I have a memphis power reference 12 that I just cant make sound right. I have it in a sealed box at 1.8cu/ft. In the hatch of my mini cooper. Its a dual voice coil hooked up at 2ohm to a Jbl 600.1 amp. The problem I am having is that it only really sounds good on songs with low bass. It will pound the crap out of my car on one song and then it will sound ultra quiet and peaky on another. Did I make the box to big? Is my car too small to get good response from a 12? do I need to add some poly fill. I think the specs say 1.2 cu/ft. for a sealed box. But I didnt think it would make that much of a differnce in a sealed application. I always thought bigger was better. I have had this sub in a ported box in another vehicle and it sounded awesome. Or is it that this is more of an spl sub and is just better suited for a ported application, and rap and hiphop. Is my car better suited for a smaller sub? Maybe two 8s or a single 10? Thanks for any input. Eric.
ps if a different sub would work better in this application please feel free to give me some suggestions. I am looking for a good 300-600 rms SQL sub for between 100-200 bucks that will fit into a sealed box and have decent sound on all kinds of music.
I will try and add some blocks to the box to reduce the volume and see if that helps. I have tried adjusting the crossover and it seems to only really sound good closer to 50-60hz. I played the bass mechanics cd and it sounded great but then go to play music and it only sounds good on certain songs. It is just a cheap sub maybe I am asking too much from it.
My friend had two 15" memphis power reference's in a ported box I built for him. It sounded great on most things. I just used the specs they provide on there site. The box was 6 cu ft tuned to 35, but that is for 15"s.
For your twelves is a sealed box they recommend what Canaan said. If you want to try the ported box do 2-2.5cu ft tuned to 35.
I would reduce the size of the box to closer to the 1.2 cu ft region. Size does make a difference, as the amount of air in the box directly correlates to the amount of damping given to the cone of the speaker. Too much air, and there's not enough damping to properly control the driver.
Keep the XO set to 50-60Hz, there I agree. Zero phase, 18-24dB Q, no boost.
Try repositioning the box. rear firing, up-firing, side or down firing (down requires something to elevate the box about 4-6" off the floor. usually "feet.")
the cone diameter has nothing to do with the size of your car's cabin. maturing a full wave is a matter of frequency, not cone diameter or surface area. Any sub producing a 40Hz tone will still be producing exactly that. A 40Hz tone, which is 40 cycles per second, which will always need the same space to mature that wavelength. Larger subs just offer more cone area, and often, greater excursion, which allow them to a: move more air, and b: have more moving mass and thus a lower Fs, typically.
Your problem sounds like a box volume issue, and possibly a directional/positioning issue.