Demagnatizing Phono Cartridges


I'm curious as to how many of the analogisti demagnatize their cartridges. What do you use and how often to you do it? Is this really essential -- is the magnetism a cumulative thing that palpably degrades sound?
jim
The Cardas Sweep Record is the cheapest method; once a month or so, and yes, you will hear the difference. On a moving coil cartridge;more silent background is noticed. I actually alternate with a Fluxbuster.
Aesthetix Demagnitizer works wonders. It should be done about once every other month and with the arm in the play position so that there is weight on the stylus--this should center the coil (MC). I've heard that using this while playing the cardas sweep record is even better. Haven't tried it yet, but I intend to.
Thanks, guys. I am familiar with the Aesthetix and while I have heard of the Cardas sweep record I have no idea how it works. Sounds like doing both would be just the right amount of "overkill" for me. Most Benz Micro cartridges have been backordered from their distributor but they are supposed to get a shipment this week. I'm hoping to have my new/old Oracle set up soon. I guess I can wait a few weeks to get de-magnatized. Thanks again.
OK, I'm going to really stick my neck out on this one and disagree with the group that believes that de-magnetizing cartridges is beneficial. Based on what I have been told by several serious audiophiles I have known for years, both of whom are electrical engineers (and one of whom has designed industrial magnetic systems), de-magnetizing the cartridge is essentially a pointless exercise.

All phono cartridges use a coil and magnet transducer system to generate electrical signals -- some have the coil as the moving part, others use a moving magnet. But, the end result is still to produce an electrical current/signal. It stands to reason that you wouldn't want to demagnetize the magnet itself, or you would get no electrical current/signal generated. Hence, the only thing you might reasonably want to demagnetize is the cartridge housing/body, or the cantilever. Most audiophile cartridges today use a non-magnetic body (wood, aluminum, etc.), so that's almost never an issue. The cantilever, therefore, is the only part that might get magnetized, but most cantilevers are constructed of non-ferrous materials (such as boron) that do not become magnetized either. If there are any parts in the cartridge that can become magnetized, they MIGHT (and this is very debatable) benefit from being de-magnetized, but they will become re-magnetized in a very short time after the cartridge is used again.

So, my read on this is that demagnetizing cartridges is largely a waste of time, unlike demagnetizing tape recorder heads (where the head has a magnet structure to produce a signal that can be recorded on magnetic tape). I state this not as a personal opinion, but rather based on the information I've gotten from people who have some real expertise in the electrical engineering field.

I'm sure there will be some dissenting opinions, and it would be interesting to hear them (really).
Sd: Well, it's okay to stick your neck out, but someone misinformed you a bit. You are not demagnetizing the magnet, you are demagnetizing the wires in the coil. The movements about the proximity of the magnet cause a current flow by induction. The problem is that the close proximity of the magnet to the coil causes the coil to become slightly magnetized over time. It doesn't even have to be in use for this to occur, although it occurs much slower when not in use. When you demagnetize, you are removing as much of the magnetic build up as possible by a controlled induction process that sweeps through a frequency range and neutralizes the magnetic effect. I haven't explained the last part very well, but it's kind of like shaking a towel full of sand out at the beach. If you shake it right--all the sand will fall back to the beach that it came from.

The second thing I would recommend--is try to demagnetize your cartridge. If you have not done it for a year--you will think you just purchased a new cartridge. And you can start the cheap route with the Cardas sweep--only $28--but the Aesthetix works much better.
Hi, Abstract: With due respect, I fully understand that one is not trying to demagnetize the magnet (which, I think, is what I said in my post). The rest of my post tried to make the point that, in almost all cases, the generator assembly, the cartridge housing, and the cantilever would NOT need de-magnetizing. Therefore, by elimination, the only parts left that might be subjected to magnetization would be the coil wire, and maybe the connecting pins. The coil wires themselves would become re-magnetized in a farily short time, perhaps within minutes, due to their proximity to the magnet. The two men that shared their comments with me are both VERY qualified to talk on this subject, and one of them has about 15 years of experience in designing electromagnetic systems. I make no claim of personal expertise in this area. After reading your post, I called my friend who has the background in electromagnetic systems, and his remark was (speaking as an electrical engineer) that there is essentially no merit in demagnetizing the coil wires in either a MM or MC cartridge. However, speaking as an audiophile, he said he fully understands the importance of the analog ritual, and never underestimates the power of expectation (his words, not mine). I'm not trying to start a heated debate here. My own experience with demag'ing a MC cartridge I once owned satisfied me that the procedure, at best, does no harm. My first post wasn't to tell folks "don't de-mag" -- rather, to point out that the procedure is, from an objective standpoint, of dubious value. (All that said, we're still friends, aren't we? We analog enthusiasts have to stick together...)
I have no problems with various opinion, theory, etc. That's what these forums are about. I am a physicist, solid state undergrad training, so I know a bit about the theory--although it sounds like your friend has far more experience than I do. I will still stand behind a difference in clarity after I demagnetize, although now that I do it regularly the difference is much less. Although the configuration is completely different--the principle is not unlike deqaussing a CRT. Instead of the coils it is the grid for the electron gun in the CRT that is being deqaussed. If you do it rarely, it makes a pretty big difference in image quality--if you do it regularly, you can hardly notice a difference.

I'm going to stick to my analog ritual. I think it works--but I buy expensive cables too (electrical engineers don't think much of that either).
van den Hul says that demagnitizing a cartridge, at least with Fluxbuster type devices, ruins them over the long haul. Does anyone know why?
Many cartridge manufacturer's say DON'T use an electronic cartridge demagnetizer. Having purchased a Koetsu RSP through our Tokyo office, I got an email to Mr. Shugano. He is strongly against them. Of course, there is some degradation of the permanent magnet when you use an electronic demagnetizer. There is just a great deal of disagreement as to how much the degradation is. I only use the Cardas Sweep Disc now.
I have an interesting question. If the coil wire is, say, copper, how does it get magnetized? Same with silver. I thought these metals to be non-magnetic.
Good point, Woodrow...

In any case, I have periodically demagnetized my cartridges using an Audioquest demagnetizer, most recently a Glider, and have to admit that I heard very little, if any, difference in the sound.
I have owned several Lyra cartridges, including my present favourite the Helikon. Scan Tech recommends frequent Demag for best performance. Presumably, it remains a matter of opinion.