1. Join Now

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

Sub position problem?

Discussion in 'Subwoofers' started by Treworgey, Feb 16, 2005.

  1. Treworgey

    Treworgey
    Standard Member

    Joined:
    Nov 17, 2004
    Messages:
    31
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    6
    Ratings:
    +0
    Hi folks,

    I am a new to this AV Forum. It's great, but is costing me loads :D

    I recently bought a BK XLS200 sub after reading the various posts on this forum. One reason for chosing this, apart from the price, was it's size. I had just the spot to squeeze it in. However after playing with it for a short while I believe I have a problem.

    I used the AVIA test disk and an SPL meter from Maplins to try and set it up. It is currently only connected via Low level connection to the mono output of my 11 year old Denon AV 3020 Amp (3805 on order :D ). I am having difficulty setting the bass level low enough, but my main problem is a null at 37Hz. I first noticed this with the sweep tests. The level all but dissappears and then reappears as the frequency sweeps down. My first thought was that I had the crossover set too low leaving a gap between the sub and my main speakers (KEF Coder 9s). However I then had a play with SigJenny running on my PC and there appears to be a null at 37Hz where I am sat (sweetspot). When I walk to either end of the room I can hear the tone again - in fact there is a 25dB variation between min and max!

    My room is 12ft x 16ft into the bay, where the Sub is. The null seems to exist across the width of the room about half way along. I had previously seen mentions of such phenomenon, but was hoping I would be lucky as I have very little choice as to where to put the sub and still get WAF! I can't believe how pronounced this effect is.

    Am I right in thinking that moving my sub is the only option? Will it in fact make any difference, or is this an acoustic feature of the room?

    Interestingly, if I open the doors into the dining room and carry on walking there is another null half way through. (Similar sized room.)

    I have loads of other questions re: high/low level connections etc. but I think this can wait until I have sorted the null (if poss) and received my new amp.

    Any advice much appreciated.

    Cheers,

    Chris
     
  2. eviljohn2

    eviljohn2
    Well-known Member

    Joined:
    Jul 8, 2002
    Messages:
    7,529
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    86
    Location:
    Near London.
    Ratings:
    +208
    I'm afraid you're right and that moving the sub is about the only way to combat the null. Unless you have another sub to put somewhere else of course. :p

    To be honest, although peaks can be treated with a parametric equaliser, there's very little that can be done with a null. Your best bet is to ignore it as from what you've said it's very localised at around 37Hz, it really won't make a noticeable difference when you're listening to normal media rather than playing with analysis tools. :)
     
  3. Treworgey

    Treworgey
    Standard Member

    Joined:
    Nov 17, 2004
    Messages:
    31
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    6
    Ratings:
    +0
    Thanks John, it had crossed my mind that that was the case. I'll leave it for now and see how I get on when my new amp arrives.

    Cheers,

    Chris
     

Share This Page

Loading...