# What happens on a THIN subwoofer if box size gets increased



## joms (Mar 10, 2005)

Given that we are talking about JL's new THIN subwoofer.
The recommended size of the JL 13TW5 is : (W x H x D) 19.0 in. x 15.0 in. x 7.75 in. (SEALED). Ported, as per manufacturer, is not recommended. 

If say i increase the width from 19 to 22, or make the depth bigger, what would the effect be on the SQ/loudness of the sub? (powered by a JL HD750/1 - 750watts rms).


Free Air Resonance (Fs): 27.52 Hz
Electrical “Q” (Qes): 0.511
Mechanical “Q” (Qms): 11.230
Total Speaker “Q” (Qts): 0.489
Equivalent Compliance (Vas): 2.10 cu. ft. / 59.47 liters
One-Way, Linear Excursion (Xmax)*: 0.383 in. / 9.7 mm
Reference Efficiency (no): 0.233%
Efficiency (1W/1m)**: 85.87 dB SPL
Effective Piston Area (Sd): 98.256 sq. in. / 0.0634 sq. m.
DC Resistance (Re): 2.793 ohm
Nominal Impedance (Znom): 3 ohm
Thermal Power Handling (Pt): 600W
Driver Displacement: 0.052 cu. ft. / 1.47 liters
Net Weight: 18.6 lbs. / 8.4 kg


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## cmayo117 (Aug 14, 2009)

The depth of the subwoofer compared to the depth of the box doesn't really matter, but changing the size of the box will affect the response. Is this going to be a ported box?


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## Oliver (Jun 25, 2007)

It will play a little lower and handle less power.



> Equivalent Compliance (Vas): 2.10 cu. ft. / 59.47 liters
> 
> Subwoofer Volume
> (net int.) External Dimensions
> ...


The Qtc will go down towards .707 if the box is bigger


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## joms (Mar 10, 2005)

this is in a Sealed enclosure. Some say that if I increase the box size, the subs will go louder, softer. Is it true? If so, how loud? tnanks


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## m3gunner (Aug 6, 2008)

It's tricky to predict that without plotting the response in your car.

A Qtc of 0.707 gives the "flattest" and cleanest response for a sealed enclosure. Anything above that will have a peak in response at the resonant frequency and anything below that will get a "droop" in response. A$$hole is dead on in his assessment.

Making the box bigger will reduce Qtc. This might work well in a car due to the transfer function (that's why most IB subs work so well), but it will also reduce the power handling of the driver and you already have plenty of power on tap to blow up this sub. In fact, JL Audio doesn't recommend running that sub with that level of power... they will void the warranty with anything over 500 watts to the sub.

Your best bet is to build a box, put it in your car and see if it's loud enough for you. If not, you might need to investigate another sub...


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## joms (Mar 10, 2005)

by the way, this will be placed in a hyundai santa fe SUV. (1 cabin)


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## Oliver (Jun 25, 2007)

Nice vehicle > http://img0.netcarshow.com/Hyundai-Santa_Fe-2010.jpg


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## sirsaechao (Jan 25, 2010)

Depending on your listening preference and space available...but I would stick to JL specs.


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## joms (Mar 10, 2005)

sirsaechao said:


> Depending on your listening preference and space available...but I would stick to JL specs.


I don't get this reply at all. What question are you trying to answer?


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## cmayo117 (Aug 14, 2009)

joms said:


> I don't get this reply at all. What question are you trying to answer?


What box size you should use depends on your listening preferences and how much space is available. Just do what he said and use JL's recommended box size. I doubt you will notice that small of a difference.


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## joms (Mar 10, 2005)

cmayo117 said:


> What box size you should use depends on your listening preferences and how much space is available. Just do what he said and use JL's recommended box size. I doubt you will notice that small of a difference.



Actually, if you look at my post, i was asking "what the effect in SQ/loudeness will be if one increases the size of the box". 

answering it with "depends on your listening preference and how much space is available" is i believe inconsistent with the question. I don't think that the effect of increased box size would have any relation to one's listening preference. Do you mean that if i want jazz and increase the box size then the result will be AAA, while if i want rock and increase the box size then the result will be BBB???


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## sirsaechao (Jan 25, 2010)

joms said:


> Actually, if you look at my post, i was asking "what the effect in SQ/loudeness will be if one increases the size of the box".
> 
> answering it with "depends on your listening preference and how much space is available" is i believe inconsistent with the question. I don't think that the effect of increased box size would have any relation to one's listening preference. Do you mean that if i want jazz and increase the box size then the result will be AAA, while if i want rock and increase the box size then the result will be BBB???


JL spent time and $ on the R&D on the TW5 to fit in a shallow box for a reason. Stick to JL's spec is best in shallow sub's...anything with defeat the purpose of buying a thin woofer.


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## cmayo117 (Aug 14, 2009)

joms said:


> Actually, if you look at my post, i was asking "what the effect in SQ/loudeness will be if one increases the size of the box".
> 
> answering it with "depends on your listening preference and how much space is available" is i believe inconsistent with the question. I don't think that the effect of increased box size would have any relation to one's listening preference. Do you mean that if i want jazz and increase the box size then the result will be AAA, while if i want rock and increase the box size then the result will be BBB???


If you wanna know the difference in SQ and loudness, then download winisd.


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