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Few questions about sub

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Spear View Drop Down
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    Posted: 14 April 2015 at 8:08pm
Hello
I am new on forum.
I wanna build my first subwoofer..
I would like to build G SUB for the first time.

P Audio 18" 1700W, 12.8kg , 476mm (428mm for installation), 30-200Hz, Fs=42Hz, Qts=0.59 , VAS=99.72 , BL=25.91 T/m, Re=5.2Ohm

Does this fit in G SUB?
What kind of wood should I use? And what kind of glue?

Edited by Spear - 15 April 2015 at 1:58am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Spear Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2015 at 8:25pm
P Audio SD18-1700EL

18" Diameter
1700W AES, 6800W Peak, 8 Ohm
4.5" Voice Coil
98 dB Sensitivity
30-200 Hz Frequency Range

Edited by Spear - 15 April 2015 at 1:54am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2015 at 2:30am
Qts too high for reflex.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Spear Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2015 at 11:39am
just found this

http://speakerplans.com/index.php?id=faq1

Qts: Driver total Q.

It had to happen at some point, we’ve hit the Q word. Q is basically a describing word, it is used to describe a quality or characteristic about an electrical or mechanical part of the driver. So Qts is the overall Q of the driver, both electrical and mechanical. Qts can be thought of as how strong the motor and magnet system are. A driver with a low Qts of around 0.20 would have a large magnet and be able to move the cone with a lot of force. This makes for a tight driver. A driver with a Qts of 0.45 would have a smaller magnet and less control over its cone. So low values of Qts give a tight and punchy sound but with little weight or low bass and high Qts values give a slow and heavy sound that will give you lots of low frequency output. Watch out for drivers with really high Qts values of 0.6 or above, these would require such a big box to work correctly that in normal size boxes you don’t get much low end. They are better of being used on the rear parcel shelf of your car, where they can enjoy a massive rear chamber.


SO LOOKS LIKE HIGH Qts IS GOOD FOR LOW FREQUENCY (and I like DUB BASS)

Edited by Spear - 15 April 2015 at 5:49pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 15 April 2015 at 11:31pm
It will work, but the bass will have a 'loose' character, rather than a 'tight' character.
djk
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MarjanM View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2015 at 12:46am
G sub is too small for that driver.
Marjan Milosevic
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www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2015 at 2:39am
That's not what he want's to hear!
 
Box size is roughly proportional to the square of the Qts, .3^2=.09, .6^2=.36, so the box size for the Qts=.6 woofer will need to be about 4x bigger than for the Qts=.3 woofer (assuming similar Vas).


Edited by _djk_ - 16 April 2015 at 2:41am
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bitSmasher View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bitSmasher Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2015 at 3:26am
Good place for me to clarify what I've read... that a high QTS (up to 0.6 or so) will want the box volume above Vas, and tuned below Fs
So you end up with a huge box that'll go low, but also suffers from high group delay
Would this be a correct summary?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2015 at 7:32am
Yes.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2015 at 9:46am
Originally posted by bitSmasher bitSmasher wrote:

Good place for me to clarify what I've read... that a high QTS (up to 0.6 or so) will want the box volume above Vas, and tuned below Fs
So you end up with a huge box that'll go low, but also suffers from high group delay
Would this be a correct summary?


Group delay revolves around the tuning frequency. Every reflex box offers a group delay. It is just a matter on where the measured (not simulated) tuning frequency lies.

Best Regards,
Elliot Thompson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bitSmasher Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2015 at 9:56am
Originally posted by _djk_ _djk_ wrote:

Yes.
Huzzah, years of reading forums and I've learnt something... one thing at least Embarrassed
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