Subwoofer Box noise

OK I've had this problem before when I wired a friend's system and now its happening on my own, I have no idea what to do.

When I installed his stuff me and my dad built a custom box to fit just right in his trunk it housed to alpine 12" type r's, when we got it all hooked up it sounded horrible, it was really shaky and rattling like mad.  I tried numerous things, different crossover settings, rerunning wires, even a different hu, but nothing worked.  I blamed it on the subs and assumed I got a bad product (which seemed too coincidental to get two subs with blown voice coils from such a great name).  Time passed and now Im installing my stuff,  me and my dad once again built two boxes to house 2 12" punch hx2's (2 ohm) running off of a 1001bd.  I hooked everything up tonight and I got the same problem, I know there is no way I got bad fosgate and alpine products, I know there is something Im doing wrong with the boxes.  The boxes I have are very small but exact cu match for the hx2s, the type r box was bigger but braced in the middle, we used 3/4 mdf, and caulked all air leaks.  The rattling sounds almost like a blown voice coil but I cant seem to figure out what we could be doing wrong

If your voice coils were blown, the sub wouldn't move.  My first guess is that your gains are turned up too high, and/or you have a bass boost turned up too high.  If so, then your amp is most likely clipping the signal, creating that horrible noise.  Turn off any bass boost, and turn your gains almost all the way down and see if it sounds better.  If it does, set the gains correctly.

If not, then it is probably your enclosure is the wrong size.  For optimum performance, a subwoofer needs a certain size enclosure.  What size is the enclosure you are using?

Steven Kephart

Adire Audio

Thanks for the help you guys, I am going to check the joints this afternoon.  To be completely honest I didnt screw them together because its a complicated box with weird joints and angles and I had heard I didnt have to.  My dad always tells me wood glue would be better because its so strong (hes a carpentry lover who is used to his old 200 watt 8 ohm system from the 70s, doesnt know how much a 2000 watt max system can pound I guess).  I am not running it off of my 1001bd right now though its back at the place of purchase on a warranty return, Im borrowing a 401s from my friend and have the bass boost up half way, although he did turn the gains up pretty high and I never took the time to turn them down for a couple of days of use, figured I would just leave the bass boost down below its limit.  So I dont think its the gains/boost, I think its probably the wood vibrating Ill screw all my joints together and try to hold it nice and tight.  Thanks again

i know...if we had felt the ground rumble in the 70's we would have dove for the cellar! 

You might not need that bass boost at all.  Halfway is pretty high.  Take the time to set the gains on that amp, even if its being used for just one hour.  It's your speakers that are taking the punishment.

     It seems like a lot of people are under the impression that the gain knob is simply a secondary volume control.  This couldn't be farther from true.

  It's very important to the sound quality of your system that the gain on the amp is set to match the output signal from your headunit.  If it's set too high you'll just have a bunch of noise.  If it's too low then your amp isn't getting enough signal.