Getting "sub thump" !!

[butterMilk 10+ year member]

When I turn off my car my subs "thump". Ive tried switching grounds.

I have separate amps for mids and subs. And its all running of a LOC (LC6I)

You guys have any ideas of how to solve the problem?

Ive read I should maybe ground my RCA cables, how would I do that?

Click to read more...

 

[maylar 10+ year member]

Turn off thump can happen if the RCA source (your LOC) puts out a pulse during shutdown and the amp is still active. Fixes include delaying the LOC shutdown until the amp is off, or using a pop eliminator (David Navone) that disconnects the RCA inputs from the amp with a relay.

Try this experiment - unplug the RCAs from the sub amp and see if the thump goes away. If it does, then this is your problem. If it still thumps it's probably the amp itself and you'll need another solution.

 

[butterMilk 10+ year member]

I unplugged the RCA's from the sub amp, and the pop is gone. But I just noticed that my mids are doing it also, its just not as loud or very noticeable.

If I run a remote wire into the LOC would that help? The LC6I doesn't need one, but there is a input for one.

How would I delay the LOC shutdown? My amps are getting their remote wire from the LOC.

 

[armykyle1 10+ year member]

Try grounding the out side of the RCA's

Is this a pioneer HU?

 

[butterMilk 10+ year member]

Inside the LC6I there is a ground selector, I switched it and it has gotten rid of 75% of the noise, but it is still there.

How do I ground the outside of the RCA's?

Its a stock HU.

 

[maylar 10+ year member]

You've proven that the pop is comming from the LOC. How do you have the power to the LC6I wired? If you power it from constant 12V does the thump go away?

 

[butterMilk 10+ year member]

The LOC is wired to my power distribution block, which also has 2 amps wired to it. So that is 12v constant, right.

I also have a constant "hissing" coming from my speakers. The LOC is next to my OEM amp, would that be the problem?

Ive checked all my grounds with a DMM and they are good.

Maybe the "hissing" is coming from the OEM head unit?

I am using a Stinger 8000 series RCA from the LOC to my mids amp, as far as I know they are good quality.

 

[maylar 10+ year member]

Wow. Dunno what to tell ya 'bout the hissing. The LOC being near the amp won't matter.

I'm dealing with turn-off thump myself, mine is caused by a cheap inline preamp. When the power to the preamp cuts off it makes a pulse that thumps the subs. If I wire constant power to the preamp instead of powering it off the remote line the thump goes away. That's why I asked how yours is wired.

A separate remote wire would probably help, but I dunno how you'd get one off the OEM system.

I think you're using the LOC the way it was intended. Audiocontrol is good stuff and shouldn't cause issues. I would email them and see if thy can give you some advice.