Help - brand new amp - is it bad?

[silver-accord 10+ year member]

Ok, have a good install with a Boss sub amp in the rear of Pilot. No noise at all. Put new MTX in, all of a sudden, I've got noise through the entire system, NOT relating at all to rpms, just steady, high pitched.

System is two amps, one mids & highs, one sub. When I unhook the RCAs from the sub amp, NO NOISE.

I think the amp is bad. Am I wrong?

Click to read more...

 

[PhatTonyDeMarco 5,000+ posts]

Ok, have a good install with a Boss sub amp in the rear of Pilot. No noise at all. Put new MTX in, all of a sudden, I've got noise through the entire system, NOT relating at all to rpms, just steady, high pitched.
System is two amps, one mids & highs, one sub. When I unhook the RCAs from the sub amp, NO NOISE.

I think the amp is bad. Am I wrong?

That would be because you are no longer sending a signal to your amp, so no noise would be created...

But check the entire length of the RCA's and make sure there isnt a splice in the line and it isnt grounding with the chasis or even another wire.

 

[johnecon2001 5,000+ posts]

are you looping out of the sub amp into the highs amp? If it's done that way, there are two things that could be bad.

#1 the rca's from the Head unit could be bad.

#2 the amp is outputing a horrible signal (most likely- its a boss amp, you get what you pay for)

 

[silver-accord 10+ year member]

No, the Boss amp is not making the noise, its fine when its in there. When I put in the MTX I get the noise.

It still occurs when the engine is off, so it can't be engine noise, can it?

Further, the noise is over the entire system, and I have 2 amps. Why is it ok with the boss amp, but a problem with the mtx? IF its the input to the sub, the noise should only be coming out of the sub. Doesn't this mean the amp is feeding noise back to the HU?

 

[johnecon2001 5,000+ posts]

so you are looping? out of the HU to the Boss, out of the Boss to the MTX?

The outputs on the boss might be bad.

 

[silver-accord 10+ year member]

No, out of the head unit are three outputs, 2 for front and rear, then 1 for sub. There isn't any looping as I understand it. So nothing is going amp to amp, its all HU to amp.

 

[johnecon2001 5,000+ posts]

well, then I would check the RCA's to make sure they're all good. then check the grounds on the amps again. and finally, check the preouts. one of them may have gone bad.

 

[RandyJ 10+ year member]

well, then I would check the RCA's to make sure they're all good. then check the grounds on the amps again. and finally, check the preouts. one of them may have gone bad.

I may be the only one noticing, but it seems as if when he sqitches the amps from MTX to BOSS, the problem goes away, but when he switces back to the MTX the problem is present. That would tell me that everything withthe RCA's is fine, as well as everything with the pre-outs as well as the grounds. It would lead me to believe that there is a problem with the MTX.

You have tried switching the boss back in place of te MTX correct? And the problem then dissapears right?

 

[silver-accord 10+ year member]

I may be the only one noticing, but it seems as if when he sqitches the amps from MTX to BOSS, the problem goes away, but when he switces back to the MTX the problem is present. That would tell me that everything withthe RCA's is fine, as well as everything with the pre-outs as well as the grounds. It would lead me to believe that there is a problem with the MTX.
You have tried switching the boss back in place of te MTX correct? And the problem then dissapears right?

Going to try that as soon as I get home, will report back.

It was like this, to clairify if I misspoke. One minute, Boss amp is in, no noise. Next minute, MTX is in, now I've got noise.

Thanks for the help guys. I"m a bit of a noob with the wiring stuff.

 

[RandyJ 10+ year member]

And both the Boss and MTX amp were wired exactly the same correct? What model amps are we talking about here, you could have some oter problems besides just noise if you are switching from a highly over-rated amp such as the BOSS to an amp that does actual power like most MTX's.

 

[silver-accord 10+ year member]

And both the Boss and MTX amp were wired exactly the same correct? What model amps are we talking about here, you could have some oter problems besides just noise if you are switching from a highly over-rated amp such as the BOSS to an amp that does actual power like most MTX's.

Boss RT345 to an MTX Thunder 311d. They are wired exactly the same way, i was very careful about that, checked to make sure no wires were crossing that were not crossing before. Made sure connections were tight.

 

[RandyJ 10+ year member]

Well you are going from an amp that presumably puts out 300wrmsX1 @ 4ohms to an amp manufactured by a company that has a reputation for actually putting out rated power, if not more. If your power wire was only sufficient for the BOSS amp, you may want to replace it. That is beside the problem at hand though.

Let us kow when you do a direct swap in.

 

[silver-accord 10+ year member]

Oh crap, wait a minute. I wired it as I thought it was supposed to be wired. I havent changed anything, but if its briged mono, if I hooked the speaker wires up wrong to the sub, would that cause a backfeed through the entire system.

Could be this stupid. Didn't have any markings on the amp to wire it mono. Shoot, I hope its this simple . .

 

[silver-accord 10+ year member]

Well, not the case. The amp is bad. Has to be. No noise at all (thank goodness) with the Boss amp back in place.

Very depressing. When I didn't notice the Hiss, the MTX was soooo much tighter than the Boss.

Am going the one amp system route with an Alpine. Will post about it in amp section.

Thanks again all for the help.

 

[RandyJ 10+ year member]

Oh crap, wait a minute. I wired it as I thought it was supposed to be wired. I havent changed anything, but if its briged mono, if I hooked the speaker wires up wrong to the sub, would that cause a backfeed through the entire system.
Could be this stupid. Didn't have any markings on the amp to wire it mono. Shoot, I hope its this simple . .

That would cause the phase to be reversed, nothing other than that though. In a single sub application you would not notice a difference.