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Musician questions

Former Community Member
Former Community Member

Hi there, 2 questions using my Seaward Apollo 500:

1- my radio connection between guitar and amplifier has a separate PSU, so is class 3? Should I simply PAT this as class 2?

2- my bass combo amp is a pretty new Ashdown Studio 15 which does not have any class marking (apart from RoHS CE) so has to be class 1? But this device fails earth continuity and I don't believe it is manufactured to earth the exposed metal parts. Can I ignore this test? If so, for what reason?

Thank you.

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    mapj1: 
     

     

    I'd not necessarily  expect the audio jacks to be directly connected to mains earth, for reasons of hum loops they may be floating or audio transformer coupled,  but the panels you can touch probably are.

     

     

     

    I've been repairing (and playing) guitar amps for over 30 years … and a lot of them are connected to mains earth. 

    Some other audio equipment too … but that's why DI boxes were invented … along with “balanced” signal and impedance matching.

    The reason being the way the body acts as an antenna and interacts with the guitar strings … especially with single-coil pickups, but also (from experience) affects humbuckers.

    May also surprise those not “in the know” that the strings (often via the bridge) are also connected to the “outer” of the jack socket.

    It's also why many pedalboards have “isolated” mains supplies to pedals (in certain setups) … not only to help eliminate “earth loops”, but also simply because some pedals are “positive earth” and some “negative earth”. I made my own “DC power isolator” simply because of the cost of commercially available ones.

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  • 0

    mapj1: 
     

     

    I'd not necessarily  expect the audio jacks to be directly connected to mains earth, for reasons of hum loops they may be floating or audio transformer coupled,  but the panels you can touch probably are.

     

     

     

    I've been repairing (and playing) guitar amps for over 30 years … and a lot of them are connected to mains earth. 

    Some other audio equipment too … but that's why DI boxes were invented … along with “balanced” signal and impedance matching.

    The reason being the way the body acts as an antenna and interacts with the guitar strings … especially with single-coil pickups, but also (from experience) affects humbuckers.

    May also surprise those not “in the know” that the strings (often via the bridge) are also connected to the “outer” of the jack socket.

    It's also why many pedalboards have “isolated” mains supplies to pedals (in certain setups) … not only to help eliminate “earth loops”, but also simply because some pedals are “positive earth” and some “negative earth”. I made my own “DC power isolator” simply because of the cost of commercially available ones.

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