is there a method to find out how much subwoofer I need/want

Discussion in 'Archived Threads 2001-2004' started by Brad Dixon, Sep 30, 2002.

  1. Brad Dixon

    Brad Dixon Stunt Coordinator

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    My plan is to use my radio shack meter to take measurements with during movie watching. What I'm hoping is to find is the approximate volume we normally listen to movies at. We currently have a Paradigm PS1000. It doesn't go very low(some measurements I took using avia gave very little sub 40hz readings during the sweep) but what it does play is loud enough for my tastes.

    With the new subs that seem to be coming out I don't think bottoming will be a problem BUT since this will be my first diy sub I'm wondering if I'd be better off going with a shiva/dvc12 and 250w. My thinking was since I'm happy with the spl of the PS1000 that as long as the sub I build doesn't bottom at the low frequencies and can reach the same spl above 40hz I may actually be perfectly happy with a shiva/dvc12.

    The spl peaks I've measured while watching a couple clips were around 110db. Room is about 15x13x8 with an opening into a dining area.
    How do you folks go about knowing how loud you'd need a sub to play? Something along the same lines or just from previous experience?

    Regarding the AV12/15 from Stryke. Does/will the alum cone affect the sound? I'd hope not but I've never seen one before so I wanted to ask. Also will they dent easily? I've got a little boy and dogs so needless to say, there is some rough play in the house.

    Slow day at work so I thought I'd ask,
    Thanks
    Brad
     
  2. Rich Kraus

    Rich Kraus Stunt Coordinator

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    is there a method to find out how much subwoofer I need/want?
    yup, check your bank ballence. [​IMG]
    realistically estimate how loud/low you want it (guess) and play with sims/designs and see if its possible given your proposed budget.
    think carefully about what is realistically possible: its gonna take a whole buch of money to get 130dB@20Hz in a 20X30 room. (structural room reinforcements, many large drivers, big amps, hearing aids....)
     
  3. VinhT

    VinhT Second Unit

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    I agree with Rich. Funding should be the limiting factor, so get the best that you can afford. Once you experience deep clean bass, you'll want more. [​IMG]
     
  4. Brian Bunge

    Brian Bunge Producer

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    Brad,

    Definitely heed what Rich has to say. You'll have to run simulations using the specific driver and input power you're considering to see if it's capable of something near the SPL readings you're getting.

    Vinh,

    Did you get my email?

    Brian
     
  5. ThomasW

    ThomasW Cinematographer

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    Yes Alu cones are fragile and easily dent. The sonics are quite good.

    The kevlar reinforced cones like those in the Tempest/Shiva/DVC12-15/BluePrint-03/etc are much more tolerant of physical abuse
     
  6. Greg Monfort

    Greg Monfort Supporting Actor

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    It's a function of distance. SPL falls between ~3-6dB/doubling of distance in a typical room, so if for example you sit 12ft from the sub and the 110dB measurement is at the listening position, then depending on your room gain the sub needs to output a 1m SPL between these two numbers over whatever BW you choose:

    110dB + (10*log 12ft/3.2808ft (1m)) = 115.63dB/m for 3dB

    110dB + (20*log 12ft/3.2808ft (1m)) = 121.26dB/m for 6dB

    Since plotting room gain is usually more than most folks want to do, then if you build for 6dB loss (or as close as you are willing to spend), then usually you have enough capability on tap to keep distortion low.

    WRT alum diaphragms, if they're well damped by design then they shouldn't negatively affect the sound.

    GM
     

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