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Shiva DIY sub??

Discussion in 'Home Theater Projects' started by darren_s, Dec 22, 2003.

  1. darren_s

    darren_s Agent

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    Hi all, I am having a very tough time deciding on the box size and type for my 12' shiva, I have the shiva and 250W plate amp on its way, I will be using Sub for 50/50 HT/Music my room size is 16x12 I have acoustic panels in all corners even ceiling corners in room so the room gain makes great bass with what i have now. I can build any size does not matter, I had first decided on sealed now I am thinking perhaps ported would be better?? I was looking at making the EBS alignment but am worried it might be to boomy?? I kinda prefer the tight solid bass sound but would still like to hit the low 20HZ, Any help at all ideas would be welcome, If the EBS would be to much for my room size or to boomy please let me know,thanks
     
  2. GrahamT

    GrahamT Supporting Actor

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    Download LSPcad from Adire Audio. It has the shiva preloaded and all you have to do is plug in the box and room info. You can experiment with different designs. ALso try WinISD.
     
  3. darren_s

    darren_s Agent

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    Thanks for info, Right now I am deciding betwwen the 85L ported or the EBS 142.5L, If anyone can give me there opinions on the EBS sound is it solid or boomy?? I was thinking if I built the 85L ported i could plug port to see how the sealed sounded. not sure how well that would work with the EBS.
     
  4. Nick Hallett

    Nick Hallett Agent

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    I have an EBS shiva with the PE 250 and can attest that it does indeed have a very tight, defined sound - with very good extension for HT. If you compare the group delay of an EBS shiva with the group delay of a low Q(~100 L) sealed unit, you will see that the delay is dead even down to 40 hz, which is the lower limit for the vast majority of most music. The 85 liter adire alignment would probably sound boomier since the point at which the group delay "goes crazy" is higher up in the spectrum. Also, the EBS has a much flatter freq. response.

    In other words, the EBS an excellent dual purpose sub.
     
  5. darren_s

    darren_s Agent

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    Thanks for replies, I will go with the EBS then.
     
  6. Nelson Au

    Nelson Au Executive Producer

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    Hi guys-

    Interesting discussion here. I looked into building a Shiva sub a few years back, but I didn't have time to pursue it.

    I'll likely have time this New Year and I was considering the project again. Since that time, I lost track of my minimal research. But I recall I was looking at the 85L cabinet size. What I'd like to do is mate this sub up with my B&W 805 Nautilas speakers for movies and music. I like tight bass, so I would not want boomy bass.

    I looked at the Adire website and I could not figure out what the EBS designation is you're referring to. Unless it was in reference to the Eminence driver?

    I'm a newbie to building speakers, but I am very good at working with wood and electronics. But I don't have the technical knowledge you guys have with regard to Q and port vs sealed and cabinet sizes. I was going to just go with a plan if I can find one on the Adire site and custom build it in my material choices. This way, I figure that Adire had the numbers worked out for a cabinet with the Shiva 12" driver and 250 watt panel mount amplifier and hoped that it sounded good with my main speakers.

    Any advice appreciated for the above questions, sealed verse ported, and cabinet size, etc.

    Thanks and Happy Holidays!
    Nelson

    PS- I down loaded the LSPcad thing, but typical for me, I'm a Mac guy. At least I can read the PDF. Was there a CAD application there or something?
     
  7. Aaron Howell

    Aaron Howell Stunt Coordinator

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  8. Nelson Au

    Nelson Au Executive Producer

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    Aaron-

    Thanks for the link. The Adire site is not very clear. Just what I needed!

    Nelson
     
  9. darren_s

    darren_s Agent

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    I have everything cut and marked out allready, I did it at work, the blueprints have wrong numbers for top and bottom.
     
  10. Arthur_King

    Arthur_King Stunt Coordinator

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    Are you using 3/4" material (MDF for example)? I would imagine if you have Plywood, or Oak, or something else and its not 3/4" (either more or less) those numbers are not going to work.

    Daffy Arthur King
     
  11. Gerry S

    Gerry S Stunt Coordinator

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    Darren:

    What dimensions did you end up using for the top and bottom?

    When I built my cabinet I initially thought something seemed wrong, but then realized the plans were correct (I built the 85L box).

    Note that the Front and back panels are completely outset,
    the Top and bottom are inset with respect to the front and back, and outset with respect to the sides, and finally the sides are completely inset.

    -Gerry
     
  12. Frank Carter

    Frank Carter Screenwriter

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    If you want a vented sub with the "tightest" sound, EBS is the way to go. I actually prefer my low tuned vented AV15 for music compared to the sealed enclosure I had it in.
     
  13. darren_s

    darren_s Agent

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    Nevermind sick with cold today sizes are ok,I am using 3/4 MDF, Thanks frank thats just what I needed to hear to get me going on this project. just checked my tracking and my sub and amp are coming tues 12/30 and then i have to wait untill friday for flared 4" port geez only ordered it a day after other orders.
     
  14. darren_s

    darren_s Agent

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    Does anyone know where I can find the dimensions for the PE 250w plate amp?? I saw them on a spec sheet but I cant find where I saw it.
     
  15. Gerry S

    Gerry S Stunt Coordinator

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    Just happen to have the instruction sheet here for #300-794.

    dimensions: 10-3/8"W x 10-7/16"H x 4-1/4"D

    enclosure cutout: 9"W x 9-1/4"H
     
  16. darren_s

    darren_s Agent

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    Thanks Gerry.
     
  17. Brian Bunge

    Brian Bunge Producer

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    Darren,

    The cutout dimensions are also on the PE website.
     
  18. darren_s

    darren_s Agent

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    I was thinking of using a base plate like the SVS subs use is this a bad idea for the EBS?? what do they use 1' MDF?? I like the looks of it that way.
     
  19. Mark>Som

    Mark>Som Auditioning

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    Does a large enclosure create more sound with the same amplification than a smaller enclosure?

    For example what will sound better? If I use 250 plate amp to push a 12" driver with a large enclosure vs. a small enclosure.

    This is used only for HT.
     
  20. Frank Carter

    Frank Carter Screenwriter

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    In a word, yes. A large enclosure is the most cost effective way to good clean bass. Here's a passage on Hoffman's Iron Law that I copied and pasted from here.

    Hoffman's Iron Law, described by Henry Kloss in the mid-1950s and later turned into an exact mathematical formula by engineers Thiele and Small, governs the behavior of woofers. Essentially, it says that a woofer's efficiency is proportional to the volume of its cabinet and the cube of the lowest frequency it can produce before losing relative level (aka the cutoff frequency). Take, for example, a woofer whose response is flat down to 40 hertz in a 2-cubic-foot enclosure. To make its response flat down to 20 Hz, you must either increase the cabinet volume by eight times (to 16 cubic feet) or use eight times the amount of amplifier power to achieve the same listening volume.
     

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