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Thread: Low Level Hum on HA-4700 Headphone Amp

  1. #1

    Low Level Hum on HA-4700 Headphone Amp

    I have hum on my HA-4700 headphone amplifier. Channel one is ok, but the hum gets progressively worse through channels 2-4.

    It is present even when the volume controls are turned down. It is NOT an earth loop or cable problem as it hums when it is connected to nothing except the mains supply and a pair of headphones. I have tried using a power conditioner and in a different room away from the studio.

    From reading posts on the Internet, it seems it is an inherent problem with this unit, so is there a modification or fix available or is this just the way it is? That would be a shame as the quality of sound is superb, much better in fact than the more expensive ART Headamp 6 pro which sounds dreadful by comparison.

    I use several pairs of very good headphones, Sony MDR-7520, MDR-7509 and Sennheiser HD25-2 and listening conditions are quite critical in a broadcast radio production studio where we often record speech only programs. Several people, especially those connected to channel 4 have commented on the hum.

    Noise figures quoted for this amp are -90db, on channel one possibly, but every other channel no way!

    Can anybody help?

  2. #2
    Dear Les,

    What kind of cables are you using? "Y" cables? How are you connecting the HA47000 with the rest of your gear?

    Kind Regards,
    Zac Ross
    Jr. Admin, CARE
    MUSIC Group US
    BEHRINGER

  3. #3
    Sorry for bumping an old thread but I wonder the same. Is there a fix to the hum of this headphone amp. My story is that I bought one long time ago. Sent it back to store wich if I understood it correctly sent it to some behringer service center. Got it back but only slightly better. Sent it back again, this time unit got scrapped and a new unit was sent to me. Now I sit here listening to the same hum, this timeat least there is two usable outputs and two hummin.
    Really sad as I have very much behringer products that I´m really pleased with. This unit though... To bad that Les mentioned the Art unit sounding bad as I was considering gettin that instead.

    Is there a fix to the hum in this unit?

  4. #4

    Behringer low level mains hum

    Quote Originally Posted by Mange Johansson View Post
    Is there a fix to the hum in this unit?
    Late to the thread I know but still relevant I hope.
    I too experienced the low level hum on the HA4700 and the RX1602 and it's caused exclusively by the toroidal mains transformer.

    Solution here...
    http://www.paulbrow.co.uk/behringerhum.htm

  5. #5
    Super User Paul Vannatto's Avatar
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    Hi Paul,

    Welcome to the forum, and thank for posting such a neat solution.

    Paul

  6. #6

    Hum fix

    Paul,

    Could there be a way to shield this transformer better, internally, ourselves, instead of moving it out of the housing?

    Jeff

  7. #7

    Shielding

    Quote Originally Posted by Jeff Sloan View Post
    Paul,

    Could there be a way to shield this transformer better, internally, ourselves, instead of moving it out of the housing?

    Jeff
    Mu-metal foil or a steel cover might work but there's not a lot of room to work with, not easy.
    Care needed too not to cause a shorted turn on the torroid.

    Enjoying the silence now though.

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