sub is bumpin - but i dont want it to

**patatoeswizard** · 09-02-2006, 01:13 PM

don't have time to run out to the car to get exact specs so heres the run down-
on lower volumes (independant of the car engines status) my sub is putting out a loud bump.. bump.. bump.. - even when my head unit is muted - when i unplug the rca cables the bumping stops - but in my old settup i used the same head unit and this was never a problem - anyways the amp is used and relatively worn - and i bought cheap temporary wiring - is this usually a byproduct of emf or bad grounding or is there something more (ie bad head unit/amp) - when the volume is turned up some the repeditive bump bump bump is replaced by the actual bass to the music - any info would be much appreciated - if you guys need more info ill give details when i get back from work -thanks a bunch

**Tidder** · 09-02-2006, 01:44 PM

Sounds like a grounding problem to me.

**RedGTiVR6** · 09-02-2006, 02:33 PM

well, if you don't have time to get specs, are you going to have time to answer our questions? I only ask because I'd hate to try and help you out only to never hear from you again!

I'd start by reading this thread:

Induced noise/Ground loop trouble shooting guide.

If you unplug the RCAs and it stops. Chances are it's not the amplifier.

Check your RCA cables and make sure they aren't being put in any kind of a bind or being pinched in any way.

Otherwise, I'd suspect the HU going down.

**Tidder** · 09-02-2006, 03:11 PM

I'll have to jump in here with personal experience. I've seen this twice so far. I dunno if it's ground loop or what, but when the RCAs are plugged in, it's just a constant thump-thump-thump-thump (like techno!). Both times it ended up being a ground problem. Way we fixed it was grounding everything to the same location.

Weird thing is it would stop if the RCA's were unplugged from the amp.

That's why I'm so quick to call the ground a dirty rotten bas**rd.

**patatoeswizard** · 09-02-2006, 10:56 PM

wow thanks for the quick support - after work tomorrow i will reground everything - im glad someone else has heard of this - i just thought it was really strange because it really did resemble a techno beat - not a static noise - i will repost after i ground my heart out

**1stclasso** · 09-02-2006, 11:03 PM

to test the grounding for the rca's

cut a piece of wire, ground one end then (with the rca's plugged into the amp and playing) touch the other end of the wire on the outside of the RCA's. try that before disconnecting anything, of regrounding

**parksgm** · 09-03-2006, 02:08 AM

Originally Posted by 1stclasso

to test the grounding for the rca's

cut a piece of wire, ground one end then (with the rca's plugged into the amp and playing) touch the other end of the wire on the outside of the RCA's. try that before disconnecting anything, of regrounding

What does that test? Since the RCA cables are only grounded through other components (and not directly), then grounding the shield would only tell you if there was a ground problem with one of the othe components they are connected to...and you would then have to solve by regrounding those connected components individually....so you might as well just do that first.

**RedGTiVR6** · 09-03-2006, 09:59 AM

This really sounds like something is grounding through the RCAs.

You can test this by picking up another set of RCAs, draping them across the seats, and plugging them in. This eliminates issues with pinched RCAs, etc.

Regarding manually grounding the RCAs. True. Some radios will actually ground through the RCAs because they aren't grounded properly to begin with. This is a lot easier to test than to start off by regrounding everything.

**1stclasso** · 09-03-2006, 01:27 PM

Originally Posted by parksgm

What does that test? Since the RCA cables are only grounded through other components (and not directly), then grounding the shield would only tell you if there was a ground problem with one of the othe components they are connected to...and you would then have to solve by regrounding those connected components individually....so you might as well just do that first.

troubleshooting
even it u fix the problems, its alway good to know the source for future installs, then sometimes u can change all the grounds and a week later the noise will come back, knowing the source is wise and less time consuming

**Quattro** · 09-03-2006, 02:02 PM

I had a the same problem with my setup. After about a month of use the problem started, I re-checked all my wires and found out that the ground for the powersupply had began to come loose, fixed that and the thumping was gone.

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