Car audio suddenly blares and distorts

[JDirkse]

I'm pretty ignorant about car audio systems, so I'm looking for any help I can get. My truck has an after-market stereo (was there when I bought it used), including an amp, sub, and a touch screen receiver. It sounds great--except that, very rarely and unexpectedly, the volume will spontaneously EXPLODE and the sound gets all distorted. It happens while driving, and it's seriously startling enough to cause an accident. Makes you scramble to turn it off. My wife refuses to listen to audio while driving. If I turn the receiver off and back on, it fixes it, and it may not happen again for 6 months. Or it may happen again in 5 minutes.
Any ideas would be appreciated!

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[Doxquzme Premium Member]

Hmmm, odd one. Manual volume knobs? Gain POT?
What is the HU, AMP, LOC if there is one?

 

[JDirkse]

Thanks for the reply Doxquzme--when I said I was "pretty ignorant", I wasn't kidding...could you please spell out the acronyms for me?
There isn't a manual volume knob, and it doesn't seem to be a volume issue really. I will turn the volume all the way down when it is in this state and it is still very distorted and louder than it should be. It does seem as if gain gets thrown out of whack somehow.

 

[Doxquzme Premium Member]

Thanks for the reply Doxquzme--when I said I was "pretty ignorant", I wasn't kidding...could you please spell out the acronyms for me?
There isn't a manual volume knob, and it doesn't seem to be a volume issue really. I will turn the volume all the way down when it is in this state and it is still very distorted and louder than it should be. It does seem as if gain gets thrown out of whack somehow.

Sorry, no worries. "HU" is the head unit. "AMP" is amplifier and "LOC" is a line out converter if you have one. It may be that the gain pot (little turn knob on the amp) is defective on the amp. Instead of regulating the constant volume/voltage on the amplifiers input, it just kinds shorts out and goes full bore. If you had a volume knob on the HU, same thing may apply though apparently that is not the case. I would almost guarantee it is the HU though, suddenly sending higher than normal, excessive output signal to the amp. How is the HU hooked up to the amp? Directly from the HU or from the HU to a line out converter then to the amp? If directly to the amp, via high level speaker inputs or through RCA outs from the LOC or HU to the amp?

 

[audiobaun 5,000+ posts]

Sounds like a bad Hu/Head Unit to me

 

[Buck 5,000+ posts]

Does it happen when you hit bumps while driving? Can you do anything to reproduce the problem on purpose? You need to check connections first, IMO, but it's hard to say.

 

[1aespinoza 10+ year member]

Any ideas would be appreciated!

I also assume it is the headunit. Since only one amp is mentioned, then the speakers are powered off the head unit. A few site visitors have had similar issues and in a few cases it has been speaker wire touching metal in the doors.

 

[JDirkse]

Thanks so much everyone for the thoughts--I'll check all those things and report back.

 

[JDirkse]

..and in response to Buck, I haven't noticed a consistent cause and haven't figured out how to reproduce it. I've wondered if it was triggered by hitting a bump in the road--occasionally it kinda sorta has happened after a bump? But it's not predictable, and it definitely happens randomly on smooth roads with no obvious bump as well.
Sometimes it seems to follow a few minutes after a loud "pop" in the speaker though, FWIW.

 

[JDirkse]

I've also wondered if it happens in response to particularly loud or bass-heavy music, as that also kinda-sorta has seemed to trigger it. But again, not predictably.

 

[Buck 5,000+ posts]

..and in response to Buck, I haven't noticed a consistent cause and haven't figured out how to reproduce it. I've wondered if it was triggered by hitting a bump in the road--occasionally it kinda sorta has happened after a bump? But it's not predictable, and it definitely happens randomly on smooth roads with no obvious bump as well.
Sometimes it seems to follow a few minutes after a loud "pop" in the speaker though, FWIW.

Sometimes loose or broken wires of any sort or someone else mentioned speakers grounding out like on door metal, I've seen that happen before all in person and have weird responses. It's cheaper to check all of that instead of buying something and still needing to check all of that. It is a lot of work, depending on how everything is with your setup.

 

[audiobaun 5,000+ posts]

I've also wondered if it happens in response to particularly loud or bass-heavy music, as that also kinda-sorta has seemed to trigger it. But again, not predictably.

Have you tried to RESET the Head unit yet ? Im also thinking maybe some loose RCAs or not inserted all the way in @ either the HU or at the amplifier/amplifiers is possible but seems like that the HU may possibly be the culprit IMHO. Good possibility that the speaker wiring is loose and not securely connected (something Ive seen more than once due to poorly crimped butt connectors on speaker wiring)

 

[audiobaun 5,000+ posts]

i know it may be a PITA, and it usually is... But id pull that HU out/ from the dash and check all your wiring connections and RCA connections. Some one may have pulled theyre existing expensive hu from the vehicle and just quickly tossed this unit in? just slapping it in and called it Good. Lol. I cant believe some things Ive encountered. LOl.

 

[AnthonyO 10+ year member]

Does you car have the noise cancelling mics from the factory? Usually right above the drivers door. If so, snip the wire to one of the mics to cancel it