Ok I built my own box and my brand new MTX 4000 12's sound like crap, the box is too big for them I think. I have a 400 watts going to them and they have no thump to them whatsoever. I made just a square box and its like 34 wide x 15 tall x 16 deep. Its all sealed up good and I hope its just the box all the stuff is brand new. What size should the box be?? Is the angled front hatch style box any better?? I really just need to know what the dimensions should be for 2 12's, they call for 1.25 cubic feet.

 

How bad do they sound? Just not as loud as you expected? Or really bad? You might have wired them out of phase with one posive speaker wire lead going to the negative terminal of the speaker. Even the best of us do it by accident once in a while. Check the vitals first before you go scrapping the box. It's pretty hard to get a box that is too big with our cars. A 2.5 cubic foot box is pretty darn big for our cars if you ask me.

 

Where do you have this box sitting? I'm guessing from the dimensions you gave that it's sitting in the back seat. First I'd do like 330hp suggested and switch the wires for one of your subs. If it is noticibly louder, that is the primary source of your problem. If that doesn't make a difference and/or makes the bass quieter then you had it wired right the first time, so switch it back. Second, open the doors and/or hatch. If you notice it get noticibly louder then you've got some reflection/phase cancellation issues. That means you need to move/reposition your box so that the subs are firing in a different direction or from farther away. According to my calculations your box is about 6361.875 cu. in. or ~3.68 cu. ft. so you would need to lose about a cubic foot. Lastly, what amp are you using? Is it 400 watts RMS or max? You could just be underpowering you subs, hence the lack of output.

 

If I unplug one of the speakers its really loud like it should be and sounds good but when I plug the other back in and vice versa it just sounds quiet and distorted when the bass hits. The amp is a Profile Claurus 800 watt max 400 x 2 RMS amp. I wonder if making the box smaller would make it sound better, it sounds like I only have 10 watts going to each speaker when they are both hooked up. Is there anyway to test the out put of the amp?? I also have 2 Pioneer 10's in my other car with the same amp and they sound better than they should so I dont know whats up. Its alot of money to spend and I know it should sound way better, the 6 x 9's hit harder than what they are.

 

yeah i had the same subs they did suck i blew 9 of the dang things before getting volfenhags never had a problem(cuircut city warrenty helped me on it).

 

800 watts max does not equal 400 x 2 RMS... 'fact I'd wager that Profile amp to be maybe 100x2... could just be that you've got the gain cranked way up and the amp is distorting. Did you use the same amp settings on the Pioneer subs?

If you had one sub wired out of phase, you'd get almost no bass out of the setup. Think of two people pushing with equal strength on a car, one person pushing from teh front of the car, the other person pushing from the back of the car- the car ain't gonna move. That's why you'd get no bass. Put both people pushing from the same side of the car, and you get some action. So if this is the case, just make sure the amp's (-) goes to the sub's (-) and the amp's (+) goes to the sub's (+), for both subs.

The profile amp -might- also have a phase switch, but I doubt it. Does your head unit allow for switching the phase? My Pioneer has that feature. Never played with it though; haven't had to.

 

How do I tell which is which as far as + and - goes it is not marked on the speakers terminals but there was a dab of red paint on one of them so I figured that was positive. The amp is from Crutchfield like my other one, they say it runs at 200 x 2 RMS. No phase controls or switchit does have gain, bass boost, and a high/low pass filter with cutoff . I will mess around with the + and - again tomorrow and see what happens.

THANKS

 

If you have a 9 volt battery, you can test the subs to see which is + and which is -. Disconnect the sub from the amp, and place the 9 volt against the sub terminals. (No it won't blow the sub.) Watch the sub cone. If the sub cone pops "out", then your orientation of the 9volt battery is correct- whichever corresponding terminal of the 9 volt battery is (+), that terminal of the sub is (+).

If the cone pops "inward", then you've got the (+) of the 9 volt against the (-) of the sub.

I -think- the + of a 9 volt is the smaller terminal... it's been a few years since I've touched a 9 volt battery

 

I will try that as soon as I can. Appreciate the help Tom.

 

do you have a divider between the subs in the box??? if you don't and you are running the subs in stereo mode you could be staring your problem in the face, try running them in mono mode and see what happens

if they are in the same airspace and running in stereo mode without a divider between them then they will have sound wave confliction and may create the situation you are describing causing what is possibly the most ****tastic listening experience of your life

hope this helps
Andy

 

Believe it or not I did remember that, if I cant figure it out by this weekend I have a sledge hammer that will fix it guaranteed.

 

Thank *** it was the phase deal. I had hooked up one speaker to the amp wrong somehow even after checking , double checking, and triple checking, Damn you would think I was a rookie. I was just fixing to yank the box out and chunk it when I seen it. I also put a system in a 92 explorer today and man it sounded good, Q logic makes some nice boxes, and you cant beat Pioneer price for quality wise.

THANKS TomP :hail: