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chuey_316

My 1st 4th order. Can someone tell me if I'm on the right track?

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I'm doing a rebuild here very soon, and I'm getting the box design figured out. I'm going for a 4 Skar SDR-18's in a 4th order b pillar wall in an 03 Trailblazer Ext, off an rp2000.1d. I'm unsure what to tune it to, so I'm working on 2 designs. one tuned to 50hz, and one tuned to 45hz. Here's what I've got so far.

Either boxes total net will be 36 cubes. 12 on the sealed side, and 24 ported,  with 506 sq. in of port area.  I'm looking for a setup that will sound good from 30 or under, up to 55-60hz, and be capable of 150's on music across the pass band, with the ability to float cans, do hair tricks, ect. Which tuning would be better to go with?

Next question is whether I'm figuring the tuning correctly. When tuning, would I tune for a 36 cube box, or just the 24 cube chamber? The numbers I've came up with so far have been figured by going off the ported chambers size, and I don't want my tuning to be way off.

I had a 7.5 cube ported box tuned to either 35.7, or 37.5 (years ago, can't remember which) with 80 or 90 sq in of port, with an RE 18HC off of 1200w that would do low 50's on music (on an AC, not a TL), and sounded good on almost anything I played. No box I've built since then in any of my vehicles have ever had the same power behind them, and I'm really trying to change that.

Thanks for reading.

Edited by chuey_316

1999 Blazer

AD-244 Alt (soon to be 2)

HU / Pioneer P7800MP

Sub / RE 18HC

Amp / Shopping for a new one

7.71 cubes 118 sq" port area tuned to 34.9hz

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You'd tune using the ported side - your 24cuft airspace.

I'll default other answers to someone who has experience with 4ths

 

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Thank you. At least I was doing something right.lol


1999 Blazer

AD-244 Alt (soon to be 2)

HU / Pioneer P7800MP

Sub / RE 18HC

Amp / Shopping for a new one

7.71 cubes 118 sq" port area tuned to 34.9hz

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I am not an expert on the matter but have built a few. I think your sealed side is going to be too small for 4 18's and that is going to hurt your low frequency response. It would be best if you could get your hands on some box build software WinIsd is good, been using it for years but it will really give you an idea of what your response is going to look like. 


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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You've got the cone area, IMO youd  be better giving up some ratio for it to dig down nice and low.


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 everyone.

How many sq in of port would be good to run? I was aiming for around 500 to match cone area, but a calculator that I'm using is calling for 718. That seems like an excessive amount to use and still keep it sounding good, but then again I'm new to 4th's.

Edited by chuey_316

1999 Blazer

AD-244 Alt (soon to be 2)

HU / Pioneer P7800MP

Sub / RE 18HC

Amp / Shopping for a new one

7.71 cubes 118 sq" port area tuned to 34.9hz

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