Having trouble finding sealed enclosure for my two SWS-12d2... Please Help


heimsothe

Member
Dec 25, 2013
66
0
Portland, OR
I am purchasing two Alpine SWS-12d2 subs and an Alpine MRX-M110 amp, it is my very first setup and I know a lot of people don't like prefab enclosures, but I've heard sealed ones aren't that bad considering they aren't tuned. Plus, I want a sealed enclosure, not ported. Alpine lists the recommended sealed enclosure size as .9 cu ft. per sub, so for two of them would I be correct in simply saying I need a sub box with 1.8 cu. ft? If this is true my trouble is I can't seem to find an enclosure that has 1.8 cu ft. The closest I've seen is 2 cu ft. Where could I find one with that size? Or am I wrong in thinking that I should be looking for a 1.8cu ft. box because of the .9 per sub x 2? If so what size should I be looking for?

Also if this matters, I believe, not sure, the displacement is .06 cu. ft. per sub... I got that from pg. 3 of the manual pdf, I think I'm correct in thinking that is the displacement. I don't know if I should be factoring this into my sub box calculations or not... for example if I buy a box that is 1cu. ft per sub (2cu. ft. total) would I subtract .12cu. ft. because of the two alpine subs leaving me with 1.88cu. ft for a sub enclosure?

So yes, as of now I do want to buy sealed and prefab for my first setup.

I hope I'm not confusing anyone or mixing anything up! Sorry I'm a newb. Just trying to get the right size enclosure, and yes sealed //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Thanks everyone

Eli

 

Jeffdachef

Gunz That Turn on Nunz
Feb 5, 2013
17,860
503
South Coast Metro, CA
I am purchasing two Alpine SWS-12d2 subs and an Alpine MRX-M110 amp, it is my very first setup and I know a lot of people don't like prefab enclosures, but I've heard sealed ones aren't that bad considering they aren't tuned. Plus, I want a sealed enclosure, not ported. Alpine lists the recommended sealed enclosure size as .9 cu ft. per sub, so for two of them would I be correct in simply saying I need a sub box with 1.8 cu. ft? If this is true my trouble is I can't seem to find an enclosure that has 1.8 cu ft. The closest I've seen is 2 cu ft. Where could I find one with that size? Or am I wrong in thinking that I should be looking for a 1.8cu ft. box because of the .9 per sub x 2? If so what size should I be looking for?
Also if this matters, I believe, not sure, the displacement is .06 cu. ft. per sub... I got that from pg. 3 of the manual pdf, I think I'm correct in thinking that is the displacement. I don't know if I should be factoring this into my sub box calculations or not... for example if I buy a box that is 1cu. ft per sub (2cu. ft. total) would I subtract .12cu. ft. because of the two alpine subs leaving me with 1.88cu. ft for a sub enclosure?

So yes, as of now I do want to buy sealed and prefab for my first setup.

I hope I'm not confusing anyone or mixing anything up! Sorry I'm a newb. Just trying to get the right size enclosure, and yes sealed //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Thanks everyone

Eli
get the 2 cubic feet box one its fine. make sure its NET cubic feet, not gross cubic feet. Gross is total number not accounting in thickness and other stuff. .1 - .2 cubic feet off, your not going to see a noticeable difference in performance.

 

Jeffdachef

Gunz That Turn on Nunz
Feb 5, 2013
17,860
503
South Coast Metro, CA
I am purchasing two Alpine SWS-12d2 subs and an Alpine MRX-M110 amp, it is my very first setup and I know a lot of people don't like prefab enclosures, but I've heard sealed ones aren't that bad considering they aren't tuned. Plus, I want a sealed enclosure, not ported. Alpine lists the recommended sealed enclosure size as .9 cu ft. per sub, so for two of them would I be correct in simply saying I need a sub box with 1.8 cu. ft? If this is true my trouble is I can't seem to find an enclosure that has 1.8 cu ft. The closest I've seen is 2 cu ft. Where could I find one with that size? Or am I wrong in thinking that I should be looking for a 1.8cu ft. box because of the .9 per sub x 2? If so what size should I be looking for?
Also if this matters, I believe, not sure, the displacement is .06 cu. ft. per sub... I got that from pg. 3 of the manual pdf, I think I'm correct in thinking that is the displacement. I don't know if I should be factoring this into my sub box calculations or not... for example if I buy a box that is 1cu. ft per sub (2cu. ft. total) would I subtract .12cu. ft. because of the two alpine subs leaving me with 1.88cu. ft for a sub enclosure?

So yes, as of now I do want to buy sealed and prefab for my first setup.

I hope I'm not confusing anyone or mixing anything up! Sorry I'm a newb. Just trying to get the right size enclosure, and yes sealed //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Thanks everyone

Eli
get the 2 cubic feet box one its fine. make sure its NET cubic feet, not gross cubic feet. Gross is total number not accounting in thickness and other stuff. .1 - .2 cubic feet off, your not going to see a noticeable difference in performance.

 

zako

CarAudio.com Elite
Jan 16, 2011
1,355
13
TX
Getting the sealed box size off by 10-20% is not a big deal. Besides the box volume, you want to get a box with thicker MDF material. For prefab boxes, the best you can have is usually 3/4 inch MDF, but there are a lot using cheaper thinner MDF.

However, I must say that Alpine's sealed box recommendation is not optimal for the 12 inch SWS models. The rule of thumb is to set the box volume to get the box qtc as close as possible to 0.7, which results in the best tradeoff between low end extension, power handling, and transient response. Getting it off by a little from 0.7 is not a big deal. The problem with Alpine's SWS sub is that in a 1cu ft box, its qtc is like 1, which is considered way off by some. They list the qtc value in the manual for each box. To get the qtc under 0.8 with the 12 inch SWS sub, you need like a 2cu ft box according to the box modeling software. An Alpine engineer mentioned that they aimed for a high qtc setup to provide a stronger thump appreciated by some car audio enthusiasts, which however, does not explain why the 10 inch and 15 inch SWS subs have a more reasonable qtc in the recommended boxes.

Anyways, just get the box that's most convenient to you. Try to stuff it with polyfill. The rule is thumb is that stuffing up to 1.5 pounds of polyfill for each cu ft of space can increase the apparent box volume by up to 30% and lower the box qtc. If you haven't bought the subs yet, consider just one 15 inch SWS if you can fit the box. They're considered to be the gems of the SWS lineup. People have got phenomenally good sound with 2 15 inch SWS each in 2cu ft box.

 

bbeljefe

CarAudio.com Elite
Jul 19, 2013
1,813
1
Shreveport, LA
First of all, your assumptions about adding the volume for the two subs is correct. I don't know about the displacement because I don't know how the manufacturer of the box you're looking at figures it. They may account for the displacement of two average subs or they may be stating total internal volume. But either way, that box will work just fine for you because as was mentioned, a 10-20% variance in sealed alignments will make no audible difference.

And if you don't mind answering... why is it that you prefer a sealed box over ported?

 
OP
heimsothe

heimsothe

Member
Dec 25, 2013
66
0
Portland, OR
Getting the sealed box size off by 10-20% is not a big deal. Besides the box volume, you want to get a box with thicker MDF material. For prefab boxes, the best you can have is usually 3/4 inch MDF, but there are a lot using cheaper thinner MDF.
However, I must say that Alpine's sealed box recommendation is not optimal for the 12 inch SWS models. The rule of thumb is to set the box volume to get the box qtc as close as possible to 0.7, which results in the best tradeoff between low end extension, power handling, and transient response. Getting it off by a little from 0.7 is not a big deal. The problem with Alpine's SWS sub is that in a 1cu ft box, its qtc is like 1, which is considered way off by some. They list the qtc value in the manual for each box. To get the qtc under 0.8 with the 12 inch SWS sub, you need like a 2cu ft box according to the box modeling software. An Alpine engineer mentioned that they aimed for a high qtc setup to provide a stronger thump appreciated by some car audio enthusiasts, which however, does not explain why the 10 inch and 15 inch SWS subs have a more reasonable qtc in the recommended boxes.

Anyways, just get the box that's most convenient to you. Try to stuff it with polyfill. The rule is thumb is that stuffing up to 1.5 pounds of polyfill for each cu ft of space can increase the apparent box volume by up to 30% and lower the box qtc. If you haven't bought the subs yet, consider just one 15 inch SWS if you can fit the box. They're considered to be the gems of the SWS lineup. People have got phenomenally good sound with 2 15 inch SWS each in 2cu ft box.
Thank you for the input Zako, I bought an audio enhancers box, the one I linked in my previous reply, which has 2 cu ft. total. 1 cu ft. per chamber. I mean I could return it/cancel the order since it's off my amazon account if you think a bigger sealed box would make my subs sound better? Or will this box suit me well with a little polyfil? Thanks!

First of all, your assumptions about adding the volume for the two subs is correct. I don't know about the displacement because I don't know how the manufacturer of the box you're looking at figures it. They may account for the displacement of two average subs or they may be stating total internal volume. But either way, that box will work just fine for you because as was mentioned, a 10-20% variance in sealed alignments will make no audible difference.
And if you don't mind answering... why is it that you prefer a sealed box over ported?
To answer your question, I know that a ported box can sound just as good if not better than a sealed any day of the weed if its a well built ported box, but I have read that it is really just hard to come buy a prefab ported that is of that quality. I don't have the knowledge nor resources to build a ported at this time either. So I chose sealed because I've read around and from what I've picked up a prefab sealed's of decent to good quality are not as hard to come by. This box is 3/4" mdf, not thin mdf by the way.

 
OP
heimsothe

heimsothe

Member
Dec 25, 2013
66
0
Portland, OR
Why do you recommend that box? I'm certainly not shooting your response down, just am curious. It has 2.46 cu. ft, plus poly fill. Wouldn't that be too much space? Or? Sorry I'm new with this stuff. Whats your reasoning?

 
OP
heimsothe

heimsothe

Member
Dec 25, 2013
66
0
Portland, OR
They list the qtc value in the manual for each box. To get the qtc under 0.8 with the 12 inch SWS sub, you need like a 2cu ft box according to the box modeling software. An Alpine engineer mentioned that they aimed for a high qtc setup to provide a stronger thump appreciated by some car audio enthusiasts, which however, does not explain why the 10 inch and 15 inch SWS subs have a more reasonable qtc in the recommended boxes.
Sorry for another reply, but also did you mean to get under .8 for the qtc on the 12 inch sws I would need 2 cu ft. per sub or total?

 

winkychevelle

CarAudio.com Veteran
10+ year member
Jun 21, 2009
3,725
43
Ponchatoula, La
those subs like large enclosures. proper sized would be 2cubes sealed each but you can cheat it a bit with polyfill.

2.5-3cubes with polyfill should sound fine really there isnt much to worry about i would fit the biggest you can or are willing to go with

 
OP
heimsothe

heimsothe

Member
Dec 25, 2013
66
0
Portland, OR
So I should go against the recommended alpine specs of around 1cu ft. per sub?

I'm not sure going with the bigger enclosure will affect this but the thought popped into my head and I figured I'd ask. Will going with the larger sealed enclosure, say 2.5-3 cu. ft, will that still give me good bass on the tight punchy songs? I listen to a wide range.

Thanks guys for all the help so far!

 
Last edited by a moderator:
OP
heimsothe

heimsothe

Member
Dec 25, 2013
66
0
Portland, OR
I canceled my sub box order on the 1 cu ft. per chamber box. I want my subs to be able to deliver a good mix of bass, not overly "boomy", and not overly tight and punchy, but a good mix of both. So what size enclosure should I go for for these 2 sws-d2s?

 

zako

CarAudio.com Elite
Jan 16, 2011
1,355
13
TX
I value practicality above the alleged SQ benefits, so I wouldn't buy subwoofers that don't cooperate well with reasonably sized sealed boxes. However, if I already had those subs, I'd just use 1cu ft per chamber, or maybe 1.4cu ft at best. It takes too much space otherwise. In the end, you normally can't buy a sealed box bigger than that. If I was willing to have a 2cu ft sealed box or bigger, I'd get the SWS-15 in a sealed box, or possibly something else in a ported box.

 

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