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Trouble integrating main with sub

Discussion in 'Subwoofers' started by ShinObiWAN, Apr 19, 2004.

  1. ShinObiWAN

    ShinObiWAN
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    Hi all,

    I recently completed work on both a subwoofer and front speakers:

    Mains:
    http://www.avforums.com/forums/showthread.php?s=&threadid=125302

    Sub:
    http://www.avforums.com/forums/showthread.php?s=&threadid=122804

    However I cannot get them to integrate properly. The fronts are astonishingly good speakers for the money they cost to create and therefore place greater demands on the subwoofer to integrate - or at least thats my view at this point. The sub on its own sounds pretty heavywieght and is certainly not subtle, definitely more HT muscle than hifi finesse.

    You see whats happening is that the sub completely ruins the sound from the mains, how? Well the treble detail disappears even when the sub is set to a conservative level. If I turn the sub on during playback its as if a mask has been applied. What I don't understand is why is this happening?!? The sub is crossed over far lower than any treble frequencies.

    Aside from the mains and sub my setup is as follows:

    Lexicon MC1
    Chord SPM 1900 5ch power amp

    Settings are:

    Fronts: 40hz (controlled by the MC1)
    Sub: 40hz (controlled by the MC1)

    I've tried various crossover setting from 120hz all the way down to 40hz which currently gives the best sound but still dissappointing.

    How can this be fixed or is the sub design at fault?
     
  2. ShinObiWAN

    ShinObiWAN
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    Tried changing the location of the sub with some success.

    Before I had it in the corner which gave good extension, seemed to provide boom which clouded the main speakers delivery. I'm now at the point where I have the sub right in the middle of the room.

    Unfortunately whilst it sounds better than before, its not practical to have such a large cabinet in this position. For starters it blocks the lower portion of the projection screen not to mention that it looks out of place.

    I'm beginning to think that its all a little too much for my small 11ft x 15ft room. A real shame as put a lot of effort into the enclosure as well as money <sigh>

    I don't know what to do now.

    I was thinking about designing a different enclosure but again since I had maximised the low frequency response in this design, anything else would be a compromise and I would lose extension.

    Another thought is start over again with a different sub design and driver but keep the BK OMP 1000 amp. An expensive mistake to be sure!

    Any suggestions would be greatly appreciated but at this point I think I'm clutching at straws.
     
  3. Stereo Steve

    Stereo Steve
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    For music, I set the crossover at the source end (dvd) to 80 and I then set the subs xover at 60. I find if I set the sub at 80 it goes all muddy. I think the dvd goes a bit lower and the sub a bit higher than their xover settings. Try it and see.

    For movies I have the amp at 60 and the sub also at 60 and it gives a nice beefy sound.

    I also tried a sound meter with my sub today and had to back it off by about 6db which improved music enourmously and made th esub 'dissapear' while the bass and rythym was still all there. I'm well chuffed with it now.
     
  4. ShinObiWAN

    ShinObiWAN
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    Thanks Steve, something for me to try tommorow for sure.

    I've also tried backing the level of the sub down but I find that when I reach something that doesn't impinge on the mains, its almost at the point where you don't know the subwoofer is there, this is especially true for HT. You just lose all the slam and depth because its set too low :(

    Another interesting point is that I don't have an SPL meter - something I've always promised myself but never got round to ordering. Will have to order one ASAP.
     
  5. ShinObiWAN

    ShinObiWAN
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    No luck :(

    I've tried virtually every crossover combination that my MC1 will allow.

    I'm now sure that either the sub is a naff design or it simply hates my room. I'm leaning towards the sub design is naff bit since I used a car audio SPL sub.

    Guess I'll have to sell the driver on, keep the 1kw BK amp and work on something sensible this time.
     
  6. Daneel

    Daneel
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    Have you tried to plot the frequency response of the sub to see what it is doing? If you have a big peak or dip that could be causing all sorts of problems.

    A BFD might be the way to go.

    BTW I'm very impressed with your projects, the speakers in particular, they look amazing.
     
  7. rob_w

    rob_w
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    posted reply in the diy section :)

    Rob
     
  8. ShinObiWAN

    ShinObiWAN
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    Don't laugh too hard when you read my reply :blush: :censored: :laugh:
     
  9. ShinObiWAN

    ShinObiWAN
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    Thanks, they sound the part too.

    Pain in the ass to build and finish though. I did have plans for matching surrounds and a center but I'm going to leave those for sometime whilst my hair returns from grey back to its natural colour :)
     

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