Okay folks, my first post on here. First of all, I must comment on the hilarity of all the posts i've perused by TUnit. I know a guy that sells Amsoil, so he loved the Amsoil cardboard sub....
I'm looking for an education on the phasing of audio signals in a car setup. I've been running my HU and 4 speakers for some time in my Civic. Recently, i've finally had the funds to drop in a sub. What did i get, Polk, of course. I've been loving my MMC690 6x9's. They're the speakers that made me a Polk customer. So, getting on to the sub...
I purchased a c300.2 and two db804 8" subs. They're designed for 0.35 cu ft each in a sealed box. I made mine a dual 0.4 cu ft, trying to account for the displacement of the woofer. I hooked up my amp and speaker wiring, following all the polarities. I mounted the box with the speakers facing and only inches from the fold-down back seat. I did this so i can haul heavy objects in the trunk without worrying about hurting the subs. With the seats down, the woofers sounded decent. By "decent" i mean that i heard clean bass, but rather little punch. I tweaked my gains and it still seemed like i really had to beat on them to feel and hear any bass. With the back seat up, which is what i really want, they could hardly be heard or felt. I would tweak the sub level on my HU and i could barely tell the difference in the sound between the subs up and down. This was even when i knew i was approaching the Xmax rating on the woofers. I was starting to think Honda put Dynamat in the back seat!
Anywho, i got the idea (from reading posts on here about component speakers) to try and reverse the polarity. I reversed only one woofer and heard a huge improvement. I then reversed the 2nd woofer and the wonder of my "new" sound was incredible. I can now listen to all kinds of music and can really tell the difference with the subs on/off. When i play some hip hop, those little guys produce excellent "feel" as well as audible sound. Even with relatively little woofer movement (far below rated Xmax), i can really hear the bass, even with my back seats in their fully upright and locked position. So whether it's a little Ice Cube or Charlie Daniels Band, these babies are rockin! Not bad for 300W.
As an additional "experiment" i hooked up only one of the db804's bridged on the amp. In that single speaker config, the polarity seemed to make no difference in the sound. Both polarities sounded good.
So, with the subs facing the back seat in a sealed box, was I getting some odd phase cancellation? Sorry for writing such a long post, but i wanted to be detailed in what i did and i'm hoping the replies I get are educational to everyone. I'd like to know about what considerations are needer in regards to phase/polarity in a multi-speaker setup. My experience in acoustics is with acoustic microscopy, so my work is in the MHz range, not Hz/kHz. I also only work only with one transducer at a time. I now have six and i'm confused :D
Thanks in advance,