Need help building enclosure

Discussion in 'Home Theater Projects' started by Richard=f, Jun 21, 2006.

  1. Richard=f

    Richard=f Auditioning

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    Hello,

    I recently purchased a Dayton Audio Titanic MK3 15"
    I would like to build my own enclosure for it, there is an enclosure design listed on the site for the i bought subwoofer though it is not the manufacture website. I am not very expirenced in building enclosures but I thought the enclosure looked pretty good. Though I have one issue, if you looked at the specs, you will see that the sub box should have a 6" wide port that is suppost to be about 33' long, though the box will only allow about a 22" port. It is noted on the site that port will have to be "angled", I can only assume this means that there will have to be an elbow the redirect the port in ordeto make it 33" long. I also am having trouble finding a 6" diameter PVC pipe and i would also want flaired ports buit I cannot find a good one. So I was woundering if running two 3" ports would effect my tuned port frequency drastically. If the effects will be very different from the original design, how do I correct that for use with two ports, also the box size given by the recommened enclosure is slightly smaller than the recommened size of the subwoofers specifications. I heard that stuffing an enclosure with foam would give the effect of a larger enclosure, would anyone recommend this?

    Lets say that I used two 3" instead of one 6" port, how much shorter would the port have to be in lenght? I am aware that people are going to want to know my listening habbits, I will use the sub for about 70% music and 30% movies. I do enjoy listening to rap at high volume levels and i would like the sub to hit at least 25hz, prefrebly around 20hz.I will be using the sub with a set of Paradigm Monitor 7s and was thinking of using a Denon AVR-1505, would anyone recommend another reciver for the Paradigms?

    Subwoofer Page http://www.partsexpress.com/pe/pshow...number=295-420

    Enclosure page
    http://www.partsexpress.com/pdf/295-420vented.pdf

    Thank everyone very much for your assistance. Sorry for the very poor spelling.
     
  2. Brent_S

    Brent_S Second Unit

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    How much power in your sub amp? With 500 watts, the ideal would either be one 6" port, two 4" ports, or three 3" ports. All exceed the length of the PE suggested enclosure and will require elbows. Two 3" ports, especially dual flared, may be acceptable, especially if your real world listening levels actually stay below 250-300 watts. With 300 watts, WinISD still predicts 108db @ 20hz, 112db @ 30hz which is plenty loud.

    The air velocity is so low with a 6" port, a flare is really unncecessary. Dual 4" ports breath almost as well and the pvc and elbows are probably easier to find...looks like they should consume a little less of your gross volume as well..

    Another option, if you have the flexibility. Change the shape of the cabinet to accomodate the 6"x33" port. The primary goal is to end up with 5 ft^3 of emtpy space after you account for the bracing, port volumes, and driver....looks like PE figures 5.7 gross for their design.
     
  3. Patrick Sun

    Patrick Sun Moderator
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    Or, just have the excess length of the 6" port stick out of the enclosure like a chimney (or create taller faux sides to hide the port from looking like a chimney).

    I had to go to a plumbing supply place to get 6" wide PVC (had to buy 12 foot long section, only $18), and I still have the leftover PVC in the garage. Doubt you'd need flares on 6" wide ports. Don't think you could fit 30"+ of 6" wide porting, even with bends, inside a 2'x2'x2' cube, without soaking up the rest of the needed 5 ft^3 of volume for the driver.
     
  4. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    FYI, Parts Express may not be the manufacturer, but Dayton is their "house brand" and I believe they designed all or at least many of the Dayton speakers.
     
  5. Richard=f

    Richard=f Auditioning

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    First of all I would like to thank everyone for there assistance, it was a big help.
    Also someone was woundering power of the amplifier I was using for the sub, it is 500 watts RMS into 4 OHMs. I already have the enclosure consturcted and I think two 4" flaired ports would be ideal. Any idea on a good length for the two ports?

    Thanks.
     
  6. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    First we need to know how big the box is. I'll assume that you've built the 5 cu ft box recommended on the PE site. To meet their 20Hz recommend tuning with a pair of 4" non-flared ports, you'd want them 30.75" long. I believe you need to add 1 more inch for flared ports (like the aeroports PE sells) so that's 31.75".

    From my WinISD sim, it looks like you might be okay without flares. Especially if you're using a plate amp with a rumble filter at 18-20Hz.

    This should be a nice, loud sub.
     
  7. Richard=f

    Richard=f Auditioning

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    Yes I have already made the enclosure from PE. One more thing, I was told that adding foam material into the box would give the effect of a slightly larger enclosure, would you recommend this to help make up for the loss of enclosure volume from the Plate amp, port, and driver?

    thank you very much for the information
     
  8. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Richard, I'd do the two 3" ports with elbows (Home Depot). Stuffing a SEALED enclosure lowers the system resonance and adds a thermal mass that absorbs the heat generated by the internal air compression. The apparent volume of a sealed box can be increased 15+%. I don't know the numbers, but stuffing material in a VENTED box has much less of volume-increasing effect. (Somebody jump in here)
    If you're going further with this speaker DIY thing, get a book or two. Several years ago I bought "Advanced Speaker Systems" by Ray Alden, at Radio Shack. I don't' know if it's out of print, but it covers the basics pretty well. You could also order Vance Dickason's "The Loudspeaker Design Cookbook" from P.E.
     
  9. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Stuffing a vented box will result in a pretty decent volume increase, but will totally screw up loss parameters like Qa and/or Qp. I've done a little work on stuffing vented boxes so far, and plan on making a test rig to do more, but for DIY'ers the best thing is to NOT stuff a vented box. Figure out the lowest frequency of the standing wave in the cabinet, go to

    http://bobgolds.com/AbsorptionCoefficients.htm

    and buy the thinnest Owens Corning 703 material that has the best combination of 1) absorption at and above your first standing wave resonance and 2) the lowest absorption at 125Hz and below. Line the cabinet walls with that material. You local HVAC dealer should have it, our you can purchase single pieces online for $15 (2x4) or six packs for like $75. I *think* that should assure good damping of the standing wave while not screwing up the low frequency loss paramaters. Again, I need to make a test rig to test all this stuff.
     
  10. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Mark is correct, just line the walls of your vented box. He's been researching Qp lately and is going to do some serious testing - hopefully he'll post occasionaly on his progress/findings.
    Mark, didn't you say you got Liberty Audio Suite?
     
  11. Mark Hayenga

    Mark Hayenga Supporting Actor

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    I've had it for a while, but I haven't had the hardware setup in a long time. Need to find a machine that will run DOS/Win3.1 with an ISA slot (I think I have a Dell P2 that will work). Also need to buy the card and mic from Jonathan that I'll be using. I sold off all the hardware I had when I shelved the hobby for premed studies, but kept the software (lost all its value since praxis came out anyway).
     
  12. Richard=f

    Richard=f Auditioning

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    Thank you everyone for the information.
     

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