Electronics / audio oddity

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  • Electronics / audio oddity
  • This could well be daft but here goes.

    I’ve got a headphone amp that works perfectly (24v dc from wall wart, not earthed) and a small mixer that also works perfectly.

    For some reason I decided to connect the headphone amp to the mixer’s tape out (via rca) and it works fine.

    The weird thing is that the amp is now always on – irrespective of what it’s on/off switch says.

    If I disconnect the RCA leads from it then it turns off / on. Or connect something else to it via rca – all fine – the switch works again.

    So its not a big deal, but I’m just curious whats up, and given that something’s wrong – why is it all still “working” perfectly. Any ideas?

    Ive got the multimeter out but not sure what to check next.


    Does your mixer have XLR inputs with phantom power?

    Thanks footflaps: I’d not even considered that! So I should see DC on the tape out’s from the mixer I guess.

    dave – yep: the xlrs are shared with rca’s (via simple adapters) on channel 1/2 that are connected to the computers soundcard. I’ve no idea if they’re powered (and no user manual).

    #Edit : it’s one of these:

    #Edit 2: The meter shows 0v dc on the rca tape outs and a happily fluctuating 0.0 – 0.3v ac depending on tunes.

    #Edit 3: Is there any way the amp could be switched on neutral and the mixer is providing an earth or something? I’ve just tried a bench psu and its doing the same so dont think its related to the wart.


    Edit Shoulda read all the thread! 🙂

    No worries trampus – you got me metering the shared inputs anyway – which was worth checking.

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