2016 Accord Coupe --- HD FM Radio Reception Issues

I recently added an amp to my 2016 Accord Coup with a 10 sub. After the installation, I noticed that my FM signal was about 80% what it once was. I stress 80% because the antenna is obviously working and everything is hooked up - Only thing I can come up with is some interference.

EXAMPLE: HD station I listen to I use to could pull about 40 miles north of the transmitter site. Now it's roughly 25 to 30 miles north. So the reduction in signal is slight but noticeable.

So there are two other unrelated issues (bluetooth was disconnected and I hear a pop in the speakers every time my locks engage) so I decided to take to a professional last weekend. To fix those two other issues, he wants to install a Audio Signal Processor and I'm wondering two things:

1- What could cause the slight (and I mean slight) reduction is signal reception after connecting my amp?

2- Could the Audio Signal Processor help with the reception? I know it helps sound (output) but wonder if it could help with gain from antenna or stereo.

3- Is it perfectly normal to notice a slight reduction in reception when adding aftermarket amps/speakers and to gain quality sound sacrificing other qualities is part of the game and I should just get over it?

NOTE: Thought about installing a signal booster but did that a few years ago on another car radio and while it amplifies fm radio distant signals, it also amplifies the ones around me and I lose any filter so anytime I go near a radio station (FM or AM), my signal would just go nuts so I'm not even playing that game again.

I suspect the power supply for the amp is generating garbage in the FM band. You can confirm this by listening to a weak station on a portable radio in the car. Turn the amp on and off and see if it makes a difference. If it does, then you can probably do some filtering. I would start with the power line. Search for "DC power line filter" and look for something sold to the 2-way radio market. Chances are you can put something like that on your amplifier power lead and reduce the noise leaving the amplifier.

This kind of thing can get tricky, so it might be best to enlist the aid of a local radio tech. But it's possible to resolve.

Dave B.

It has been a bit since I stopped modifying my car stereos (too much computerization in cars) BUT before adding a processor, which will likely not solve the problem (but will make your installer more money), make sure of the following:
1. Make sure they ran the power directly from the + terminal of the battery. I have seen too many people try to short cut this. It will cause many weird issues.
2. Just as important if not moreso: Make sure they have the BEST ground possible for the amp. A crappy ground will also cause a lot of issues like this. It also could be that your amp is not rubber isolated (or some other kind of isolation, from the car, causing a kind of ground loop.
3. Bad rca cables can cause this
4. You may need a noise surpressor on your accessory wire , ground wire or (which I hate) antenna wire.
5. Don't ever use ground loop isolaters on a car stereo. They just mask the real problem.
Read the section in this article about amp noise: https://www.crutchfield.com/S-4EW2w...car/noise_suppressors_installation_guide.html