SUBS KEEP CUTN OUT..help?

i need help so any suggestions will be appreciated... k so here is my story.. when i turn my system up  my subs cut in and out.. good bass when the volume is low but fucks up when i turn it up(pardon me French) at first i thought it was a power issue so had the battery checked its got 750 cold cracking amps  with 12.5 volts and my alternator is charging capacitor is good  subs r... so maybe the amp(dude at the shop thinks its fine) but like i said its good down low and yesterday it was fine back to its old self then today it took a shit again... could it be a the deck..
have the same setup for about 2 years with no problem  ..

not anuff power to the amp...was the car/truck runing when this happened

yes it was runing.. dosent matter if at idle or driving down the freeway.. like i said never was a problem before.. about a yr ago my old battery went to shit and u could watch the damn vlots drop to like 9 1/2 -10  lights demming and all and it would still bump  i gota fosgate pwer 1100 runin 2 12" kicker L5s  and p2002psuhin focal hgihs all ran of a kenwood dnx7120

I had the same problem with my old memphis amp, try turning the gain down to around 3/4 or 1/2 and then you could turn it up.  Basically what is happening the amp is trying to push so much current through and it's shoots itself in and out of protection real quick, because it can't handle the draw.  Basically you don't have enough current to keep your amp at full gain.  If you still have this issue, you could either upgrade you alternator to a larger one I'd say 200-250 amp, upgrade all grounds, return lines, and sending lines to 4 gauge (alternator to battery, battery to fuse box, battery ground to chassis, battery to starter, starter ground)  just to name a few.  Or you can buy 2 new batteries to run a secondary, depending on how new the one you have is.  If it's old then you have to buy two, because the new battery won't get full amperage if an old battery is in there.   Not judging you in any way so don't think I am, but why use a capacitor, no point what-so-ever, they don't help with larger set-ups and higher ampage.  They cause more damage than what they are worth.  In my opinion, run a secondary battery, upgrade all wiring under the hood, and throw away that damn cap. If you have any more questions let me know, always willing to help.

Check the wiring on the subs. You might have blew one?

my first question is the setup new in any way?  or have you had the same subs and amp for a while now and all of the sudden this started happening, if that's the case then most of the responses above I agree with.  If you just put anything new in, it sounds more like you are running your amp at the wrong ohm level, too low to be exact.  Make sure you have the subs wired correctly per your amp and that the amp can even handle the ohm load you are giving it

i had the same exact problems with my 15's and it was just loose wires... make sure you check that before you do anything else...

sounds like maybe a blown sub...at higher volume the amp is running more power to the subs and obviously is gonna generate more heat and is causing the voice coil to heat up and short out.....

i just got this problem solved with mine.. i am running a JL Audio slash 1000/1v2 with 2 10w6v2-d4. i adjusted my amp, check my ohm levels, now i can turn the deck up to 70 and no more cutting out.. i would adjust everything check the ohms, if still keeps up throw a extra battery or even a cap. if it still dont solve the issue. ask a buddy if they have a amp you can try.. maybe the amp is starting to me up..