Front-firing sub in dedicated media room...

JackJD · 03-10-2004, 03:40 PM

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

Wayne A. Pflughaupt · 03-10-2004, 06:08 PM

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

JackJD · 03-10-2004, 08:11 PM

Mr. Pflughaupt,

Thank you so much for your reply...

The only potential problem I see is all the space you’ll need. Do you have enough available?

Perhaps I was not clear on my intentions... I would like to cut a hole and mount the driver(s) to the front of the sealed box; The amp to the inside of the box; using the entire box as the sealed enclosure...
It measures 40"across x 29"depth x 26"front-to-back.

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.

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

Wayne A. Pflughaupt · 03-10-2004, 09:48 PM

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

JackJD · 03-10-2004, 10:12 PM

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

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JackJD · 03-12-2004, 12:17 AM

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

Andrew Pierce · 03-12-2004, 04:43 PM

Have you considered 4 or 5 Shivas?

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.

Wayne A. Pflughaupt · 03-12-2004, 05:09 PM

Jack,

Quote:

So it seems the enclosure is too large for a "normal" sub...

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

ThomasW · 03-12-2004, 06:37 PM

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.

JackJD · 03-16-2004, 12:28 PM

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