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Discussion Starter · #1 ·
Hi guys,

Iv'e been reading through so many great posts on decide I would like to have a stab at my own SLLT.

I have an idea that I would love to get some feedback on:

I have 8x JBL GTO1214 woofers lying around that I would like to use as they would be a no-cost option (I realise people will have mixed feelings about these). I realize they are not the most suited drivers to this with there Qts of 0.47, Fs of 28hz and their relatively average Xmax 14.5mm, however with the amount of cone area, low-ish power and small listening area I was hoping that output would be good enough without resorting to my usual, anti-WAF large enclosure approach.

Thiele smalls here:

http://www.jbl.com/resources/brands/jbl/products/productrelateddocuments/en-us/boxesandparameters/gto1214td.pdf

As mentioned above I will be supplying them with only 100wrms a piece as to not kill them with excursion which I think will be sufficient considering the listening area is only slightly bigger than the proposed SLLT enclosure itself! I will be using manifolds to house the subs as I imagine 8x12"s on one baffle may cause some issues!
Of course I will be bracing the board etc I just didn't think it was worth putting onto the sketchup model.

The SLLT enclosure itself is a room that was added to the existing lounge some time ago it plots at roughly 512ft³ and using the existing arch as a port yields a tuning of roughly 17hz. At present there are two arch ways either side of a fire-place leading into the solid brick extension. I plan to seal off one of the arch ways and use the other as the port for the SLLT as mentioned above.

I realise that the roll off is a little steep below tuning and that the tuning is above the 15hz mark hence why it may not be technically fall into the SLLT criteria however it is very large and very ported and without messing up the house even more I can't really change the tuning. Any ideas?


Here are some plans and plots:














Measurements:







Plots:












So in a nutshell that is the rough plan.

Any ideas on helping smooth off below 17hz response would be great and that is my first attempt at modelling a room on sketchup so I know it's far from perfect!

I would also be interested to hear from those with experience how these will sound for music, or more specifically if they will 'punch' or just be a big floppy sine wave creator!

Thanks for looking guys and any feedback would be great!

Cheers, Ed.
 

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So you are modelling this by calling the back room the box and the entryway the port? I think that you need to treat the current port as two flush/flanged ends, not one, since no port protrudes into the enclosure. In theory that seems like it'd work... In terms of tuning that response is peaky at tuning which shows that the volume and tuning is too big for the drivers. There would be ringing around the port tuning, but given that's below the audible spectrum I can't guess how the subs will sound.

Nonetheless, looks interesting! Can you make an interchangeable manifold/baffle so you could use alternate drivers in the future and/or can you close off the space entirely so you could go the IB route?
 

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Discussion Starter · #3 ·
Yes that's right, spot on!

Yes good idea I think somewhere down the line I might change the subs for something more suitable but since I have them I want to use them! So yes interchangable baffle will be used.

IB would be my ideal goal however the WAF factor means I will not really be able to close up the other side as it would make the lounge quite dark blah blah blah :)
 

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I can't provide any guidance or assistance I'm afraid, but I did want to compliment you on your ingenuity. That's a very unique design, one I've never seen before. I'm not sure having all that low frequency directly blasting a wall hanging TV is such a good idea, but beyond that I like your concept.
 

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Discussion Starter · #5 ·
Thanks Jim for your kind words! It's a bit of a stretch to whether this will work or not however it is a bit of a compromise setup that i'm hoping will work out. The other half is meant to have her office in that back room hence I need minimal sub intrusion!

I see your point about the TV but I don't have much choice, time will tell!
 

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If the entry way on the left side of the fireplace is supposed to be the port then this won't work. No port opening can exceed the Sd of the driver/drivers/ manifold opening/s. The back wave of the drivers is going to cancel the front wave, the frequency can be determined by what the distance is from the drivers to the arch way opening.
 

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Discussion Starter · #7 ·
Ahh right ok, I wasn't sure to be honest if it would work or not. I might give it a go and then if not just build in a box behind the subs and enclose them as a large sealed possibly!
 

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Discussion Starter · #8 ·
The distance from the driver to the midpoint of the arch or port is about 3.5m therefore a quaterwave of 27ish Hz (correct me if I'm wrong)? For some reason I thought it would be the distance from one side of the baffle all the way to the other (7m) until there were cancellation and or phase issues.

On the flip side in my seating position (back corner) I would be a further 3 metres from the 3.5m midpoint discussed earlier so how might this change things? Sorry for the questions I've only ever dealt with 'normal' sized enclosures before so this is a learning curve!
 
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