Noise Questions

[plazman 10+ year member]

i been having this hissing sound everytime i hit my brake at lower RPMs that come out from my tweets.

I took it back to my installer and he said its becuase of my HU.

Its not alternator whine... its whenever the car hits a low RPM... i get this hissing sound. Even when the HU is off... if i put my ear next to the tweets... i could hear a slight hiss. I had them check all wiring and separated the wires... same thing..

They also wanted to install a noise filter... but im like.. wtf would i want that... if you do it right in the first place.. then you dont need that.

Also... does our HU have a remote turn on wire? OR is that wire in the trunk only for the amp.

All wires in the amp have loom over them.

Could it be the ground... or the only problem related to ground is alternator whine? I check the resistance of the ground.. and im getting 0.05. He moved it from the factory ground location on the left to a new ground to the sheet metal behind the rear seat. Looks Ghetto to me they way he did it.

Is he right about all my noises disappearing if i change my HU?

Tried a couple of things...

unplugged the Power and high level from the EQX, noise is still there.

I get Alt whine when RCAs are unplugged, gone when i plug them in.

Removed input wire from Xover. Noise is still there.

Tried ground the RCA, noise is still there.

whats next?

Click to read more...

 

[themainjam 10+ year member]

so your tweets hiss even with the headunit off?....... that should not be possible should it guys?????

oh and did they have to do a line converter from the speaker leads to RCAs??? it could be a problem.....

the remote wire is just to let the amp know when the HU is on. the remote shouldnt have power unless the HU is on....

 

[plazman 10+ year member]

Yes... if the HU is off... i could put my ears next to the tweets and still here a slight hiss. Anything the engine RPM dies down/or when i brake ... its a loud hiss. Not alternator whine, just a hiss.

Im using an AudioControl EQX as my line out converter. I unplugged that completely.. noise is there there.

 

[themainjam 10+ year member]

hmmm is your amp still on when you HU is off?

check the remote wire for power. it shouldnt have any when the HU is off.....

 

[Slody4Futbol 10+ year member]

he's using a stock headunit... which doesn't have a remote wire coming out the back of it... so the remote wire is spliced into an accessory or ignition wire... so the amp is still going to have power even if the head unit is off... unless he puts a switch on the remote wire to turn the amps off

 

[themainjam 10+ year member]

thats what i ended up figuring. so he will hear the hiss until he puts in a new HU which will turn the amp off when the HU is off...

 

[plazman 10+ year member]

My HU does have a remote turn on. I think it was used to turn on my factory amp.

http://www.projectbimmer.com/BmwWiring.htm#top

My installer installed a relay. Could it be related that.

If thats true what you guys mentioned... then that explains the constant noise in the tweets... but about i about when i brake? You hear a loud hiss that you can actually hear.

 

[Slody4Futbol 10+ year member]

well get a meter and check the amp for voltage when the head unit is off... and see if it still has voltage coming through...

 

[plazman 10+ year member]

I'll check on that tomorrow.

Dumb Question.. Heres a pic of my DMM.. Where exactly do i turn the dial to? And which port should i plug it in?

So when the HU is off.. goto the AMP and place tips on + and - terminals correct?

also... when the car shuts off... amp is off... when the car is on.. Amp is on.. even if the HU is off.

 

[themainjam 10+ year member]

VDC ~20 V i cant really make out the selections though.... then touch the ground and touch the remote wire.

the reason you would here the hiss change might be because you are getting no signal through the RCAs to override the interference.......

you should also have a light on your amp and if the light is on when the HU is off then the remote is getting power when it shouldnt....

where the installer grounded the amp did he sand the paint away? my installer didnt and i am never going back to him....

 

[plazman 10+ year member]

He did not sand the ground down. All he did was screw the terminal into my back seat with a sheet metal screw.

hes telling me that my HU doesnt have a remote turn on... im like ... yes it does.. i have the diagram to show for it...

i try that tomorrow and see how it goes..

 

[themainjam 10+ year member]

yeah that ground is crap. he needs to sand it down to make sure it gets good contact that could contribute to the break noise change thing...

and now we know the hissing is from the amp always being on because the guy was looney..... and didnt wire it right... Good luck man

and just to let you know that wasn't a professional install.

 

[plazman 10+ year member]

yea i kinda figured that the install wasnt professional

i had the ground in two locations factory spot where the HU and factory amp was grounded and this new spot.. pretty much the same..

so your saying he didnt wire the relay properly? Do you think i could probably redo the wiring for it?

 

[johnecon2001 5,000+ posts]

sheeoot, make them rewire it for you the way you want it done. Make sure the way you want it done will work, maybe test it that way then take it apart and mak.... wait nevermind the goal is to make them do it.

Just make them redo it untill it works. They messed it up they need to fix it, your a paying customer. Maybe you can make them pay you for teaching them what to do?? that would be wicked cool.

 

[plazman 10+ year member]

im gonna try to do what i can... then put it back the way how it was..

and have them do it... they been working on my car for a total of 3-4 hours!