Speaker Buzz from Alternator Whine

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alaskalife

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Jan 16, 2014
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Getting speaker buzz from the alternator whine in my 99 Adventurer.  It has an aftermarket stereo I put in to replace the other aftermarket that was there.

Already tried running a new ground wire and still does it.

One source was the audio line from TV to stereo.  I got a ground loop isolator to kill that extremely loud buzz and the isolator works well. 

However,  there is still a constant buzz on speakers even with the stereo off.  And it increases with engine RPM...obviously from alternator spinning faster. 

Was thinking about replacing speaker lines cause the factory ones (that are the same large gauge wires used all over the RV) go into the harness and all and no telling where they are all running.  Think the noise is being induced on the speaker lines directly and so thinking new speaker lines running more direct to the stereo away from the engine might help... 

Anyone else dealt with the buzz and found the definitive cause? 

 
alaskalife said:
Getting speaker buzz from the alternator whine in my 99 Adventurer. 
Click to expand...
Alternator whine is a very common problem. See here for some ideas.

Same stuff for vehicle alternators, I just though this one explained things better than other info I could find, even though it's for aircraft.

-Don-  Reno, NV
 
Depending on the requency of the Buzz/whine it might not be the alternator, Alternator whine is very high pitched bordering on ultrasonic.

This is a very common problem among Ham Radio operators, there are entire books on controlling Radio Frequency interference and mobile radio interference (Alternator, Ignition, Fuel pump) issues.. You can find them at www.arrl.org and click on the store link.
 
Well, after playing around with a few things...disconnect antenna - still had noise...disconnect radio harness...still had noise.  So it was the speaker wires like I thought.  It was some form of engine noise being induced onto the lines, because it increased with RPM's.  Similar noise was also there when generator ran.  And there was no noise when both engines were off.

As I started running new speaker wire, I noticed there were only 2 of the 4 channels used in the factory harness.  So...2 channels were being split among 6 speakers (2 front, 2 rear, 2 in the floor).  That alone was probably causing some headaches.  The factory also used the same heavy gauge wire used for the 12 volt wiring for the speaker wiring... 

I am not using the floor speakers...they are in useless places anyways.  I have 3 of 4 new speaker wires ran (directly to radio) and no more noise.  Got to do the 4th on another day...it's on the slide out so its going to take a little more effort. 
 
You disconnected the radio harness and STILL had noise.. Mose unusual since there are parts in the radio that are a MUST for the speakers to wine at you.. Lines to the speakers are balanced, by their nature you need an unbalanced part (Diode, transistor, power source) to get whine out of them

Most Dash radios are low power, perhaps 10-20 watts..  Thus in an RV they often have an audio power amp hidden away (mine is under the dash on the left (Driver's) side wall) and that is the source of your whine if you have one, disconnecting the harness from the radio leaves that amplifier still in the circuit.  Or at least it should.. long story there.. Major pain in my operating system.. but it was not the amp, it was another box nearby.. And it was not whine.. And I finally fixed it,, but I sure saved money on hair cuts tracking it down.
 
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