10 replies to this topic

[crikey87]

Hi everyone

I've replaced my head unit (Sound System) recently and now have buzzing through the epeakers when the engine is running, this escalates as the revs increase. I've spent a heap of time checking grounds in the system. I have a full FOCAL system with amp and subwoofer unchanged from the previous head unit. I've thoroughly checked grounds and found some loose fittings and thought I'd fixed but no change. The only other item replaced is a new 85amp Alternator, could this be the issue?

I'd be really grateful for any tips, thanks.

Len P

[greenhj]

Does the new alt have the capacitor fitted on the back?

[Rockoz]

A whine noise is generally attributed to the alternator.

Buzzing would normally be attributed to ignition system.

 

A suppressor capacitor should be fitted to the alternator output.

And another one fitted to the coil.

 

These are the primary sources of interference.

 

A toroid filter on the supply wire to the audio system may also help.

 

Cheers

 

Rob 

[Dr Terry]

What he said ^^^^^

 

Dr Terry

[crikey87]

Thanks DR Terry, Rockoz, and greenhj for the suggestions. I'll check and or add as suggested.

Cheers

Len

[LXCHEV]

All great advice above and should sort you out. Failing that, many years ago after I'd installed an amp into the Torana - I experienced this too and ended up fitting an off the shelf "ground loop isolator" into the system. Sorted mine out beautifully.

 

Look them up - they're cheap and plentiful.

[rodomo]

I get it too..............................Doc reckons its tinnitus. 

[crikey87]

Thanks LXCHEV.

I'm running out of options, nothing seems to be rectifying the issue but have read about ground loop isolators. This'll be next I reckon.

Cheers

 

P.S. Did you fit yours to the amp? Mine has 4 channels so I'm a little unsure how this fits?

Edited by crikey87, 11 July 2025 - 01:46 PM.

[Dr Terry]

Get someone who has (& can use) an oscilloscope. Have a look how smooth the incoming 12V supply is. If the 12V is good, then it maybe induced thru the speaker wiring.

 

Dr Terry 

[LXCHEV]

Thanks LXCHEV.

I'm running out of options, nothing seems to be rectifying the issue but have read about ground loop isolators. This'll be next I reckon.

Cheers

 

P.S. Did you fit yours to the amp? Mine has 4 channels so I'm a little unsure how this fits?

 

We're going back a long way here - but yes, my memory is that I installed the ground loop isolator inline to the amp (RCA connectors). I also recall that the positioning of the power supply cabling in relation to the audio cabling is the likely primary cause of the issues. i.e. running the power cables and the RCAs/speaker wiring together down the same side of the car. If you can separate them and keep power away from the audio, then that's good practice and may also help eliminate.

 

4 channels may require 2 ground loop isolators? I honestly can't remember!

Edited by LXCHEV, 11 July 2025 - 04:06 PM.

[crikey87]

Thanks LXCHEV.

I do remember taping all the cabling together before I pushed the stereo back into the dash. Need to separate as suggested, plus I've orered 2 ground loop isolators.

Cheers

Len P