box w/less then recommended volume
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=29143
Printed Date: April 28, 2024 at 6:20 PM
Topic: box w/less then recommended volume
Posted By: nyguy4u
Subject: box w/less then recommended volume
Date Posted: March 27, 2004 at 10:25 PM
I have 3 JL 15" W3V2's that are going into a 2001 PT Cruiser. Box will be sealed..made of fiberglass, and sides..bottom.. and back of 3/4 MDF, front will be fiberglass. 80% of the MDF portion of the box is done. Here's my question.. I wasn't going to chamber off the subs, I was going to have the 3 subs in one common chamber, I was told NOT to do that. So i'm taking everyone's advice and building a chamber for each sub. Now, if anyone knows the back of the PT, they will know it's not all that big. Looking at the specs from JL.. here's the recommendations for a sealed enclosure.. 22"W x 16"H x 14.75"D ..volume 2.125ft Now, I am very limited for space, measuring each chamber of my box, it will end up being.. 16"W x 18"H x 16"D I don't have much of a choice, I used every inch of the trunk, and that's all I can get in there. Question is, being it's not exactly to what JL says (it will be smaller then what they recommend), what will happen?. Will it sound odd in anyway?. Again.. not much of a choice for my space, so i'm hoping it will be ok. My width is the biggest problem, pretty much the width of each chamber will be the same width of the sub, but at the same time.. i'm adding approx. 2" of height and depth over of what they recommend. So i'm assuming it will balance out. Am I right?
Replies:
Posted By: DYohn
Date Posted: March 27, 2004 at 11:18 PM
You're putting 3X15" JL subs in a PT Cruiser.?!? Jesus... OK, you made the first good choice about not sharing air space. These babies could destroy each other in one enclosure. With each chamber at 16X18X16, you have almost exactly 2 CUFT for each sub. Taking into account the displacement of the woofer, you are at about 1.6 to 1.7 CUFT, which is a great size for a small sealed enclosure for this driver. You will end up with a great SQ system. The only negative effect that might (and I say MIGHT) be noticable is a lack of very low bass, as a sealed enclosure this small will result in an F3 of about 35 to 40Hz and the increased dampening from the small air space will limit the woofer's excursion. I highly recomend filling the chambers 3/4 full with acoustic stuffing to increase the effective enclosure size and regain some of the lost low frequency ability. You should be fine. How are yu powering them?
Posted By: DjRDifacs
Date Posted: March 27, 2004 at 11:19 PM
you'll be alright ....but I would rocommend all three drivers sharing the same air space (if wired in parralel). Just make sure you brace well and you're good to go.
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Posted By: superstreet786
Date Posted: March 28, 2004 at 5:40 PM
if your volume is less that recommended you will probably blow your sub/subs in time
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---- 1996 Chevy S10 ----
1 Lightning Audio S2.600.2 Amp
2 Lightning Audio 12" Subs
1 Lightning Audio 1 Farad Cap
Posted By: DYohn
Date Posted: March 28, 2004 at 5:50 PM
Same air space: NO. That is foolish and can lead to all sorts of bad things like lowered SPL, blown subs, etc.. Smaller enclosure blows subs: NO, not by itself. It actually allows them to handle more power. They just won't play as low with the same efficiency as they would in a properly sized enclosure. But whay nyguy4u is proposing is actually the RIGHT SIZE sealed enclosures for these subs. Go for it. Don't forget your earplugs in the PTC.
Posted By: Alpine Guy
Date Posted: March 28, 2004 at 6:00 PM
The only draw back of less air space is that you will need to feed them more power to get the full capabilitys.
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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.
Posted By: xTimx
Date Posted: March 28, 2004 at 6:27 PM
3 15"s in a pt cruiser...dude you ahve to post pics of when your done this project!
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xTimx
Posted By: nyguy4u
Date Posted: March 29, 2004 at 12:01 AM
Thanks for the replies so far guys... really really appreciate it!! As far as the 3/4 stuffing.. do I just lay a layer of 3/4 of that stuff on the floor of each chamber and that's it?? You can be sure i'm going to post pictures of this when it's done. Should be soon too, because I want my car back on the road!! Thanks again!!!
Posted By: DjRDifacs
Date Posted: March 29, 2004 at 1:49 AM
DYohn] wrote:
Same air space: NO. That is foolish and can lead to all sorts of bad things like lowered SPL, blown subs, etc..
If a pair of drivers (or more) are wired stereo, then yes it would be foolish to share the same air space. The reason why is because music tracks tend to bounce from the left to right channel during play back, and would throw the drivers off sync with each other. Another reason why is because the left channel could sometimes be recorded louder than the right (or visa versa).
Now if they are all wired together sharing a mono output, two or more drivers will work together and act as one, delivering lower bass notes then they would in seperate chambers.
Either way will work, this is my suggestion and my experience with enclosures.
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Posted By: Ketel22
Date Posted: March 29, 2004 at 1:54 AM
in theory your belief is correct, but all drivers are not exactly identical. the smallest of manufacture errors can throw the subs against each other in a shared chamber.
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Quad L Handyman services
Posted By: speedwayaudio1
Date Posted: March 29, 2004 at 4:25 AM
yes you can use one air space, BUT it's not safe for your woofers. I use chambers in my encloser. I have 8 12's in a 87 full size bronco. 1 cu per sub+stuffing. there is no flex and it's strong and safe any box i have ever build was chamberd a will always be chamberd good luck with your project. post photos when your done.
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Big Dave
Posted By: stevdart
Date Posted: March 29, 2004 at 1:01 PM
I like to use Acousta-stuf https://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-317 Pull the stuffing apart until it is fairly loose and place it in the box up to about the basket height. 1/2 pound per cu ft is more than enough. Don't stuff the box tight. The fibers need room to vibrate.
Posted By: thapimpfromchi
Date Posted: March 29, 2004 at 1:03 PM
Hey fellas. I am running three MA Audio 10" subs in a shared volume box. After displacement its around 2.7cu ft. It hits around 140 db give or take a few. Are you all saying that if i built another box with sepereate chambers, it will be louder?
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1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp
Posted By: xTimx
Date Posted: March 29, 2004 at 6:45 PM
WHAT!!!!!! you have MA audio 10" subs in a shared box and your hitting 140? how many subs you have? i have 2 12" MA Audio's and i'm hitting 137dbs
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xTimx
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