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Help with Sub - frequency "hole"

Discussion in 'Subwoofers' started by Buckster, Apr 17, 2005.

  1. Buckster

    Buckster
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    Hi there all,

    I'm wondering if you can help me - I have a REL Storm MK1 subwoofer .... ran Avia test DVD yesterday and I seem to have almost zero output (you can hardly hear it) between 70-50Hz on the Sub. Is this more likely to be room dynamics or the REL filter gone a bit weird ? I've tried moving it around (to a limit) and still have this massive hole - or is it normal ?

    Thanks, Mark.
     
  2. micb3rd

    micb3rd
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    Have you got a phase switch? Try swapping the phase switch position.

    This may help if the problem is you subwoofer and other speakers playing them same frequnecies and canceling each other out.
     
  3. Buckster

    Buckster
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    Yes - it has one - makes no difference to this hole though. Thanks for replying though.

    Its rather bizarre, Mark.
     
  4. micb3rd

    micb3rd
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    You have not got any low pass fiters or processing going on anywhere in you Processor or AV receiver do you?

    You could be running two crossovers at the same time and effectivily doubling the db per octave slope for the roll off of the filter.

    If you had a SPL meter you could do a near field test near the driver and plot the fr response, then repeat the test at your listening position then you could tell if the subwoofer is actually giving out the notes and if the room is affecting them.

    If you don't have a meter handy play some music or tones in this problem area and then walk around the room and listen. Also try right by the subwoofer this can help you to find if is a room issue.
     
  5. Jeff

    Jeff
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    It might not be a hole between 50-70Hz, it could be a big peak at around 40Hz and the hole is a result of the sub level being to low.
     
  6. stevej

    stevej
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    Are you measuring spl with a meter? If yes, leave the sub in it's current location and move the meter. Your listening position could be in a null. If moving the meter fixes the problem the easiest solution is to relocate the sub.

    Steve
     
  7. JBL 4645

    JBL 4645
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    Buckster hallo there; :hiya: I for agree with SteveJ move the sub hears what to do.

    Step 1 place the SPL meter in the listening position in an up right position and turning it around so that when you are moving the sub around you can see the needle moving up or down. :thumbsup:

    Step 2 have you got any test discs that have a spot frequency sine waves?
    If so play the sine wave and have it on repeat track this way you won’t have to keep running back to repeat the track. :thumbsup:

    And if you have a RTA real time analyzer with microphone; play wideband pink noise sub bass only and this way you should see the peaks and dips in the sub bass’s frequency response. :thumbsup:

    And when EQing the sub bass always use cuts never :nono: boost the frequencies, if you want more gain turn the sub bass’s volume level up. :thumbsup:

    And the aim is to have a flat response as possible… :thumbsup:

    That’s that for now.

    I am a former cinema projectionist.

    Ashley… :)



    T
     
  8. Ian J

    Ian J
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    What is he supposed to be EQing the sub with :confused:
     
  9. JBL 4645

    JBL 4645
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    Hallo :hiya: there Ian J

    Dubbing stages cinemas all riley on EQing the sound system :thumbsup: as I have done with my home cinema, I don’t use the built in amplifiers on my Kenwood KRF-X9050D THX select, instead I use the pre-outputs to ovoid the many problems that will often happen like front stage 3x matching speakers and getting the timber matching spot on, same goes for the side surrounds and centre back surround, and sub bass getting the flattest response as possible at the listening position… :thumbsup:

    I am a former cinema projectionist.

    Ashley… :)
     
  10. davehk

    davehk
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    Could he not put the sub at the listening position and walk around with the SPL meter? Find a spot with a suitably high reading and that's the place to put the sub?
     
  11. 30CenturyMan

    30CenturyMan
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    I don't understand what this is supposed to mean at all. :confused:

    Could you clarify why using the pre-outs (and connecting to what?) would avoid 'problems' (what problems?) and get the timbre matching spot on?
     

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