Diagnosing an audible hum

Reply Subscribe

Thread Tools

Search this Thread

Aug 23, 2013 | 11:52 AM

restorick

Thread Starter

Cruiser

Joined: Nov 2007

Posts: 199

Likes: 1

From: Hometown of Willie G

Diagnosing an audible hum

OK, may have spoken too soon. While the new speaks are incredible, I now have an audible hum when ignition is active. Accessory, no issue.

Hum is constant and happens regardless of FM or iPod input.

System is:

Sony 210 HU
Arc KS 125.2 amp (not BX)
Polk MM6501s in fairing

I pre-wired the RCA leads from the HU to the tour pak in anticipation of the SS amp install and speaker pods. Is it possible that the RCA cable routing (past the battery) for the rears could be the issue with the fronts?

Thanks in advance...

Rick

Aug 23, 2013 | 07:14 PM

Red-line

Tourer

Joined: Jul 2012

Posts: 322

Likes: 1

From: Montreal, QC

You have a bad ground. Try making sure that the point where you grounded the amp is making contact to bare metal, and that it is as short as possible.

Aug 23, 2013 | 09:30 PM

Lowcountry Joe

Elite HDF Member

Joined: Sep 2007

Posts: 4,928

Likes: 69

From: Near Myrtle Beach, SC

Quote:

Originally Posted by restorick

Is it possible that the RCA cable routing (past the battery) for the rears could be the issue with the fronts?

I route my low level outputs through coaxial cable to the Arc 125-4 in the tour pak. Works great. Crystal clear and loud. They run right by the battery and ecm area. You need to run quality cable regardless.

I agree with the comment about grounding. Lots of misconceptions about where to ground, how to prepare the metal surfaces to ensure future continuity, etc.

Aug 23, 2013 | 09:48 PM

Junkster

Road Captain

Joined: Aug 2012

Posts: 736

Likes: 1

From: Iowa

Hum/EMI can be caused by plugwires bad grounds or cheap cables letting in EMI. You have no hum on accessory but do when running. Make sure your cabling isnt close to your spark pack or plug wires or any other strong electrical forces. Coaxial cable has a shield around it. Works well. If you really want isolation strip it back some and ground 1 end of the shielding.

Aug 30, 2013 | 11:57 AM

restorick

Thread Starter

Cruiser

Joined: Nov 2007

Posts: 199

Likes: 1

From: Hometown of Willie G

Remedy

Guys,

Thanks for the feedback. Turned out to be a loose RCA connection on the left channel connection from the Sony HU to my Arc amp. Grounds were all valid, but as soon as I moved the RCA connection the hum went away.

This happened before with cheaper RCA cables to the amp, so these cables are 1ft long with custom soldered connectors on both ends. If this happens again, I'm thinking I may have an issue with the female end coming out of the HU.

Thanks again,
Rick