how do you know if a subwoofer will be decent?

Discussion in 'Archived Threads 2001-2004' started by JasonS, Nov 29, 2002.

  1. JasonS

    JasonS Stunt Coordinator

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    I'm just curious as to how you interpret the specs of a subwoofer driver to determine whether it would be decent for home theater. I know about the Tempest, Shiva, and a couple of others that are supposed to be good, but what specifically makes them good?

    ~Jason
     
  2. Andrew Pratt

    Andrew Pratt Producer

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    the easiest way to find out is to input those parameters into a program like ISDpro or UniBox etc and see how well they perform in the box of your choice. The nice thing about this method is you'll quickly get a feeling for what the various parameters do as well as what happens to that driver in a larger or smaller box for example
     
  3. JasonS

    JasonS Stunt Coordinator

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    Thanks for the response. Okay, this may be a dumb question, but using those programs, what tells you whether it will sound decent? I've used WinISD a couple of times, but I am unable to understand what the graph is telling me.
     
  4. KurtJ

    KurtJ Stunt Coordinator

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    One graph to look at the one that shows SPL (Sound Pressure Level) and frequency. For instance, let's say you want a subwoofer to hit 16 Hz because you like organ music. Look at the SPL for 16 Hz. Is it at 75 dB, or 75dB or 105dB?

    Let's also assume you want to hit 100 dB in your home theater. Each 3 dB difference will require 2x the power to get you there.
     
  5. Peter_A_M

    Peter_A_M Stunt Coordinator

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    Jason,

    WinISD Pro's help section provides succinct explanations of each graph. I suggest you start there if you haven't already.
     
  6. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    I look first at Xmax, Fs, and Qts. If those are decent then I look at Vas and Impedence. Here's how I generally evaluate them:

    Xmax - more is better. Using this and the price you can get a general feel for bang-for-the-buck

    Fs - I prefer 18 to 25Hz. Any lower is overkill. Any higher won't really give you that great, subsonic, HT extension.

    Qts - Generally between 0.3 and 0.45 is fine. If its a little higher it might make a good infinite baffle sub. Anything over 0.6 is unacceptable.

    Vas - This gives me a general feel for how big a box it'll need. I compare to known drivers (Adire) and think about whether a specific alignment will have room for adequate porting or will require a passive radiator

    Impedence - This tells me whether single or dual woofers, single or dual voice coils will work best with my amp to extract the most power without presenting too difficult a load.
     

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