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Help: buzzing subwoofer!

Discussion in 'Subwoofers' started by dwsadler1, Oct 10, 2001.

  1. dwsadler1

    dwsadler1
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    My new Monitor Audio ASW 100 subwoofer buzzes when connected by a phono lead to my Yamaha DSP-A5 amplifier. The loudness alters when I rotate the phase switch through 180 degrees (a dial, not a switch on this model).

    I took it back to Sevenoaks and it tested fine on their system. They suggested the problem may be in my amp's subwoofer output stage. I thought so too because there was no buzz when I first connected the sub to my old Yamaha prologic amp. On rechecking, the buzz is now present with both my amplifiers!
    I have tried plugging the sub into various power outlets and tried a few different phono leads but the problem persists!

    Could it be the electical power supply in the house? What can be done about this?

    Any suggestions before I take it back for a refund and give up. PLEASE! :confused:

    [ 10-10-2001: Message edited by: dwsadler1 ]
     
  2. Rob

    Rob
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    Are you using a screened cable? If not give it a try. Chances are it will solve the problem.

    Regards Rob.
     
  3. dwsadler1

    dwsadler1
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    Thanks Bob.
    I was told any single phono lead would do. I have been trying cheap crappy old phono leads.
    I have just tried using the best phono lead I have - one of my audioquest jade pair, but the buzz is there. Is this lead likely to be shielded?
    What other kind of lead should I try?
     
  4. Reiner

    Reiner
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    It's either picking up some noise (so you need to improve the shielding) or it's affected by a ground loop - i.e. you need to remove the shielding. There are also special cables or adapters for that purpose available if you don't want to cut your cable.
     
  5. dwsadler1

    dwsadler1
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    Reiner,
    I have been using cheap phonos but I have ordered a 12 foot Acoustic Research HT152 subwoofer cable from beyondhifi.com. Not sure if it shielded, certainly hope so.

    My subwoofer buzz is present with all the (cheap) phono leads I have tried but only starts when a LFE signal is received (and the "signal" LED lights up).
    Is this more suggestive of a subwoofer cable shielding problem?

    Also, the volume of the buzz is affected by altering the phase switch 0-180 degrees (noise goes from loud to louder)

    What is a ground loop? How can I check if this is my problem? What kind of adapter would solve it?

    Thanks

    [ 11-10-2001: Message edited by: dwsadler1 ]
     
  6. Reiner

    Reiner
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    1. Disconnect the line level cable and crank up the volume at the subwoofer. Any buzz?

    2. Take one of the cheap leads and see if you can cut the insulation / mesh at one end.

    3. Adapters should be available in electronic shops or car accessories / car-"hifi" installation stores.

    Ground loop means the device is grounded from two different points but with a different potential, i.e. some current runs around and causes the distortion which is picked up by the amplifier and causes the noise.
    Advise 2. should help to identify and 3. to prevent this.

    I also have a MA sub (ASW110), but no such problems. Only the amp and driver melted once ... :D
     
  7. dwsadler1

    dwsadler1
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    Thanks Reiner, you are a great source of knowledge and advice!
    I found a good website which explains ground loops (www.epanorama.net).
    I will try disconnecting everything tonight and rebuilding the system connections. I have cable TV going into VCR & TV - a common source of ground loops, I understand. But why is it my new sub is affected, yet the fronts, centre & rears are not?!

    1.There is no buzz from the sub when there is no input signal

    I am still confused by your advice, points 2 & 3.

    2. How much insulation should I cut back off the amp to sub phono connection cable and why? From which end? What effect should this have?

    3. What kind of adapter do you refer to in point 3.

    Sorry to keep pestering but I am sure others must also have been affected by this problem.

    Thanks,
    David
     
  8. dwsadler1

    dwsadler1
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    SORTED!!

    The new shielded subwoofer cable did the trick. The buzz has gone. WOOHOO!!

    Thanks Rob and Reiner for your help.

    Dave
     
  9. Reiner

    Reiner
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    Glad to hear! [​IMG]
     
  10. Rob

    Rob
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    Well done, Its usually something simple. :)

    Rob.
     

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