Use of Ferrite Cores for EMI Reduction???

Those RF Stoppers were used on a much different rig than my present setup. I was having a lot of RFI problems from trucks on a nearby highway; I'm surprised that my amp or speakers didn't blow up when some of those clowns went by with their (non)linear amps broadcasting simultaneously on all 40 channels. Their $hi! was supersaturating an older preamp, then of course the hash was amplified by my PA. I put those RF stoppers on the analog interconnects driving the PA; I clamped them on the cables within a few inches of the amp. The RFI was indeed substantially reduced to the point of being tolerable, but they just ruined the sound, & these were just the 'junior model' RF Stoppers. They do have spacers on the inner diameters of the clamps in order to help avoid the aforementioned assymetrical positioning problem. I used some electrical tape for that purpose but I do like the wrapped-paper idea because then the clamp can be moved up or down the cable for positional optimizating.
I've seen ferrite cores installed on power supply cables & AC cords (the Audioquest AC12) which maybe makes a little more sense, but when used on analog interconnects they were awful.
Respected designer Charles Hansen (of Ayre Acoustics) actually told me that when Ayre was experimenting with ferrite AC filtering, they found that the initially realized improvements were degrading over the long term due to a "magnetic buildup" within the cores, which had to be degaussed periodically. He also mentioned that ferrite was causing some sort of 'grunge effect' on the sound, another reason that they didn't like it.
Francisco thx for the Powerwrap report; I need to order one to play with but I'm hoping to find an alternate source vs. the near-north retailer that sells them in our area. I still have a bad taste in my mouth leftover from my latest dealing there; it's not a BFD but next time I'm going elsewhere if possible. Does the package show the manufacturer's name & address? Please advise if you have this info? thx

I bought some rat shack ferrite cores for my CDP 'power cord'tuner power cord and pre power cord.cant tell any difference but I sure sleep better at night!

In my case the rf stoppers work best close to the pre amp.
I just added the paper towel wrap. Sounds the same to me.

Ferrite beads should only be used on wires not carrying the audio signal, where you are filtering out unwanted noise.(If you use them at all) The reason that made these peoples systems sound bad is the same reason shielded cables sound bad. The audio signal is AC which generates a varying magnetic field around the conducting wires. If you attempt to collapse or restrict this field, you will influence the signal that is producing it. If you MUST shield your interconnects, then try using unshielded interconnect (30ga. solid) wire inside a MUCH oversize flex tube wrapped with appropriate shield material and a drain. Preferably, each wire + and - on each run will have separate shielded tubes as their fields also interact, especially when buched right next to each other as in a standard interconnect. Standard interconnect topology is designed for convenience, not sound, even though high end mfrs. would have you think otherwise. Use tube at least 1 inch diameter with teflon discs to center the wire in the tube. Be sure to connect the shield to one RCA plug end only , as a drain.Or drain directly to a chassis mount lug. The dynamics will stun you.

Twl, the cables that you mention would be quite high in inductance. Then again, the treble roll off that takes place might somewhat balance out the somewhat leaner and brighter sound passed on by using such a fine gauged conductor.

I think that the guy that basically came up with ideas like this and pushed the envelope as we know it was David Magnan. He has gone to great lengths to minimize time smear, skin effect, etc.. in cables like nobody else that i know of. I've got a couple sets of his cables that make use of 36 gauge conductors that are air insultated and somewhat spaced apart. His newer designs don't even use wire at all, as they use some type of conductive "paint" to minimize skin effect. Never heard or used them, but some say that they are the ultimate. Sean
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