MRK

I have this week upgraded my bass box, sub and sub amp. Upon turning everything on there is an interference buzz coming from the front speakers only, when the engine is running. This increases with engine rpm

The amp which drives the fronts and rears has not changed. There is also NO buzz from the rears.??.

If I connect the front output leads from the head unit (I forget what the leads are called) into the 2 channels that power the rears then the rear speakers buzz.

I can only assume something has happened to the front output leads, but what?? They are only a few months old. And nothing has been touched up front, only a new amp and sub in the boot??


Can anyone help


Thanks

M

IWatkins

MRK,

What about power and earth feeds to the new amp ?

I was always told to power the head unit and all amps from the same point and to also earth all the kit to the same point as well, otherwise you get a 'ground-loop'. I have no idea what that is except I had one once and I also got some nasty revs related humming

I'm sure more knowledgable people will be able to explain better.

Cheers

Ian

rockin'Ru

First check all of the wire routes and make sure you don't have any power wires near your speaker or signal(rca)wires.That's the #1 cause of "alternator whine".

Timpreza

I had the same problem some time ago.
I managed to solve it by passing the power cable through the leftside of my scoob and all others on the right.

bennetm

I had this on a previous car and used a monster power cable as the alternator / distributor (?) cant remember which, was interfering with the thinner one.

MB

chiark

I think it could be the routing of your cable, but that doesn't make sense really as it hasn't changed...

...unless you caught it and have put it a bit closer to the fuel pump or something?

I have had an RCA lead fail completely in use, which then buzzed like a very buzzy thing. Can you undo the shroud on the RCA lead ends and check that everything's still connected?

MRK

Thanks ALL for your help

The wiring hasn’t been touched except where it all enters the boot, when I unplugged everything to install the new sub box and new amp.

It’s the old amp that the front speaker lead goes into.

Power leads straight from the battery, then split via a very expensive block into the two amps.

Earth leads to the same point and only 100mm in length.


I think after playing with it again?? Over the weekend that it’s like Chiark said the RCA has failed, maybe I bent it or something pulling it out. I was just hoping I wasn’t as having to pull my head unit out again and change the RCA then to put the damn head unit back OUCH that’s a nasty job.


Thanks again guys, much appreciated. I’ll let you know how it goes J


M

Chris.Palmer

I had the same problem when I upgraded one of my amps & it took me ages to pin the problem down. Annoying Engine Whine that increases in pitch and volume with revs.

As stated earlier this is often caused by an earth ground loop.

In my case the RCA leads weren't tightly connected to the new amp, centre pin was fine (else there would be no sound at all) but the earth shroud was loose.

I just squeezed the shroud on the RCA lead to ensure as really tight connection & problem resolved.

I can still reproduce this problem now by half removing the RCA leads so the center pin is connected but the earthing shroud isn't.

One final tip, that could help diagnose this: Disconnect the RCA's from the Head unit (but leave them connected to the amp) then rev the engine and see if the whine is there (adding additional alternator load such as headlights on full beam should make it even louder), then disconnect the RCAs from the Amp and try again, if the whine disappears this a clear indication of an earth ground-loop between the head unit and the amp.

Best of luck & let us know how it goes.

MRK

DAMN its my amp

Its a four channel with only two working 100%. The other two the right channel makes the most noise with the left only slightly.

I take it this scenario is a take it back to the dealer fix. CAN IT BE FIXED.


Thanks

M

Jonathan Witts

I have just installed my Kenwood 4 x 100 amp in my new B4 and had the same issue. In the end I tracked it down to two of the channels being very buzzy, or intermittent.

My amp is out of warranty so I took the cover off and found that while I took the amp out of my Scooby I must have knocked it and loosened where the audio in plugs go. I simply got out the soldering iron, cleaned the joints with a small file and soldered it firmly on - Job done - Sound great now.

In the end it was very simple to sort - i hope yours in so easy.

Yours

Jon

chiark

It can be fixed, and it may be worth looking for a dry joint in somewhere obvious before paying someone to look at it...

Where in the country are you?

MRK

Top advice Jon. Thankyou


I shall check it out!!


M

MRK

Hey Chiark


I'm in ESSSSSEEEEEEXXXXXXXX.

Why??

E-mail me.

M

chiark

Because I can recommend a repairers in this area. Failing that, try Decibels in Billericay? A friend swears by them...

MRK

Why THANKYOU Chiark.

I know where Decibels are


M

john banks

I am getting "alternator whine" on my Pug install. I am pretty certain it is a ground loop. I am using factory head unit speaker outputs to speaker level inputs on the amp. The inputs on the amp also have a ground cable which is unconnected so far. Connecting this to the chassis of the head unit makes little difference. Do I:
1. need to connect it to the ground supply of the head unit?
2. connect the ground supply of the head unit to the same point as the amp ground?

Interestingly, when I use a line level converter (which I think is a resistor network and transformers) and plug into the amps rca inputs the noise is virtually eliminated, but I think the converter is degrading the quality so I want to avoid it. What do you suggest of option 1 or 2 or other from above?

Thanks.