FeFu (Pack of 20pcs) Clip-on Ferrite Ring Core RFI EMI Noise Suppressor Cable Clip for 3mm/ 5mm/ 7mm/ 9mm/ 13mm Diameter Cable, Black

So good I ordered another set! These solve a lot of RFI problems!

Ferrite beads or toroids? Best answer: some of both. I have purchased these before and bought more so I can control RFI leakage and common mode current around my radio room. The variety is nice and they are easy to install/remove.

It seemed to help reduce the interference from my overhead LED lighting to the one FM station it was messing up, but eventually connecting the stereo to a high quality outside roof level antenna resolved this issue.

I put one of these on every DC power lead and on the coax leads. Noise can be cumulative, so these can help reduce noise little bit by little bit amounting to much better performance.

I had recorded a 45 minute podcast on my Zoom H6 recorder at a new location, brought the SD cards into my office, started listening to the audio, and heard something horrifying. I could hear a radio station in the background. It was subtle, but noticeable. It had ruined the entire interview. There is a massive radio tower nearby and the interference was being picked up on my recorder. After some research, I ordered a set of these, put them on the XLR cables near where they plug into the Zoom H6, and the problem was solved. I love recording at this location, and without these on my XLR cables I would never be able to. This was money well spent!