port phase and combined chambers

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=89805
Printed Date: May 13, 2025 at 8:06 AM

Topic: port phase and combined chambers

Posted By: cmrs2k
Subject: port phase and combined chambers
Date Posted: January 30, 2007 at 8:23 PM

Greetings. I have an 03 Tahoe that just saw it's first audio competition over the last weekend. On their Term Lab, I could only pull a sad 145.7db. I didn't expect really high numbers, but I was not happy with what I pulled off. This being said, my system was not complete at the time. I was working with 1 JL audio 1000/1 and 4 Diamond D3 12's. I now have my 2nd JL 1000 back (just a few days too late) and I will be returning my other 2 subs into play. 3 subs per amp again, instead of 4 on 1. I feel that my numbers basically sucked. It seems like I should have been about 2-3 db louder. My subs and ports face up, and each sub is individually chambered. I plan to build a new enclosure in hopes of getting higher numbers. The questions:

1. Should I go 90 degrees out of phase (maybe subs up, port(s) back)?

2. Should my new enclosure house all six chambered together, or should they stay apart?

3. If I do chamber all of them together, should the specified volume per sub be combined verbatim or should I "de-rate" some(ex. each sub needs 2 ft, should I do 12 ft, more, or less)? If so, is there a specific formula?

4. Are there any other thoughts on the subject?

All help and advice is welcomed and appreciated. Thanks.

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Chris R.

Replies:

Posted By: aznboi3644
Date Posted: January 30, 2007 at 9:24 PM

i'd try a crx style box

Posted By: stevdart
Date Posted: January 31, 2007 at 12:44 AM

Everything I know of speaks of keeping driver and port firing in the same direction. You may want to experiment with distance (from the tail gate) and firing direction of your sub enclosure. You may also want to experiment with box size and tuning freq. I would chamber each driver individually, if for no other reason than you will achieve the greatest box strength with that design. If chambered together, there is no de-rating or prorating of air volume. Each identical sub shares the same amount of air space.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Posted By: cmrs2k
Date Posted: January 31, 2007 at 7:14 AM

I'm sorry, I'm unfamiliar. Can you be specific or lead me to pictures of a CRX style box? I don't know that I have ever laid eyes on one. Thanks.

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Chris R.

Posted By: aznboi3644
Date Posted: January 31, 2007 at 4:04 PM

Basics of CRX style box