Annoying hum

Discussion in 'Archived Threads 2001-2004' started by Boris_V, Nov 17, 2001.

  1. Boris_V

    Boris_V Agent

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    For my taste there is to much hum that is produced from my speakers. When i come very close with my ears i can clearly hear the hum in the sound (receiver volume is set to 50), when i carefully listen i can swear i can hear it further away (normal listening position), too. If the volume level is set very high (that is 70 and above) the hum becomes annoyingly loud. Interesting is also that every time the volume level goes exactly to 70 i realize a popping sound for a brief moment. Is that normal, especially when i own quality speakers (B&W), receiver (Onkyo 595), cables (QED) and the computer is digitally connected to the receiver?
     
  2. Boris_V

    Boris_V Agent

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    No comments? I would appreciate some.
     
  3. Jagan Seshadri

    Jagan Seshadri Supporting Actor

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    Boris, here are some possible causes:
    The hum may be caused by electromagnetic interference from a nearby computer monitor or other computer equipment, cordless phone, or wireless device. Your speaker cables may be positioned in such a way that they act as reception antennas that draw this unwanted radiation into the receiver. There could also be noise coming in from the power line, or a faulty ground path might cause some hum in your system.
    So, try:
    - running the receiver with your computer (and monitor)turned off
    - repositioning your speaker cables until the hum goes away
    - power your receiver from a different outlet
    - if any equipment uses a grounded plug, make sure that outlet is electrically connected to ground (in older houses they may not be - but of course, be careful around 120/240-Volt outlets).
    As for the popping of your Onkyo 595 receiver at the exact volume of '70', that question would be best answered by Onkyo owners on this forum. That may actually be normal behavior for the 595.
    I hope these tips solve the speaker hum problem!
    -JNS
     
  4. joe goswami

    joe goswami Stunt Coordinator

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    Hi Boris,
    Your problem is an age old one. Oddly, the better the quality of your equipment is, the more likely your system will be susceptible to 60Hz line hum.
    One cure is a quality line conditioner. This can become expensive. Another much cheaper route is ferrite clamps around your electrical cords. Radio Shack is an excellent source for this stuff. One more thing to try is running a barecopper #12 or #14 AWG wire to your AC outlet's wallplate centre screw (this in essence is GND).
    Good luck. I've had these same problems as you.
     
  5. Boris_V

    Boris_V Agent

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    Thanks guys! I will try some of the things you have just said and will see if it helps.
     
  6. Henry W

    Henry W Stunt Coordinator

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  7. Boris_V

    Boris_V Agent

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    I turned off (and unplugged) all the other devices so that only the receiver was on. Then i selected dvd input (coax 1 input) which of course hadn't any input signal (so that i could test the speakers without playing something) at that moment and set the volume to maximum. The funny thing is that the hum is only as loud and annoying as i described in my previous post when the receiver is set to stereo or surround mode (DPL2) - and therefore probably in DD and DTS, too - but not when i selected direct mode (like stereo but without the sub). Then i deselected the subwoofer in the settings so as it would not be connected and found out that the hum almost disappears in stereo mode, but not in the surround modes where it remains. Could someone please explain this strange behavior?
     
  8. Jagan Seshadri

    Jagan Seshadri Supporting Actor

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    So let me get this straight:

    "Direct Mode" is free of hum?

    Are the other humming modes non-Direct then (i.e. Stereo ond DPL2 that you mentioned)?
     
  9. Boris_V

    Boris_V Agent

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    Yes, Direct Mode is (almost) free of hum and also the Stereo Mode (non-direct mode) when the sub is disabled, the other modes are non-direct (isn't that logical - one is direct mode and the others are not?).
     
  10. Tony Aguila

    Tony Aguila Stunt Coordinator

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    Does your sub have the 3-prong AC power connector? I've had a hum problem with a couple of subs before and the remedy is to either cut off the ground prong of the power cord, or get an adapter... you know, that kind that will convert a 3-prong connector to 2-prong, and then don't connect the grounding wire.

    Good luck.
     
  11. Boris_V

    Boris_V Agent

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    I have the Sony SA-WM40 and it has a 2-prong power connector.
     
  12. Boris_V

    Boris_V Agent

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    Please people, could someone tell me what's wrong? Perhaps someone with the same receiver who had the same problems. It would be great if someone with the same model would test his unit the same way i did and then tell me what he gets. Please, i need feedback.
     
  13. David Cohen

    David Cohen Agent

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    It sounds to me that you have created an external ground loop problem that is reacting with Onkyo's closed loop internal design.

    The subwoofer suggestion is a good one- using a 2-prong cheater plug, that is.

    If it isn't that, then it is likely that a cable or an external component (like a TV) is the culprit.

    While the hum is audible, I would disconect any components connected to the receiver, one at a time and see which one causes the hum to stop. If this identifies the problem component, you could try replacing the connector with a well grounded design, or re-routing the cable away from any source of interference.

    If an individual component cannot be isolated, try unplugging the power cords of likely interference causing devices, such as cable/sat tuners or TV sets. If one of these is the problem, you should be able to find a way to isolate them.

    I have also worked with engineers who have suggested that amplifiers and peripherals share a common circuit to eliminate ground problems. I'm not sure about that one.

    Good Luck
     
  14. Boris_V

    Boris_V Agent

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    But i did all that what you have said - everything in the room was turned of and disconnected from the receiver (even the subwoofer) but it didn' help.

    Now that i turned the computer on and connected it back again i realize less hum on the other inputs (which aren't used) on the receiver than before (when everything was disconnected from the receiver) but the input where the computer is connected nevertheless hums like before, maybe even little louder (now even in the Direct Mode), such as it would absorb all the hum. Now i am totally confused.
     
  15. Boris_V

    Boris_V Agent

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    Is nobody out there who can help me? Please...
     
  16. Jagan Seshadri

    Jagan Seshadri Supporting Actor

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    Do you, by any chance, have fluorescent lights turned on nearby?
     
  17. Boris_V

    Boris_V Agent

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    No, i have not.
     
  18. Ken Donowho

    Ken Donowho Auditioning

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    I feel for you. I've had to track down ground loops myself and it can be very frustrating. You've disconnected everything from the receiver AND the A-C circuit? The only way to know for sure is to find the breaker that controls the receiver circuit and flip it off and see what else in the house goes off. Unplug anything else that may be on the same circuit. Check the recepticle that you are plugging the receiver into. Make sure it is wired correct. A lot of older houses only have two wires to each recepticle, no isolated ground, and the ground and hot leads are sometimes reversed (I've seen it happen in new homes as well). If everything checks out and nothing else is on the circuit and the only thing hooked up are the speakers to the receiver, you are left with two possibilities. 1) the receiver is bad, 2)your incomming A-C is bad. A line filter might solve the problem. A bad receiver is.......an excuse to upgrade! [​IMG]
    Ken
     
  19. Boris_V

    Boris_V Agent

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    As you might now i am not from an englisch speaking country so could you please explain what a "recepticle" and a "breaker" is?

    BTW, thanks for your replies.
     
  20. ToneK

    ToneK Auditioning

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    Hi, quick english->slovenian:
    breaker = varovalka
    recepticle = vticnica
     

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