I think there are a number of issues why I have the problem.
I have a high gain roof Yagi-Uda array. I'm about 45 to 50 miles from the transmitter at Blackduck MN. I get a good signal though. On my Quad FM 4s only the very top LED is partially lit. When the LEDs are off then I have no noticeable background noise.
I have used ultra high efficiency LED bulbs, not available in stores, that are for commercial use. These higher quality bulbs are known to produce more interference.
These would meet secs demanded by the EEC.
In addition I have a lot of LEDs, around 150 over the whole compound. Of course they are not all on at once. Most of the bulbs are on the highest standard Maestro dimmers.
I have a lot of cans with some long runs. So there is a lot of wiring to transmit the RF.
There are five levels in the home, but only the top three and the lowest level have LED bulbs.
All of the top three levels transmit the interference to the antenna. The lowest level does not.
The interference does transmit to my vehicles and they have to be a significant distance from the house before the interference is not audible.
This program is saving on average 200 Kilowatt hours per month.
This is actually not a big problem as HD transmission is now finally better than analog and is totally silent.
Also this is better then the incandescent lighting dimmers, which sent enough interference to be just picked up by my Marantz pre/pro. These LED dimmers do not.
The only difficulty is that I can not use the Quad FM 4 down on the first level if any of the LEDS are on, on the three upper levels.
This issue has been a much bigger issue in Europe, as incandescent bulbs have been phased out for much longer. This has forced many to migrate to DAB or Internet radio. In any event for classical music from the BBC Internet is the best way to go, as it is 320 kbs HE AAC MPEG DASH.
I am able to get that, and because the BBC are certainly the best recording engineers around, the actual quality is about the best available and better than most CDs, as their broadcasts have such realistic perspective and balance. On iPlayer downloads the bit rate is 640 kbs with the same codec.
The BBC are hoping to launch US subscription streaming and download site this year.
In my view it is time for broadcasters to start phasing out terrestrial transmission and migrating to high quality Internet transmission. Traditional transmission is now starting to sound very jaded to me, and below the quality of other available options by miles now.
This will help explain the issues.
You can see images of the spectral patterns here.
FM radio transmission is now nearly 70 years old. It is time for it to blend into the pages of history gracefully.