175 ltr ported Tempest

Discussion in 'Home Theater Projects' started by williamN, Jul 13, 2004.

  1. williamN

    williamN Agent

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    I am thinking of trying the above Dan Wiggins special and was wondering if there was a plan available or if anyone had tried building one and could comment at all?

    "For good "tight" sound, a Q of 0.577 is often used. It's maximally flat in terms of phase rotation (group delay). But, for HT, you wnat pretty low Fc (down around 20 Hz or so). So, how's this:
    175L per Tempest
    64 ounces of stuffing
    Tune to 17.5 Hz (4"ID by 13"L vent; note that our 4" flared vent kit would work well here - yes, that's a shameless plug...)
    You'll have a response that:
    Has an F3 anechoic of 22 Hz with the typical LFE crossover.
    Is power limited to 500W above 15 Hz (for linear operation).
    Mimics a 3rd order Q=0.577 Fc=20 Hz filter to +/- 0.25 dB down to 13 Hz.
    Should provide a typical in-room F3 around 17 Hz.
    Is capable of more than 110 dB SPL from 16 Hz and up, anechoic.
    Is capable of more than 118 dB SPL from 17 Hz and up, in a typical room."

    I estimated Dan used 15% internal volume increase caused by the 64 oz of polyfill stuffing - that gives an Lv of 13.05" So, I used an overall length of 14" on the dual-flare port tube. No "chuffing", no port noise and it continues to drop jaws
     
  2. GrahamT

    GrahamT Supporting Actor

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  3. Cam McFarland

    Cam McFarland Supporting Actor

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    I get 88 dB (uncorrected, about 108 dB corrected) measured 14ft away from my Adire
    Alignment Tempest at 10Hz...why not just follow that plan?


    EDIT: What is the definition of "anechoic" in this usage?
     
  4. williamN

    williamN Agent

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    Cam, I don'thave a clue about the "anechoic" bit, the first sentence was mine and the rest is what I copied from my internet search; I think it was written buy a chap called Hank?

    I thought that as it purports to be a DW plan and the spec sounded pretty good and used a flared 4" port and Tempest (both of which I have) it might be worth a try. Still, if the plan fell by the wayside and the std adire plans remained I guess I should just conclude that std may be the way to go.
     
  5. Brian Bunge

    Brian Bunge Producer

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    This is a design that Dan posted on the forum a couple of years ago. Hank Frankenberg has built it, as have I but with the DVC 15" from PE. This design is an excellent choice if you want a "reasonably-sized" ported Tempest.

    As far as anechoic, this refers to the response in an anechoic chamber, which would not have any room gain. This would basically be the same as measuring the sub's response outdoors, far away from any type of reflective surfaces. In a nutshell, you'll have more output down low in room than you will "anechoic". How much depends a several factors, including room's dimensions, it's construction, where the sub is placed in the room, etc.
     
  6. Cam McFarland

    Cam McFarland Supporting Actor

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    ....which of course means nothing to us & our HT
    evironment.....
     
  7. williamN

    williamN Agent

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    Thanks Brian, do you any pictures of that sub at all?
     
  8. Brian Bunge

    Brian Bunge Producer

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    Well, I wouldn't say that it means nothing. It does give you a general idea of what you can expect from the sub in that it should have at least that much output in room. Of course there will be room modes to deal with as well, but that's not really what this current discussion is about.

    William,

    I'll have to see if I can find some pics. I may have some somewhere on my hard drive.
     
  9. Patrick Sun

    Patrick Sun Moderator
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    I built the sonosub version of a 6 ft^3 ported Tempest sub (called the Sunosub III).
     
  10. williamN

    williamN Agent

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    pretty comprehensive build diary you have there Patrick! I'm sorely tempted to try a sonotube design to save buying a table saw.
     

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