HT box size and port for a JBL MKII 15" ? - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 11 Old 03-02-16, 04:05 AM Thread Starter
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HT box size and port for a JBL MKII 15" ?

I'm looking for specs to build a large ported enclosure for a Home theater application.

I'll be running (1) JBL MKII 15" subwoofer with the coils in parallel for a 3 ohm load for a Crown K2 amp. So might be around 1500 watts RMS? (If this isn't enough bass I might use a second 15" in an identical box)

There is no limit on the size of the box and It's strictly for HT. What size box and what slot port dimensions do you guys think I should use? I don't have access to a program so I'm asking the experts here for advice.

My old box with a 15" was ported at 28 HZ and I know that was way to high. Please give me some good advice for this JBL 15"?

Thanks,
Bill
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post #2 of 11 Old 03-02-16, 09:46 PM
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Re: HT box size and port for a JBL MKII 15" ?

Do you have the T/S parameters for the drivers, and can you post them?

And yeah a 28 Hz tune is pretty high for HT, especially with a 15".


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post #3 of 11 Old 03-02-16, 11:52 PM Thread Starter
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Re: HT box size and port for a JBL MKII 15" ?

I have a spec sheet with them listed but unable to upload it, not sure how
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post #4 of 11 Old 03-03-16, 12:00 AM Thread Starter
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Re: HT box size and port for a JBL MKII 15" ?

ok, I think I got it ...check them here
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HT box size and port for a JBL MKII 15" ?-w15gti00.jpg  

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post #5 of 11 Old 03-03-16, 12:02 AM Thread Starter
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Re: HT box size and port for a JBL MKII 15" ?

here is the ported box suggestion but it's for Car audio so the tune is to high in frequency and box maybe to small for efficiency?
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post #6 of 11 Old 03-03-16, 12:17 AM
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Re: HT box size and port for a JBL MKII 15" ?

How big is the room the sub is in? Large and open or a closed off room?

You'd only need one channel of the K2, but you could do 8cuft tuned to 15 Hz with two 4"x34" (or one 6"x38") round ports, or a 15"x1.75"x35" slot port. So you could build two and use the one amp. It would need a 12 Hz subsonic filter if the amp doesn't have one built in already.
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HT box size and port for a JBL MKII 15" ?-w15gti_1b.png  

HT box size and port for a JBL MKII 15" ?-w15gti_1a.png  

HT box size and port for a JBL MKII 15" ?-w15gti_1.png  

Attached Files w15gti.wpr (1.6 KB) 


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post #7 of 11 Old 03-03-16, 12:20 AM
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Re: HT box size and port for a JBL MKII 15" ?

If it's a closed off room, a sealed sub configuration would be better.


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post #8 of 11 Old 03-03-16, 01:58 AM Thread Starter
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Re: HT box size and port for a JBL MKII 15" ?

I think the Crown K2 plays flat to 5 hertz but no subsonic filter.

My theater area is a rectangle on 3 sides and is open in the back to the rest of my basement so its around a 1600 square foot area total.

I don't think sealed I can get enough output. Ported low is best I think.

So you think 2 ported boxes 8 cubic feet each with a JBL 15" in each box will be good enough output? 15 hertz tune?
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post #9 of 11 Old 03-04-16, 06:00 AM Thread Starter
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Re: HT box size and port for a JBL MKII 15" ?

bump for info?
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post #10 of 11 Old 03-05-16, 03:43 PM
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Re: HT box size and port for a JBL MKII 15" ?

Quote:
probillygun wrote: View Post
I think the Crown K2 plays flat to 5 hertz but no subsonic filter.

My theater area is a rectangle on 3 sides and is open in the back to the rest of my basement so its around a 1600 square foot area total.

I don't think sealed I can get enough output. Ported low is best I think.

So you think 2 ported boxes 8 cubic feet each with a JBL 15" in each box will be good enough output? 15 hertz tune?
ya! Sorry for the delay in response. I think that would be a good way to go.

You could try it without an HPF but go easy with a few movies to test the limits of bottoming the subs out with deep LFE content. You should have more than plenty of amp power for the two.


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