How much hum is too much?

Discussion in 'Archived Threads 2001-2004' started by Andrew_Ballew, Mar 15, 2002.

  1. Andrew_Ballew

    Andrew_Ballew Second Unit

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    What do you consider an acceptable level of hum in your speakers? (Other than none[​IMG] ) I have a Carver 806x amp, and I get a small amount of hum in my center and surround channels. It is practically inauible with no sources engaged, likewise with just my Newcastle Pre-pro engaged. But when I engage a DVD, the hum rises from near inauible to audible from within 1 foot of the speaker. The hum does not increase along with the system volume, so it is really a non-issue, but I know it is there, and that is enough to drive me crazy. I have tried all the usual ground loop remedies (except for the cheater plug, as I see no use since the amp's plug is already two prong) to no avail.
    Would you consider this level of hum acceptable in your setup? Or should I just live with it? Might one of those power conditioners I hear so much about do anything at all to improve the problem? How about balanced power? But thats really expensive, isn't it? Haha- the joys and aggravations of this hobby.
    Thanks
    Andrew Ballew
     
  2. Jagan Seshadri

    Jagan Seshadri Supporting Actor

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    Acceptable hum to me is only audible when by ear is right up next to the driver and I can tell the electronics are on. If hear hum without trying to find it first, then it is too much hum.

    -JNS
     
  3. chung

    chung Stunt Coordinator

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    Here's what I would do to trouble-shoot:

    You have your TV/cable, DVD player, pre-pro and power amp electrically connected, and there is hum.

    If nothing is connected to power amp, except the speakers, is there still hum? (I expect not).

    If nothing else is connected to pre-pro, except the pre-pro's outputs are connected to the power amp, is there hum? Is the hum different between L/R and the other channels? Have you tried using cheater plug on the pre-pro? Is your power amp's power plug polarized? Is the same outlet powering the pre-pro and power amp? If you swap the pre-pro with another source, is there still hum?

    You said you hear more hum when DVD is engaged. Is that because your TV is now connected (via DVD-to-TV video connection)? Try breaking the connection between TV and your sound system. How's your DVD player connected to the pre-pro? Have you tried using only the optical connection? That way there is no electrical connection between the DVD player's ground and the pre-pro/amp ground.

    Trouble-shooting ground-induced hum is not all that difficult. Make sure you can reduce the problem so that it is hum free with just the pre-pro and the power amp, and then add additional component/connections. One common culprit is that cable antenna connection. A lot of times, the external cable box (outside of the room) is not grounded to the house's mains' ground solidly.

    You should not be able to hear any hum from your normal listening position. That would be your goal.
     
  4. Andrew_Ballew

    Andrew_Ballew Second Unit

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  5. chung

    chung Stunt Coordinator

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    Does this happen with all discs? Does it happen with CD's played on the DVD player?

    You may have a defective DVD player. Perhaps you can borrow one from a friend and see if the problem goes away.
     
  6. PaulKH

    PaulKH Second Unit

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    I can't hear any hum even with my ear against the speakers.
     
  7. Peter Johnson

    Peter Johnson Stunt Coordinator

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    IMO, who cares if its there, but I wouldnt want to hear it from my listening position.
     
  8. Andrew_Ballew

    Andrew_Ballew Second Unit

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  9. PaulKH

    PaulKH Second Unit

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    Hum is usually a power supply issue. Might consider looking at your power bar, or get a good one, or try disconnecting all components (power) and then reconnecting one at a time until the hum reappears. If you have nothing connected to power except the amp/receiver and you still have hum, then it's the power circuit in your room or the power bar or the amp/receiver itself.

    I know what I said above is pretty obvious, but maybe it will help! I know what it's like trying to track something down!
     
  10. joe logston

    joe logston Stunt Coordinator

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    i have no hum at all even with my ear up agianst the drivers but some cds that where remasterd have some tape hiss or hum, my system is dead quit. most hum is from tv cable or you have a ground loop hum from the ac inputs
     
  11. Andrew_Ballew

    Andrew_Ballew Second Unit

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    I have determined the source of the hum- my pre-pro- the Sherwood Newcastle AVP-9080, introduces the hum playing back in any surround mode. I came to this conclusion after I discovered that someone else who owns the same pre/pro had the exact same problem. It is not noticable from the listening position at all, so it should not be an issue. But since I am unfortunately a perfectionist, I will be keeping my eyes out for a good price on a potential replacement. Any suggestions? How much is that new outlaw 950 going to cost when it is released?

    Thanks!

    Andrew
     
  12. chung

    chung Stunt Coordinator

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  13. Andrew_Ballew

    Andrew_Ballew Second Unit

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  14. Jeff

    Jeff Supporting Actor

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    Funny, when I started reading Andrews post and he mentioned the center and surrounds, I immediately thought of my Sherwood Newcastle pre/pro. Then he mentioned he had one. [​IMG]
    I have the same hum with mine and it's the center and surrounds as well. I've always known it was the Sherwood because my Parasound amps are dead quite with just the speakers connected. I've mentioned this on this forum before and had many Sherwood owners dispute this, but I've had two units (still using the 2nd one) and they both do this.
    The best way to hear it is to select prologic (Not Dolby Digital or DTS, because you need a digital signal to hear the hum) and you will immediately hear it. The fronts will be dead quite.
    The humming isn't bad but anymore than a foot away would be a problem.
    Fortunately for myself, my Parasound amps have individual volume controls for each channel. What I've done is slightly turn down the center and surround channels and compensated with the Sherwoods speaker settings. Turning these channels up higher on the Sherwood does not reintroduce the hum. Now I can only hear the hum with my ear into the speaker.
    Jeff
     
  15. Andrew_Ballew

    Andrew_Ballew Second Unit

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  16. Matt_Key

    Matt_Key Agent

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    I have an odd audible hum in my system that will only occur at certain times during daylight hours. The hum only affects my amplified sub and a pair of amplified monitors (vtf-2 and event 20/20 bas). The vtf-2 will stop humming if i unplug the rca cable. The 20/20s will hum with no audio in plugged. A denon 3802 with b&w 602s are unaffected.

    What I can't understand is it only happens in the day time. And I havnt been able to pinpoint a certain time schedule it occurs. No appliances are running.

    I live in a small guest house, and used to live in a different house on the same property. This different house also had the odd daytime hum. I checked all the ac outlets in the old place. I am beginning to live with it...

    Any ideas on the source?
     
  17. PaulKH

    PaulKH Second Unit

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    Isn't the Sherwood Newcastle pre/pro pretty high end? Sorry I'm not that familiar with it, but it doesn't sound (sic) like it should hum!
     
  18. Andrew_Ballew

    Andrew_Ballew Second Unit

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  19. Jeff

    Jeff Supporting Actor

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    Now it's not considered high end as far as pre/pros go. But it's one of the best for the money. I don't think the slight hum takes away the sound quality, otherwise you wouldn't have such good reviews on this forum and audioreview.

    I had a Chiro pre/pro which originally retailed for around $3000 and all 5 channels had a constant hiss from 1 foot away. I tried three units and they all did that. Of course I just did the little "trick" with my Parasound amps and that took care of the hiss as well.

    Jeff
     

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