Bad grounding? Buzzing sound in accessory position


idkcaraudio

CarAudio.com Enthusiast
Jun 16, 2020
29
7
United States
Just installed one of my amps for my front speakers. It sounds really nice so far except for the fact that there's a buzzing sound coming from both speakers when I have the ignition in the accessory position, regardless if the headunit is on or off. If the amp is powered up, it's there. The only exception is there's no buzzing when the car is not powered on at all, even if the headunit is powered up. I'm using my factory headunit, and it's a strange one because it let's you turn on the stereo even if the key isn't in the ignition. To clarify, when the car is completely off, keys out of ignition, there's no buzzing even if I power up the headunit. Is this a grounding issue? I'm a little confused because I thought I grounded it correctly.
 
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idkcaraudio

CarAudio.com Enthusiast
Jun 16, 2020
29
7
United States
So I actually took a closer look at it and when I disconnect the rca and the high level input the sound goes away completely... so I'm guessing this is not a grounding issue then?
 

1aespinoza

Junior Member
May 22, 2013
335
96
Pharr, Texas
so I'm guessing this is not a grounding issue then?
Is the routing like this? Radio speaker output-LOC-rca-amplifier. If yes, then your wiring is correct. Only suspect is a bad ground. I say this because you mentioned that radio may be powered sans keyed accessory. When in this mode, I believe it receives power by an separate relay than the keyed accessory relay. Keyed relay powers radio, windows, wipers et cetera. That is when you get a grounding loop that causes radio interference. Therefore grounding radio chassis to bare metal in the dash, should prevent that loop bleeding into your radio signal.
 
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idkcaraudio

CarAudio.com Enthusiast
Jun 16, 2020
29
7
United States
Is the routing like this? Radio speaker output-LOC-rca-amplifier. If yes, then your wiring is correct. Only suspect is a bad ground. I say this because you mentioned that radio may be powered sans keyed accessory. When in this mode, I believe it receives power by an separate relay than the keyed accessory relay. Keyed relay powers radio, windows, wipers et cetera. That is when you get a grounding loop that causes radio interference. Therefore grounding radio chassis to bare metal in the dash, should prevent that loop bleeding into your radio signal.
yes thank you, actually I had grounded the high level input on the amp but I guess I wasn't supposed to because when I ungrounded the high level input, the buzzing went away? so problem solved :)
 
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idkcaraudio

CarAudio.com Enthusiast
Jun 16, 2020
29
7
United States
Awesome possum. Would you elaborate on grounding high level input? This will help others with your same issue.
yup ofc, basically my headunit gives speaker level outputs, and one of my amps had a speaker level input. The input for the amp had five wires coming out of it; pos and neg for the left channel, pos and neg for the right channel, and a middle black wire which I assumed was the ground. Initially, I had connected the middle black ground wire to the same location where my amps were grounded. I got buzzing at all times with the key in the ignition from the speakers. Later, just to see if it would change anything, I disconnected the middle black wire from the grounding point and found that there was no buzzing anymore at all. I ended up just cutting the middle black wire off and it's working fine now. :)
 
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idkcaraudio

CarAudio.com Enthusiast
Jun 16, 2020
29
7
United States
Is this adapter the LOC? I have used a few and wondered how grounding that wire would help. Now we kniw to let it be. Thanks for updating.
Sorry I edited my post to clarify, this amp has a high level input, by adapter I meant the 5 pin connector that connects to the amps high level input, not an LOC but I'm guessing it would work exactly the same way. :D
 
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