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-   -   Build your own 2x12" TH (The Kraken 212 TH) (http://www.diyaudio.com/forums/subwoofers/160879-build-your-own-2x12-th-kraken-212-th.html)

Petter Persson 8th February 2010 06:55 PM

Build your own 2x12" TH (The Kraken 212 TH)
 
Drivers can handle 350W RMS/piece (700W total) 14 mm X-Max
Model JBL GTO1214
Net volume is 500 liter.


Simulated for corner placement, 2,83V, driers in parallell. 135 dB @ 20 Hz.

http://proxy1.pixbox.se/arkivet/synl...30258079.jpg?0


Braced with 12 mm plywood/MDF, as image below

http://proxy1.pixbox.se/arkivet/synl...30414595.jpg?0

http://proxy1.pixbox.se/arkivet/synl...30258080.jpg?0


http://proxy1.pixbox.se/arkivet/synl...30258078.jpg?0


Internal dimensions, materialthickness 22 mm

http://proxy1.pixbox.se/arkivet/synl...30258077.jpg?0


Build your own and tell me if it works:)

oilcanracer 9th February 2010 03:33 AM

you could probably flatten out the higher spl response by flaring out the mouth, but then you would not have a nice rectangle dimension. i bet the distortion would increase as volume does with that port shape as well.

of course i am a big fan of large curved flared "tuba" ports for subs. they sound smoother too.


what ideas do you have for lining the first couple of meters in that design?

FlipC 9th February 2010 04:07 AM

Tx for sharing.
Interesting layout.

Side note -
I haven't come across a TH build where the high end is as simulated/ Always less.

Also post the HR data.
To lazy to re-figure that out.

Petter Persson 9th February 2010 08:12 AM

Quote:

you could probably flatten out the higher spl response by flaring out the mouth,
No, just increase the high freq. sensitivity on cost of low end sensitivity.

Quote:

but then you would not have a nice rectangle dimension.
Yes, thats true. This box design is made to be as flat as possible and to just fit on a standard 120x240 cm sheet to maximise acoustic output compared to the material used.

Quote:

i bet the distortion would increase as volume does with that port shape as well.
Why? Plese explain. At these waewlengts, i can't see why...

Quote:

of course i am a big fan of large curved flared "tuba" ports for subs. they sound smoother too.
Smoother tha all tapped horns...A bit too much generalization maybe...

Quote:

what ideas do you have for lining the first couple of meters in that design?
Since I have not built them, I don't know. One has to study the measured freq. response and listen too determaine such things is my experience.



Quote:

Tx for sharing.
Interesting layout.
Welcome and thanx:)

Quote:

Side note -
I haven't come across a TH build where the high end is as simulated/ Always less.
Well, that depends on the folding. This folding will make the horn measure
quite the same as the simulation. For a single fold, the first dip will be filled
in. for example in my own tapped horns. 2 pi measurement and simulation.
The high end seems pretty intact...Levels are normilized. No Smoothing applied,
measured 2.5 meters from the mouth on axis, ground plane.

http://proxy1.pixbox.se/arkivet/synl...30417795.jpg?0

Quote:

Also post the HR data.
To lazy to re-figure that out.
Naa...too lazy do that, if it is of eaugh intrest, you just have to do some back engineering:p

Petter Persson 9th February 2010 09:58 AM

http://www.jbl.com/resources/Brands/.../GTO1214TD.pdf

oilcanracer 10th February 2010 01:24 AM

Quote:

Originally Posted by Petter Persson (Post 2078631)


Why? Plese explain. At these waewlengts, i can't see why...



Smoother tha all tapped horns...A bit too much generalization maybe...


i meant flared sub "horns" not ported tubes. my bad.

well in my experiences building subs with wider more flared mouths produced less distorted and more musical sounding compared to just the smaller or square opening at higher volumes.
i would have to guess it might have to do with moving air maybe.


i could be splitting hairs as most sound that low is more of a thud/boom/puff kind of sound and not musical.

Petter Persson 10th February 2010 07:29 AM

Aha, okej, then I understand better. A larger mouth creates a better coupling
between the air in the horn and the surrounding air and reduces air speeed in
the mouth region. The mouth area in this horn is 1625 cm2, about three times
the SD, so it's pretty large any way...As you mentioned, a larger mouth would
not fit in the desiered outer dimensions.
A larger mouth also lowers the q at the res. freq. and then lowers the group
delay, giving a more tight "musical" sound on cost of efficiency/box volume though.

tb46 10th February 2010 02:44 PM

1 Attachment(s)
Hi Petter,

The SD area is 2x 511cm^2, isn't it?

Regards,

BP1Fanatic 10th February 2010 03:01 PM

Correct! So, 3 x Sd would = 3,066cm^2.

Petter Persson 10th February 2010 04:24 PM

Nice job Oliver:) The only difference is about 0,5 dB around the 70-Hz-peak and
since this still only is a simulation, the differences are of academic value...


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