Sealed trunk issues

[FCS530]

So I was pretty impressed at my first show with my car. In my signature you can see I have 2 SQ sdc2.5 12's on a Hifonics BE 1700.1. It was in my civic with the subs and port firing backwards. It did a 141.9 at 38hz (MECA @ headrest). With this setup there was a very small noticable difference with the seats up or down. Upon some advice and research I did tons of work to completely seal off the trunk and spin the box around. It involved completely removing the back seat, all plastic panels and all trim. I made a cardboard template and cut a peice of MDF that fills about 80% of the space. After I secured that I used Great stuff and sound deadener to seal off the rest of the gaps. Short of a few small slots for the seat belts, It should be all sealed up. So I now have the subs and port forward with the port on the driver side. First impressions: doesnt sound as good, lower frequencies are about as loud but the higher ones are almost gone, shakes the roof way more (now cracked by sunroof) and I get nearly no sound with the seats up. The real kick in the balls was going to the Reno shows this weekend and only being able to hit a 138.6 @ 38hz (MECA @ headrest), and this was with beating them up way more than I like to. I have also put in a larger alternator between shows. So at this point I am ready to "unseal" the trunk and put it back the way it was. I had way more trunk space and it was much nicer to be able to get bass with the seats up. I understand that accoustics are tricky and this is a relatively small system, but over 3 db is a big deal to anyone! Thoughts?

[soundstream15]

Try and open your trunk? If its louder with it open then your not 100% sealed. Some ppl gain, some ppl don't gain and in your case some will loose.

What kind of car?

[__d_a_v_i_d__]

Did you try opening your trunk and get it metered like that ? If there's a significantly gain that means you aren't sealed correctly .

Only thing I can think of, it's not for every car .

I did gain by doing it. Hell I gain hairtricks .

[FCS530]

I didnt get it metered both ways, but to the ear it makes no difference (trunk open or closed). The trunk lid doesnt even move now (the only advantage). It certainly moves alot more air through the front windows now, I guess thats a good thing? I just prefer the way it sounded before, I like being able to put my seats up and higher numbers! The only thing keeping me from putting it back is the amount of work that went into it! I was just hoping that I was missing something.

[DubNDodge]

Your peak will be different for sure. If it was at 38hz before, it could've moved up or down from that 38hz. My guess, would be down. Did you play low stuff before you sealed off? Try playing those same songs to see if they are louder. You will just have to do more testing to see where you gained and where you lost.

[n8ball2013]

Did you sesl the resr deck too

[Bump4life]

did you meter at any other frequencies? my peak changed from 46hz to 42 hertz when i turned my subs and fired inward. and youll notice a difference by ear when you open your trunk. you dont need a meter to tell fully. unless you are almost there.

[FCS530]

I tried from 36 to 41 (tones) and it definetly peeked at 38. Same as the other direction. I havent changed any songs I play. Definetly not louder on anything, tones or music. It just moves more air. And rear deck is sealed w/ deadener, except that the 6x9s are still in there. I am NOT going to remove them! LOL! I think I am just going to tear it all out and go back to where I started. At the very least I can have bass with people in the back seat!

[TRTC360]

some cars just don't do well like that, I believe anton millers cavalier didn't work well sealed, he also has a gap where his box rests on where his spare tire used to be, if he covers that gap up he loses on the meter, it's weird how it works but that's just how it is.

[FCS530]

^{OK, may have a theory. See if anyone else agrees. I thought my box was tuned around 33hz. I just ran the numbers in torres and it put me just over 30. On the RE calculator it says just over 28. I originally used the 12volt calculator and I may have messed up some of the calculations. Now I was thinking the the back pressure or resonance from facing back was actually increasing the tune to a more usable frequency? Maybe with less pressure on it, the tune is just to rediculously low now? I may be able to remove some of the length of the port and get it up to 34 (according to torres). Possibly the issue?}