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-   -   Not clear on box size, Help please! (http://www.diyaudio.com/forums/car-audio/114164-not-clear-box-size-help-please.html)

skooter 24th December 2007 03:04 AM

Not clear on box size, Help please!
 
went to down load and it ask for Qtc. Manual dosen't list it. just Qts.

Fs-32Hz
Qts-0.72
Qes-0.83
Qms-5.397
Vas (Cu.Ft.)-2.26
Vas (Liters)-63.99
Re-1.5ohms
Le-0.43mH
Mmd-126.5 grams
Xmax- +/-8mm
RMS-400 watts
Sd-480 sqcm
Freq. Resp.-20Hz-500Hz
Efficiency (2.8V)-92.7
EBP-39
Displacement- 0.23Cu.Ft.

can someone please run this and let me know what size box I need to build for these subs. Thanks, I hate to be so stupid.

Clipped 24th December 2007 04:00 AM

what size, brand sub is it?

skooter 24th December 2007 04:19 AM

It is a Dub200 12" dual 4ohm. Yes I know it is a cheap sub. but I ain't got much money. Thanks.

jol50 24th December 2007 05:17 AM

What Hz you want to tune it to? Ported, slot or tube? A pair right, in one box?

I have a digital audio 12, its pretty cool with that huge surround but SQ people scoff at them.:) No matter, your enclosure makes much more difference.

Clipped 24th December 2007 05:39 AM

how many subs and what kind of car?

ported:

just make the box between 2.25-2.75 cuft
with 14"-16" of port area per cubic foot.
start the port length at around 22" and keep cutting off 1 " at a time until its loudest. 16"-18" port length is just about right for most subs.


this is the way competitors do it.

skooter 24th December 2007 05:43 AM

2 12" subs
1 sealed box
back of 97 cherokee, subs pointed to back hatch.
Hz? listen to rock, metal, some bass stuff
running them with a PPI PCX2200 mono 4 ohm load

The manual recomends .75-1.50 Cu.Ft. (per sub)

skooter 28th December 2007 11:39 PM

Ok, I am building tonight my new sub box. I have decided to stick my 2 12" in a 2.70 Cu.Ft. sealed box. wish me luck!

tsmith1315 29th December 2007 05:03 AM

Skooter asked:

Quote:

went to down load and it ask for Qtc. Manual dosen't list it
Qtc is the resulting system Q of speaker+box combined.

Therefore, you have to specify what Qtc you want before box size can be determined.

Smaller box = higher Qtc

And Skooter said:

Quote:

Ok, I am building tonight my new sub box. I have decided to stick my 2 12" in a 2.70 Cu.Ft. sealed box. wish me luck!
Obviously my post is moot at this point. But just for reference, from the parameters you posted:

Subtracting 0.23 cu ft per speaker from the 2.7 leaves 1.12 ft per speaker.

In that size box, your Qtc (theoretically) will be 1.25. This is a little high for some folks, but works well for rock and metal IME. What it means is that you will have a couple of dB rise in frequency response around the system resonant frequency. In this case that will be about 55Hz.

Your -3dB cutoff (in free space) would be about 40 Hz.

The confined space of the car will add quite a bit of low end boost, and you should be happy with the results.

Good luck and have fun building!

Tim

skooter 29th December 2007 05:38 AM

Good to hear a positive reply! My music normally consists of rock and roll, steve miller, motley crue, don henley, corn, metalica, cure, billy squire, 75% of the time. then I have some of the newer r&b stuff that is out. and I like to listen to instimental stuff like kraftwerk and some pink floyd too! but thanks for the input!!

jol50 29th December 2007 05:46 AM

Oh great, now I have to dig out my billy squire and cure CDs.... :)


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