Speaker Whistle

[matt45 1]

Hi all,

I have an isssue where i am getting a whistling/whining noise through my front speakers, the noise increases the higher the engine revs, altho if i turn them up i can drown it out. This happens on my front speakers which are amp'd but not on my rears which arn't.

I am thinking my amp may be poked but was woundering if anyone else had any surgestions before i rip it out and try another one.

Thanks in advance.

[SIR E30 68]

What you are talking about sounds like alternator whine. Check that all your signal cables and power cables to your amp are routed on seperate sides of the car. If routed close together the magnetic field that power cable creates will interfere with the signal the speakers are meant to be getting.

It could also be a ground loop, where youve got more than one ground. IE something is shorting out somewhere. Check all the cables for cracks or splits and make sure they arent passing over any sharp edges.

Failing that, ask someone else on here that has more knowledge That is just my very limited knowledge opinion, but hopefully it helps you out.

Edited June 15, 2009 by SIR E30

[Mark 178]

It's an earthing issue I believe.

[bravo 35]

Read this

[pjay 8]

Just from my small experience.

1. Check your grounds. Sand back to bare metal. Ground all your amps to a single spot

2. Check your RCA's aren't running alongside your power cable, same with your speaker wire.

That's always fixed mine.

[matt45 1]

thanks for the fast replys,

Amp is mounted in bracket where stock cd staker normally is (above battery in boot), and scince it is so close it has been wired directly to the battery terminals, i assume this is ok as it is a very small amp (someone please tell me if this is a mistake).

Will try seperating the speaker cables better when i get home too see if that helps ... will report back.

Thanks all.

[BM WORLD 1286]

if your rca cables run along side any major positive power cables it will cause whistle ,

also make sure the volume gain on the amp is not set to high , crank up preamp gain if the head unit has that option

[bravo 35]

Ground should go to bare metal chassis/body point, not directly to negative terminal on the battery. Positive is fine direct to battery. Check the ground is good by disconnecting the positive battery terminal from the battery so the car is totally dead. Disconnect the earth lead from the amp, but leave it attached to the car. Measure the resistance between the amp end of the lead and the negative battery terminal with your multimeter set at 200OHM scale. You should get less than 0.5OHM if the ground is good.

Also, if th enoise is present when testing the amp as described in the link I posted, , check that the speaker terminals, and link wires if speakers are 2 or 3-way, are not touching the car body or speaker chassis as this creates an earth loop. The link doesn't mention this possibility.

Check speaker wires for breaks or contact with the car body where they pass over or through body panels.

If the headunit is at fault you may have blown the fusable links on the RCA's - did you plug them in while he headunit and/or amp was turned on? You should only pug RCA's in with everything turned off.

EDIT: I should mention, that if you are using large guage wire and the negative wire isn't anywhere your RCA cables, then you can go directly to the battery. The reason is that the car's chassis usually has less resistance then the wire, so creates a more effective ground. This is not always the case, but generally is.

[matt45 1]

power and ground is 4 Gauge cable, probably only half a meter long, amp is a little 2 channel (cant remember rating).

Will have a gork when i get home... might have to get some longer cable to ground it elsewhere.

[pjay 8]

Keep your ground as short as possible. Preferably liek 30cm's tops

[bravo 35]

. might have to get some longer cable to ground it elsewhere.

That would defeat the purpose. If the closest possible ground point is the battery - use it.

[matt45 1]

Ok so I’ve rerouted the power as far away from the audio wiring as possible and shortened it.

So far can't hear the noise ... so fingers crossed it stays that way when i get around to taking it for a drive.

Thanks all for your help.