Got my Svs Ultra, have question about setup with 2 subs

Discussion in 'Speakers' started by Michael Eriksen, May 8, 2008.

  1. Michael Eriksen

    Michael Eriksen Stunt Coordinator

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    The Svs PB ultra13 finally arrived at my home yesterday. Now im trying to get it to work with my paradigm servo 15.

    When calibrating the speakers are set to 75 db om a test signal, and using one sub the output is around 80. Ok, using 2 subs now should give me a 6 db increase. So what do I do ?. Adjust the level down on the subs so they still have a db output of 80 together, and if I do that, what does the 6 db increase means ?

    If I dont adjust it down it reads 84-85 db, which is 10 db higher than the speakers and seems a bit to much.

    Michael
     
  2. Robert_J

    Robert_J Lead Actor

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    You turn down your subs 6db so that the bass level is the same as with one sub. The 6db increase is just head room.

    Have you tried running just the SVS? That low distortion, underhung driver should sound much better than running two subs.

    -Robert
     
  3. Michael Eriksen

    Michael Eriksen Stunt Coordinator

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    Thanks. Im experimenting with it right now.

    I tested from 20 hz up to 80 hz and I get an db increase at every stage (every 10 db), so there is more bass using 2 all over.

    But maybe I should just go with the svs and then turn it up if I want more bass, or maybe add another svs later. That should be better than running 2 different subs even though i set the fase so they dont cause any drops at any hz ?
     
  4. brandonchenry

    brandonchenry Stunt Coordinator

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    I was thinking that they were out of phase, but if you have that dialed in, I would start erring on the side of personal listening preference. Are they right next to each other? or in different locations in the room?
     
  5. brandonchenry

    brandonchenry Stunt Coordinator

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    BTW- when I calibrate, I set my speakers to 76 and my subs to 82-84. Just the way I was brought up I guess. Do you have a receiver with Audyssey room correction software on it? That is an installers best friend for helping to capture full sound potential.
     
  6. Michael Eriksen

    Michael Eriksen Stunt Coordinator

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    They are on each side of the screen but placed somewhat assymetric.

    They are both in fase with each other and with the front/center speakers, so basically there is no problem. No decrease of bass at any hz.

    I find it very hard to hear any difference using just the svs or both...more bass when using both...but maybe its more clean just with the svs. All i know is i have a severe headache from listening to low db testsignals for some time. :-(

    So please tell me that running 2 different subs always will be a bad idea. :)

    Im using the denon avc-a1se as a pre and the sunfire grand cinema as amplifier, so no Audyssey yet, but will buy the Marantz av8003 when it coming out in juni, then I will get it.
     
  7. Michael Eriksen

    Michael Eriksen Stunt Coordinator

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    Tried and run the testsignal again. I get these numbers, on the same sound level. I ran them 3 timers:

    The PB13 Ultra alone / The Svs and servo together:

    20 hz - 75 db / 75 db
    30 hz - 77,1 db / 76 db
    40 hz - 62,5 db / 62,2
    50 hz - 62,6 db / 73,4
    60 hz - 72 db / 82,2
    70 hz - 66,3 db / 75,5
    80 hz - 74,6 db / 70,6
    90 hz - 73 db / 73,8


    From 50-70 hz i get around 10 db more using both subs. Below 50 hz its about the same, and on 80 hz its actually 4 db lower than the svs alone.

    The svs alone varies from 62 hz to 77.
    The 2 subs varies from 62 to 82 hz. A 20 db jump.

    Would I be better off using just the svs alone to get a more even level ?

    And would you use the PEQ at these numbers if using the svs alone and at which frequency ?

    Michael
     
  8. JohnRice

    JohnRice Lead Actor

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    Just remember, you don't actually listen with an SPL meter. My first step would be to dial in the SVS alone and try going with just that. You seem to be thinking in terms of amount of bass, instead of quality. The Ultra will blow away the Paradigm in quality, and using the Paradigm will most likely only drag the SVS down, quality wise.
     
  9. CleanSeeker

    CleanSeeker Extra

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    My God man... Do you live in a gymnasium?

    The Ultra is 155 lbs. of 10HZ velvet covered sledgehammer!

    Can you really have it maxed out and be asking for more? [​IMG]
     
  10. chuckg

    chuckg Supporting Actor

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    that's kinda what I was wondering... :O
     
  11. Michael Eriksen

    Michael Eriksen Stunt Coordinator

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    Actually i dont want to use 2 subs to get more bass, but to even it out thought out the room more.

    When I meassure the svs alone there are some drops at some listening positions at different hz, probably because of my room, furniture ect. One listening position meassures 75 db on 70 hz, and the position right next to it drops to 60 db on 70 hz.

    So im kinda emperimenting to get the bass as even as possible on all 4 main listening positions.

    Im quite convinced the svs covers my need for loudness.
     
  12. drobbins

    drobbins Screenwriter

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    Maybe this study will help. In my old theater with more room, I had one sub center front and the other center back. After calibrating my BFD eq, I never noticed ANY bass difference in between my 8 seats. I did not do a study and take measurements though. I figured that if it sounded good, and it did, I should be happy.
     
  13. Martino

    Martino Supporting Actor

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    Wow - that 30 page experiment with sub placement was sure impressive. The 50 subwoofer experiment, and then the 5000 sub experiment were kind of funny...

    http://www.harman.com/wp/pdf/multsubs.pdf



    It looks like their conclusion matches what you found. Thanks for the link...

    "Two subwoofers, at apposing wall midpoints, performs very nearly as well as four at the midpoints and gives a much better LF factor"
     

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