Amp installed and lost AM reception

[ksauers 10+ year member]

I just had an amp installed and afterward my AM reception is crap. Hit the seek on the HU and it won't stop at any station and there are some strong ones. You can manually tune them but they are very poor ,almost unlistenable, compared to what they used to be. Is there something causing interferance that should be shielded. The installer said no.

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[dB-r 10+ year member]

The PWM power supply in the amp could be running at a frequency close to your AM band, and since most people don't listen to AM, noone else would have noticed that the power supply in the amp has Radio Frequency emissions near the AM broadcast band. Try more/better grounding. Other than that you may have to just get a new amp. Maybe add some .01uf disc caps from the power rail + and - to ground inside the amp. Easy to do if you know what's what inside an amp. Would be a cheap fix, but if you can't do it yourself you may be out of luck. And it may not work anyway. The amp may already have similar caps in it, but isn't enough, or this fix may just not work on this amp.

Before everyone else lectures you on listening to AM (what the hell do you listen to AM radio for?) I get that all the time. Talk radio isn't for everyone, some of us like it better than the same 12 songs all day long, and some of us listen to AM radio for sports too.

 

[n2audio 5,000+ posts]

I listen to AM quite a bit.

My class D interferes bad.

I put a switch on my sub amp remote wire and mounted it on the instrument panel on my console. It almost looks like it belongs there.

When I switch over to AM I just turn the sub amp off.

Unfortunately, my freaking cell phone interferes almost as bad when it's charging.

 

[dB-r 10+ year member]

I may do some experimenting and put together a tutorial on my site for installing some filtering in AB and D class amps that cause interference to the AM broadcast band. I know I have had those kind of problems in the past and just dealt with it by putting a switch on the remote wire to turn that particular amp off during AM listening, but it shouldn't be too hard to at least attenuate a little bit of the interference with the right caps in the right places inside the amp.

And yes cell phone chargers are really bad about it too, and some power inverters.