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poor output from subbox with pictures


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eric21 
Copper - Posts: 49
Copper spacespace
Joined: May 20, 2009
Posted: September 30, 2009 at 8:12 AM / IP Logged  

I built a ported box for 4 12" alpine type r's to go in the back of my crew cab pickup and the bass output is quite lacking imo. Each sub is getting about 750 watts each so 3000 total which should be plenty. Note that this is only for strret pounding and not SPL.

The enclosure is 8.5cu.ft. net and has a port that is 15" x 6" and 22" long. The bass is ok from about 25-35 hertz (still not impressive though) and all other frequencys totally blow.
I've tried the box pointed foward, back and up with the best results being from having the box point up.
I assumed that maybe my port was tuned too low so I made it 12" long instead of 22". It still plays about the same as before believe it or not.
I've noticed that the speakers quickly begin to stink and at many frequencys sound like they are playing freeair. So i'm thinking that I have too much port area for these subs (i know its only 90 sq.in.) but they sound like they need alot more back pressure.

Guys please take a look and see if you notice any places for cancelation or other flaws that might make this box sound so poor. Any design change ideas would be qreatly appreciated.

Thanks!!
Picture of box without speakers 

poor output from subbox with pictures -- posted image.

Picture of inside the box

poor output from subbox with pictures -- posted image.

ragsports 
Copper - Posts: 192
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: March 17, 2008
Location: Michigan, United States
Posted: September 30, 2009 at 9:19 AM / IP Logged  
One flaw i can see is that there is no internal bracing. For a box of that size you have to brace the walls of the enclosure. There is most likely some flexing going on here...
eric21 
Copper - Posts: 49
Copper spacespace
Joined: May 20, 2009
Posted: September 30, 2009 at 10:29 AM / IP Logged  

ragsports wrote:
One flaw i can see is that there is no internal bracing. For a box of that size you have to brace the walls of the enclosure. There is most likely some flexing going on here...

Yeah you are right about that, I got alittle lazy. After I figure out my new design i'm going to add a good amount of bracing. Thanks!

Now if anyone can see anyother problems with my port/box design please let me know! Thanks guys

tommy... 
Gold - Posts: 1,901
Gold spacespace
Joined: December 10, 2004
Location: United States
Posted: September 30, 2009 at 12:14 PM / IP Logged  
Sorry if this seems noobish...But the subs wiring was done correctly...?
M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
eric21 
Copper - Posts: 49
Copper spacespace
Joined: May 20, 2009
Posted: September 30, 2009 at 12:16 PM / IP Logged  

Thats ok, yeah I checked all the phasing of the woofers and even switched them to hear the difference and they are correct.

Thanks though

icearrow6 
Copper - Posts: 497
Copper spacespace
Joined: February 02, 2009
Location: California, United States
Posted: September 30, 2009 at 12:40 PM / IP Logged  
My vote is too big of a box. ~2.1 per woofer is too much in my opinion. I also vote for bracing or individual chambers. Try 1.5 airspace per woofer.. with the 12" slot port.
eric21 
Copper - Posts: 49
Copper spacespace
Joined: May 20, 2009
Posted: September 30, 2009 at 12:54 PM / IP Logged  

icearrow6 wrote:
My vote is too big of a box. ~2.1 per woofer is too much in my opinion. I also vote for bracing or individual chambers. Try 1.5 airspace per woofer.. with the 12" slot port.

Do you think I may be getting cancelation because of the one common chamber for all the subs?

I like the idea of seperate chambers, do you think a 4" areoport per chamber would work ok?

aznboi3644 
Gold - Posts: 2,600
Gold spaceThis member consistently provides reliable informationspace
Joined: May 01, 2006
Location: United States
Posted: September 30, 2009 at 1:27 PM / IP Logged  
icearrow6 wrote:
My vote is too big of a box. ~2.1 per woofer is too much in my opinion. I also vote for bracing or individual chambers. Try 1.5 airspace per woofer.. with the 12" slot port.
Custom Enclosure Design
eric21 
Copper - Posts: 49
Copper spacespace
Joined: May 20, 2009
Posted: September 30, 2009 at 1:46 PM / IP Logged  

aznboi3644 wrote:
icearrow6 wrote:
My vote is too big of a box. ~2.1 per woofer is too much in my opinion. I also vote for bracing or individual chambers. Try 1.5 airspace per woofer.. with the 12" slot port.

When you say 12" slot port, what dimension are you refering to?

KPierson 
Platinum - Posts: 3,527
Platinum spaceThis member consistently provides reliable informationspace
Joined: April 14, 2005
Location: Ohio, United States
Posted: September 30, 2009 at 2:00 PM / IP Logged  
It's hard to tell from the pictures, but there doesn't appear to be any river rocks, moon rocks, pop rocks, or any other types of rocks in the box.
Kevin Pierson
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