cu footage?

Discussion in 'Archived Threads 2001-2004' started by Takosan, Jan 24, 2002.

  1. Takosan

    Takosan Stunt Coordinator

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    Is there a formula to use for which SVS subs? Roughly 4536 cu. ft. (21 x 20 x 10.8 high vaulted ceilings) with 8 x 5 opening on one side to kitchen.

    I was at the SVS website for the millionth time & now instead of the 20-39CS I'm thinking about the 20-39CS+ ... is it too much, too little, or just right for my room dimensions?

    Takosan
     
  2. ColinM

    ColinM Cinematographer

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    I've got >2400 cf and 1 20*39 CS. If my room were much bigger I'd want the Plus.

    Something to think about, you should err on the side of too much bass capability.

    My .02

    Good Luck -

    - CM
     
  3. Takosan

    Takosan Stunt Coordinator

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    Thanx.

    I think going the non-powered route will at least give me the flexibility to add a 2nd later if not enough.

    One thing that puzzles me is that the numbers I read like 105dB(!) ... I can't usually go aboe the -1dB when listening to 2 channel music & +10dB is usually pretty loud for most movies.

    So with the above will the CS+ still be a good choice? I'm guessing that I might be misunderstanding the dB stuff.

    Takosan
     
  4. Steve Zimmerman

    Steve Zimmerman Second Unit

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    Yes, go with the CS+ for sure!

    As for the dB measurements you are seeing... They won't make much sense unless you use a sound level meter to calibrate your system. Also keep in mind that we're talking about low frequency sounds which don't sound nearly as loud to the human ear (nor are they as dangerous).

    Most people calibrate their system using a sound level meter so that an 85 dB test tone playing from a single front speaker reads exactly 0dB on the receiver. That is considered "reference" -- but not very many people actually watch a movie with the volume that up loud. The reason they don't is because the test tones do not represent the maximum volume that can be played from a sound track. In fact, with your reciever calibrated at played at "reference" volume, your subwoofer can recieve LFE channel information that plays at 115 dB!!!

    So, if you watch movies at -10dB on a "reference calibrated" system, your subwoofer needs to be able to reach 105 dB. To test this, buy or borrow an SPL meter (Radio Shack sells them) and watch the THX intro to Phantom Menace or the first five minutes of Toy Story II. If you watch these movies with a calibrated receiver set to -10 dB, your sound level meter will likely approach 100dB at times. Assuming your sub can handle it, of course.

    Once you factor in the low frequency error of the RS SPL meter (for example, you have to add 5dB to the meter reading for a 25 Hz tone), it's easy to see for yourself that your sub must be able to put out 105 dB even if you're listening at 10 dB below reference!!

    Based on that, it's not hard to see why Tom and Ron readily recommend a dual sub setup. Even with *great* subwoofers like the SVS, with really big rooms you can't get cleanly above 105 dB without two (or more) of them.

    Hope that makes sense,

    --Steve
     
  5. Takosan

    Takosan Stunt Coordinator

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    Steve,

    Believe or not I have purchased a RS SPL meter & is ready to be put into use (guess my mind was racing ahead before even getting the sub).

    So I think I'll go with CS+. Honestly speaking, though, I'm still not quite getting it as far as dB, reference level, & the use of SPL goes. I hope I will soon. I do have the VE disc & I haven't gone through the sound part yet; only did the video part to do basic stuff after I got the RPTV. :b

    Takosan
     

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