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Old 7th December 2011, 01:31 PM   #1
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Default Advice on 'slimline' sub..... please

OK chaps, I've done the search to death and can't find anything to be honest ...
I'm not a complete novice with speaker builds but design is a weakness and I've never tried a sub.
What I'm looking to make is a powered sub for LFE on a 5.1 system.
I'd like to have it behind the settee right up against the wall behind us.
Problem is that the gap is only 6"... height and width are not an issue but anything front firing would probably be useless although there is a gap about 6" wide down the side under the curve of the couch arms.
I have built everything else... decoder, amp, FR front & rear speakers and it sounds really good, just needs that little more ooomph on the special effects.
I need some help here guys.

Cheers
Lee
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Old 7th December 2011, 02:43 PM   #2
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As you know, this is really constraining driver size. Within your size limits, 2 Dayton ND105-4 (wired in series) in 16 liters net and tuned to 47 Hz will give F3/F10 at 42/36 Hz. 100dB w/ 15 watts. These drivers provide amazing bass for their size. You will be output/excursion limited with these drivers. They are robust and can survive excursions to their mechanical limits (~10 mm)

You would get higher efficiency w/ a pair of ND105-8's wired in parallel, but I haven't measured the specs on those drivers. I do know that the factory specs are off by more than the usual on the ND104s.

I can help w/ box design and vent sizing if you'd like.


Quote:
Originally Posted by Lostcause View Post
OK chaps, I've done the search to death and can't find anything to be honest ...
I'm not a complete novice with speaker builds but design is a weakness and I've never tried a sub.
What I'm looking to make is a powered sub for LFE on a 5.1 system.
I'd like to have it behind the settee right up against the wall behind us.
Problem is that the gap is only 6"... height and width are not an issue but anything front firing would probably be useless although there is a gap about 6" wide down the side under the curve of the couch arms.
I have built everything else... decoder, amp, FR front & rear speakers and it sounds really good, just needs that little more ooomph on the special effects.
I need some help here guys.

Cheers
Lee
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Last edited by fastbike1; 7th December 2011 at 03:02 PM.
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Old 7th December 2011, 03:01 PM   #3
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by Lostcause View Post
OK chaps, I've done the search to death and can't find anything to be honest ...
I'm not a complete novice with speaker builds but design is a weakness and I've never tried a sub.
What I'm looking to make is a powered sub for LFE on a 5.1 system.
I'd like to have it behind the settee right up against the wall behind us.
Problem is that the gap is only 6"... height and width are not an issue but anything front firing would probably be useless although there is a gap about 6" wide down the side under the curve of the couch arms.
I have built everything else... decoder, amp, FR front & rear speakers and it sounds really good, just needs that little more ooomph on the special effects.
I need some help here guys.

Cheers
Lee
Hi, Here is a very slim sub(<5.5 inch) suggestion I recommend you to build(a couple of? ) that fits your narrow space :

b
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Old 7th December 2011, 03:41 PM   #4
bjorno is offline bjorno  Sweden
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Adding a link:

35hz 120litre TH?

b
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Old 7th December 2011, 04:23 PM   #5
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How is the output with such a small mouth (hole) on that ?
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Old 7th December 2011, 04:59 PM   #6
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Quote:
Originally Posted by fastbike1 View Post
As you know, this is really constraining driver size. Within your size limits, 2 Dayton ND105-4 (wired in series) in 16 liters net and tuned to 47 Hz will give F3/F10 at 42/36 Hz. 100dB w/ 15 watts. These drivers provide amazing bass for their size. You will be output/excursion limited with these drivers. They are robust and can survive excursions to their mechanical limits (~10 mm)

You would get higher efficiency w/ a pair of ND105-8's wired in parallel, but I haven't measured the specs on those drivers. I do know that the factory specs are off by more than the usual on the ND104s.

I can help w/ box design and vent sizing if you'd like.
Hmm this sounds like it will certainly fit the size restrictions and those drivers are a temping price, nice suggestion fastbike.
I need to do some sketching me thinks......
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Old 7th December 2011, 05:01 PM   #7
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Quote:
Originally Posted by bjorno View Post
Hi, Here is a very slim sub(<5.5 inch) suggestion I recommend you to build(a couple of? ) that fits your narrow space :

b
Woa they are lovely..... what height are they?
I could make those no problem..... I'll give that thread a good read tonight
Thanks for the pointer bjorno
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Old 7th December 2011, 05:31 PM   #8
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by m R g S r View Post
How is the output with such a small mouth (hole) on that ?
Hi mRgSr,

A good question: If you compare a T-TQWT_T-QWP with a 4:th order BP using the same port-area and same fb tuning:

The Lp filtering action of the port and airways return path is much more effective than the single ported front (echo)chamber of a BP.

The BP will sound much worse(off-band leak effects) at x-max due to no damping material in front of the driver, normally only in the closed chamber.

Further, The BP driver sees the port area that usually is >= Sd/3 considered= OK.

Unlike the BP,the T-TQWT/ T-QWP is loaded at the driver front by at least twice of this area, whereas one half is always LP filtered by the damping material in use.

IMO the SQ at x-max is second to none if compared with a corresponding 4:th order BP.

Port noise?, I never herd that from a T-TQWT as I always play my subs well below x-max and if I need more SPL I just add another one.

b

Ps:

The size of the port shown in the pictures here-above is ~3" and the compression rato~(2.94:1).

IME: When sitting at a coach 'hugging' a newly built T-TQWT placed next to you and hooked up to your Stereo, you be surprised of the low FR end SQ now appearing from your main speakers and have no localization effect from the sub if the T-TQWT port is pointed away form your own body.

Last edited by bjorno; 7th December 2011 at 05:46 PM.
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Old 7th December 2011, 07:01 PM   #9
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Slightly wider than you might want, but the tapped horns linked in my signature do a decent job of special effects. They're just over 7" wide, but they are really really good - I've tried them with movies like the Dark Knight, and I just kept turning it up louder and louder.
I used a pair of them with a pair of 12" coaxials in a rather big room (20m by 10m), playing It's Oh So Quiet by Bjork (has some low stuff on a double bass), and they kept up fine. The 12"s had about 10w per side (98dB@1w), and the tapped horns more like 150w.
Highly recommended.

Chris
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Old 7th December 2011, 08:21 PM   #10
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Quote:
Originally Posted by Lostcause View Post
Woa they are lovely..... what height are they?
I could make those no problem..... I'll give that thread a good read tonight
Thanks for the pointer bjorno
The external height is ~48" or 122 cm. The box dimensions are (LxWxD)=
48" x 8.27" x 5.32" or (122cm x 21cm x 13.5cm).

I've posted this design somewhere here at Sub-woofer's earlier: Simulations and real measurements included .but cannot find the thread(s).

b
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