high pitched squealing

[ruggj]

I'm getting a high pitched squeal from all the speakers as soon as i turn the head deck on. happened about half an hour ago, i turned the car on to leave work, drove about 2 metres and then the sound just went to an extremely loud squealing sound. i turned it off, tried turning it back on again, same deal. Got home, turned the car off, put it on accessories and turned it on, it made the same noises but just not as loud.

Should i just assume there is a bad ground for the head unit? I can't see why if it's been working perfectly for a whole year now, that it would just happen like that. The only differences are i put splits in the front on tuesday, and a new monoblock. i remember making sure everything was in tight on the monoblock, and same for the splits, like on the amp i made sure that the ground was in good etc. All i had done was just replaced original parts that had been there when i originally got the sound system professionally installed, so for the amp it from the amp, and wired it to the new one, and for the splits, we used the wiring that the installer had put in for the original speakers i had in.

Also a friend did notice some engine noise from the rear speakers about a week ago.

the set up is like this

Cadence 1200w 4ch amp, which powers 2 Alpine Type R splits and some Pioneer 4 way 6 by 9s

and an Alpine 1100w Monoblock that powers a Kicker Sub

and a Pioneer DEH3000ib head unit

as there are only 2 outputs on the Pioneer headunit, the RCAs on the cadence amp are split, theres 2 RCAs split into 4, and the other 2 RCAs go to the monoblock


If any more information is required let me know.

Thanks guys

[anarklov3r]

Easy fix, next time it happens while your driving, just pull over and tell that bitch to get out.

[scozz76]

Check under your wheel arches, you may have run over a pig.

On a serious note......

Try pulling the RCA leads out of the amp... does this stop the noise?

[ruggj]

Check under your wheel arches, you may have run over a pig.

On a serious note......

Try pulling the RCA leads out of the amp... does this stop the noise?

Yeah, as i pulled out each RCA the noise stopped from those speakers only.

Everything has power, i've checked the grounds for the amps, they seem fine, i gave them a clean (just with a brush), and yeah, it's definitely metal onto metal, they are both grounded to behind the rear seats, one on each side.

the head unit works fine, like i can go through the menus as per normal, but with the volume on 0, it still plays this annoying squeal, the only way to stop it is to turn the head unit off.

So i'm still thinking it's either the headunit or the headunits ground. It was exposed to a bit of sun this morning, the car would have gotten pretty hot, could that have done anything?

Also, where is the factory ground for the headunit? i want to see if it is still ok

cheers, Jarrod

[cewing]

im no expert on car electrics, but as an electrician what i'd do is check the resistance from the earth point for the amp and the headdeck(found somewhere in the plug behind the headdeck) to the 0v on the battery.
Its very well that ur earthing point is a clean contact, but what if the point ur attaching to, and ur head deck earth has a high resistance back to the battery.
If that fails, and noone else here has a magic answer, try process of elimination. Could be something fried. getting hold of a mates ole headdeck would be very handy

[holdenboy]

Sounds like a poor earth or the RCA earth inside the head-unit.
Start by checking / re-doing the earths at the head-unit and at the amp. If this dosent solve the problem then remove the unit and get a small length of wire, connect one end to earth and the other end to the outer "ring" of the RCA plugs at the back of the head-unit while its on / playing music. If the noise disappears then its the internal earth of the head-unit.

[cewing]

^^^ theres ur magic answer from someone who knows their stuff lol
if that fails it mite be worth checking resistance between the core and sheath in each rca cable (unplugged obviously) to check the cable isnt damaged somewhere.

[ruggj]

Sounds like a poor earth or the RCA earth inside the head-unit.
Start by checking / re-doing the earths at the head-unit and at the amp. If this dosent solve the problem then remove the unit and get a small length of wire, connect one end to earth and the other end to the outer "ring" of the RCA plugs at the back of the head-unit while its on / playing music. If the noise disappears then its the internal earth of the head-unit.

thanks guys for the info.

Do you happen to know where the earth is the head unit in a VX? the installer just used the factory earth.

I was playing around with the negative terminal of the battery, i cleaned the connection on the lead and on the battery (just with a rag), put it back on, and now music plays, but with this annoying sound on top of it all.

Right now the battery has died again for the 3rd time this week, and I'm waiting for someone to get home to help me jump start it, could a tired battery cause this?

originally i didn't think it would be the battery because it died twice, so i put it on a charger for 24hrs until it was charged, put it back in and it had been running great until this morning, so before this morning i thought my battery problems were solved.

I'm getting a new battery anyway tomorrow, but with the stereo running on a tired battery, could this cause this? I was still able to drive around while it made this sound, like the car was starting fine and it was still making these sounds, until today.

cheers guys

[holdenboy]

A flat (or nearly dead) battery wont cause interference like this.

[ruggj]

well it turned out to be the head unit, we did like you said, connected the earth to the outer ring of the RCAs and it went away. so luckily the head unit still has warranty, sent it back today. thanks heaps for your help guys i really appreciate it

[holdenboy]

No problem......in the future just make sure everything is off and all power / earth connections are made to the amplifier and head-unit before plugging the RCAs in.
I beleive this happens because one of the components (amp or head-unit) isnt gounded properly and when you plug the RCAs in the offending component tries to "earth" through the RCA cable.

[ruggj]

No problem......in the future just make sure everything is off and all power / earth connections are made to the amplifier and head-unit before plugging the RCAs in.
I beleive this happens because one of the components (amp or head-unit) isnt gounded properly and when you plug the RCAs in the offending component tries to "earth" through the RCA cable.

Ok cheers mate, thanks again

[anarklov3r]

this just dawned on me, my attempt at putting RCA line out plugs on my headunit failed epicly with engine noise. I should have tried grounding my RCA's to the chassis to see if that solved the problem! Will do it tomorrow :P

[holdenboy]

Pioneer head-units are prone to this problem.....they have an internal "fuse" for the RCA ground, it can be replaced by the user but you will void warranty (if this applies) or could potentially damage the unit permanently if not done properly.

Im unsure if this occurs with other brands....if it does its less often.

[ruggj]

Pioneer head-units are prone to this problem.....they have an internal "fuse" for the RCA ground, it can be replaced by the user but you will void warranty (if this applies) or could potentially damage the unit permanently if not done properly.

Im unsure if this occurs with other brands....if it does its less often.

Glad to know I'm not the only one to get this problem then, as my head unit was a pioneer. I still had a month left of warranty so i just took it back under warranty

[anarklov3r]

You actually had 13 months left, you had the extended warranty

[ruggj]

was it? i think it was just 1 year. i'll have a look tommorow lol