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SVS sub woofer set up

Discussion in 'Subwoofers' started by karkus30, Jun 27, 2004.

  1. karkus30

    karkus30
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    Yes, same topic. Does anyone produce a definite guide to doing this. Having downloaded snap bug and worksheets and aquired an SPL meter.

    Basically the response curve is all over the place, theres as many sharp troughs as there are peaks. Certainly there is a very strong peak around 30-40Hz, but its way over 12 Hz attenuation using PEQ on the SVS. Then I noticed a comment, mentioning that you should be using pure stereo and not 5.1 doh.......then you should use warble tones...double doh :rolleyes:

    TBH Ive got the freqency set to around 35Hz, Q at around half way and level at the top of its range. Ive moved the sub around, set it on blocks etc. Then I just sat down and watched the Matrix. Is the sub calibrated correctly ? who knows :rolleyes: the Helicopter crash scene sounded amazing, something was vibrating (might have been the sub itself, difficult to tell at those volumes). I noticed that one of the bell mouths on one of the port tubes was vibrating against the heat sink on the bash amp, turned it through 90 degrees, which seemed to solve the problem, but maybe it starts to move at higher volumes.

    I tried the test tones on my hifi through the full range speakers and was amazed to find that they managed 20Hz without a problem and had a flatter frequency range from 25Hz to around 55Hz well into 90dB. But that might be because its pure stereo.

    Is it really necessary to do all this equalisation stuff ? I really dont see how you can rid the room of resonance, standing waves and peak frequencies, but maybe Im wrong?

    Any thoughts, a nice open discussion would be good.
     
  2. karkus30

    karkus30
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    :rolleyes: Im waiting :lease:
     
  3. Thunder

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    Its not possible to eliminate room modes completely, but its definatley possible to get a flatter frequency response, eg TMREQ :clap: However it does take time and patience to get it right. It also help to read up as much as possible to get an understanding of what frequency response graphs actually mean in reality. The difference between my system with EQ engaged and EQ switched off is considerable, however if your system sounds fine to your ears without EQ then thats all thats important. In which case dont bother mate. The EQ on the Ultra amps is rather basic and inaccurate (only one filter I believe). If your going to do it do it with something like a BFD. :thumbsup:
     
  4. karkus30

    karkus30
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    Very limited really, if you just had an odd frequency that was out it would work.
     
  5. chrisgeary

    chrisgeary
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    snapbug guides, the excel spreadsheet and your SPL meter should give you the right tools for the job - although don't expect a ruler flat response! basically, you should follow this:

    - set all speakers to small (otherwise any bass management you do with BFDs etc becomes largely meaningless)
    - set the xover to 80hz as this is the basis to which most DVDs LFE channel is recorded
    - don't bother with warbles unless you have real time analysis software.
    - download, or acquire some test tones: 20, 25, 32, 36, 40, 56, 63, 72, 80, 100hz fixed frequencies and burn to CD. using sweeps is great but not much use if you can't control them or know the frequency (assuming you use the excel method of graphing.
    - set the SPL meter to 80db, slow response, c weighting. position it in the listening position as close to ear level as possible. aim to get approx 75db SPL for each frequency. don't try to play it any louder as the voice coil may overheat and cause permanent damage. you don't masses of volume to measure the room response.
    - at each frequency, enter the meter reading into excel, the sheet should compensate and show you the room response at the measured position when you are done.
    - if you have one big peak to solve, you may find the PEQ on the ultra solves it. so play the frequency that is the problem, and adjust the PEQ until the measured reading in excel shows a flattening. re-measure the adjacent frequencies to ensure the bandwidth of the filter applied isnt too wide or too narrow.
    - if you find you have more peaks to deal with, consider purchasing a BFD and repeat the above!

    this is the first steps to room harmony - you can get a good deal more complicated, but experiment with your SPL meter and excel chart first. it will give you a good understanding of how it all works, and you may find you hit upon a solution that pleases. don't forget to rule out speaker/sub placement too! although you will have to redo your measurements again if anything like that changes.

    hope this helps? anyone anything else to add or remove?
     

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