change in design/placement, output loss?
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=111517
Printed Date: June 15, 2024 at 1:37 PM
Topic: change in design/placement, output loss?
Posted By: j.p1nk
Subject: change in design/placement, output loss?
Date Posted: February 11, 2009 at 9:54 PM
i have a 19 and 72 chevrolet monte carlo, with two jl 12w7's powered by 2 jl 1000 amps
okay heres the deal. when i got all of the components of the system, i threw everything in the trunk to see how it would sound. the subs came in a single chambered ported box that would only fit in the middle of the trunk, with subs facing the rear of the car (red square) i hooked everything up and it sounded amazing! everything i could have wanted and more, but the equipment was just loosely thrown in there.
i ran into problems wanting everything to look nice. i ended up building the dual chambered box as pictured above. it has basically the same amount of interior volume as box 1. the only difference is, it's two chambers and it's tucked neatly under the package tray, and it sounds nothing like box 1.
i figure i have all that "energy" trapped in the trunk area because this box is literally about to blow my trunk lid off, box 1 didn't do that. i added two ports (lime arrows above) to try and get some of it up to the cabin and couldn't really tell a difference, i have room for two more ports (blue arrows above) but i don't really think it's gonna help my situation
Basically all i want to know is, there anyway to get all that "energy" trapped in the trunk, into the cabin without scrapping this box. could i scrap the speaker ports and port through the rear deck? do i need to knock the divider out? i have a lot of time invested in this setup and don't want to go back to the drawing board. any ideas or suggestions are appreciated?
Replies:
Posted By: soundnsecurity
Date Posted: February 11, 2009 at 10:09 PM
you said that the original box only had one port, was that one port for both subs in the same box? if so, did you keep the same port length as the original box and use it for each side in the new box? if so the port tuning for each side could be off because you used the same port length for each sub as they originally used for 2 subs in the same box. this can make a huge difference in how it sounds
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Posted By: soundnsecurity
Date Posted: February 11, 2009 at 10:16 PM
and also i just saw how you did those side ports. anytime you pass air through a tube port like you have it can have a good or bad effect. if i were you i would lose those side ports and just make a bigger hole for air to pass through. basically what you have made is a giant bandpass box out of you whole trunk. it sounds like you are about to blow your trunk lid off because all of that air is trying to go through those small ports on the side and small air gaps around the box as opposed to when you just had the original just sitting freely in the trunk. it looks nice though
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Posted By: stevdart
Date Posted: February 11, 2009 at 10:19 PM
Go back to square one, the original box. If you redesign it to make it fit the car better, use exactly the same airspace (cubic inches) and vent structure as the original that you said sounded good. Energy doesn't get trapped in the trunk. Sound waves go through walls like, um, Casper. ------------- 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: j.p1nk
Date Posted: February 12, 2009 at 12:47 AM
yeah the original box had two ports side by side like the box i built, but it has no divider (two ports, one chamber). the box i built is practically identical as the original, except mine fits under the rear deck and has a divider down the middle (one port per chamber) it has the same amount of airspace, same port size and length
i'll knock those round ports out tomorrow, and cut oblong holes on each side of the box. it didn't really come to mind that i was turning my whole trunk into a bandpass box. definately not the route i'm trying to go.
Trust me, this "energy" is trapped and not happy about the situation at all! Soundwaves go through trunk lids like, um, Bebop and Rocksteady. I'm joking, if i knew i wouldn't be in here. i appreciate the input guys
Posted By: j.p1nk
Date Posted: February 12, 2009 at 2:25 PM
instead of cutting it, i ended up taking the carpeted trim panel, in front of the box, out today. there was a lil bit of improvment, but still not like the box sitting freely in open trunk.
i've pretty much came to the realization that i can't fill that cavity (behind the rear seat, below the package tray) with speaker box, and still get the sound i'm looking for. i see it done everywhere, it's just not working in this trunk.
i take pride in doing things myself, but this is driving me crazy! bout to head up the the local audio shop, and see how much it'll set me back to this done right. i'll be sure to stop and get some lube!
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