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View Full Version : C37 as a Subwoof Enclosure



John Y.
06-02-2003, 06:45 PM
Hi, Guys -

I have waited a while to post this because I wanted to see what came out of previous forum postings. Thanks, Giskard and Mr. Widget, et. al. for your input.

I have a project where I plan to use an old, resurrected, C37 enclosure as a subwoof box. I have two choices, assuming use with a BX63, which I have:

Use the C37 with new 2235H or recone D130 with C8R2235H.
Enlarge cabinet and use a 2245H.

In the first case, the existing volume is 5.77 cu ft, so I would cut down the volume to the 4.5 cu ft size of a B380. Could even add half inch ply to the inner surfaces for more rigidity and still fall under the required 4.5 cu ft. I might use the 2235H mounted to the rear of the baffle, using the existing grill assembly, making it easier to install in the C37.

In the second case, I could expand the cabinet by rear 6 inch extensions to make it 8 cu ft, or use stuffed fiberglas for the equivalent. In this case, I think I would front mount the 2245H and devise a new grill assembly.

Questions arise:

What is the downside of rear mounting for a subwoof driver?
Would the 2" setback of the front panel (C37) be bad?
Can I stuff the 5.77 cu ft C37 to make it usable with a 2245H?

Appreciate the help.

John

4313B
06-03-2003, 10:22 AM
"What is the downside of rear mounting for a subwoof driver?"

Nothing sonic that I know of... the BX63A has an upper limit of something like 126Hz.

"Would the 2" setback of the front panel (C37) be bad?"

I highly doubt it.

"Can I stuff the 5.77 cu ft C37 to make it usable with a 2245H?"

Probably not, that's a whole bunch of fiberglass and that much could cause problems. How about a pair of LE14H's? Will they fit on the baffle? Two of them are roughly equivalent to 1-1/2 2235H's. Plus you'd end up with double the power capacity of a single 2235H and roughly 2 to 3 dB more output. Anyway, just another thought to help confuse the issue. I can't remember how big that baffle is and I'm too lazy to look it up.

*****

Oh, BTW, that reminds me. I can get the new LE14H-3's. If you've ever suffered foam surround rot (I personally haven't but I've seen plenty of it) you might think the rubber surrounds on the LE14H-3's is cool. G.T. certainly is excited about it! :)

Mr. Widget
06-03-2003, 10:59 AM
Since I like the 2235 in a five cu ft box and the older JBL cabinets can be a bit lively (read under braced) I would brace the hell out of it and make it a 5 cu ft box and use a 2235. For bracing adding a sheath of MDF on the inside is fine, but I would definitely add some kiln dried 2 X 4s as well. Remember not to forget the volume of ports and the woofer to be added to the 5 cu ft. You really need about 5.4 cu ft. after the bracing.

I do think Giskard's idea of twin LE14s sounds interesting too though.

John Y.
06-03-2003, 11:08 AM
Giskard,

Thanks. You just won't let me use my 50 year old speaker system (C37 + D130 reconed with 2235H) without a fight. Also, what am I going to do with my (need to be refoamed, but never used) 2245H? BTW, I have two new 2245H's from the tent sale waiting to be used in my home theater when I get, or make, 8 cu ft enclosures.

I like your idea of the two LE14H-3's. The baffle of the C37 is about 34 x 22, so it would work nicely and I still could use the enclosure without increasing the volume from 5.77 cu ft. What volume would be ideal for the pair of LE14H-3's? Bet I could line the inside of the 3/4" cabinet with half inch baltic ply for rigidity and still come out with a volume big enough.

John

4313B
06-03-2003, 11:24 AM
Yeah, Mr Widget is right, that box will need some beefy bracing.

"I do think Giskard's idea of twin LE14s sounds interesting too though."

Just thought I'd toss a wrench in and see what happens. The mutual coupling from the closely spaced dual LE14H's is torrid. Well, you should know how closely spaced dual 2235H just walk all over a single 2235H :)

One thing about LE14H's and 2245H's, no mass rings to warn you that you are exceeding xmax, lol.

John Y.
06-03-2003, 11:35 AM
Mr. Widget,

I had planned on bracing the enclosure with 2x4's and had taken that into account on my expansion of the cabinet volume for a 2245H. Requires about 6 inches expansion of the cabinet depth, which then necessitates additional bracing where the joint lies.
Really makes the use of a 2235H more attractive (easier).

Giskard,

Sounds like two LE14H-3's would also require cabinet expansion, though not as much. If I made use of the C37 front 2" setback and brought the baffle forward, I might be able to create a volume large enough, but still there is the bracing volume. Hmmm. It wouldn't look like a C37, so why bother?

John