Car Stereos: subwoofer static/cutting out, high output alternator, watts rms

Question
QUESTION: Hello,
I recently installed two 10" sony xplod subs with a 1000 watt amp.  When they are turned up to around 30 - 35 they start cutting out, producing a lot of static when they hit. What might cause this?  
Thanks,
Aaron

ANSWER: Aaron,  When you get into that much power, there are many factors involved in the performance of the system.  Right Off the top of my head, I would say that your amp has too much power for the subs you are using.  When you start talking about watts, you need to refer to the "rms" watts, not the max watts.  If the rms watts of the amp are higher than the rms watts of the subs, then it has too much power.  It is ok to have subs with more rms power than the amp, because it is just excess.  If you truly had a 1000 watt rms amp, you would need 0 or 2 gauge wire for power and ground, 60 amp fuse, high output alternator, and at least 1 farad capacitor.  These are the minimums.  So, check out the rms wattages of amp and subs.  Either turn the gain on the amp down proportionally to the amount of power overage there is or just get some subs that can handle whatever rms power your amp is putting out.  Hope this helps, Scott

---------- FOLLOW-UP ----------

QUESTION: Hello again,
The amp is 185 watts rms x 2 @4ohms,or 1000w max x 1 @4ohms,  the subwoofers are 300 watts rms, 4ohm SVC or 1100 max. They sound good at low volumes, but when turned up some,they start to kind of cut out and static when they hit.  it's not really loud though, like it should be.  I wondered about the box sizes, they are in two boxes behind the seat of a truck, not too large, they are ported, would they work better in sealed, or does it matter? Also, I tried one on someone else's amp, it sounded great. I was also wondering about the wiring, they are each connected to one channel of the amp, i think this is at the 4 ohm rating, is there a better way to hook them up, or what should I check next?
Thanks again,
Aaron

Answer
Ok, those numbers make a little more sense to me.  If you are bridging the subs into one channel, you are causing a higher amp "rms" wattage than what your subs can handle.  However, it is not enough higher to cause that much distortion.  I do think I see the problem though.  When you bridge your two subs together into the one channel of the amp, you are creating a 2 ohm load, and the amp is probably not stable to 2 ohms in bridged mode.  I would try wiring one sub to each channel.  185 watts will almost drive you out of the car.  As far as sealed versus ported.  The rule of thumb is sealed is better for smaller boxes, and ported is better for tuning to lower frequencies.  If your subs came in the boxes, from the factory, then they probably tuned them to work with the ports.  If you just added your subs to a couple of ported boxes, then you may get better results from a sealed box.  It is easy to test.  Once you get the subs wired correctly, crank it up, and see how it sounds.  Then, stuff something in the port and cover the hole with a chunk of board taped to the box, and crank it up.  If the sealed box sounds better, you know what to do.  If the ported box sounds better, then use it that way.  Good Luck, Scott