How often do you demagnitize your MC cartridge?

In most cases it's not recommended. The cartridge normally must be magnetized. Even if you believe on such drastical improvements tend to do it not any often than twice per year no matter how often you play your records.
Don't ever do it with MM cartridge and keep it away from strong magnetic fields.

Wes, you're completely right and you've chosen absolutely the right path to follow advices of engineers instead of marketeers as done by many "pro" audiophiles. I think bases of electronics are easily explainable to everyone in the public and they realy can help not to swallow crap very often offered by dealers.

"engineers" get paid to promote nonsence sometimes believe it or not or to promote their own product to demagnetize it in particular. they can fool ya with their knowlege and yo gonna believe as lambs sometimes to wolves instead of sheepherds...

i own helikon myself and benz m.09 as a back-up both of the cartridges adviced to be demagnetized...

did anyone try to find some vintage cartridge demagnetizer??
tape heads need to be demagnetized since they every time accept variable magnetic field from the tape what about cartridge???

Tom, you forgot to mention magnets that are present in both MC and MM cartridges otherwise there will be no emf i.e. electro-magnetic force.

Gmorris,

Lyra Helikon manufacturers quote the following:

The Lyra Helikon uses a polepiece-less magnetic system. The signal coils operate in a magnetic field created directly by two powerful, precisely shaped disc magnets of nearly equal size, mounted fore and aft of the coil gap - in the simplest and purest manner possible.

I'd say proceed with your ehem... confidence of demagnetizing I guess these valuable magnets that is a part of cartridge's structure and continue to trust ehem... "engineers"(I guess from the Immedia distributor domain).

a-little is enough to wage the gradient of random propagation of so-called residual magnetization and compare its effect to a global demagnitization of the whole cartridge along with permanent magnets. also there's always either 0+ or 0- and it cannot be always clear and pure zero.