Thump from speakers when car turned off

Astron_Boy · Post by **Astron_Boy** » Tue Mar 24, 2009 2:10 pm

Okay, so the new system is installed.
Meanwhile, everytime the headunit has power turned off, the speakers make a loud thump.
Depending on how long the powers been on, means the thump is even bigger.

I was informed it could be that the amp needs to be powered down first, before the headunit.
So I installed a switch off the remote wire, and then tried turning off the amp whilst the headunit was outputting.
Still thumps.

Was told to try and pull out the RCA leads whilst there was still throughput.
I THINK this worked, but was hard to tell, as I was leaning into the boot, so couldn't hear.

I have installed a filter cap inline with the amp, it is about 50cm before the amps positive cable.

I'm out of ideas.

Last thing I can think is a smaller filter cap on the headunit power, and see if that works...
It's becoming annoying.

Post by **vipfto** » Tue Mar 24, 2009 2:24 pm

bad earth me thinks

Astron_Boy · Post by **Astron_Boy** » Tue Mar 24, 2009 3:02 pm

I do need to add more earth leads, there's only the factory one coming off the battery, and it's rather small.

Jamie · Post by **Jamie** » Wed Mar 25, 2009 7:23 pm

+1. I think you have a bad earth. Not so much at the battery but at the amp or head unit. Also is the sound coming from all the speakers?

Astron_Boy · Post by **Astron_Boy** » Wed Mar 25, 2009 7:41 pm

ignore.

Astron_Boy · Post by **Astron_Boy** » Wed Mar 25, 2009 7:42 pm

Jamie wrote:+1. I think you have a bad earth. Not so much at the battery but at the amp or head unit. Also is the sound coming from all the speakers?

Funny you mention that.
I do have sound from all speakers, the sound is awesome.
But when I first powered the amp one it was finshed, I had left channel only.
Which went away after I turned the car off and then back on 1hr later.

I only have the equivalent of 1 4GA wire comning off the batter which terms at the chassis arch and then the gearbox from factory.
Was going to bump that up, but the new negative terminal is to large for the battery.

I suppose though I could bump up the amps negative to a 4GA from an 8GA.
Even though it shoudln't technically need it.

Jamie · Post by **Jamie** » Fri Mar 27, 2009 11:00 am

The sound is awesome

I meant is the "loud thump" sound coming from all the speakers?

Astron_Boy · Post by **Astron_Boy** » Fri Mar 27, 2009 6:51 pm

oh

well fine, dont ask me how the sound is!

lol

yeah, thump is through all speakers.