Possible RCA output or cable issue, please help

[John Z]

About a month ago I got a sub and amp installed in my jeep wrangler, a JL audio ported 10" subwoofer with a 300.1 JL audio amp, the place I went to installed everything for me as well. At first, I was in love with the purchase and the sub hit nice and hard. About a week ago I was driving and I noticed the sub wasn't hitting as hard, so when I got home I looked at my amp and realized my (I think positive) red RCA cable was out of the amp about half way so I plugged it back in all the way and everything was fine again until a couple days later. The sub started to feel weaker for no reason and his pushing bass at about half of what it usually would. I checked all my connections and I even drive back to where it was installed, luckily to be there at the same time as a man who worked for JL and checked my stuff out, saying that everything is good. I've been checking over things and I have noticed that if I spin the RCA cables around a little bit inside where they connect to the amp, there's sort of a sweet spot where the bass will kick back in to almost full power, but then die down to about half power after a few minutes. So I am assuming that my problem lies there, but correct me if I'm wrong because I don't know much about this stuff. If I am right, is my problem the RCA inputs on my amp, or do I just have a set of crappy RCA cables? The guy who worked for JL said my system is fine but all he did was slightly adjust my input sensitivity very slightly up. It did nothing. I'm frustrated because I had a kicker hideaway box last yr and the same thing appended where the bass just died down to about half power after having it for about a month. So I am curious as to whether or not my battery may be a problem as well, as in maybe it is t supplying enough power. My positive terminal has been corroded for a couple years but my battery still reads 12.7 volts around there, it's an interstate battery.

Click to read more...

 

[CSCStang]

Start with swapping out the rca's with a new pair. Is that 12.7 with the car running idle? If it is, you have a problem there. Should read around 14.4 with the car running.

 

[John Z]

Yea it's 12.7 with the jeep idling, the battery is 3 yrs old but has been holding up, I'm guessing cause it's an interstate which according to all the mechanics I know are great batts and that mine is ok, but the positive terminal always corrodes even before I had the sub and I'm just gonna install a new one. Any recommendations on what RCA cables to get, the ones I have we're given to me on install and they just look like cheap pieces of s*** themselves.

 

[CSCStang]

I use Krystal Kable rca's, but there are plenty of good choices of there. I would test the batt without running and compare it with it running. You may have an alt issue.

 

[John Z]

Now how exactly would I determine if my alternator has a problem? I have minimal comprehension when it comes to electricity.

 

[CSCStang]

Test the battery with a dmm as it sits, then test it when you start the jeep. If you get a higher reading after you start it, then your alt is working. If it stays the same or drops, you have a problem. You said the + post is corroded, so clean that sucker and clamp it down tight and see if that gives you a better reading before you do anything else.

 

[John Z]

Alrighty, I understand, thanks a bunch. Only thing is I have cleaned that terminal several times and it persists to corrode all the time, so maybe a new batt.

 

[John Z]

I bought new RCAs and that wasn't it. I cleaned my battery terminal and tested them, they're fine. I went through all my connections including looking inside the amp and the actual cone of the sub, everything is fine....so I'm not understanding why my sub is hitting less than it used to, or not as hard. Could my amp have a problem that isn't visible to the naked eye? Such as my RCA outputs being bad?

 

[CSCStang]

Troubleshooting *****. What kind of Hu do you have? Does it have a separate sub control/bass boost? To rule the sub out, you could test the resistance and see if the coil is toast. Could also be an issue with the rca inputs. Anyone else got ideas?

 

[John Z]

I have a Kenwood head unit, 50W 4 channel output and yes, there are sub controls in it. I have subwoofer level which I keep at +5, it goes from -15 to +15. The LPF is at 85htz. I also haven't changed any setting for the sub in the headunit or on the amp since the install, nor have I tuned anything differently since then. How do I know what numbers I'm supposed to get in my test readings?