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Help w/Rod Birch's Subwwofer box w/rear seat delete

 
Old 07-04-2007, 12:33 PM
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America
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Default Help w/Rod Birch's Subwwofer box w/rear seat delete

I just bought a used set of subwoofer enclosure made by Rob Birch of Car Audio Innovations. After the install of the enclosures, I could not put the rear seat delete storage unit back on. The enclosures lifted the storage unit about 1/2". Anyone have these enclosures and the storage unit installed on there cab. I want to make sure it's not me before I start to chop up the enclosures.
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Old 07-05-2007, 04:30 PM
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No one. Might have to chop them up.
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Old 07-05-2007, 11:59 PM
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You got any pics?
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Old 07-12-2007, 03:18 PM
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Update, after getting everything installed and tunned...I was a bit disappointed. The 8" sub did not kick or hit as hard as I wanted. I was not surprise because when comparing subs and amps at a local store, the 10" subs hit a lot harder. This is what I went with: Kicker 06ZX4001 ZX Series 400W RMS Mono Amplifier and Rockford Fosgate Phase 1 8" subs. These are not high end components, but the middle of the road. Did anyone use different component and got a better results? I know it's everyone has there own sound quality, but if it will make a big difference I will exchage the components.

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Old 07-12-2007, 03:48 PM
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Keep in mind that going from 10" subs to 8" is a big decrease in surface area. The two 10" subs have roughly 50% more surface area compared to two 8" subs. In addition, larger speakers have a lower resonant frequency.

Did you confirm that the enclosures are air tight and well sealed between the sub and the box? That will make a big difference. Also, what's your cross over arrangement? What's your head unit? Are you running low level cables from the head unit to the amp? Are the subs wired in parallel or serial? What's the impedance of the speakers?
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Old 07-12-2007, 05:30 PM
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For sure the enclosures are not air tight. Where do you get the impedance rating from? Is the rating of 4 ohms the impedance? I believe I did a parallel install, but need to go home to look at my diagram again. As for the low level cable...what the heck...I did read that in the manual, but I didn't have one. I just split the signal from the other amp under ther seat with regular RCAs. I don't know if the head unit cable to the first amp is low level. It was install by professionals. That might be the problem, but I think it's more the 8" sub than anything else.
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Old 07-12-2007, 10:44 PM
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The 4 ohm is the impedance. If they are in parallel, then your impedance load on the amp is 2 ohm. That amp can go down to that. If they are two ohm and you are in parallel, then you are over loading your amp.

You didn't mention a cross over. If you are sending the whole frequency range to your subs, that is no good. I think your amp has a built in cross over, but you should ensure it is set properly.

If your enclosures are not air tight, that is one problem, without a doubt. Subs require back pressure to "hit hard." Pull the subs, caulk the hell out of your boxes. Also make sure they are rigid. You mentioned earlier that you were going to cut on them. Did you end up doing that?

If 8" subs are set up properly they can sound rather surprising. However, they are not very forgiving. Big subs can be slapped in with duct tape and still sound pretty good because they can still move a lot of air. But little subs really require attention to detail.
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Old 07-12-2007, 11:54 PM
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My subs are 4ohms and are wired to parallel like my diagram. I set up my built in cross over to a low frequency. The only other thing is that my subs are not air tight. I am not sure how to make it air tight as there is carpet around my sub enclosure. In the corners of the sub I can squeeze my fingers through. I going to take them apart again and see how I can make it more air tight.
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Old 07-13-2007, 10:26 AM
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The sub really has to be air tight to the enclosure. In addition, the sub boxes have to be totally air tight, all corners, all seams, etc.

If there is enough space for you to slip your finger into the enclosure, you have found your problem.
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Old 05-31-2009, 04:28 PM
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If the 8" subwoofers are wired properly (one could be out of phase, backwards, which will negate the output of both, this can be checked by disconnecting one sub, and if the bass is suddenly "louder" then the problem is one wired backwards. When subs are wired out of phase/polarity, they actually absorb the output from each other, since they're moving opposite, if that makes sense. We still come across that every now and then in our installations, even if you're sure you followed wiring at both ends-it happens. A pair of 10's will make more bass, all things being equal, but not so dramatically as to make the dual 8's appear inferior. The surface area isn't that much greater... I suspect if someone's not getting much output from these enclosure panels, even without the subs we recommend, the panels are not fastened securely and sealed pretty well. They don't need to be perfectly sealed, the car interior is very forgiving, but not fastening them down will greatly reduce their efficiency and output, as well as lower frequency response. If they're close to airtight, rigidly mounted, and wired properly, the bass will be clean, tight, and have very satisfying response. Period. There are about 800+ of these setups in operation worldwide as of late 2008 or so....
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Old 05-31-2009, 05:59 PM
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I have the same setup, different amp, and older 8" subs, and it kicks butt. Probably a wiring issue, I can feel it in my back they work so well.

Well it did until I had the Roll Bar installed, they don't fit anymore, and really can't hear sh*t with the windows down, and the helmet on.
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