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Audio Hum and Noise?

RNST Feb 7, 2016

  1. RNST

    RNST Entrusted Devil Super Moderator

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    I have an analog system going with a turntable, preamp, headphone amp with gain and a powered speaker and output to an additional speaker for more base (poor man's sub woofer :) )

    It's all connected to a supposedly low noise power bar.

    Periodically, not consistently I get significant amount of ground loop, 60 Hz noise coming out of my speakers.

    I have on order from ebtechaudio humX noise reducers for the AC portion. I'm wondering if I should explore the noise passed via audio connections on the 3.5 mm jacks.

    It's expensive buying these isolation devices at $60 or more a pop.

    Any ideas how to isolate these noise problems?

    Waterdogs??
     
  2. waterdogs

    waterdogs Brigade Member Brigade Member

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    I`m reading you five-by-five, Brother.

    I would start by examining whatever else shares that circuit. Any flourescent lights, or anything with a small motor that might be generating RF interference ?

    If possible, try to isolate one 15-amp circuit (at least temporarily) and dedicate that line exclusively to your stereo. You want to try the process of elimination method to see if you have a noisy circuit, or if it`s something common to the whole household .

    Good luck ! :thumbsup:
     
  3. Glenn

    Glenn Sol Invictus Knife Maker or Craftsman

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    I'm not waterdogs. Butt,


    This would lead me to believe you have a bad "ground" in the mix acting up.

    Have some metal polish in the house ? If so, clean the cable ends well.

    May resolve the issue for you. :devilcorn:
     
  4. Obijuan Kenobe

    Obijuan Kenobe Our only hope! Brigade Member

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    I don't have a high end stereo, but I fight 50hz noise all day long.

    For sure, make sure there is nothing on the same circuit that is electronically loud. It could be as simple as that.

    Good luck!

    obi
     
  5. Clydetz

    Clydetz Forever straight and true Brigade Member

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    Maybe I can learn something here. A little background... I'm deaf but with one hearing aid I manage to 'hear' somewhat. I notice that there is one light in my gf's house that causes my hearing aid to 'hum' every time I walk past it. Any idea what causes this? It's not a fluorescent light.
     
  6. RNST

    RNST Entrusted Devil Super Moderator

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    Thanks, I have a good idea where to start with the problem. It's noise passed from one powered speaker to another via a 3.3 mm audio cable. It's not all the time and when the gain is turned up on the headphone amp it shows itself. So two powered speakers and a headphone amp are suspected. I'll put noise eliminator on those psu's.



    I actually cleaned them before posting this.
     
  7. waterdogs

    waterdogs Brigade Member Brigade Member

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    Do you have any copper-based anti-sieze on hand? If so, lightly apply to those 3.5 jack plugs, it might help with continuity.
     
    Last edited by a moderator: Feb 8, 2016
  8. waterdogs

    waterdogs Brigade Member Brigade Member

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    Any dimmer switches on the circuit might also cause a problem.
     
  9. waterdogs

    waterdogs Brigade Member Brigade Member

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    Also, how is your main house ground configured ? Is it connected to the cold water main coming in from the street, or ?
     
  10. Obijuan Kenobe

    Obijuan Kenobe Our only hope! Brigade Member

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    HAMs use a ferrite ring to get rid of noise from the circuit/mains.

    You could do try that trick for like 5 dollars.

    obi
     
  11. Worker

    Worker Slacker Brigade Member

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    Such a frustrating problem. I built a sound room in my home with a dedicated 20amp set up to run large amps and had a terrible hum. I had a ceiling fan in the room and the remote for it caused the hum. I pulled the ceiling fan and put in a chandelier and got rid of that problem.

    All I can say is keep experimenting. Those HUM-x only help if the problem is coming from the power source as I have played with those also.
     
  12. RNST

    RNST Entrusted Devil Super Moderator

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    Yes to ceiling fan, yes to chandelier with dimmer :wtf: :D

    All the cabling is from Audioquest. Lots of interconnects from Turntable to preamp to headphone amp to powered speakers. i.e. lots of opportunity to develop noise along the path since they are all radiating. I did pay for a higher spec cable with shielding too.

    All are this grade: some are RCA and some are 3.5 mm

    http://store.uturnaudio.com/products/audioquest-evergreen-rca-cables

    I removed all of them from their sockets a few weeks ago and wiped with isopropyl alcohol. It also allowed me to ensure all the jacks were fully inserted into each stage.

    No noticeable improvement lowering or eliminating the hum.

    The HumX devices are supposed to be delivered from Amazon today. I'll be working on it later this afternoon.
     
  13. RNST

    RNST Entrusted Devil Super Moderator

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  14. falcon125

    falcon125 the express train to mayhem Brigade Member

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    [YOUTUBE]oZUkNWdeeGc[/YOUTUBE]
     
  15. institches

    institches Little member

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    Are you certain it is a ground loop issue? If you disconnect the signal from the powered speaker does the hum go away? If yes, then it is a ground loop. If the hum does not go away with signal disconnected the problem is the speaker = poor amplifier design or a bad component.
     
  16. RNST

    RNST Entrusted Devil Super Moderator

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    I reached out to a couple of the manufacturers and one acknowledged there could be RF/EMI issues with their AC / DC converter. I isolated it onto a new separate "low noise" power strip that doesn't have bells and whistles like USB's etc. Just a straight power bar, surge suppressor and it is actually a lot lower 'noise and hum' in the system now. Once I have those HumX devices I will put them on the power speakers, headphone amp and the Pre Amp.

    Interesting read on surge protectors etc.

    http://www.cnet.com/news/9-things-you-should-know-about-surge-protectors/
     
  17. BigEdge

    BigEdge Little member

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    What he said..^^^^

    I would do this to first find the root cause before attempting to fix with the filters.

    Also, run and extension cord from another circuit to power first the amp and then the speaker, and then both to see if it quits. If its coming from your AC circuit, it almost certainly will not still happen from another circuit. Hum is often not from a ground issue but from one circuit crossing another of the second phase of your feed, or crossing a 220V circuit (which has both phases) and picking up the second phase through induction.

    If this is it, try the cheapo ferrite rings, it could help. It would also help if its not AC induced but coming from something else on the circuit, all of which can generate oscillations if something is wrong with them.

    If is not AC then its coming in airborne at interference to your amp, in which case you will be forced to build a Tesla cage around your gear!

    Good luck!
     
  18. Worker

    Worker Slacker Brigade Member

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    I run my Mcintosh MC452 straight into the wall socket which is a dedicated 20amp with no power or surge protection. I have heard of surge protectors and power supplies causing hum.

    Any updates?
     
  19. waterdogs

    waterdogs Brigade Member Brigade Member

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    Good advice here! :thumbsup: Also, remember that it`s not a good idea to loop or bundle power cords together (like for the sake of neatness)....it`s better to keep them separated and not crossing over each other.
     
  20. RNST

    RNST Entrusted Devil Super Moderator

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    Ok I have two HumX AC adapter / noise and hum eliminators tried out now.

    I put one on the powerbar and one on the AC Adapter from the UTurn Turntable.

    Applications at HumX said they had gotten a lot of calls about the AC Adapter that came with the turntable.

    So far so good but I can still detect some noise.

    BTW I did try in on the AC input to the powered speaker but there was no improvement. Therefore it's got to be either the turntable, Pre Amp, Headphone Amp in front of the powered speaker.

    I need to get someone with a very good low end hearing :D :manganr:
     

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