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My subwoofer measurements..help please

Discussion in 'Subwoofers' started by jonnyv, May 6, 2002.

  1. jonnyv

    jonnyv
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    [​IMG]

    Blue line is with granite slab on top of sub, pink line is without. Measurements taken with sub only..

    Obviously the frequency response isnt as flat as i would like..

    what can i do to smooth it out ?

    any thoughts on the effect of the slab ?


    Sub is positioned next to right frount speaker and facing the listening position...

    cheers
     
  2. Jase

    Jase
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    Hi jonny

    You need to experiment with the placement of the subwoofer. Also try keeping it in the same position but turning the sub round either to the side or so the driver is facing away from you.

    You´ll have to take measurements of the test tones each time you move it.

    Take the measurements roughly where your head would be at the listening position.

    For mine, I had the amp set to Pro-Logic, the master volume set to -20db (Denon) and then played the test tones. And got the results seen in the other thread.

    As per your PM, you may not get anything for the lowest test tones as your sub may not be able to produce them. My room is boosting those frequencies which is why I get something.

    The effect the slab may be having on your results is too reduce boom which is why the levels appear lower.

    How does it sound to you?? better?? worse??
     
  3. jonnyv

    jonnyv
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    Thanks for the reply jase...I shall try moving the sub today..i am limited by a 3 meter sub cable..

    in my chart the blue line is with slab..and pink is without slab..

    The blue line(with slab) is higher than the pink (without slab), does this mean the slab is making more bass ?

    Im not sure if the slab has made any difference..??

    cheers
     
  4. Jase

    Jase
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    Getting my pink & blue mixed up!!:eek:

    If its round the other way then maybe (again maybe!!) the slab is having the effect of boosting the bass, the exact reasons behind it, I dont know!! Could be the weight of the slab stopping the sub cabinet from moving when the cone moves forward and backwards??? We need an expert in on this!!!!

    The important thing is how it sounds to you.
     
  5. GaryG

    GaryG
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    You might find this of interest.

    www27.brinkster.com/jmag999/


    Before equalisation my sub response was similar to yours, using a BFD I've now tailored the response to augment my main speakers which tail off at 32Hz. Using the BFD I now have a response that's reasonably flat to 20Hz (the BFD filters come in very sharply after 32Hz so that there's no interference with the main speakers).
     
  6. jonnyv

    jonnyv
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    Not quite sure what i was doing wrong..but here is my chart again with sub in original place...Test tones ran from 20hz - 89hz.

    Test with sub only connected..Sub's lowest frequency (according to paradigm web site) is 27hz.

    My sub is set to take the bass from frount speakers at 50hz..

    Therefore, (unless i'm mistaken) the response seems pretty good ??

    opinions ??
    [​IMG]
     
  7. Jase

    Jase
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    If your sub is taking the bass from 50hz down then it doesnt look too bad.

    40hz downwards is fairly flat and tailors off when your sub reaches its lowest frequency.

    If it sounds good then thats the important factor.
     
  8. lmccauley

    lmccauley
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    Hmm, I'm a bit concerned about what's happening between 50 and 80Hz. If the crossover is set at 50Hz, then I'd expect nothing measurable by 60Hz.

    The lower end looks pretty good, as Jase says.

    It would be interesting to see how the whole system measures - i.e. including the main speakers.

    Cheers,
    Liam
     
  9. jonnyv

    jonnyv
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    I Think its to do with the amps crossover setings..its a pioneer thx amp and the crossover is set at 80hz..although i did have my sub set at about 50hz..i have now changed the sub to handle the bass from 80hz down..

    I may do another chart with frount speakers as well this afternoon....

    cheers
     
  10. jonnyv

    jonnyv
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    OK, heres my latest test...this time sub and frounts..

    Amp crossover at 80hz (didnt realise before) , sub crossover also set at 80hz..speakers set to small...

    any opinions are welcomed..

    cheers
     
  11. jonnyv

    jonnyv
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    OK, graph shows subs new position in blue and old position in pink.. I havnt altered the subs levels so it may be a little too loud for the new (nearer) position.. How many db's would you say it needs to come down by to match the frounts ?


    cheers
     
  12. Jase

    Jase
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    jonny

    We´re doubling up replies here, best keep it to one thread now mate.

    cheers
    Jase
     

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