Why Go Sealed?

Discussion in 'Home Theater Projects' started by Travis_G, Aug 11, 2005.

  1. Travis_G

    Travis_G Agent

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    I am modeling a coffee table sub with Win ISD. I'm using an AE AV15 in a 12ft^3 box with dual 4 " vents tuned to 17 Hz. Above 31 Hz, GD actually looks about the same on the vented enclosure as on the sealed of same internal volume.

    Below 31 Hz the sealed box has great looking GD but doesn't have that much output very far below 31 Hz anyways. Besides what do you play below ~ 35 Hz that requires great GD? It's mostly pipe organs, T-Rex footsteps, and explosions.

    I bought some Brent Plugs from Home Depot to plug up the vents when I listen to music, but now I wonder, why even bother? If I were tuning a box to 30 Hz I might be more concerned with using the plugs.

    Any thoughts?

    Travis
     
  2. ThomasW

    ThomasW Cinematographer

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    Whatever turns you on.....

    The very best box subs I've ever heard are the 'E-cubes' from Epiphany Audio. Their GD numbers are 7ms according to 'Mr. Epiphany', Ken Bates.

    http://www.epiphanyaudio.com/ecube.html
     
  3. Leo Kerr

    Leo Kerr Screenwriter

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    I'm not a sub expert, and I've not spent a lot of time auditioning them. However, the few that I've heard - and for speaker systems in general, the ported systems I've heard tend to have a very strong bass-hump.

    Granted, many of these are not particularly well designed units, but it's kept me in 'sealed-land.' While they may be 'anemic,' they don't sound bad.

    The sub I inherited (kind of lousy,) is an IB. I'm planning on building a sono-sub soon (nicely alliterative,) and I'm kind of planning on sealed for there, too.

    Leo
     
  4. ThomasW

    ThomasW Cinematographer

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    Are you talking about a small sealed box or a 'true' IB subwoofer?
     
  5. Leo Kerr

    Leo Kerr Screenwriter

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    It's at least a "near-IB." It was from a 1960's home audio (mono) system. ~14" woofer, coaxially mounted tweater, in a cabinet that's roughly 36"H x 18"W x 16"D. At least fairly stuffed with fiberglass, and, in my use, the external amp is fed with the low-pass output of my DSP-A1.

    During things with active, vigorus bass, it tends to make ugly farting noises as the cone slams the X-max...

    Leo
     
  6. Chuck Bogie

    Chuck Bogie Second Unit

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    I've got both ported and sealed, using the same drivers.

    In my basement, I've got a pair of ported Quatro 15s, and they will scare you.

    Right now, in another room three hallway bends away, I've got Keb Mo playing acoustic blues, and the pair of 3 cube sealed Quatro 15s blends nicely with a pair of Maggie MMGs.

    I think that ported subs are a little harder to tune and control. But if you're looking to make stuff fall off the walls, they'll do it.
     
  7. Travis_G

    Travis_G Agent

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    Thanks guys. A well designed ported sub will not have a strong bass hump, and at 30 Hz and up, where it matters most this one will more or less behave like a large sealed enclosure anyways.

    I am wondering how often transients lie below 30 Hz, which would be degraded by excessive GD. Kick drum fundamentals are about at 35 Hz. The cannons in the 1812 overture will probably be degraded noticeably but aside from that I can't think of any program material with transients down that low.

    Of course I don't have alot of practical experience in this area. I have built several ported subwoofers and only one sealed subwoofer. I have never done an AB comparison a sealed and a ported subwoofer using the same driver (I guess this will be my chance). [​IMG]
     

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