XLR line out topology

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This topic contains 7 replies, has 3 voices, and was last updated by Profile photo of CameronProAudio CameronProAudio 1 month, 4 weeks ago.

Viewing 8 posts - 1 through 8 (of 8 total)
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  • #102604
    Profile photo of CameronProAudio
    CameronProAudio
    Participant

    Hi there. I’m wondering if anyone knows if the servo balance XLR outputs on the surface can safely drive a single ended/unbalanced input? If I want to use XLR to 1/4 TS adapters where cold is shorted to shield, is the driver topology designed to handle it? Topologies that don’t tend to distort.

    Thanks.

    #102622
    Profile photo of SteffenR
    SteffenR
    Participant

    wires are passive
    it depends on the following devices

    #102624
    Profile photo of CameronProAudio
    CameronProAudio
    Participant

    wires are passive. it depends on the following devices

    That’s not correct. Only certain topologies of fully active balanced output can handle going into an unbalanced input where the cold is shorted to ground. This connection of cold to ground happens well before the input stage of the downstream device. Transformer coupled balanced outputs are one type that tolerate driving an unbalanced input. With direct active balanced outputs, it depends on the topology of the active drivers and how they’re connected internally.

    #102625
    Profile photo of CameronProAudio
    CameronProAudio
    Participant

    Ok, I found my answer here are far as the type of active balanced output required when driving a single ended/unbalanced output:

    https://forums.prosoundweb.com/index.php?topic=111181.0

    The output needs to be servo balanced to safely short cold to ground and not lose signal or create distortion. I checked the Avantis specs and they only state “Local analogue outputs shall be provided on 12 balanced XLR sockets.” So A&H engineer folks, are the output servo balanced?

    Thanks,
    Greg

    #102634
    Profile photo of SteffenR
    SteffenR
    Participant

    electronically balanced

    #102635
    Profile photo of ioTon
    ioTon
    Participant

    Und auf’s Neue: Antwort vui daneben… ;)!

    In my understanding, CameronProAudio want’s to know if outputs are use either active circuitry on both the hot and cold
    lines so both have equal voltage but in opposite polarity, or using an “impedance balanced” (only Resistor to Ground) topology.

    I think technically both are electronically balanced…

    So your answer is nonsense…

    #102637
    Profile photo of SteffenR
    SteffenR
    Participant

    I’m sorry not being detailed enough…

    The block diagram shows that electronically balancing circuitry is used with voltage on both the hot and cold pins.
    As far as I know no transformers and no impedance balancing is used.

    #102641
    Profile photo of CameronProAudio
    CameronProAudio
    Participant

    There are different topologies for actively balanced lines where the hot and cold lines are actively driven. Unless the topology is “servo balanced,” distortion and output circuit damage is possible if a connection where cold is shorted/jumped to ground is made – a fairly common scenario. I just want to confirm if the outputs are servo balanced. I already know that they aren’t impedance/pseudo balanced. If they were, that would be safe for the scenario I described since there is no active cold driver to ground out.

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