Sundown Sa-12 Box help

[austinoliveira 0]

I have a Hummer H3 with dual Sundown sa-12D4's running off a Hifonics BRZ1700.1 with 145 amp alt, big 3, 0 gauge, 8 gauge power wire for the speaker wire. I have them in a box with dimensions 38x21.25x14; .75 mdf. The port is 12.5x4.5x31.5 long. I have made the port longer and shorter and can't seem to get it to peak around 34hz. It sounds like it is peaking around 38 or so to me. I have built many single sub boxes, and all of them end up being just about perfect, but I can't seem to get this dual box to sound correctly. I have made 3 different boxes trying to get my box hitting the lows well, but can't seem to do it. Could somebody please help me to get the right port length for 34hz peak. I have the subs facing up and the port facing towards the right side of the vehicle. Any help will be appreciated.

[lithium 358]

how are you determining that its peaking 38hz? by ear in the vehicle?

[lithium 358]

according to the calculator i used the box is tuned about 33hz. I'm guessing the acoustics of the vehicle can account for the perception of higher tuning. just EQ down the peak until you have the desired frequency response.

[austinoliveira 0]

I'm just gauging by ear, but all the notes around that low don't have the emphasis that they should. The higher 30's tend to be the loudest, and the lower 30's are barely audible. My box is built strong, and sealed all correctly, I even sound dampened the whole roof to make sure i wasn't losing anything through flex, but do you think the vehicle acoustics could really make that much of a difference?

[lithium 358]

I'm just gauging by ear, but all the notes around that low don't have the emphasis that they should. The higher 30's tend to be the loudest, and the lower 30's are barely audible. My box is built strong, and sealed all correctly, I even sound dampened the whole roof to make sure i wasn't losing anything through flex, but do you think the vehicle acoustics could really make that much of a difference?

yes, trying moving the box around. change the direction the port and subs fire and you'll likely hear a difference.

all make sure the port isn't obstructed (firing too close to a wall).

[lithium 358]

what are lowpass and subsonic setting?

[banskevie 0]

I'm guessing the acoustics of the vehicle can account for the perception of higher tuning.

[Dangercdv 4]

Move the box around, change its direction, move it, and test it in different places. Also make sure your port is not too close to a wall or something.

This way, if you dont manage to fix your frequency problem, you can at least find your favorite listning position