Engine noise through rear speakers (Fixed)

[Phewsion]

Hey All

I've tried to figure this out myself with bits n pieces of info I've found on google and on here but I'm still stumped

I've got a pioneer Hu connected to pioneer components up front (No engine noise)

I had an amp at the rear just powering a sub (no engine noise)

I took out the sub and connected 2 kicker 6x9s I had from another car, as I'm planning on custom making a fibreglass enclosure for 2 10" in boot so took out the 12" with box while sorting it out.

Now when I first plugged in the 6x9s all I was getting was bass and muffled voices (But again no engine noise), Took me awhile to click that the amp was in Low Pass mode so I flicked it to All Pass and then bam engine whirr through speakers which increases in tone when engine revs up.

It also does it while in ACC With engine off but it's a very muffled hummmmmmmm

It doesn't do it in the ignition part just before ACC (Not sure on technical name) before all the lights on dash come on, only stereo + amp

I've got the power from batter running along left side of car, RCAs from HU running along right side so they aren't interferring, speaker cable coming out of amp aint anywhere near the amp power cable

Basically the info I could find said power is to close to audio signal, but it's not, if it was wouldn't the noise come through no matter what amp setting (LP, AP or HP) it only happens on AP and HP

Any help appreciated

P.S If anyone wants to know I'll be making an enclosure similar to this, But with only 1 amp for subs

[legacy666]

check and double check all connections, especially the earth. soldering will ensure a strong connection. also try adjusting the 'gain' on you amp. check here for more http://www.the12volt.com/installbay/forum_posts.asp~TID~85479~PN~1

[subieboy]

It will be a poor earth connection or another non earth wire is being earthed somewhere (not necessarily the speaker or amp wiring either)

[Phewsion]

All the wires are soldered, The earth point is right under the flap at the back off the boot (base of seats) could it be because the speakers are sitting in boxes virtually on top of the metal the earth is connected too?

I mean the only thing between chasis and speaker boxes is the foam/boot liner

 legacy666 said:

check and double check all connections, especially the earth. soldering will ensure a strong connection. also try adjusting the 'gain' on you amp. check here for more http://www.the12volt.com/installbay/forum_posts.asp~TID~85479~PN~1

The gain is pretty low on the amp already, wanted to get rid of noise before fiddling with settings

[DaktaPhil]

Definately try moving ground, i had a similar problem though not rev dependant on more than one occasion in two diffrent cars, where i mounted the earth to rear passenger seat or near it. once in my ae111 and when i first put my amp into my bg.

Its not really that hard to test though is it? (earth that is)

[calibre]

maybe try one of these? http://www.jaycar.co.nz/productView.asp?ID=AA3081

[Guest]

I had the same problem with one the missus car. The battery in the boot amp under the passenger seat. Ran the power and and noise cables different sides of the car for the rear 6x9s. Put in a noise filter and only reduced the noise. Didnt try moving the amp just ended up wiring the 6x9s to car loom off head deck as couldnt sort it. Keen to know how you fix it.

[spark_38]

How good is the soldering? What are you soldering to/from?

A proper crimp is a far better (electrical) connection, esp if it's a poor solder (dry joint) connection. The main earth and power wires should never be soldered - anything larger than 8-AWG wire should be either crimped, or replaced with a single wire, the only joins being in the fuseholder and distribution block.

[Guest]

 spark_38 said:

How good is the soldering? What are you soldering to/from?

A proper crimp is a far better (electrical) connection, esp if it's a poor solder (dry joint) connection. The main earth and power wires should never be soldered - anything larger than 8-AWG wire should be either crimped, or replaced with a single wire, the only joins being in the fuseholder and distribution block.

If youre crimping big cable either get a proper crimper or take it to a sparkie. Farmers use hammers and vices and such then melt battery terminals through bad terminal connections...

Men of the old school prefer solder. As above minimize number of joins too.

[resurrection.inc]

Righto after many an install (especially nissans for some reason) this is what i have found. Make sure the amp is not placed by any part of computer in boot if your going to screw amp to floor paneling screw it to mdf then screw that to floor ( no carpet in between) when finding a ground if you dont use spear tyre well use that point or a seat belt point. BUT u must sand paper the paint and crap off connection as much as possible and make it clean as u can. Use full length wiring rather than joins and always make sure ground and power wiring is as big as possible. I prefer to use 4 awg but then u get awsm amps made by reputable brands and they give you this tiny bloody hole to try and screw a massive wire into! Not cool!

[Phewsion]

Thanks for the advice everyone, I bought a RCA Noise Filter from Jaycar and that fixed it, so the noise was coming through the RCA cables

My soldering is not that good as I've only just started doing it, before that everything I did was crimped

This is my 6th car I've done audio overhauls in but it's the first time I've had 6x9s in the boot so I got a bit muddled, usually I just put nice front components and sub D:

Since I'm trying to build the 2 sub enclosures in the first posts pic I took it out to make room but still wanted decent sound

First thing I'm doing is replacing the entire booth liner with MDF

EDIT The only thing I solder is audio wires, Power/Ground/Remote is just 1 long wire from battery/radio to amp, I got a block thing on battery to connect wires too when needed

[boon]

Google Pioneer fusible link. It's a pretty well-known thing - the RCA ground in the deck is fused by a tiny surface mount pico-fuse. If you unplug/plug in RCAs on a Pioneer head unit while the system is turned on you'll pop the fusible link.

Often people only discover they've popped it when they amp speakers, as the low-pass on a subwoofer hides the ground loop whine you get when the link has popped.

The Jaycar noise filters use an electrically isolated transformer pair which solves this problem. Or you can open the headunit and either solder across the points on the board or replace the popped fusible link. Some people put in a 1 ohm surface mount resistor which also solves the problem.

[Phewsion]

Ah that's exactly what I did, plugged it in while the stereo was on, I'll have a look at that, thanks