First Time DIY Sub Project

Discussion in 'Archived Threads 2001-2004' started by SimonInd, Sep 11, 2001.

  1. SimonInd

    SimonInd Auditioning

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    Hi,
    I'm about to embark on a DIY Sub, my first, and just wanted some re-assurance that I'm on the right path.... Initially I was considering more esoteric ideas, such as ELF / Linkwitz transforms etc. but have now decided that I should learn to walk before trying to run. I'm pretty much sold on the Adire audio low Q ( 0.577 ) Sealed Tempest design. It's big, but I can live with that, I already have a butt-ugly rear projection TV and a meter high flexy-rack with all my equipment on it.
    My room is approx ( 4.5 x 3 x 2.2m LxWxH ) and the sub will be powered by it's own 300W MOSFET amp. The rest of the system is a Denon AVC-A1D ( 5700 in the U.S ), Epos ES22 floorstanders at the front and B&W DM601s as rears. I'd like the sub to perform well for music as well as movies and I'm hoping this'll do both. The Epos speakers go down to about 40Hz and are pretty 'tight'. I don't want the sub to muddy their sound - hence selecting the sealed design.
    Has anybody had any experience building this design? Also is it a good way to start? If it works out then I wouldn't be surprised if I had a crack a different design in the future but I want to start of with something acheivable.
    I have played with LSPCad and have realised how important positioning/room size etc. is on the frequency response, although I'm hoping that a sealed design will be less tempramental than a ported one for a beginner.
    Any advice would be appreciated
    Thanks
    Simon
     
  2. Jack Gilvey

    Jack Gilvey Producer

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    That Tempest design will be outstanding, sealed is a good way to go for a first project, being very forgiving. I've not used that alignment, but folks who do low-Q Tempests get in-room response right down to 20Hz.
    Also, you could add the Linkwitz transform at any time, if you wanted to experiment with a different Qtc and f3, that's the beauty of the circuit. It doesn't have to be designed from the ground up as a LT system, as an ELF does.
     
  3. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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  4. Kyle Richardson

    Kyle Richardson Screenwriter

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    I know that Dan Wiggins of Adire runs a sealed Tempest design so it must be good. [​IMG]
    ------------------AOL Instant Messenger Name: kyler70
     
  5. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Hi Simon,
    I can't post much since I'm at work now (not getting much done today anyway it seems...) but I am building sealed Tempests and have a site up here:
    http://www.hayenga.com/mark/tempests/tempests.htm
    Will post more later tonight.
    Mark
     
  6. tim verry

    tim verry Auditioning

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    I just got done with my third shiva sonotube enclosure. You can't go wrong with sealed.
    The first was a 12" tube 48" high, about 92 liters.
    The second was a 12" tube 25" on its side - front firing - heavily stuffed, at about 50 liters.
    The third was an 18" tube 39" high, about 142 liters with a port on top tuned to 21 Hz.
    Nearfield measurements of all three look exactly like the textbook curves one would expect. But I am absolutely baffled as to which one SOUNDS best. THe problem is that the in-room frequency response is just all over the place at various listening positions. The room itself is BY FAR a bigger factor than these 3 completely different enclosures.
    To test how they sound I listen to a variety of melodic music with pitchful bass. I MUST be able to hear the lower notes of a bass guitar with nothing but the sub on, for instance.
    I'm pretty sure the 92 liter one is in the lead, but the main thing though is that they all are better than my velodyne ct-120, better than a friend's Anthony Gallo (it's pitchful/percussive but a bit underpowered), and they definitely compete with another friend's Infinity HPS 1000.
    I've used the shiva, the driver from the velo, the amp from the velo, and the pe 300-793 amp in various combinations. The tubes kickass on the velo enclosure, and the shiva driver is somewhat better than the velo driver (unknown specs).
    Definitely check out this freeware spreadsheet, I found it very easy to use: http://www.danbbs.dk/~ko/ubmodel.htm
     
  7. SimonInd

    SimonInd Auditioning

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    Thanks for the encouragement guys, I'm sold on the sealed Tempest, and am about ready to start ordering parts. One question, if I order a 'plate-amp' to mount in/on the enclosure should I change the dimensions of the box to make up for the air displaced by the amp or would a bit more foam/fibre-glass stuffing make up for this?
    I expect the displacement within the enclosure to be about 7.7 litres which as a percentage of 230 litres is tiny. So should I worry about it?
    Cheers
    Simon
     
  8. Geoff L

    Geoff L Screenwriter

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    You could account for this loss, but it's minior to say the least and from an audio point, you most likely would not ear the difference, though it might be able to be measured.
    In short-NO dont add for it. Sealed ~ and at that size, very forgiveing.....
     
  9. tim verry

    tim verry Auditioning

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    I made a simple wooden frame to mount my amp in, got some 45 degree rca connectors and it fits on my gear rack. A heck of a lot easier than trying to mount it into the tube and then try to seal it.
    Also there is a debatable idea that the vibrations from the sub will actually make the amp sound worse. People spend a lot of money "isolating" their amps, recievers, cd players etc. With that line of thinking, the worst place for an electronic component would inside of a sub enclosure.
     
  10. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Simon, I made an enclosure for my AVA250 and attached it to the side of my sonosub. If you can live with the protrusion, you'll avoid worrying about enclosure volume adjustments and sealing a big opening. The picture on my web page doesn't do it justice - the amp enclosure really doesn't protrude but about 4 inches:
    http://www.geocities.com/hankbond1/My_page.html
    [Edited last by Hank Frankenberg on September 17, 2001 at 01:11 PM]
     
  11. SimonInd

    SimonInd Auditioning

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    I'm building a box rather than a tube based sub so it shouldn't be too difficult to mount the amp on one of the sides. As far as the vibrations go, I'm not too worried as 'plate-amps' are designed to be mounted in speaker cabinets, and aesthetically it'll be much easier to get by the misses if the project doesn't involve 'another black box'...
    I think this'll be the amp to use ( http://www.bkelec.com/Diy/bsb500.htm ) as importing an AVA250 will probably cost nearly as much after shipping and customs charges...
    Simon
     
  12. Magnus Lindqvist

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    Simon!
    I sent Ls-wagner in Germany an email some time ago regarding the Tempest and AVA250, the total cost incl. shipment to Sweden was 800DM(400£)
    Maybe this would be cheaper than to order them from Adire.
    ------------------
    /Magnus Lindqvist.
    The "Finish Fetish" guy!
     

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