So my subs and everything used to work great but now for some reason after about 15 minutes the sub stops hitting as hard.....It doesnt turn off it just turns down. Has anyone experienced this? I'm sure I could figure it out, but if someone knows whats going on it could save some time. Thanks in advance.

 

that is kind of a vague question. It could be any number of things, ranging from an issue with current coming into the amplifier to the amplifier itself. depending on what type of amplifier it is, the amp could be rolling back the output to compensate for heat or some other problem.

gimme a breakdown on what is in the car, and I will give you a few things to check.

 

I found a similar problem, but then did the hold down the "audio control" "A" button for 3 seconds.....turns out I was tC mode....

 

well the weird thing is......every time i first get in my car the system hits just fine....then after about 10-15 minutes it hits very quite.....I dont know its wierd...

 

i had that problem the amp was going into protection mode... my highs and mids where doin that when one of the speakers was grounding out.

 

check your wiring, make sure you have ENOUGH ground to begin with. not enough ground will cause, not only your audio equipment, but all electronic components to act funky.

also, a thing about amplifiers, there are some designs that recomp. depending on the thermal temp increase. make sure that your amp is in an environment that alows it to vent enough to keep it's optinal performance.

there is also something known as amplifier apparent VAs. if you are powering your system at near full output of the amp and at the same time have tons of bass boost, apparent VAs sky rocket. this causes MASSive thermal increase and the amp will redirect the amount of output.

imagen a wire thats rated not to go higher then 15amps of current, and you send 50amps through it for 15 minutes. it's going to get hot enough to melt, apparent VAs is the same concept. an amplifier can only do so much before it goes out of it's limits... you could have a 1000watt RMS amp and only be using 300watt out of that with tons of bass boost and you would be exceeding the amps maximum pull and outputbecause the apparent VAs are higher then the amp can handle.

another example, JBL BPX2200.1 has a 2,450watt RMS @4ohm load capability but in apparent VA load which means REAL true power, it has about 2,050VAs of available headroom. now with that said, if you were to use only 400watts of available power from this specifc amp with about a 10db bass boost, already the BPX2200.1 is seeing 2,500VAs and could potentialy lead to thermal meltdown or in other words, the amp will compensate and adjust the input levels internaly.

Apparent VAs = heat, heat = an amplifiers worst enemy.

a good way to learn what your amps VAs are, goto http://www.linearteam.dk/default.aspx?pageid=winisdpro and download WinISD Pro. specify your subwoofers that you are using and what it's TS specs are. specify box size and tunning if needed, your EQ settings and how much power you are through at the subwoofer from the amplifier.

generaly an amplifier's apparent VAs are going to be anywhere from 75%-80% of what the highest RMS power rating is. in other words, the amplifier's efficiency percentage, get your hands on the percentage and you will know what you'r available apparent VAs are. Example: 1000watt RMS @4ohm, efficiency of 85% = 850VAs of apparent VA headroom.

i hope this helps.

EDIT: JBL BPX2200.1 has a 83% efficiency, so a easy way of doing it would be for ever 1000watt theres 830VAs of head room. maximum RMS is rated 2,450watt @ so thats 1660VAs of headroom with the first 2,000watt. now take the last 450watt, take 450 and multiply that by 0.83 and you get the last 373.5VAs. all togethere thats 2033.5VAs of available headroom which goes back to what i mentioned above, get the efficiency and you'll know the VA headroom.

 

maybe try turning down the gain on your amp?

 

Yeah, it sounds like after it heats up it's going into protect mode. Turn it down a bit and see if it will hit longer before shutting down.