

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This topic contains 12 replies, has 6 voices, and was last updated by Profile photo of Mike C Mike C 2 days, 18 hours ago.

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  • #95849
    Profile photo of ianhind
    ianhind
    Participant

    Wondering the conversion, noise floor, THD, etc

    For line level I/O is bypassing the pre’s and going straight into the TRS sockets a better path? I checked the manual but didn’t see much info on specs.

    I plan on inserting four Neve 5045 on vocals and trying to keep the path as clean as possible.

    All local I/O is free to use as I’m using remote I/O.

    Eg:
    Channel Insert>TRS Output A>Neve>TRS input 1 L
    Channel Insert>XLR Output 1>Neve>XLR Input 1
    Channel Insert>XLR Output 1>Neve>TRS input 1 L

    #95856
    Profile photo of volounteer
    volounteer
    Participant

    @ianhind

    Depends who has the better ADC into the SQ for THD.
    But with digital there should be no difference that makes a difference wrt noise floor.

    You could try both and see which your golden ears prefer.

    #95858
    Profile photo of Mike C
    Mike C
    Participant

    You don’t have many TRS IO choices on an SQ mixer to start with and none on the stage boxes. There are two ALT outs and two stereo pairs.
    In one way or another you will be using some XLR IO to patch in all 5045’s channels.

    On the QU series mixers each input has both TRS and XLR the TRS input still uses the mic preamp only it is padded down and can not receive phantom power.

    I always wanted to try a 5045 on a podium or lapel mic in the live sound setup!

    #95879
    Profile photo of tourtelot
    tourtelot
    Participant

    So, true? No local input line inputs that don’t go trough a mic pre?

    D.

    #95884
    Profile photo of volounteer
    volounteer
    Participant

    @tourtelot

    diagram shows two TRS stereo inputs that are direct with no pre .

    other inputs are mike level and go into pre. there is a 29dB pad available.

    #95889
    Profile photo of Mike C
    Mike C
    Participant

    So, true? No local input line inputs that don’t go trough a mic pre?

    I’m going to say the 1/4 TRS inputs hit the same “pre-amp” that mic inputs have only
    set with different PAD and gain levels.

    On analog boards you could actually bypass the pre-amp by sending line level
    signal into the channel insert jack.

    #95890
    Profile photo of volounteer
    volounteer
    Participant

    @mikec

    Then how does the block diagram make sense?
    Are you saying AH misleads us with what is actually happening?

    #95893
    Profile photo of Mike C
    Mike C
    Participant

    Then how does the block diagram make sense?
    Are you saying AH misleads us with what is actually happening?

    It makes sense and shows it plain as day!!
    All the inputs are fully balanced and the first thing they hit is the differential amp / preamp right before the ADC.

    They show the gain control on the mic inputs, ST1 and ST2 also have adjustable gain.
    I would guess they use the same differential input amps on all the inputs short of maybe ST3 on the QU since it is an unbalanced input.

    Attached are the input block diagrams for the QU and SQ. the same except for the pad on the SQ.

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    #95908
    Profile photo of volounteer
    volounteer
    Participant

    @mikec

    The stereo has NO adjustments to the preamp.
    One of us is very confused.
    It might be me but in this case I really doubt it.

    There is *A* preamp, but nothing says it is the same preamp nor using the same gain.

    #95910
    Profile photo of Mike C
    Mike C
    Participant

    The stereo has NO adjustments to the preamp.
    One of us is very confused.
    It might be me but in this case I really doubt it.

    There is *A* preamp, but nothing says it is the same preamp nor using the same gain.

    As I said earlier they would not be using the same gain, though most likely the same amp/chip set with a fixed gain…maybe.

    Ok the stereo channels level refers to it as trim so it’s probably happening is the digital path and not in the very short analog input path.

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    #95913
    Profile photo of Mfk0815
    Mfk0815
    Participant

    The trim is part of the channel processing (you can setup the trim individual for each channel which uses the same input socket) and therefore definitely in the digital path.
    And of course there is an individual preamp for every analog input socket.
    And at last, thephysical layout and naming suggests that ST1 and ST2 are two stereo inputs. but in fact they are four mono input sockets.

    #95916
    Profile photo of KeithJ A&H
    KeithJ A&H
    Moderator

    Hi All,

    Dedicated line inputs in the SQ do not run through a preamp.
    The differential amp is there to ‘unbalance’ the balanced signals from TRS inputs (hence the lack of ‘+’ and ‘-‘ on the unbalanced 3.5mm stereo input).
    So mic and TRS stereo/line inputs appear the same on the block diagram, as they are taking balanced inputs and outputting an unbalanced signal to the ADC. This stage for the mic inputs also includes the preamplification, shown with the connected gain control.

    Whilst the preamp is at the socket and comes before ADC, trim is part of the input channel processing (i.e. it belongs to the channel, not the socket).

    Cheers,
    Keith.

    #95917
    Profile photo of Mike C
    Mike C
    Participant

    And at last, thephysical layout and naming suggests that ST1 and ST2 are two stereo inputs. but in fact they are four mono input sockets.

    True, I was going back an fourth between QU and SQ and only had my QU out to grab a couple screen pics from.

    You can almost do the same thing with a QU and using a stage box to patch to the ST inputs.

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