Cost-is-no-object DIY sub

Discussion in 'Archived Threads 2001-2004' started by Dave Milne, Apr 13, 2002.

  1. Dave Milne

    Dave Milne Supporting Actor

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    I've tried to surf through the plethora of DIY sub info in this forum but bogged down under the mountain of posts.

    I'd like to build a front (main) sub to complement my LFE sub (which is built into the platform for the second row of seats in the theater... it makes a nice buttkicker as well as LFE sub). The LFE sub uses a JBL 2245 18" driver in 10 cu.ft. vented, equalized. It's flat to 22 Hz and puts out 121dB at 300 watts.

    Bottom line: What's the best DIY sub assuming that driver cost is not an object -well, OK, under $1000.

    Cabinet complexity is also not an object (PR, high-order and compound designs OK) but total volume is less than 8 cu.ft.

    Electrically assisted is OK, i.e. sixth-order vented, equalized.

    Power will be 550 or 750 w (I have a couple of bridgeable amps available)

    By the way, my Lexicon MC-12 pre-pro has fully adjustable crossovers and separate delays for the LFE and main subs so that's not a problem.
     
  2. Jeff Rosz

    Jeff Rosz Second Unit

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    hello dave,
    subjective but enviable, but let me just throw this out there...
    how bout ~3/4 of this?... 12 Shivas Dancing
     
  3. Mark Seaton

    Mark Seaton Supporting Actor

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    Hi Dave,
    While I understand the cost-no-object factor you mention, with current drivers on the market, and the box size you are considering, you will find that your main task will be making the best use of the 550-750W you have. While I'm still waiting to see a driver which can achieve the same bandwidth and efficiency of our ContraBass, there are some great options if you open up to the purchase of a new amplifier like a Crown K2. The ContraBass kit will likely be going away soon, but they are available at the moment.
    If I was designing a cost-no-object, 8 cu.ft., DIY subwoofer, I would look in the direction of the new Adire XBL^2 15" home theater driver discussed in This Thread. That page contains the projected T/S parameters of the driver. What I see as the killer 8 cu.ft. solution would be 2 of these drivers with 4 18" Stryke dual spyder PRs massed up to their limits (I would actually go past some, but you do that at your own risk), with a box fully stuffed with Miraflex, you should be set. From there just add a BIG amp and ideally an EQ to maximize the low end performance. This should equal the output of your current sub to 14-16Hz in-room, and so long as you don't let 5Hz dyno-stomps through, you will never bottom it out. Having a pair of drivers will help greatly with any power compression at moderate levels while allowing the high power to take care of dynamics, just how you want it.
    One critical issue you didn't mention to us is the size of this room? Had you possibly considered using a pair of smaller subwoofers? What are you using as mains so we can compare what sort of headroom is justifiable? If absolute sound quality is your goal, I would suggest using multiple sealed drivers with lots of power and electronic correction.
     
  4. Greg Monfort

    Greg Monfort Supporting Actor

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    >The ContraBass kit will likely be going away soon, but they are available at the moment.

    ====

    Just the kit, or is the CB being superceded with a new design?

    GM
     
  5. Mark Seaton

    Mark Seaton Supporting Actor

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    Greg inquired:
     
  6. Vishwa Somayaji

    Vishwa Somayaji Stunt Coordinator

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    What about a sub based on that SV18 driver from subwoofers.com? That driver alone is $749 and its specs look great. For an 18" driver it has a great excursion.
     
  7. Robert_Gaither

    Robert_Gaither Screenwriter

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    I don't know about the SV18 but the Northcreek Leviathon driver seems to be the best 18" out there but at it's price I think one could use multiple drivers from either Blueprint, Stryke, or Adire for the cost of either one of the above.

    Of course if price is truly no limit then maybe getting a few custom built driver with the specs you abosulutely want are the way to go (contant TC sounds).
     
  8. Dave Milne

    Dave Milne Supporting Actor

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    Thanks guys, you've pointed me to some great stuff.
    Jeff, I'd LOVE to do an IB, but there's just not any room available to use as an "enclosure" --they don't do basements in Arizona.
    Mark, the XBL^2 driver looks interesting but geez... is there enough surface area on an 8 cu.ft. box for two 15" drivers and 4 18" PRs [​IMG] 85dB sensitivity is a paradigm shift for me; would need to step up to some serious amplifier power. BTW my speakers are all custom-built Dynaudio; L-R are Myrage (WMTMW config with 2x24W100, 2xD76 and 330D Esotar), center and sides are Twynn (MTM with 2x17W75 and D260 Esotec) rears are Xennon 3/75 (17W75, D54, D21). The theater is 14x22x9. And what is ContraBass? I surfed the servodrive website and there's no mention of subwoofers or drivers...
    Robert, the Northcreek Leviathan looks nice. However, one forum thread I saw indicated that it was a re-badged Seismic 8196E. Would Seismic sell this driver directly?
    You guys have me jazzed to cut some MDF... thanks!
     
  9. Mark Seaton

    Mark Seaton Supporting Actor

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    Dave wrote:
     
  10. Dave Milne

    Dave Milne Supporting Actor

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    Mark, thanks for the info and links.

    Wow! I didn't realize the ContraBass was such a unique approach. I think I'll settle for conventional drivers in a conventional box. Call me old fashioned.

    So I understand the recommendation is 8 cu.ft. with two XBL^2s and 4 PR18s massed up to 3Kg each. I haven't tried to model this in BassBox Pro (the only program I have at the moment) but I infer this is an Fb of 16-18Hz (?)

    My PR experience is limited, but I assume that it would be acoustically equivalent to create two 4 cu.ft. boxes --each with a single XBL^2 and two 3Kg PR-18s. This would provide some extra placement options and ease the transportation (weight and size) problem.

    Any updates on the release date and pre-order price of the XBL^2? Meanwhile, I guess I'll start shopping for a big amp like the K2. I'm also finishing a preamp for my measurement mic so I can map out the best placement options...

    Dave
     
  11. Robert_Gaither

    Robert_Gaither Screenwriter

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    The emails I've exchanged with Northcreekmusic in the past stated that they literally just use the frame of the seismic and customize it for their use (Wilson does the same) with a different cone material, surround, and motor (since if I remember correctly the original Seismic was designed for pro use). Unfortunately to me, this driver would be hard pressed compared to a pair of the newer 15" (or 18" from Blueprint) woofers from the sources I stated earlier eq'ed and I'll take it from Mark about the PRs (this is one subject that I'm trying to learn about and am interested in is the PRs).

    What's also nice about buying any of these drivers is that you will definitely get direct support in building your new sub and they should steer you in the correct direction from most likely the individuals who spec'ed them out.
     

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