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Front-firing sub in dedicated media room...

Discussion in 'Home Theater Projects' started by JackJD, Mar 10, 2004.

  1. JackJD

    JackJD Stunt Coordinator

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    I have been looking at various subwoofers for some time now to use in my dedicated media room. I have a theatre with 4 full-range (each w/ 12” powered subs) and a powered center speaker. I also listen to a lot of music (especially multi-cannel DVD-A and SACD). So non-boomy, tight bass is a must.

    The room is a long rectangle; approx. 24’x 14’. In the front of the theatre, under the screen I have a built-in equipment rack which extends across the entire front of the room. This was built originally not only to hold equipment, but to house the water meter, which is at the extreme right in an enclosed 40”wide x 26” front-back x 29” deep (floor to top) box. Because the meter takes up very little space in this box, I was wondering if it might be a good idea to mount a sub or two in the front face of this box.

    The box is made from extremely dense hardwood-plywood (3/4”). There is one 2x4 framing piece running directly in the middle of the front of the box – leaving room for 1 or 2, 12” or 15” drivers... There is also room on the extreme left (away from the water meter) to mount a plate amp.

    What do you guys think? Is the water meter a problem (it’s bone dry inside the box, I have speaker wire running through)?

    Doable? If so: How many drivers(1 or 2)? What size(12”or 15”)? What brand/model driver? What brand/model amp- how many watts?

    Any thoughts/help is appreciated... JD
     
  2. Wayne A. Pflughaupt

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    I don’t see the meter as a problem (so long as it can withstand the sound pressure and vibration. The only potential problem I see is all the space you’ll need. Do you have enough available?

    For instance, something like a single 12” Shiva should be more than enough for your room, especially for a primarily music system, but it will require 3.5-4.0 cubic ft. for maximum extension with a sealed design (my personal preference for music). However, if music really takes priority you can get away with an even smaller box. Mine are in boxes a mere 2.5 cubic ft., and I love them for music. A bit shy for serious movies, though.

    As far as an amp, I'd say something on the order of 250 watts with that driver. I'm driving mine with 325 watts, but I need the headroom because of heavy equalizing.

    Regards,
    Wayne A. Pflughaupt
     
  3. JackJD

    JackJD Stunt Coordinator

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    Mr. Pflughaupt,

    Thank you so much for your reply...



    I don't think I over-stated my use of the room for music, but I may have under-stated the need for substantial bass for movies in the theatre... I also watch alot of movies... So both are of importance.

    So, I think I'm looking for answers to the same questions considering the large size and shape of the enclosure.

    Thank you, again... JD
     
  4. Wayne A. Pflughaupt

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    Hmm - so you have an easy 17 cubic ft. to work with (sorry that slipped by me before). Certainly more than enough.

    The shape of the enclosure isn’t important, only the total volume. I recently contemplating making some changes to my subs and some knowledgeable DIYers told me that increasing the size of my box to 4.0 would help extension (which I’m getting now largely by equalization) with no penalty to musicality.

    However, if you have that much space available, you could easily use a 15” sub. Probably even two (which would certainly be mind-blowing in a room that size), so long as they were internally separated.

    Another possibility with that much volume available may be an infinite baffle design. There are forums dedicated to these things; they could let you know of 17 cubic ft. is large enough. I’ve heard they’re amazing for HT; not sure about music. Be sure and find out.

    Bottom line, I don’t see any reason why you can’t pull this off, so long as you can reduce the internal volume to what’s appropriate for the driver you select) in the case of a sealed or ported design).

    Regards,
    Wayne A. Pflughaupt
     
  5. JackJD

    JackJD Stunt Coordinator

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    Once again, thank you so much for your reply Mr. Pflughaupt...

    OK, so I'll add the Infinite Baffle question to the others for all of you experts...

    Is 17 cu. ft. enough for IB?

    Is IB good for music?

    How would YOU do it if it were your theatre? (How many drivers(1 or 2)? What size(12”or 15”)? What brand/model driver? What brand/model amp- how many watts?)

    I thank you for sharing your knowledge/experience.. JD
     
  6. JackJD

    JackJD Stunt Coordinator

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    A kind reply from another forum...

    You'd have to subtract the water meter volume from the internal box volume to get the effective box volume. The rule of thumb for an IB is to have an effective box volume at least 4x the Vas of the driver. See this IB FAQ,

    http://home.comcast.net/~ttriff/

    17 ft3 is about 481L. I don't know of any 12" or larger drivers that have a Vas low enough to allow that box to be an IB for them. You would need a sub driver with a Vas no larger than 4ft3 or 120L.

    The box would be large enough for a smaller driver (say a 10"), but it won't produce the spl at low frequencies a larger driver would. Check out "Cult of the Infinitely Baffled" for any questions about IB subs,

    http://f20.parsimony.net/forum36475/

    So it seems the enclosure is too large for a "normal" sub; but too small for an IB...?

    Anyone have any thoughts/comments/suggestions? Anyone...?
    I could really use the help... JD
     
  7. Andrew Pierce

    Andrew Pierce Stunt Coordinator

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    Have you considered 4 or 5 Shivas? [​IMG] That's not so bad a size then since you divide the volume by the number of drivers.

    Seriously, 4 Shivas would run you ~$500 (the PE 12" DVC equivalent would be $436), a NADY pro amp which can drive 1400 watts into 4 ohms runs you $300. So for $800 plus shipping, you've got enough clean bass to start your own revolution.

    Or you could subdivide the room to make 2 smaller enclosures.
     
  8. Wayne A. Pflughaupt

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    Jack,

    Surely there’s a way to reduce the size of the enclosure? Or do you not have a good access to the interior of it?

    Regards,
    Wayne A. Pflughaupt
     
  9. ThomasW

    ThomasW Screenwriter

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    Hey, you've got the box size so save some money and use a single AL-1804. Might want to reinforce the box a little more though. [​IMG]

    [​IMG]
     
  10. JackJD

    JackJD Stunt Coordinator

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    Wow! That is a monster!!!

    I have no experience with 18" (or that brand) sub drivers, is this appropriate for music use?

    Anybody have one of these in use?

    I would appreciate the comments... JD
     
  11. Allen Ross

    Allen Ross Supporting Actor

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    for strictly music why not snag a couple of those JBL subs that PE is blowing out, there was a thread here week ago, it seems very musical, don't know how it would model in your box but i am sure that those will be plenty.
     
  12. ThomasW

    ThomasW Screenwriter

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    Jack

    The was a company called BluePrint. They made a series of drivers, the 1803 being the largest.

    I've used their 1203 and 1503 they were and are great drivers.

    The company was sold and the new owner couldn't get it together. As a result the remaining inventory was sold to AudioLiquidators.

    There were motors and cones for the 1803 but not frames. So AL had the original mfgr (Resonant Engineering) create the 1804, using a new frame and the remaining 1803 parts.

    For the $260, NOTHING is a better a value. You'd need to pay about double that for any other good 18"
     
  13. Russell R

    Russell R Stunt Coordinator

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    Hello ThomasW,
    What are your suggested alignments using the 1804 driver? It looks promising. I want a new HT sub.

    Thanks,
    Russ
     
  14. ThomasW

    ThomasW Screenwriter

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    I haven't used the 1804. I've used the 1503 ported and sealed. Note that that the 1503 and 1804 share the same motor.

    The 1804 has a mid Qts, so ported or sealed either will work. If you go ported then plan on using a HUGE port 8" minimum. To keep the box size down it would probably work with 3 of the 18" Stryke PR's.

    Grab a copy of UniBox and play with some sims.....

    BTW, regardless of the rated efficiency, these drivers like horsepower, so think nothing smaller than 500 watts
     
  15. Pete Mazz

    Pete Mazz Supporting Actor

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    That size enclosure would be ideal for 2 Tempests in a sealed or ported alignment.

    Pete
     
  16. Wayne Ernst

    Wayne Ernst Screenwriter

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    I loved reading that sentence - and thought it was worth quoting again. [​IMG]
     
  17. Russell R

    Russell R Stunt Coordinator

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    ThomasW,
    I have a 250w plate amp that I want to use with my new sub. Would this be enough to drive the 1804 to respectable levels until I purchase a larger amp? Currently, I am using a single Shiva EBS in a 12x13 room and this will be replaced by something new. I will play with the alignments tonight. What is the pro's and con's of the 1804 versus multiple smaller drivers? How would the PE 15" JBL driver compare to the 1804?

    I just do not want to purchase a new amp at this time. My wife would kill me. I bought it last month with intentions on using it and now it is sitting in a box taking up space.

    Thanks,
    Russ
     
  18. ThomasW

    ThomasW Screenwriter

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    Russell,

    Don't know........

    The only amp I've ever used with any 1503 is an Aragon 8008. They do about 400watt/channel into a 4 ohm load. That was loud enough to shake my entire 2500 sq ft brick house. [​IMG]

    The 1804 is more efficient than the 1503, but both these drivers need a fair amount of EQ. That in and of itself uses up power...
     

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