Hum after aftermarket HU install

diggler30 · Post by **diggler30** » 26 May 2013, 21:07

Hello all,

I just put in my Kenwoood double din HU and as soon as the power kicks on I get a constant hum through the speakers. I get sound and everything is working. This is in my 97 850r and i am retaining the factory amp. What can I do to fix this?

Thank you for your help.

Derek

Post by **mikealder** » 27 May 2013, 01:26

Fit a ground loop isolation device between the head unit and the amp, somewhere like Radio Shack should sell these - Mike

diggler30 · Post by **diggler30** » 27 May 2013, 14:48

Thank you, I will give that a shot. I have installed probably 20 stereos in my life and have never come across this before. Thanks again for your help!

diggler30 · Post by **diggler30** » 27 May 2013, 16:52

That didn't fix it. Sounded exactly the same. Tried it on front and rear outputs from the HU with no help. I can't use it on the amp since it uses the din cable. What should I try next? Different ground on the amp? New ground for head unit?

Thank you.

Post by **mikealder** » 28 May 2013, 04:40

Connect the headunit ground and the amp ground together then add a new single wire from this junction to ground on the car, this way ensures both grounds are at the same potential - Mike

diggler30 · Post by **diggler30** » 28 May 2013, 14:18

I figured that was the next course of action.

Should i disconnect the ground that is currently there or just tie in a new ground to the existing one on the harness? Also, can I just ground it under the dash somewhere or do i need to run it to the engine bay? Just want to make sure I do this once and and not have to keep messing around with it.

FYI, I am surprised how good this sounds with the stock amp. I am very happy with that. My next issue will be to try to figure out what to do with the trim. The Kenwood double din is surprisingly smaller than the stock unit and there is a decent sized gap to fill.

Thank you for your help again!

Derek

Post by **mikealder** » 28 May 2013, 14:21

I would disconnect the existing ground and join both the head unit ground and amp ground together and then take a new wire to ground at a convenient location, make sure the metal you attach it to is cleaned up and devoid of any paint - Mike

diggler30 · Post by **diggler30** » 29 May 2013, 10:48

Thank you very much for your help. It shouldn't be to difficult to find a good spot under the dash. Surprisingly its hardly noticeable when driving due to the road noise.