Weird Audio problem.

[Dave 88 LSC]

I can not figure out this problem, maybe you guys can.

I installed a 10 inch JL audio box in the trunk using my trusty JBL b300.1 amp.
It kicks like a mule and sounds great. Problem is, when my radio is up at 20 % volume, the amp stops pumping after about 10 seconds, if I crank up the volume to say 45% and up it comes back on.
Its not the power to the amp. So at low volume the amp or the woofer doesnt kick and at 50% and up volume it plays as it should.

I never heard of such a problem, usually the amp cuts out if its overloaded, in this case its the other way.

Power is run from the battery, remote from the fuse box, and I am getting the signal through a sliced RCA cable connected to PRE factory amp wires (rear back speaker).

Any clues?

 

[stu]

My guess is that you do not have a good signal going to the amp

 

[Frogman]

Did you consider your trusty jbl amp might just be on it's way out?

 

[Dave 88 LSC]

Did you consider your trusty jbl amp might just be on it's way out?

Was working fine a year ago in my Lexus pushing 2 10's. I thought about it.

 

[Lownslowlsc]

think he meant the oem one.

are you running a loc?

 

[Frogman]

Was working fine a year ago in my Lexus pushing 2 10's. I thought about it.

I understand that. But that was last year. A few moons have come and gone since last year. Just because something was working last week, (let alone last year), it don't mean it will work today.

Beg, borrow, steal or buy another amp and try it out. If the problem(s) persist, then it wasn't your amp. It's a hell of a lot easier than tracing wires.

Of course, the deck preamp transistors may be on their way out. This is kind of hard to diagnose over the Interwebs, me thinks.

 

[stu]

I am getting the signal through a sliced RCA cable connected to PRE factory amp wires (rear back speaker).

What do you mean by sliced? just spliced into the line?
If so I would get a line converter. A bad signal from the head unit would cause a loss in sound. thats just my guess.

 

[Dave 88 LSC]

Well, I took a an RCA cable and spliced it into the cables going from the radio to the factory JBL amp. I taped into right rear speaker cables. Amp has RCA inputs and high level inputs. I am plugged into the RCA input, 1 rca cable.

I have a 4 channel amp JBL GTQ 200 that I can test things with i guess.

I was thinking perhaps the radio is sending a weak signal, like someone just mentioned. But would it not work at all if that was the problem??

 

[Frogman]

Electronics do strange things, sometimes. They may work on one setting and be dead on another previously operational setting.

 

[stu]

Does your amp have high level inputs or just rca inputs? I ask because if you just run the rca like you have them, It will send a weak signal to the amp. If it has high level input run it that way. If not Get a line converter and see if that fixes the problem.

 

[keatonsdad]

+1 ^^^

 

[chris2523]

My guess is that you do not have a good signal going to the amp

the factory system is so weird. the guy in my town that i trust the most with audio stuff will not touch mark viiis. too weird. he hates them.

Just because something was working last week, (let alone last year), it don't mean it will work today.

Beg, borrow, steal or buy another amp and try it out. If the problem(s) persist, then it wasn't your amp.

i would start here myself.

Of course, the deck preamp transistors may be on their way out. This is kind of hard to diagnose over the Interwebs, me thinks.

this actually happened with my stock radio. bass was wonky, and then one day, i just had none.

 

[zmt325]

does your amp have high level inputs or just rca inputs? I ask because if you just run the rca like you have them, it will send a weak signal to the amp. If it has high level input run it that way. If not get a line converter and see if that fixes the problem.

+3

 

[Dave 88 LSC]

+3

I dont mind doing it this way either. But I thought the post amp signal will be compressed and distorted, since the JBL amp is sending a specific signal to a specific speaker, this is why getting the signal pre amp and using a RCA cable into the aftermarket amp is what i did. Some people here recommended it from this board as well.

 

[stu]

I dont mind doing it this way either. But I thought the post amp signal will be compressed and distorted, since the JBL amp is sending a specific signal to a specific speaker, this is why getting the signal pre amp and using a RCA cable into the aftermarket amp is what i did. Some people here recommended it from this board as well.

No to the post amp.
Line converter before amp.
run rca's from converter to amp
hopefully fixes problem