[Pack of 10] Clip-on Ferrite Core Ring Bead Anti-Interference High-Frequency Filter RFI EMI Noise Suppressor Cable Clip (13mm Inner Diameter)

These ferrite cores arrived on-time as expected. And they function quite well to boot. Unfortunately for me, they were not enough to mitigate the signal noise I was experiencing with two different pairs of USB-powered PC speakers. The speakers in question are the Amazon Basics USB powered speakers and the Dell AE215 USB powered speakers (without subwoofer). Both sets of speakers suffer from extreme amounts of signal noise when drawing power from the host PC while connected to the 3.5 mm connector. I added a core to the audio cable near the source and near the speakers themselves and the signal noise was significantly reduced but not eliminated. I then added a core to the USB power cable, again, on each end, and the signal noise was reduced further! Sadly, the signal noise affecting both sets of speakers was so bad that even 4 ferrite cores each would not eliminate the noise completely. Although these cores do not necessarily work for this particular application, I am holding on to them for posterity because they do work well, they just can't overcome really and truly terrible signal noise. Also, I'm not totally sure that this is what ferrite cores are actually for. So maybe I'm just a dummy. Oh well, these were cheap and a good learning experience.

Very quick delivery and the quality of the product seems good. I use these for preventing EMF radiation from travelling up the wires on headphones. I did have some problems opening them, as the clips are a bit tricky and quite small but eventually figured it out.

5 star product

Wasn't sure if I should place one or two or four of these on my cables so I went overboard and placed two at each end and was not disappointed. I didn't know RF noise was a real problem when it came to microphones until I got back into studio equipment and when I first connected my microphones to my recorder I thought my recorder was broken; I kept hearing this high pitched beeping and fuzz reminiscent of when phones back in the 2000s used to interfere with speakers. Turns out that's the sound of wifi and other wireless transmissions being picked up by cables that are unintentionally acting as antennas. You can usually remove the sound in post but it's always best to ensure you have something of high quality going in (after all, garbage in, garbage out). Tossing these simple, cheap magnets onto your cables just might save the day. I have tried different mics on the same cables and found that the mics themselves were picking up RF interference and when that's the case, these won't help. They're perfect for cables though (I have WBC XLR cables and the 7mm versions of these are perfect). I even picked up a second 10-pack of these so I can attach them to other unshielded, unprotected cables for piece of mind because once you hear the annoyance of RF interference, you don't want to hear it again and at under $10 for a pack, these can't be beat.

This didn't work for my application, but I'll grant it 4 stars anyway-- they're well-made. The description and picture are slightly misleading: "(3mm/ 5mm/ 7mm/ 9mm/ 13mm Diameter)" and the picture makes it look like you're getting as assortment of different sizes. I spotted that discrepancy and asked, and the seller answered accurately (I ended up buying them anyway, mostly by mistake; will hold onto them for other uses). This is actually 10 identical (small!) pieces with a 3mm inner diameter-- ok for something like a headphone or USB cable, perhaps small DC power cords; but not anything larger than that.