1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Sub woofer feedback dilemma

Discussion in 'Subwoofers' started by Lost Pants, Dec 24, 2001.

  1. Lost Pants

    Lost Pants
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Ok, I'm getting really frustrated with my subby and am just about to break something. Here's the dilemma. I have a Sony powered sub hooked into my Yamaha system which also runs a DVD, VCR, Playstation and CD player, everything is sweet there. However a problem has arisen since getting satellite/cable TV installed. I cannot use the sub with the cable, I can't even have it plugged in to the amp because the feedback is deafening. I have had the cable guy out and he says their equipment is fine, we have isolated the problem to the sub. Even when switched off the sub emits this awful feedback which also comes through the rest of the speakers so I have to unplug it completely. I know the problem is caused by the cable and the sub not getting along all peachey but surely there must be a solution to this? i have tried a different power outlet, different cables and tried plugging the cable tv in through any and all inputs but to no avail. Any ideas? Anyone?
     
  2. Lowrider

    Lowrider
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Try disconnecting the earth on the sub, and connecting it to a different power outlet...
     
  3. Lost Pants

    Lost Pants
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Umm...forgive my ignorance, but how would i go about disconnecting the earth? Wouldn't disconnecting the earth cause a power short or are you talking about a different type of earth?

    Thanks
     
  4. Stuart Wright

    Stuart Wright
    AVForums Founder Staff Member

    Joined:
    Jan 24, 2000
    Messages:
    13,870
    Products Owned:
    6
    Products Wanted:
    2
    Trophy Points:
    167
    Location:
    Birmingham, UK
    Ratings:
    +9,614
    Lowrider is thinking of an earth loop. This occurs when two items of electrical equipment are connected together - e.g. your sub and, say, your TV via your amp - but are plugged into different sockets using different mains earth loops (?).
    By disconnecting the earth connection in the plug of the sub you are isolating it from the earth and therefore removing any potential loop.
    Of course you need to be very careful when doing something like this.
     
  5. Lost Pants

    Lost Pants
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Thanks Stuart. I'll look into that more closely, migh consult an electrician as the last thing I want to do is blow something or myself up! Here's hoping something good happens! Thanks also to Lowrider.

    Feel free anyone to suggest any other potential causes/fixes.
     
  6. Reiner

    Reiner
    Active Member

    Joined:
    Jul 16, 2000
    Messages:
    3,315
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    61
    Location:
    Germany
    Ratings:
    +13
    Try using different AC outlets (e.g. same for all equipment) first before cutting any wires and keep in mind that there is a reason if the earth is connected to some electrical equipment - and this reason is your health/life, so you should ideally NOT cut it off.
     
  7. greeny

    greeny
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Extension leads are good for this purpose. Buy a good quality extension lead with 4/6 outlets on and connect all your audio equipment to it.

    However this could be a different problem as you shouldn't really get feeback (in my experience) but more like a hum!!
     
  8. Lost Pants

    Lost Pants
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Thanks to those who posted recent replies. I thought by cutting wires I could run the risk of doing myself harm so I will steer clear of that one. As for different AC outlets, I have tried the sub on different outlets via extension leads, even outlets that are on different circuits but the darm problem has not gone. I also tried plugging the cable tv into the different outlets with no more success. The TV, VCR, DVD, CD and PSX are all through the same outlet and there has never been a problem. The only solution I have so far is to disconnnect the sub from the amp when watching cable and to disconnect the cable tv when I want to use the sub. Annoying yes, but at least cable is in surround, albeit without a sub. I guess this will have to do until the problem is fixed. I am perplexed and vexed by this confounding dilemma I find myself in, oh why can't life be easy??? This sounds like a rare problem to me as you guys are the only people who have any sort of clue as to what may be causing this! One day we will conquer this. Thanks to everyone who has given me suggestions so far, keep em coming!!
     
  9. Reiner

    Reiner
    Active Member

    Joined:
    Jul 16, 2000
    Messages:
    3,315
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    61
    Location:
    Germany
    Ratings:
    +13
    The idea is actually to use the SAME outlet, not a different one which we suspect to be the cause for the humming.
    Hence connect all equipment to one extension cord and plug this into any wall outlet.

    If this does not work try an isolater (?) for car-hifi which disconnects the shielding from the line level (RCA/phono) connection. Should be available from car-hifi dealers or car accessory shops.
    (Again you could try to cut the shielding from your current RCA/phono cable at ONE end if you dare, there is no 'health' risk here.)

    Or try a higher quality (better shielded) cable as opposed to that.
    Ask your dealer if he can loan you one, and if it works you will purchase it.
     
  10. Lost Pants

    Lost Pants
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Thanks Reiner, a few different options for me to try there. I will give them a go and let you know how things go. Wish me luck!
     
  11. Stevemj

    Stevemj
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Using the same outlet for all equipment should be no different than using any outlet in your home, if your house is wired correctly all earths in every socket are connected together. Even if you use sockets from different ring mains they should still be connected at the main fuse box all on one terminal.

    Removing an earth from equipment will not affect the function of the equipment or 'blow it up', however the earth is used in equipment requiring it to provide a route for the electricty to use should an earth fault occur. An earth fault could occur if a fault arrises in the equipment and the live of the equipment is then connected to the earth/casing. This would result in the live been directly connected to the earth and the fuse would blow(or circuit breaker trip) however if you had removed the earth and this fault occured no fuse would blow and the outer casing would be live and touching the casing would result in an electric shock(as you would be providing the earth through your body). So be carful when removing earths, while this situation is rare it does sometimes occur.
     

Share This Page

Loading...