Viewing: Squealing Speakers??

**Nalderz** · 17-10-2010, 12:43 PM

Ok i need a little help.

I did have 2 x 1000W Subs in my boots, nicely installed, all working fine and decided to change to change the Subs for Front speakers so got rid of them and now have Front speakers and amps to suit. I used the wiring that i used for my subs which was working fine.. Now when i turn my HU on the Front speakers give out quite a loud high pitched squeal

Can anybody help me on what i can do to get this sorted????

**turbonutter69** · 17-10-2010, 01:25 PM

Have you put the rca leads near the power leads?

**Nalderz** · 17-10-2010, 03:56 PM

No, The rca leads are run down the left side, power down the right. I suppose they are near each other when they get into the boot and run into the amp but that shouldnt make too much interference

**turbonutter69** · 17-10-2010, 07:47 PM

how long is the earth lead?

***HDi fun*** · 17-10-2010, 08:11 PM

Is it a constant pitch squeal? Is there still other sound besides the squeal?

Automotive power-amps utilise switched mode power supplies and these can generate significant amounts of HF noise which, if not correctly filtered, will cause this type of interference.

This, initially anyway, does sound like a faulty bit of kit to me. Rather than an installation problem.

**Nalderz** · 18-10-2010, 08:39 PM

The earth cable is about 2ft ish..

Yes its a constant pitch squeal, except for when i switch the engine off but then theres a deep humming sound. I havent tried reving the engine so not sure if the pitch or volume changes.

I really dont have a clue what this could be... anymore ideas?

**turbonutter69** · 18-10-2010, 08:42 PM

I'd say it your earth.

Leeyon17 · 19-10-2010, 01:23 PM

yeah, its most likely to be ur earth cable locate the earth point on the body of ur car and use some sand paper to clean the point. also if ur using a ring terminal make sure it makes contact with the body of ur car, because sometimes vibrations tend to loosen the if so use a spring washer under the screw or bolt to make sure it keeps firm on the body.

**turbonutter69** · 19-10-2010, 01:27 PM

You want the earth lead around 13-15 inches from the amp. Any longer and you'll get interferance which is what I suspect is the problem here.

**badger1980** · 19-10-2010, 09:09 PM

Also check the speaker locations the speakers maybe earthing out on the body if so you need to space them away from the doors

***HDi fun*** · 19-10-2010, 10:47 PM

Can you get us a quick wav file recording of the squealing?

**Nalderz** · 23-10-2010, 12:44 AM

Interesting... Well tomorrow i will be checking the earth & speaker locations and i will let you know how i get on. If a .wav file appears here then you know nothing worked

***HDi fun*** · 24-10-2010, 07:46 PM

Bad earthing can cause the SMPS to pollute the signal chain but it's likely to cause lots of other problems besides.

**Nalderz** · 28-10-2010, 12:26 AM

Ok so i moved the earth point.. made sure contact was fine good enough and still the squeal carries on.

The squeal does change pitch when i rev the engine

I do have a sound file but how can i upload it??

**turbonutter69** · 28-10-2010, 11:00 AM

Somethin is definitely interfering. Or you have rubbish cables.

**pgarner** · 28-10-2010, 07:56 PM

just a thought. try another set or RCA cables. my carputer started whining on the left speakers. checked everything then changed the RCA from the sound card to the AUX in sound back to normal.

looks like one of the cables may have became damaged somehow

**badger1980** · 28-10-2010, 09:38 PM

Quote:

Originally Posted by Nalderz

Ok so i moved the earth point.. made sure contact was fine good enough and still the squeal carries on.

The squeal does change pitch when i rev the engine

I do have a sound file but how can i upload it??

That sounds as if the speaker is picking up interference from the alternator u could try to improve the grounding on the the battery by removing the negative cable and rubbing down where the cable attaches to the car so its free from dirt grease etc and apply some copper grease to the bolt hole and the bolt and the both ends of the negative cable to see if that improves things for u.

***HDi fun*** · 29-10-2010, 10:02 PM

If it's alternator interference then the pitch will change with engine speed. And even with a 3 phase alternator (yes, many are) the frequency will be well below the threshold of human hearing, and also well below the threshold of the equipment's LF roll off.

It is, of course possible that what's being heard is a 3rd order harmonic of the actual fundamental frequency.

I still suspect that the SMPSU is leaking interference, perhaps a decoupling cap that's gone open circuit.

**picassoonwheels** · 10-01-2011, 01:08 AM

Quote:

Originally Posted by Nalderz

Ok i need a little help.

I did have 2 x 1000W Subs in my boots, nicely installed, all working fine and decided to change to change the Subs for Front speakers so got rid of them and now have Front speakers and amps to suit. I used the wiring that i used for my subs which was working fine.. Now when i turn my HU on the Front speakers give out quite a loud high pitched squeal

Can anybody help me on what i can do to get this sorted????

Wrap a piece of copper wire around the left & right RCA out of the HU.

Ground it to the chassis of the HU or the metal frame.

Now push in the RCA leads again.

Viola! you done it, all told!