Loud Dimmer Buzz

Pittdawg

Original poster
Member
Dec 5, 2011
538
After installing two aftermarket head units, each head unit elicited fairly loud dimmer buzz. When I turn the dimmer all the way off, the buzz disappears completely. I have now had two different car stereo installers look at this issue and they both are stupified. They checked all connections and grounds and can't find anything wrong. My set up is Pioneer Avic HU connected through a gmos4 and axxess module to the factory bose amp??? Anyone aware of what causes this condition on our vehicles? I saw some postings about this same issue on the other OS but no solutions. Thanks.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Did they disconnect the dimmable instrument lamp circuit from the head unit to see if the interference was caused by direct input or through RF (through the air) pickup? Our dimmable lamp bus isn't a smooth analog one, but a digital on/off PWM (pulse width modulation) signal. I'm surprised we don't get even more reports of interference than we do. Adding a capacitor to the lamp bus (like a DRL killer circuit) may smooth it out if you don't find the exact path the interference is taking.
 

Pittdawg

Original poster
Member
Dec 5, 2011
538
the roadie said:
Did they disconnect the dimmable instrument lamp circuit from the head unit to see if the interference was caused by direct input or through RF (through the air) pickup? Our dimmable lamp bus isn't a smooth analog one, but a digital on/off PWM (pulse width modulation) signal. I'm surprised we don't get even more reports of interference than we do. Adding a capacitor to the lamp bus (like a DRL killer circuit) may smooth it out if you don't find the exact path the interference is taking.

This is all way over my head. Can you point me in the right direction of where I can purchase a capacitor to the lamp bus? Thx.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I've never tried that trick, just a guess from my engineering background. Better is to locate the exact root cause of the interference and cure it properly. Can you try the direct speaker outputs from the HU and bypass using the Bose? That will at least divide the problem in half.

Calling all audio experts.....
 

Pittdawg

Original poster
Member
Dec 5, 2011
538
the roadie said:
I've never tried that trick, just a guess from my engineering background. Better is to locate the exact root cause of the interference and cure it properly. Can you try the direct speaker outputs from the HU and bypass using the Bose? That will at least divide the problem in half.

Calling all audio experts.....

That was my original thought process but I thought the Bose speakers only run at two ohms which the Bose amp does but my headunit does not?
 

itstrick

Member
Dec 10, 2011
29
0I have had the same issue for a couple of years now, (avic d3 the gmos04 an the usb input) the company that had orignally installed mine had tried the capacitor and that never worked the buzz was still there and it was even worse when the heated seats were on. My problem went away yesterday though after I took the works out and plan selling it or something Maybe someone will hav some better ideas on what to do
 

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