David_Wallis

you dont have a car phone / mobile phone hands free kit do you?? as I have seen these create noise, similar to the noise from a ground loop.

David

Edited to say.... unplug the input at the amp end does it go away?
If yes plug it back in, then try unplugging at the head unit end, does it go away? Try just connecting the inner part of the rca, what happens then?.. Try getting your hands on a ground loop isolator from maplin if all else fails... as I had a really annoying noise in my old pug.. bad enough I put it down to my nakamichi mb100 and had it replaced twice.. on adding a isolator it was perfect.

[Edited by David_Wallis - 11/9/2001 9:26:56 AM]

AJC

I recently installed a pair of Infinity 655CS speakers in the front of my MY2000 Turbo and have since noticed that when the engine is running there is a distinct and annoying buzz coming from the front left when the engine is running. What's strange is that I don't think that it was there for a while after I installed the new speakers.
Also it doesn't seem to increase as I turn the volume up (although that's subjective) so I don't think it's anything to do with a fault in the Sony head unit. I'm not running an amp either.
Has anyone got any ideas what it might be and, more importantly, how I might get rid of it?

Any thoughts much appreciated

Cheers

Andrew

john banks

Could be any of faulty alternator, ground loop, faulty headunit, dodgy crossover, damaged speaker, poor connection, crimped wire in body etc.

Does the sound vary with engine speed - ie louder and higher freq at increased RPM? What happens when you move the balance? What if you swap the left and right speakers or wiring? Can you try another headunit? Does the volume vary with alternator load - ie turn on all the lights and heated window?

AJC

Looks like I need to be a little more scientific in my approach to this one. I'll do some more tests with a variety of different situations and come back with an update.

Andrew

john banks

If it is when the engine is running then you are picking up alternator noise most probably, esp if varies with revs and increases in volume with alternator electrical load. Without an amp, then the finger is pointing at the headunit to be honest. Could try a noise isolator in its power supply, but you shouldn't need one for an aftermarket headunit in a modern car. The headunit is one of the quickest things to swap out (?try original Philips piece of junk) to test this hypothesis. Wiring is unlikely to be snagged if you are using the original loom/plugs and speaker wire. A faulty crossover (test by swapping it with the other door?) could be picking up noise if connections are dodgy. Speakers themselves are unlikely to be faulty as work fine with engine off. My money is on the heaunit.

rockin'Ru

I must disagree,but only on a hunch.john,correct me if I'm wrong,but isn't the computer and harness on that side of the car?(Like my left drive "hooker")?
my guess is he has the speaker wires too close to a power wire on that side.But I really don't know those cars well at all...Just a thought.

rockin'Ru

i only mention this because I had the same problem once,and it was the fuel pump hot wire causing the noise.

john banks

Yeah the ECU is on the left in the UK, so that is a good possiblity also. My thinking is that induced noise in the headunit could be amplified.

In installing a very electrically noisy car with huge alternator and toys galore - eg cruise, auto wipers, heated and electrically adjustable everything, I ended up putting a power supply filter on the headunit which helped after I had already cured ground loop problems with another isolator in the form of a matching transformer.

MartinM

ttt - any solution found???

I have EXACTLY the same problem with the front left speaker - doesn't change volume or pitch, only happens when engine is on etc etc

Don't really want to spend hours fiddling if someone's found the cause and cure

Ta, Martin

rockin'Ru

Martin,that sounds like the fuel pump wire problem I had in the Camrey.The buzzing didn't change pitch with rpm's like alternator whine.It was a constant.
Once I got under the car I noticed 3 wires on one side that were not run inside the car,they were run through the rocker panel.They couldn't be seen with the interior out.I laid speaker wires right on top of it without knowing.
This COULD be what you hear.I don't have the diagram for those cars so it's only a guess.
I hope this might help.

chiark

Where are your passive crossovers?

I picked up noise badly in a crossover when it was located under the dash (driver's side - near all the cabling in the footwell).

Solution? Move it away.

It's rare for passive x-overs to have noise induced in them, but if you think that there's a bloody great coil of wire in there then it's not that surprising.

Can you describe the symptoms a bit more?

Nick.

MartinM

No phone, no crossovers...

...its just a bog std Scoob (P1) where I fitted a Kenwood MP6090R to the standard wiring (with an ISO adaptor) to the standard speakers.

I've never been anywhere near the speakers/doors/passenger footwell/behind the dash etc

...but writing this has just reminded me that it was all a bit of a squeeze behind the head unit when pushing it in (in fact, I had to push v.hard ), so there may be some intimate closeness of some wires to others

I guess I'm just gonna have to take it out and see, and then I'll report back...but keep the suggestions coming in the meantime, ta

MartinM

OK...update time. Remember, left hand front speaker only, only happens with engine running (not AUX) and whenever front plate is on head unit (even with ALL OFF showing). Kenwood MP6090R, no phone, no crossovers, no amps, never turned it up really loud, bog standard P1

Pulled head unit and ran it on the seat...still buzzing

Swapped left front and right front speaker output pins in head unit connector..should have moved buzzing to RHS speaker...NOPE, still buzzing from LHS

Removed LHS trim and carpet..all wiring just as Subaru intended ... moved it all about anyway ... no difference

So, its not the head unit (swapping front outputs doesn't change side that is buzzing)..but why does it happen with the face plate on even with ALL OFF showing - surely there's no feed to the speaker in this condition (but if you take the face plate off, buzzing stops straight away)

Can't be fussed to take 2 door panels off to swap speakers L <-> R to potentially isolate it down to LH speaker or LH wiring

Any more ideas?????

chiark

Erm, I think you may be down to re-cabling this one... I know you can't be bothered, but I can't think of a quick and dirty fix...

MartinM

Thanks - I think its dealer time now..I've got enough background info to help them make a quick start on it. I expect they'll initially take the "nothing to do with us sir, you put the radio in" stance, but you've hardly got a choice with not getting a radio at all to start with!