My little project

Discussion in 'Archived Threads 2001-2004' started by Demas, Feb 19, 2003.

  1. Demas

    Demas Agent

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    Hi guys, i been subjected to absolute BS from dealers with regards to subwoofers and what is *best*.Funny, this THX dealer told me that the 5000thx [email protected] is the best subwoofer money can buy.MMMMAAAAAAAAA!!! I'm aware of SVS and is a viable option as i haven't been conditioned to subsonic bass yet, but hopefully........


    I'm thinking of building an IB from Stryke av15 drivers, as i've heard they are the best bang for the buck. Two manafold arrays each with 4 av15's.Its just so damn cost effective to build an IB, and I think 250 watts per driver is optimum, what do you think? What kind of displacement am i looking at? 18 litres VD[​IMG].The only problem......okay it could be a HUGE problem, is a tin roof(attic).And does parts express ship internationally, as i'm from South Africa?Is there a way to counter the *tin roof* problem, or am i done for? Please, some needed advice.
     
  2. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    The Stryke av15 is a very good driver. If I was planning to use it for IB I'd definitely want the DVC option so I would have the option of using resistively damped operation to get a desired rolloff.

    Parts Express does not carry the Stryke line. So you should be concerned about whether Stryke ships internationally.

    That is, unless you were considering using the Dayton IB15 driver from Parts Express. This driver already has a desirable Qts value for IB use and actually beats the av15 in displacement-per-dollar unless you're still getting the pre-order pricing on the av15.

    8 AV15's could displace 30.4 liters.
    8 IB15's could displace 18.7 liters.

    Why two manifolds? Its usually pretty easy to fit more drivers into a single construction. And you don't want to create any phase/room mode problems.

    Saturday I'm going to visit a guy who's got 4 IB15's in his attic. I'm thinking that's enough headroom for even the largest rooms and after that return on investment drops off quickly. But I'll have a better idea once I've heard them.
     
  3. Dave Poehlman

    Dave Poehlman Producer

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  4. ThomasW

    ThomasW Cinematographer

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    I'm pretty sure John J (Stryke) can do international shipping. He uses BAX Global

    8 AV-15's are really gross overkill and a waste of $$$$ unless your house is the size of a soccer field.

    Re: the tin roof, post some details about the actual construction ie drywall ceiling? insulation? etc, etc.
     
  5. Stephen Dodds

    Stephen Dodds Second Unit

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    Mein Gott! Thomas saying something is gross overkill? Phrases about pots and kettles come to mind.

    [​IMG]

    Steve
     
  6. JimRHIT

    JimRHIT Stunt Coordinator

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    Lol ... Thomas speaks of overkill...no way...it is just a "comfort" to know that you could destroy your own house if need be. 12 Shivas Dancing (cough cough) [​IMG]
    Have fun with whatever you do [​IMG]

    Jim
     
  7. Demas

    Demas Agent

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  8. ThomasW

    ThomasW Cinematographer

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    Demas
     
  9. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    " I think it might just look better seeing two behomoth's instead of one, but if there are serious issues regarding room acoustics, cancellation... please let me know of the repercussions?"

    Usually with an IB you only see the "behemoth" when you're in the attic/basement. Anytime you seperate your bass sources you can have issues with cancellation. With the signal originating from two seperate source points you can never match the phase at all frequencies or at all listening positions. I've got two ported sonosubs on the same wall, about 9ft apart since I don't have the room to co-locate them. The response seems pretty good but you never know until you try it. And with an IB you can't just move it 2 feet to the left to play with response. If you had two identical sealed subs then you could place them at the points where you're planning to locate the manifolds and see what kind of response you get. No, its probably not an easy thing to do since the manifolds will probably be in the ceiling.

    Vented subs have different phase response than sealed. When I replace one of my ported subs with a sealed in the same location I get crazy cancellation effects and might as well turn off the other ported sub. So I wouldn't even bother experimenting unless you've got sealed subs to play with.

    Here's what I'd recommend. Build a manifold that's large enough for eight 15 inch drivers - two on each side, one woofer above the other. Order 4 of the parts express IB15 woofers. Install those and apply 100 - 150 watts per driver. If that's not enough order 4 more. Eight of the IB15's can displace as much air as 12 Shiva's ... super-overkill as you put it.
     
  10. Demas

    Demas Agent

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  11. ThomasW

    ThomasW Cinematographer

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    Look HERE for examples of manifold array installations.

    It's not the tin (steel) sheathing material itself. Is it (the tin) installed over a wood roof deck? Is there an insulated attic space?. Is there a drywall or other similar barrier between the listening room and the attic?
     
  12. Demas

    Demas Agent

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    Thomas, to answer the question fully, i do not have an attic per se.There is a small space where i can barely stand and move around, but i do not think this is a proper attic.Attics store things, but this just doesn't seem.......Basically i'm moving inside my roof.[​IMG]

    In America, most houses probably have attics, but not me as i'm not from........There is tin covering the wood all round, so i would expect major vibrations and rattles.Can it still work or are my plans dashed.Oh well, it would have been nice, but i could always dream.Maybe i should give SVS a call or should i say email.[​IMG]
     
  13. ThomasW

    ThomasW Cinematographer

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    Demas

    The space needs to be no less than 32cu ft for 4-AV 15"s to operate. Bigger than that is of course better.

    The space needs to be sealed, no common openings with the listening room. Common openings to other rooms isn't a problem.

    The space should have some insulation for control of the rear wave, standard fiberglass (R-13 or greater) is fine.

    Don't know about the exposed 'tin' roofing. If it has loose spots those will vibrate and buzz. If caulk/adhesive is applied to the 'joists' that the metal is attached to that should eliminate most of the problems. The tin will of course 'flex' when the space is presurized. I don't know if that will be a problem.

    To 'test' the existing space for noise/vibration borrow a sub that will fit through the opening and place it in the space. Close off the opening and play some loud bass. If everything starts buzzing it's a no go......

    Does the room sit on a concrete pad or is there a crawl space below the floor? If there is a crawl space that would be another mounting option.
     
  14. Demas

    Demas Agent

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    Thomas, there is some crawl space however small.I think i have enough space to mount the drivers, and i'll borrow a friends sub in the meantime.

    When i looked at the ceiling, i saw water marks and a dent, which suggests that the vibrations could physically mess up the ceiling.Most people talk figurativly with regards to house destroying bass, but in my case it could be literal[​IMG]

    I think i will take photographs to show further analysis of my humble abode(in a week), and i thank you for taking the time to help me.The neighbors are right next door, and no amount of insulation can prevent cops at my door.[​IMG]

    You are lucky with regards to your shivas, as they have enough output to literally crack the foundations, i'm sure of it!There is no point in ever upgrading again, as you have absolute usable output and best sound quality.What is there that is better.Maybe a cup of old tea but what?By the way, do you remember the overall cost to your 12 shivas and amps?Must be so comforting that you have basically infinite output based on actual usable volume, and will never bottom out, even if you try:b


    Thankyou again, and i hope to talk to you soon.Not entirely sure what time it is over *there*, but it's almost 12 o'clock in S.A.Good night my friend and sweet sounds.zzzzzzzzzzzzz[​IMG]


    Demas
     
  15. ThomasW

    ThomasW Cinematographer

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    Demas

    Water marks could mean problems for more than just the drivers.....

    I made a one time purchase of 20 Shivas, so I received a quantity discount. I'm using custom made pro sound amps that are 20yrs old.

    You might want to go with a ported or PR based design using a couple of AV-15's. Not in the same league as a IB, but quite a bit more practical and certainly worthy of consideration.
     

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