Allen & Heath Zed 6 Stereo channel inputs unbalanced

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This topic contains 6 replies, has 3 voices, and was last updated by Profile photo of SteffenR SteffenR 1 month, 1 week ago.

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  • #110499
    Profile photo of djtetei
    djtetei
    Participant

    I have two Allen & Heath Zed 6 mixers and, overall, I am very satisfied with their built quality and sound.
    However, there is one issue with the stereo channel inputs on these mixers. Although they are fitted with TRS jack inputs that can accept both balanced and unbalanced audio signals, the ST1 and ST2 channel inputs are unbalanced. This means that if you take a balanced audio output and connect it to the stereo 1 or stereo 2 TRS jack inputs, have the signal is lost leadind to a signal level drop of 6 dB.
    What is the point in fitting TRS input jacks that accepts a balanced audio signal level if you loose have of that signal level because of the unbalanced wiring of the mixer input connection?
    Suppose you have two DJ mixers, both fitted with balanced master outputs, and you want to connect them to the same PA system.
    You should be able to take the balanced master outputs of both DJ mixers and connect one output to the ST1 TRS input jacks and the other output to the ST2 TRS input jacks, maintaining the balanced connection and the the nominal signal level of +4 dBU. Instead, because of the Zed 6 stereo input channels unbalanced wiring, you lose the balanced connection and 6 dB of the audio signal level.

    #110502
    Profile photo of KeithJ A&H
    KeithJ A&H
    Moderator

    @djtetei

    The ZED6 has impedance balanced stereo inputs and outputs which operate at 0dBu.
    The stereo input channels have a trim control which can provide up to +15dB of gain (or trim down) if required.
    So you can connect consumer -10dBV line level or professional +4dBu line level or anything in between and adjust to suit.

    It would be good to know what has led you to thinking the inputs are unbalanced (e.g. is there a shop listing somewhere or datasheet which is incorrect?)

    Thanks,
    Keith.

    #110508
    Profile photo of djtetei
    djtetei
    Participant

    Question: What led me to thinking the stereo inputs are unbalanced?
    Answer: You may find this funny, but the answer came directly from Allen & Heath support, in the statement of Mr. Chris Panks.
    Looking at the other Zed series models it looks like they all have unbalanced stereo inputs.

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    #110511
    Profile photo of djtetei
    djtetei
    Participant

    Is the any model in the Allen Heath mixers lineup which has true balanced stereo inputs, able to maintain the nominal (+4 dBU, +2 dBU or 0 dBU) signal level coming from another mixer balanced master output, with the input gain knobs positioned at unity?

    #110512
    Profile photo of KeithJ A&H
    KeithJ A&H
    Moderator

    That is funny!

    And also, I must admit that I jumped to answer without double checking and was wrong about the stereo inputs being balanced.
    Chris was correct – on the ZED6 the stereo inputs are not balanced, the cold signal when using a balanced feed is tied to ground via a 0 Ohm resistor.
    The mono inputs are impedance balanced however.

    I’m still not sure what you’re wanting to do that isn’t possible though.
    You can connect two stereo balanced (or unbalanced) signals, at a range of input levels (which is the point of a trim), and mix them to an output… ?

    Thanks,
    Keith.

    #110513
    Profile photo of djtetei
    djtetei
    Participant

    The setup I am using is like this:
    – Denon MCX 8000 standalone mixing system, with balanced XLR outputs at +4 dBU nominal level
    – Reloop RMX 60 Digital mixer, with balanced XLR outputs at 0 dBV (+2 dBU) nominal level
    – Allen & Heath Zed 6 mixer
    – Behringer FBQ 6200 HD equaliser
    – Behringer CX 3400 crossover
    The Denon MCX 8000 mixer balanced XLR master outputs are connected to the Allen Heath Zed 6 stereo input channel (ST1) with a Cordial XLR to TRS cables and the input gain knob, channel level knob and the main mix output fader are set to 0 dB attenuation (unity gain).
    The Reloop RMX 60 mixer balanced XLR master outputs are connected to the Allen Heath Zed 6 stereo input channel (ST2) with a Cordial XLR to TRS cables and the input gain knob, channel level knob and the main mix output fader are set to 0 dB attenuation (unity gain).
    Now, although the MCX 8000 balanced master outputs are sending a +4 dBU signal level, the output on the Zed 6 main mix is only around 0 dBU when it should hover around +6 dbu mark on the output meters.
    The Reloop RMX 60 mixer balanced master outputs are set to send +4 dBU signal level and the Zed 6 main mix level meters are hovering around +6 dBU mark, as it should be.
    I opened a support ticket explaining the situation and I also asked if there could be any mismatch between Denon MCX 8000 balanced master output impedance and Allen Heath Zed 6 stereo TRS (supposedly balanced) input impedance.
    Mr. Chris Panks from Allen Heath support replied: “The TRS jacks on the stereo inputs are not balanced. ST1 and ST2 are unbalanced. They will accept TS and TRS jacks.”

    #110606
    Profile photo of SteffenR
    SteffenR
    Participant

    I think you should learn something about level measurement in analog consoles.
    Reference levels are not real output levels.

    And btw, the gain knobs are for level matching the input signals.

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