Ok, I'm getting a high pitch feedback at a certain RPM, this feedback is coming from my speakers.

This happens at a certain RPM, bad in winter, on and off in the summer.

The range is 45 mph to 75mph (dont know the rpm range, its an STX with no tach)

What can this be, its done it off and on over the past 5 years, but getting real bad this year.

I turn off the radio, it still does it, I discountect any add on electronics(XM, ham radio), still there.

Gas pedal throtle sensor, altenator, something in the trans, filter on the radio any ideas, if this a known problem?

Ken

 

Sounds to me kind of like the old electrical interference you'd get from cars with spark plug wires that didn't have proper suppression (although that was usually more of a "buzz", because you'd hear it from a nearby idling vehicle). However, when that vehicle's engine revved, the sound would change to a whine.

But, you don't have plug wires and unless there's something funny caused by aftermarket COPs, I wouldn't expect that to be a factor.

Do you have an aftermarket sound system? If so, possibly the speaker wires are not properly shielded or, you might be able to install a "choke" on them to reduce or eliminate the whine. I suspect a good "sound" shop might have some ideas.

- Jack

 

Everything is stock. I have XM and a ham radio, but unplugged them completely to rule them out.

 

Sounds like something isn't grounded or a reversed polarity, such as a speaker or so on.

Try searching for a polarity reversing or a bad ground, not just the radio, speakers, but the truck in its entirety.