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Subwoofer distortion despite accurate speaker levels

Discussion in 'Subwoofers' started by Shenoizy, Oct 25, 2005.

  1. Shenoizy

    Shenoizy
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    Earlier in the year I bought the Acoustic Energy Aegis Evo 3B 7.1 speaker package and Denon AVR-2805 receiver. I'm very happy with both, especially the clarity on the AE's. I understand that the subwoofer is probably the weakest part of the package but this is a problem that may affect other systems.

    I've set the speaker levels (both by SPL and Denon's auto-setup) and all channels (including .1) sound fine and accurate when played at a reasonable level. Recently I've tried bumping up the main volume by a couple of dB on some loud films and in a few action scenes the sub has distorted. It basically rattles instead of rumbling and my attention is diverted to the sub instead of the bass being felt. If I turn the volume down it returns to normal.

    I'd like to know what I can do to prevent this distortion and whether these should be done permanently or only when using the higher volume e.g

    1) Buy a second sub woofer (obvious but expensive and impractical)
    2) Share .1 sound with LFE+Main channels and not just LFE as it currently is
    3) Reduce LFE sound level on receiver by a few dB
    4) Reduce LFE sound level on sub woofer (it's currently fixed at half way)
    5) Change the cross over frequency (currently 80Hz on receiver and maximum of 120Hz on subwoofer - which shouldn't matter as .1 specification on Dolby Digital and DTS is fixed to 80Hz.

    Reducing the LFE level is the most sensible choice but then at lower volumes the bass doesn't have as much impact which is a shame. This is my first post so I'm sorry it's long.
     
  2. MarkE19

    MarkE19
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    Distortion on a sub is common and can only truely be eliminated by spending more money on a new & better sub. Adding a second sub will help as long as they are both up to the job and then setup can become a nightmare! If the speakers can handle low bass then getting them to do the work may help, but this is dependent on the amp/receiver and the speakers. Changine the crossover will only cause a gap in the sound rather than reducing distortion, unless as stated the speakers and amp are up to handling low bass.

    Many cheaper subs will have a high THD of over 10% and the only way to get around this is to replace the sub or lower the volume. Spend big money on something like the Velodyne Digital Drive subs and you get a THD of around 0.5% but these cost several thousands of pounds. Others such as those from SVS, B&W etc if set up correctly and not overdriven will also give great results.

    Mark.
     
  3. Nimby

    Nimby
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    The most obvious question is whether your subwoofer is in a corner? Or out in the open somewhere? You get maximum output from a corner placing somewhere close to your main speakers. Anything else is handicapping your sub's performance.

    The further you place your sub from your speakers the greater the chance of cancellation occuring which will reduce perceived output at particular frequencies.

    An alternative is to try placing your sub very close to your seat. But it may also draw attention to itself.

    Nimby
     
  4. Cable Monkey

    Cable Monkey
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    ...by shaking you out of it! :D
     
  5. Nimby

    Nimby
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    Th_th_ank_y_ou_for_th_tha_that_deep_deeply_ly t_t_t_tech_nical ass_assess_ment_of_th_the_phys_physi_ physio_logical_p__p_pr_problems asso_asso_c_iated_wi_wi_with_co_co-locating_ones_ones_self_self_with_one's_own_s_s_sub_sub_subwoofer. :)

    Nimby
     
  6. Shenoizy

    Shenoizy
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    Thanks guys. Although it is placed next to my front speakers and near a corner/wall I will have to play around a bit to see what settings help things. I guess a new sub woofer will be required eventually but for now I shall make the most of what I have.
     
  7. binbag

    binbag
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    I'll ask the obvious. Have you checked that all the screws on the sub are tight and all the feet have a good contact with the floor? Have you tried changing the surface it sits on? Any of these can produce a noticable rattle.
     
  8. bob1

    bob1
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    The best option is to buy a better subwoofer as it doesn't sound upto what your after.
    You could try setting the speakers to large ,if you set them to small all the bass from them will go to the sub as well as the lfe channel, could be worth a try but it seems you have a taste for bass the sub just can't give you.
     

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