Drivers for Infinite Baffle Sub

Discussion in 'Archived Threads 2001-2004' started by Bob Christensen, Feb 14, 2002.

  1. Bob Christensen

    Bob Christensen Stunt Coordinator

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    Thinking of installing an infinite baffle sub in my living room (home theater room), which is 11x25x9 (I know, not ideal). Would be used almost entirely for HT (I have 3 other subs available for music duty, including an SVS). I am looking at perhaps dual tempests or maybe other drivers in the same price/performance range in a transition box (semi-isobaric chamber) mounted in the basement, opening into the floor of the living room. I can drive the sub with a variety of amps that I have available, including a Crown CE1000 or a QSC RMX2450. Heck, I might even be inclined to add another amp to my rack if I feel the need. EQ would be via a BFD.
    Ideally I would like the Q to be in the .5 - .7 range. Am I correct in assuming that the system Qtc would be exactly equal to the Qts of the driver?
    Drivers that may be up for the task? I am considering the Tempest, based on the common usage in such applications (based on the Cult of the Infinitely Baffled forum: http://f20.parsimony.net/forum36475/index.htm But I am also considering an array of less expensive drivers such as the Madisound 15254 DVC or the 15258 DVC. I could effectively double the number of drivers to 4 for the same price. Thoughts? Other driver options? Experiences with infinite baffle systems?
     
  2. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    I like the idea of DVC subs in an infinite baffle. Drive one voice coil on each sub and shorts/resistors on the other to play with Q to your hearts content. I have no actual experience with IB's, but this seems like the way to do it.
     
  3. Dustin B

    Dustin B Producer

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    How about this driver:
    http://www.stryke.com/SAE1503.html
    Currently on preorder for $99 each. Very close in specs to the Tempest, just a few less mm of excursion capability, a slightly lower Fs and a higher QTS.
     
  4. kevin_u

    kevin_u Agent

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    Bob,
    I finished a wall mount 4 Tempest IB a couple weeks ago. It is the best bass I've heard. Read my post from the Infinetly Baffle Forum. The pitch definition is excellent. The IB is such an efficient system your big amps won't get out of 1st gear.
    The Stryke 1503 is probably not going to be available for quite some time.
    Where in Dakota territory are you? North or South?
    Kevin
     
  5. ThomasW

    ThomasW Cinematographer

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  6. Rich Kraus

    Rich Kraus Stunt Coordinator

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    id buy the tempests if i were building an IB.
    (oh ya, i DID buy the tempests for my IB....) [​IMG]
     
  7. Travis G

    Travis G Stunt Coordinator

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    Madisound 15254 DVC specs:

    Xmax 5.5mm

    fs 24Hz

    Qms 5.93

    Qes 0.68

    Qts 0.61

    Vas 406.7l

    Polypropelene Cone

    Madisound 15258 DVC specs:

    Xmax 5.5mm

    fs 19.4Hz

    Qms 4.95

    Qes 0.56

    Qts 0.50

    Vas 540 l

    Polypropelene Cone

    Both speakers cost $75.50

    Thomas I read a post where you seemed to imply that Poly was an inferior cone material. Could you elaborate on that?
     
  8. ThomasW

    ThomasW Cinematographer

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    Drivers like those from Adire, the BluePrint 03 series, PE DVC, etc., use a pulp cone, with a layer of carbon fiber laminated on with epoxy. That makes for a cone that's inherently very stiff. This is a desirable trait.

    The Xmax on the Madisound is too low. And as Jack pointed out it would take approx 3 of them to equal the output of a single Tempest. So yes they are 'cheaper' to buy, but you gain nothing.
     
  9. Bob Christensen

    Bob Christensen Stunt Coordinator

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    So the concensus is that the Tempest is probably the best driver as far as bang-for-buck in am IB sub? I realize that in a "money is no object" system, a few HE15's would brobably sound really nice, but back to the real world....

    Any drivers I have overlooked that may have some application in the IB?

    What about the relationship of Vas to Xmax? I see little mention of Vas figures wrt IB suitability, rather the Fs, Qts, and Xmax seem to be the driving factors, would one NOT wnat a large Vas as well?

    BTW, I am from the "Northern Dakota", and a "semi-isobaric chamber" is a fancy term for a transition box in which the drivers are mounted in a plenum opening into the listening room.
     
  10. Jack Gilvey

    Jack Gilvey Producer

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    These DPL12 12" drivers from Adire are in limited quantity, excess from an OEM client order. Intended for dipole apps, they seems ideal for IB use, and a 16.3Hz Fs to boot. From the site:
    "This is a custom-built 12" subwoofer designed for dipole use. It was designed for a larger OEM client, and we have some excess stock left. We're clearing out 22 extra parts at a reduced price. The driver uses a stout 12 spoke cast basket, 0.375" thick top plate, 1.5" long, 2.5" diameter voice coil, 84 ounces of magnets, paper/Kevlar cone (like Shiva and Tempest), large foam surround, rubber boot on the magnet, push-terminals, and dual 8 Ohm voice coils. The basic T/S parameters are: Fs: 16.3 Hz Qms: 11.1 Qes: 0.41 (voice coils in parallel/series; 0.82 with one voice coil driven, other open) Qts: 0.40 (voice coils in parallel/series; 0.8 with one voice coil driven, other open) Vas: 150L Re: 6.72 Ohms per voice coil Le: 4.76 mH per voice coil BL: 13.88 Tm Mms: 230 grams Sd: 506 cm^2 Xmax: 16.2mm one way (FEA result, linear) They are big, long throw, and ULTRA quiet. The basket is VERY open, and there is considerable venting below the spider (large grilled opening in the frame). Additionally, the 2.5" diameter pole piece is drilled through with a 1.375" diameter hole. At full excursion at 10 Hz, you hear NO air noise - dead silence. Four wired as a single 4 Ohm load work great as a dipole woofer; could also be a great option for Linkwitz' PHOENIX subwoofer. "
    EDIT: These are all sold out.
     
  11. Marv

    Marv Stunt Coordinator

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    Bob, I’m in the process of putting my IB together. I choose the Audiobahn 1805x (slightly more VD and $50 less than 2 tempests ). It is a DVC (4ohm each), with both coils powered you have Qts-0.385 , one coil powered Qts-0.714.

    It's 4" voice coil handles more power than I can throw at it, heck the vent on the pole piece is 2.5" which just looks weird. My HT is above my garage the driver will be visible in my HT with the garage acting as the rear enclosure. I'm hoping to get the floor moving as it pressurizes the garage. This will be my first IB so I guess I'll find out soon enough if I like IB or not. I have all the "measured" T/S parameters if any of you want them.

    -Just another driver to consider-

    Good Luck,

    -Marv
     

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