Why do amps hum and receivers dont?

Discussion in 'Archived Threads 2001-2004' started by Ken Custodio, May 16, 2002.

  1. Ken Custodio

    Ken Custodio Second Unit

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    I recently added a Parasound amp to my HT and as soon as I hooked it up I got a ground loop hum from my digital cable tv. My cable company is coming out sunday, hopefully they will be able to fix it. Anyway, I just wanted to know why are amps so sensitive to ground loop problems and receivers aren't? I've had three different types of receivers and have never had a problem with ground loop hum. Just curious.
     
  2. Saurav

    Saurav Cinematographer

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    Did all your receivers have 2-prong plugs, and your amp have a 3-prong plug?
     
  3. Michael Marklund

    Michael Marklund Stunt Coordinator

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    Amps only hum because they don't know the words.
    MM[​IMG]
     
  4. Arthur S

    Arthur S Cinematographer

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    Good question. So many people buy a separate amp to bolster their reciever. Often they are quite disappointed that the first thing they notice is hum and other noise with the separate amp.
    I've never had a receiver that had either mechanical transformer buzz or electrical noise that could be heard from the listening position with no signal present.
    Not true of amps. The transformers in many amps are large. The larger the transformer the more likely it will buzz. This has to do with the laminations and how tightly and carefully the whole transformer package is designed, manufactured and installed.
    But the 3 prong plug issue is a major source of this discrepancy between amps and receivers.
    Never the less, you hear far more about hum, buzz, and hiss from separate amps than you do about high power receivers.
    What ever you do, don't use a cheater plug [​IMG] .
     
  5. Ken Custodio

    Ken Custodio Second Unit

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  6. Saurav

    Saurav Cinematographer

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    OK, so it isn't that then [​IMG]
     
  7. Aslam Imran

    Aslam Imran Second Unit

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    Because most amps consume higher power than receivers (even when the ratings are similar), have bigger power supplies with torroids that are notoriously buzzy. Just take a wrench and tighten it down and you should hear no buzzing. Thats the nature of the beast.
     
  8. Chu Gai

    Chu Gai Lead Actor

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    Personally, I wouldn't go about opening up your Parasound and start tightening things as that would probably void your warranty (and besides, I think you're talking about something else). Rather than go through a litany of possible things for you to check, while waiting for your cable person to roll in, do a Google search on the terms Ground Loop Problem. Pick a few likely sites and run through the possible solutions. If possible, please post back as to what you found.
     
  9. Mark Austin

    Mark Austin Supporting Actor

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    Separate amps tend to be more sensitive to noise. After having the cable company change the ground to no avail, I went to a local B&M A/V store that did installations, and they had a cable ground breaker for like $5. Works like a charm. Another place to check would be sat installers who would also have them.
     
  10. Kevin. W

    Kevin. W Screenwriter

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    Never had a problem with my Rotel RMB-1066 and humming.

    Kevin
     
  11. Ken Custodio

    Ken Custodio Second Unit

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  12. Jeff

    Jeff Supporting Actor

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  13. Nathan Cook

    Nathan Cook Agent

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    i hooked up an amp with some cheap unshielded cables that were run along the mass of all my other cables and such and i about blew my ears out with electrical noise when i turned the amp on.
     
  14. Aslam Imran

    Aslam Imran Second Unit

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    I was assuming only the humming of the amp from reading the orignal post. This is differentiated from speaker hiss due to the amp which is a result of ground loop problems. If the speakers are hissing then go about it in ways described above but of there is humming coming from the amp interior, none of the above is going to help and the only solution is to tighten the torroid.
     
  15. Todd Hochard

    Todd Hochard Cinematographer

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    Is there adequate voltage supply at the outlet the amp is plugged into? If the voltage is sagging when the amp is powered up, that will tend to increase the hum. It should stay above 110VAC at all times.
     
  16. Robert Elliott

    Robert Elliott Stunt Coordinator

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    I have a completely different answer based on a reading of Bob Carver's patents on the Sunfire Subwoofer.

    Your receiver doesn't hum because there is no ground loop issue with its internal amps. When you connect the receiver or pre/pro to an external amp via interconnects you have created a ground loop. The voltage/ground of the separate items is/can be different (based on your household ground loop I suspect) and when connected to each other via the interconnects, you introduce the 60hz hum.

     
  17. Arthur S

    Arthur S Cinematographer

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    Jeff

    "What ever you do, don't use a cheater plug."

    Take a closer look at the smilie.

    Artie
     
  18. Tim Hoover

    Tim Hoover Screenwriter

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    Pardon my ignorance (or perhaps I'm just missing the joke!) but why would you not want to use a cheater plug w/ a power amp?

    Paranoia runs in my family...
     
  19. Robert Elliott

    Robert Elliott Stunt Coordinator

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    A minor annoyance called electrocution comes to mind. Likely? Probably not. Possible? Very.
     
  20. Arthur S

    Arthur S Cinematographer

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    Seriously

    If you hug your power amp every day, don't use a cheater plug.

    Artie
     

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