Amp trouble??????? Need advice.

[jleger98]

I've got my system in and running. I have two issues.
1. the left-rear speaker is always "dirty". By that I mean it always sounds overmodulated.
2. After the system is on for a while, I get a nasty buzzing noise, no matter what the volume is set to.

Things I've tried:
1. Ran completely new wire to the left rear speaker. no change. Have not tried swapping speakers yet to see if its actually the speaker or the channel. Speaker wire goes in on the opposite side of the amp from the power so I doubt thats an issue.

2. I tried very hard to keep the speaker wires away from the power cables. that said, I think the pre-amp from the HU goes in through the same hole as the power. Will that make a difference? I don't get the buzzing initially, but after a while....like when the amp gets warmed up. I have not tested this very methodically, but, if I leave the door to the compartment open it seems to not buzz, but other times does.

3. I've played with the adjustment dials on the amp, and that has little effect on #1. Can affect #2, but couldnt tell you how off the top of my head.

Is my amp bad? Its a kicker refurb that I jut bought this spring. K600 I believe, cant think of the model for sure, but its a 600.

[dogbert]

Is the power source and ground different from your head unit? If so, you may have voltage building up between the two units. In this case, the quickest fix is a ground isolator in between your amp and your head unit. You'll need an extra sete of RCA cables if that's how your HU is connected to your amp.

[jleger98]

Well it all comes off the same battery (2nd batt)

HU gets a feed across a 12g (maybe) wire and the amp gets the feed off a 4g wire. Both originate from the same battery

[dogbert]

Directly, or is your head unit wired to your ignition switch, accessory switch, etc. If so, it's not the same thing. Ultimately, all my wires end up in the same place, too, but it's not the same power source or ground wire loop.

[jleger98]

The remote on lead comes through my acc switch. But I believe (would have to check) the pwer comes direct. ground might not though.....

[dogbert]

Get a ground isolator and it will solve your problems. Your set-up is the same as me. My amp is bigger, so the problem was more pronounced.

[jleger98]

and the ground isolator would go where?

Something like this?http://www.radioshack.com/sm-see-all...i-2062214.html

If it is, then seems like it would just go in the RCA's between the HU and the amp. So would I need 2, or 3 then? 1 for front 2 speakers, 1 for rear speakers and one for sub?

[dogbert]

It just goes between the head unit and the amp. Looks like the one you have pictured comes with cables...mine didn't. But that's what you want. If your sub and amp are on the same power source/ground, then you should be fine. I have only one between my head unit and the 1st amp in my daisy chain of amps. If I get an amp for my interior speakers, I'll need a second since they would come off a different output from the HU.

[jleger98]

Cool, I'll go pick one up tonight and try it out. Lets hope that solves it

[philwsailz]

I've got my system in and running. I have two issues.
1. the left-rear speaker is always "dirty". By that I mean it always sounds overmodulated.
2. After the system is on for a while, I get a nasty buzzing noise, no matter what the volume is set to.

Things I've tried:
1. Ran completely new wire to the left rear speaker. no change. Have not tried swapping speakers yet to see if its actually the speaker or the channel. Speaker wire goes in on the opposite side of the amp from the power so I doubt thats an issue.

2. I tried very hard to keep the speaker wires away from the power cables. that said, I think the pre-amp from the HU goes in through the same hole as the power. Will that make a difference? I don't get the buzzing initially, but after a while....like when the amp gets warmed up. I have not tested this very methodically, but, if I leave the door to the compartment open it seems to not buzz, but other times does.

3. I've played with the adjustment dials on the amp, and that has little effect on #1. Can affect #2, but couldnt tell you how off the top of my head.

Is my amp bad? Its a kicker refurb that I jut bought this spring. K600 I believe, cant think of the model for sure, but its a 600.

Woah, hold on...

The issue you are describing can come from a few things....

You suggest turn-on of the amp is through accessory switch? If so, you might really be hitting a different battery, if there are more than one in the boat. It could cause some funny stuff, but prolly not the noise you are talking about...


A systematic approach is in order.

1. go to the amp and switch the RCA inputs at the amp, moving left to right and visa-versa. DO THIS ONLY AT THE AMP!!!!, (i.e. not both at the amp and the radio).

Did the dirty sound move from left to right?


Do this first and let us know, and then we can take the next step....

[philwsailz]

Okay, I will keep this from being a serial-installment soap-opera... I know, the suspense is killing some of you.

IF IN THE STEP IN THE POST ABOVE THE "DIRTY" SOUND MOVED FROM ONE SPEAKER TO THE OTHER:
The problem is "foreward" of the amp, i.e. in the RCA cables or in the radio, not the amp.
Things to try:


try switching left for right and right for left ONLY AT THE H/U. DOES THE DIRTY SOUND MOVE AGAIN? If so, the step-by-step check points to a bad RCA cable. If not, the problem is almost certainly in the H/U.


If the VERY FIRST RCA switching did not cause the sound to move, the problem lies in the amp, or between the amp and speaker, or in the speaker. Try substituting a known -good speaker and see if the dirty sound remains...

[jleger98]

Good advice Phil, I'll try that tonight as well.

FYI, I did make sure that the power to the ACC switch did come from the same battery as the rest of the system

[philwsailz]

Good advice Phil, I'll try that tonight as well.

FYI, I did make sure that the power to the ACC switch did come from the same battery as the rest of the system

The steps all make sense, right? Just double-checking before I disappear for the day...

[jleger98]

yep. thanks.

[jleger98]

So I did some poking around tonight and determined a few things.
1. I have to get some circulation in there. Its a sealed compartment and it is warm in there even when the sun hasnt been out all day.
2. The left rear speaker is not bad. I switched some wires at the amp and the dirty sound moved.
3. I think I do have a bad channel on my amp. Here's what I did after I put the speaker wires back where they were.

a. I put in the ground loop isolator that Dog recommended. Heard no buzz after that, but I had the access door open. We'll see it it happens tomorrow out on the lake.
b. I turned the HU to the full forward on the fade to isolate one amp.
c. I swapped the RCA's from one to amp to the other (there are two built in amps in my one amp). There was a definate difference between the two.
d. to check the rear channel I did the same thing with the HU tuned to the rear channel. Same result.

**one interesting note. When I had the "bad" amp on, and I shift the balance over to one side, so as to isolate one speaker, there is sound coming out of both speakers on that side. I triple checked the speaker wires and the RCA's and they are correct. If I switched back to the "good" amp the speakers acted as they should. also, on the bad amp, the sound was very distant sounding. Almost like when you have a short in a speaker wire. Also, to make sure I didn't have a bad RCA cable, I tried both kicker cables on both the front and rear channels. Both sounded the same.

Thoughts? Dog? Phil?? Anyone else???