Just finished my new install, a 12" xcon in a 2.75ft^3 box tuned to 31hz. This is in the trunk of my 96 Accord. I listen with the seat down so the sub and port are firing into the cabin. All my boxes and setups have taught me that each setup is very different and showcase different songs better than others. The "show off" songs that sound awesome on the previous setup don't usually sound as good when you change things. I get that and accept that, but now I have a new issue.

 

So after I got my xcon playing I was setting the gains and playing around with different songs and was not super impressed, it was loud but I knew it should be louder. so I popped the trunk to go back and check my settings and make adjustments and as soon as the trunk lid opened it seemed like the spl doubled...it was unreal! Why would that happen and is there anything I can adjust to create that effect without having to have my trunk open when I demo? I have the speaker holes in my rear deck sealed off and am going to unplug those holes and see what happens. Will that help? What are the physics at play here? Each install has taught me something but I am at a loss on what I am learning here...

i believe its called port loading/unloading

will box orientation fix this?

You're getting wave cancellation with the trunk lid closed due to the long wavelength at bass frequencies. Things you can try are flipping phase of the subwoofer or using TA if your deck is capable of it to correct for this. Also play around with sub aiming. You may get a better response for SPL with the enclosure completely against the back wall of the trunk firing toward the cabin. I've seen this ends up producing the loudest response of the bunch, but it's harder to blend with the front stage.

Good to know, I will start tinkering this week

Mine was doing the same thing in my malibu. I take it your not sealed off to the cabin? I basically shoved the box as far forward as possible and stuffed sweatshirts real tight around the box.

will box orientation fix this?

It very well could.

 

i've always found the loudest orientation in a sedan was sub and port back, aim toward the license plate, and the box a few inches from the trunk lid. i haven't tried firing forward and sealing off around the enclosure with the exception of my IB install currently. you would also want to seal the rear deck 

Mine was doing the same thing in my malibu. I take it your not sealed off to the cabin? I basically shoved the box as far forward as possible and stuffed sweatshirts real tight around the box.

 

 

I second this ^^^.  I've never had a sub/port firing forward into the cabin setup work right without sealing around the box.  Using old sheets, blankets, sweatshirts, etc. is a good, non-permanent way to test and make sure it is going to produce the results you're looking for.  Then if it doesn't work out there's no fuss or mess to trying something different.  On that note I've always been a fan of firing forward like that.  It's always sounded the most natural to me and it greatly reduces (or completely eliminates depending on the vehicle) trunk and light rattle in the back of the car.  As mentioned by Brendan when you seal up around the enclosure be sure to leave your rear deck sealed up as well.

Thanks, I built the trunk around this setup and I really don' want to completely redo the setup already. I will definitely try leaving the rear deck sealed and sealing around the box. Thanks for all the feedback. You guys rock