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Discussion Starter #1
I have recently read online (It must be true!) that "A 10 inch woofer in a 2 cubic foot box will put out deeper bass than an 18 inch woofer in a 2 cubic foot box." This is because the 18 inch woofer is suffocating and choking in a box that is to small. Is this correct and what are the limits? would a JBL GTO 8" in a small box play deeper than a JBL GTO 10" in the same small box? I have been out of audio for a while and I was always under the impression that the bigger the sub; the lower it plays.
 

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I have recently read online (It must be true!) that "A 10 inch woofer in a 2 cubic foot box will put out deeper bass than an 18 inch woofer in a 2 cubic foot box." This is because the 18 inch woofer is suffocating and choking in a box that is to small. Is this correct and what are the limits?

It's probably correct but there are very sharp limits. Load a subwoofer's T/S parameters into WinISD and first let WinISD choose the optimal sealed box. Now half the size of this box. The deep bass output at lowest frequencies will drop a couple dBs or so. If you make the box bigger, the opposite happens. Not a huge difference in SPL. However! While keeping the much bigger box, switch to the cone excursion graph. The excursion at lower frequencies has probably gone wild! So yes, you get a little more deep bass extension in a bigger box, but now you lost you subs power handling! Not a smart move. And besides, in order to match a 10s output, an 8 inch subwoofer needs to move a lot longer.. hitting its limits faster..
 

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It depends on the sub, some play deeper in a small box but are usually less efficient thus need more power to go same loudness. They might take a ton of power and end up going louder.

All equal a larger sub in an ideal box will play deeper and have more output. More cone area gives it more efficiency so it has more output, and typically larger sub will have a lower tune (Fs) so it can play lower.

If you take the same box and put a larger sub in it (that has the same build/etc) then it will tune higher; will have a higher Q. That means it will have more peak in the response and at higher frequency. It really depends in if that is what you want the sub to do. Otherwise find another larger size sub that has a better response in the small box.

WinISD is not that hard to use, really a good idea to just model the subs you are interested in to see what they do. You can download lists of subs for the database with a lot of common subs in them so you don't have to enter them all. There are some great posts here on using winisd, if you put the specs in by hand there is a particular order you put them in....is the only common problem with it, that is because it calculates some values and sub makers often round them off or lie lol.

The important thing is subs with a larger box do play lower, but the smaller the sub the less output it will have. So you get an 8 to play to 30Hz and you can hardly hear it....so how loud do you need it to go? So maybe you find an 8 with massive xmax because you can only fit an 8, and make it work. If you put a larger sub in a smaller box and raise the Q, it will drop off faster under the peak so you can get significantly less output below the peak. But every sub is different, reacts differently, so these are only guidelines it really depends on the sub how much it will vary from the typical.
 

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Discussion Starter #4 (Edited)
Thanks guys. I will do some more reading.

I have recently rediscovered early 90's rap (Public Enemy/Skee-lo/Coolio/Eazy-E) and attempting to relive my youth before my wedding this Aug. I may just pull the stock Audiophile sub enclosure (In Ford Expedition) and fill it with water to find out the internal volume so I can better determine what sub to replace the stock 8. I have read on another forum that simply replacing the stock 8 with a JBL GTO 8 will make a huge differance. Any advice on a high excursion 8 that is very efficent and has a 4 ohm load? I have read good things about the JBL GTO, the Tang Band W8-740P, The infinity ref, Cerwin vega used to make a great sub but I dont know about the new stuff. If a high excursion 8 will not work, I may have to do some fiberglass work to expand the OEM enclosure (There is a lot of extra room behind the trim panel that hides the stock sub) and go with a shallow mount 10 or even 12 if space permits. I would prefer the easy rout and just swap the 8. Also, I want to be able to have in-car boom, but I do not need/want to rattle other cars (I turn down my stereo at stop lights b/c I do not want to annoy others (I am getting old)). The stock ford sub sounds good to me, I would just like the lower-sub notes to have more boom. The stock sub is very "Peaky" at the higher end of the low range.
 
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