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Enclosure size

Discussion in 'Home Cinema Building DIY' started by Howard0000, Jul 12, 2003.

  1. Howard0000

    Howard0000
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    Could someone please calculate the ideal subwoofer enclosure dimensions, non-ported, if I was to use the Audax speaker driver as below. All relevant information (I think) is there.

    Thanks in advance :) :)
     

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  2. Exeter Man

    Exeter Man
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    Howard0000,

    Download WinISD via link below.........

    http://www.linearteam.dk/

    Feed in the parameters, and have a fiddle - it's more straightforward than you might think.

    Running it through WinISD, looks like it could be more suited to a vented application. WinISD defaults to the smoothest (but not necessarily the 'best') plots, which would give you the following:

    45.3l sealed, Qtc=0.71, F3=66.5Hz
    79.8l vented, tuned to 37.8Hz, F3=41.6Hz

    You could probably improve things a bit by adjusting volumes and tuning frequency, or even better, by trying some alternative drivers. There are several links to suppliers in the recent 'Looking for parts' thread.

    Hope this helps.

    Regards
     
  3. Howard0000

    Howard0000
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    I tried running it through WinISD, and the dimensions it gave were 39x61x25 CM (wxhxd), which seemed to me a bit tall and thin? Is this right, and how would I make it a little more "Cubic" while keeping the same volume?
     
  4. micb3rd

    micb3rd
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    I have this driver and use it in a 25 liter enclosure (roughly 1 cubic foot)

    Although to use it properly and get good deep bass out of it you should order a plate amplifier from www.iplacoustics.co.uk

    The 120 rms plate amplifier from IPL has built in EQ which is perfect for this driver.

    Check out this page http://www.iplacoustics.co.uk/ipl_sw2_active_subwoofer.htm

    If you have any questions feel free to ask.
     
  5. Exeter Man

    Exeter Man
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    Howard0000,

    For subs, dimensions aren't that critical, provided volume remains the same.

    To calculate volume in Litres, I usually multiply internal length x width x height in Metres, x 1000. Remember to deduct bracing, amp, driver and (if applicable) vent from gross volume to give the net volume.

    Regards
     
  6. Howard0000

    Howard0000
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    Would building the enclosure to the same size as the sub on the site micb3rd posted (392x326x326mm) be right then? It looks to be the right sort of size!
     
  7. micb3rd

    micb3rd
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    That size is correct if you are using one of the amplfiers I surgested, The Equalisation is built into the cossover of the amplfier so as you ajust the crossover frequency the EQ is also ajusted acordingly.

    This is one way of how you can use a small box and still get deep bass.

    IF you use a standerd amplifier with no EQ the Audax unit in a small enclosure will mostly will not drop down for the deeper bass.
     
  8. Exeter Man

    Exeter Man
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    micb3rd,

    Presumably your enclosure is stuffed ?

    Regards
     
  9. Howard0000

    Howard0000
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    Sorry, I did not quite understand this. How does that give me litres?

    Can you recommend me a cubic box size that has an enclosure volume of 45.3 litres?
     
  10. Exeter Man

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    Howard0000,

    There are 1000l in 1m3.

    For example, for an enclosure with INTERNAL dimensions of 350x350x370mm:

    Volume = 0.35x0.35x0.37 = 0.045m3. Multiply this by 1000 to convert to litres. 0.045x1000 = 45.3l.

    However, you would need to deduct the volume of the amp, driver and bracing to give a net value, which is what the WinISD curves are based on. In my own DIY sub project, the volume of this lot was about 10l.

    'Effective' volume is also affected by stuffing - see link below for more details on this:

    http://www.integracaraudio.com/caraudio/resources/fiberfill/

    Regards
     
  11. RichardH

    RichardH
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    In WinISD, when you have the dimensions dialogue box up, alter two of the dimensions, then click on the label of the dimension that's left (it will go red as you mouse over it). The third dimension will then be calculated for you. Play until you get a set of dimensions you like.
    WinISD is designed for all speakers (not just subs), and non-sub woofers are usually designed to be the proportions WinISD defaults to.
     
  12. Howard0000

    Howard0000
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    Superb! :D

    Many thanks guys!
     
  13. Exeter Man

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    Richard,

    Good point :lesson:

    I usually make things more complicated than they need to be :D

    Regards
     
  14. micb3rd

    micb3rd
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    Actually it is not, it has got additional bracing but no polyfill.

    Howard0000 what amplifer are you going to use for the subwoofer?
     
  15. Howard0000

    Howard0000
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    Probably an old Tandberg integrated amp/receiver thing until I can afford to buy something a little more suited. It's a great amp with really deep bass anyway so it shouldn't be too bad.
     

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