I got a new Alpine Amp installed in my Scion XB... They did a great job making it look professional and they mounted it under my passenger seat. I didnt really want to lay out 2-300 bucks for a new head unit, so I just decided to keep the stock pioneer head unit. They told me it was fine, and rather then using the rca inputs on the amp they would use the "speaker level input." Ever since they put the new amp in, when i rev my engine or am just driving im hearing like a buzing from my speakers which changes in frequency when I go faster. This noise still occurs even when the head unit is powered off. The only way I can get rid of the noise is to unplug the cable from the speaker level input, in which case I cant play any music obviously.. I did some research and people told me it could have been a bad ground wire, but I took it back to tweeter and they insist to me, that because the stock head unit doesnt have rca outputs, thats why IM getting interference. They said if I get a new one, it will fix the issue.. Is there any thing I can do temporarily to fix this issue until I get a new head unit for xmas? The amp is an Alpine MRP-F240.

 

ground loop. its those hi level speaker inputs. turn the gain down on the amp and it may help just a lil bit. id get the rca connector that lets u add rcas to yer stock deck and then use a ground loop isolator in the rca line.

 

BAD ground. Don't let anyone tell you otherwise. It's like you have a audio tach, right? If so, bad ground.

Bad ground, bad ground, whatcha goin' to do? Whatcha goin' do when the bad ground comes for you?





Sorry. Just jumped in my head righ then.

 

id figure bad ground but with a shop doin the work they can normally get at least the ground right

 

same thing happened and i got the adapter..maybe its just the stereo..im grounded and all..ill check tomm and lower the gain

 

Well, too much gain can cause a buzzing, that is for sure. However, it should not sound like a audio tach. If it's just too much gain, it should sound like it's distorted, maybe even a bit like clipping.


I have done a few installs in the past, however, since it's been a while since I stuck my head under a dash to put in a amp or stereo, I can't be 100% sure.. This is why I pay someone to do it now. Keeps me from having headaches.

Good luck!

 

it also might be that the rca cables are crossing with the power wire..i'll check my buzzing noise i forgot to check this morning.

 

What exactly is an audio tach?

 

An 'audio tach' is just a term to describe the sound that comes through the speakers, when it's not grounded correctly.

Sounds like your car's engine is going through the speakers, in a whiney way.

At least, that is what it means to me.

 

so how do I get RID OF IT!!!!!!! Where is the ground wire located?

 

it is located in the amp to some part in the chassis of the car

 

the ground wire is usually black, check for.......

hey wait you got it installed somewhere for you?

why don't they fix it. they F'ed up!!

 

Take it back to Tweeter for all the $$$ they charge they should have no problem fixing it and don't leave without getting it fixed.

 

You are both wrong. Ground loops do NOT cause engine noise. Ground loops cause popping noises when using another accesory in the car because the two items are sharing the same ground path and the resistance of one is greater than the other. If you knew what a ground loop was, you wouldve never said that it was a bad ground.

Tbone- what youre experiencing is commonly reffered to as induced engine noise. Basically whatever signal wire that you are running to your amp, be it a set of RCAs off of a converter or just regular speaker wire to the high level inputs, is picking up radiated noise from other electronics in the car. ABS computers, ECMs and high current circuits are usually the problem here.

If you want to find out exactly where your noise is eminating from, you can make what is called a "noise sniffer" which is nothing more than a cassette walkman. What you do is take the tape head out of the unit and extend how it connected to the cassette player by soldering some longer wires to it. The tape head will then act as a microphone. Put the headphones on and press play on the player as if there were a tape in the unit and then run the tape head over the path of where your wires are run. Do this as your car is running. Any noise will come through the headphones and you can single out where you are getting the interference. Move the wiring for the amp to a more appropriate place away from the noise and youre done.

 

i thought it was a bad ground too, but if u unplug the speaker inputs there is no more noise, so I figure if it was bad ground I would always experience the noise.. I think basically all the wire is hidden, so its nothing I can fix... I tried to get tweeter to fix it, but they told me the only way it could be fixed was getting a new head unit with rca out..

Here is the pic of the right side of my amp. The speaker inputs is going into that weird connector called "speaker level input". If I pull that wire out the noise goes away.


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Hmmm, looks like I was right......

Tweeter is wrong. Most shops like Best Buy, Circuit and Tweeter wont do much to fix engine noise other than tell you to buy something else. At my store I will always do my best to eliminate because unlike alot of retail installers- I know wtf Im doing or if I dont Im not ashamed to let the customer know.

You can fix this yourself, I promise you. Get a cheap 10 dollar walkman and make the noise sniffer that I described, if you need help or have questions ask me.

 

Thanks, but no. I was responding to what he wrote, and that can be a bad ground. If it sounds like that.

There are other things that it can be, I would suppose, but I am not wrong, per se.
My degree in SOUND ENGINEERING tells me that.

Your answer is correct, for certain situations. And, your solution with the "noise sniffer" was nothing short of brilliant, although it may be out of his league.

 

What college gave you a degree in 12volt auto applications? Im not trying to be rude or anything but Id like to know some more about your crudentials. I know plenty of people who have degrees but arent much smarter than the next guy.

FYI- Im not the smartest guy either when it comes to car audio but I have had 10 years exp and First Class MECP cert. Ive never seen grounding point causes engine noise in any car that Ive worked on yet but then again I dont go grounding source units or amps to the same exact point as another acc. in the car.

 

I have close to zero experience in car audio, but I can tell you that I had what I would describe as real bad alternator whine, and fixed it by using good rca's, and establishing a seperate ground for the hu(something circuit city did not). Fixed it yesterday.

You may want to pull the hu and run the ground to the firewall area, away from the harness.

Again, not to get in the way of two credentialed folks, but it may work, and if not, just call it a waste of ten minutes of your time.

 

I wish you were located in PA BrianxB... I wish i knew how to make that noise sniffer... So your saying there is a possibility that there could be no interference noise with a stock head unit and not using rca outputs? I plan on getting a new head unit for christmas, but im only 17 so I dont really have the money or much knowledge on how to fix this.. Does anyone have instructions on how to remove the front passenger seat? My amp is mounted under the seat, so I have to take off the seat and see where they put the ground..