tuffluck

iTrader: (4)

i have had problems with my amp seeming to suddenly lose about half of it's power (to my subs). it did this a few years ago and for some reason i unplugged the rca cables and then plugged them back in and it worked fine at full power. fast forward a few years and now it's doing the same thing where it will be half power sometimes and full power other times...more often than not it is half power, like one of the rca cables or one of the amp inputs isn't working. i tried the unplug/plug back in trick and it did the job for a couple of days...now it's back to half power. i've asserted the problem is either the rca cables has one bad one or the amp rca input has one bad one, but i don't know which. is the best way to figure out the problem to buy a new set of rca cables or is there something else? re-running the rca cables is kind of a bitch, not to mention $$ i don't want to spend if that isn't the problem.

cfallsguy

iTrader: (1)

Maybe borrow some if anyone you know has a spare set for a few days? Just try them running straight from the HU to amp, dont bother trying to hide em if it does the same thing. If thats not it its possible the RCA jacks may be going bad. Know anyone with an amp u could possibly borrow as well? My bet would be the RCA jacks on the amp but it could be a number of things. How old is the amp? Have you also checked your battery wire, ground wire or remote wire for the sub?

tuffluck

iTrader: (4)

yeah everything looks good...the amp is a jbl but is pretty old. bp1200.1...

http://www.testfreaks.com/car-amplifiers/jbl-bp1200-1/

well i've had it for years and when i first got it and had this problem i solved it for a couple of years, which makes me think if it were the cables themselves they wouldn't have started shorting out and worked fine for a few years...

is there a fix for the inputs on the amp or am i pretty much looking at buying a new one?

dragonrage

Probably a bad connection on one of the wires, or I suppose the connector (probably the wires though) which will halve the voltage and quarter the power output.

cfallsguy

iTrader: (1)

Bad connection with RCA cables? I don't think a bad RCA cable would result in power loss the way he's explaining. And that amp is fairly old so its possible it could go bad as well. I have an amp thats around that old and i noticed that 2 of the channels (4 ch amp) went completely bad. So check all the wiring and connectors before getting another amp. Don't cheap out on an amp.

tuffluck

iTrader: (4)

i think i'm going to unplug one rca cable at a time...see if i can get all bass to stop coming from the speakers completely. at this point i will know WHICH connection or wire is bad, then i can simply reverse the wiring and plug the good rca cable into the bad input (and switch them where they plug into the deck) to see if there is still no bass coming out, at which point the problem is the amp. if bass comes out, the wire went bad...i can even plug the *bad* wire into the good rca input on the amp for confirmation.

pentavolvo

easy way to see if its the rca connector or the rcas

the bp has 2 sets of rca inputs, front and rear. both will do the same thing
so swap it from what its on to the other. (ie if they are plugged into front, move them to rear)

tuffluck

iTrader: (4)

woah, that's really easy! thanks for the help, i will do that.

tuffluck

iTrader: (4)

looked like the same problem was there when i switched inputs, which means that it's probably the rca cables. i doubt the same inputs would not work on both front/rear on the same amp.

anyone know how many feet of rca cable i should buy to run from the very back wall of the trunk, down the driver's side of the car to the head unit is? it's been years since i did this so i really don't remember. 17ft?

cfallsguy

iTrader: (1)

I think i did 15' but im not 100% sure. Its always better to have too much than too little.

tuffluck

iTrader: (4)

turns out it was my RCA cables for sure. i'm surprised as old as my amp and deck is, that neither of them were at fault. thank goodness!

actually i had a relatively cheap pair of rca cables in my house from when i did my install. i decided to run those as a test pair and see if i got noise through them, which i did not. they sounded just as good as the more expensive RCA cables that had just quit on me. so i decided to use them and now all is good.

my rca's run on the opposite side of the car from my power wire, so i don't have problems with interference even with cheaper RCA cables.

cfallsguy

iTrader: (1)

Thats weird the RCA cables would cut off power to your amp, never had that happen, always is the remote wire or battery wire (maybe i read the problem wrong, i dont know). Either way least you got it fixed and how long did you go w/ the RCA's?

tuffluck

iTrader: (4)

when i first did my install years ago, after about a year this problem happened. i reset the rca cables and it went away and resurfaced again probably a year or two ago and has been at half power for some time. i have 1200 watts rms so 600 is still a nice punch and i guess over time i just didn't realize what was missing until randomly one day a few weeks ago the other half of the bass came back and i realized that the problem had been existent consistently for the last year or more.

the problem was that one of the cables on the RCA cables just didn't work. so no matter what channel you plugged it into on the amp, no signal would come out of it. the other cable worked just fine.

cfallsguy

iTrader: (1)

Oh your signal wasn't very strong, which now makes sense ha. When i first read the question i thought you meant you weren't getting any power to your amp.