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Ever seen this? Varying port area in same box


rambronco

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So I bought a prefab box.....I know, I know. Its for a buddy who has the typical 10" in a .5 cu.ft. box and wonders why it doesn't get low. I picked up the prefab after measuring it and was pretty happy with my findings .95 cu ft Net with 25 sq in of port 22" long. (I know that is a lot of port area but my Sundown SD-2's are running near identical and the combo is solid). I noticed that at the "L" for the port the inlet to the port is 12.5 sq. In. and as mentioned the outlet is 25 sq. In. its almost like a box for 2 - 10" subs cut in half but it was clearly built for 1. Any insight on what effects this might have on performance? the small surface area is considerably shorter than the large so the actual port volume is more like a 25 sq In. port. I have never seen this before and was unable to find anything online.

Thanks in advance RB

01 Chevy Silverado X-cab

2 Sundown Z18v4 walled on 2 Lanzar Opti 7k's strapped at 1/2ohm = each amp wired to 1/4ohm. Havent checked impedence rise so not sure what they are actually seeing. 6 group 31AGM's.

2-Eclipse 34230's each one running 2 Eminence 6.5" Beta 6A. These are beastly mids rated at 350w program power. I was skeptical but the eclipse amps are 370w x 2 and when there was 4 mids on 1 amp I could push it into thermal protect within a song so added the 2nd amp. 

Eclipse 4212 running 4 CT sounds Meso tweeters. and 2 DLS ultimate tweeters up high to raise the soundstage.

 

96' Ford F350 4wd 4d long bed 7.3 diesel with 91k miles. Will be the sound quality rig if I can ever find the time.

 

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Thanks Joe. I know that there is an issue but was hoping that maybe someone had experience with this exact issue or what the effect would actually be? I am going to take it back tomorrow and see if all were built the same (I am guessing that they are) and if so, return it.

RB

01 Chevy Silverado X-cab

2 Sundown Z18v4 walled on 2 Lanzar Opti 7k's strapped at 1/2ohm = each amp wired to 1/4ohm. Havent checked impedence rise so not sure what they are actually seeing. 6 group 31AGM's.

2-Eclipse 34230's each one running 2 Eminence 6.5" Beta 6A. These are beastly mids rated at 350w program power. I was skeptical but the eclipse amps are 370w x 2 and when there was 4 mids on 1 amp I could push it into thermal protect within a song so added the 2nd amp. 

Eclipse 4212 running 4 CT sounds Meso tweeters. and 2 DLS ultimate tweeters up high to raise the soundstage.

 

96' Ford F350 4wd 4d long bed 7.3 diesel with 91k miles. Will be the sound quality rig if I can ever find the time.

 

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Quick question. Is the width and height of the port at the opening the same as the width and height inside the box? If you devide the L into an upright and a leg, the upright and leg can be two different lengths. That would make some feel that the port dimensions are different. Its all about the port width and height being the same at each end. The length can vary according to tuning.

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If it is built for one sub, it should be the same size in the back as the opening.

Only when it is for two subs with the port in the middle should the rear portion be half the size of the center portion.

Current system:

1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s

Previous systems:

2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz.

1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz.

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