Help with interference/ground loop?

[kitehigh]

Hello,

So in order to get Bluetooth through my 6000CD RDS in a Focus mk1 I have added a Parrot MK6000, then a Connects2 CTVFOX001 to link into the CD changer port on the head unit.

So the Parrot takes it's 12v and ground split from the same source as the HU.

Then line out from the parrot goes to the connects2 RCA inputs.

The connects 2 is powered and grounded via the CD changer port on the HU, with the line out from connects 2 also going into the CD changer port (L+/- R+/-).

So with this setup I get a buzzing sound, varies with the engine revs. I added a ground loop isolator on the line out from the parrot to the connects2, which stopped the buzzing but also affected the sound quality (tinny, no bass).

I tested the GLI by disconnecting the Parrot and just taking a 3.5mm jack from a phone playing music to the GLI and on to the connects2 RCA input - sound quality was fine here. Also Phone to connects2 without the GLI produced no buzzing so the problem is not the connects2 itself.

Does this sound like a ground loop problem? Not sure how to cut the loop without using the GLI which affects the SQ of the Parrot line out - anyone have any suggestions?

12v&Ground split from HU-->Parrot (line out)-->Connects2 (12v&Ground and line out)-->HU (changer port)

 

[Perry Babin]

It sounds like a ground loop.

Some of the GLIs are directional and will reduce the low frequency signal significantly if you use the wrong end for the input.