Is cartridge Demagnetizing Necessary?

None of this is necessary. The question is does it make enough difference to be worth it? 

Demagnetizing definitely works. Do it regularly. One, play the demagnetizing tracks on the XLO Test CD. One sweep tone, one low frequency fade out. Totally makes a difference. Lots of others out there, probably a lot of them equivalent. Just get one and use it. 

This method does everything from the CD to the speakers. Why? What's it do? The idea is that even really high quality conductors will have some particles or regions in them that can over time become magnetized. Makes total sense if you know how things get magnetized in the first place. Slowly over time the amount of these regions increases and these fixed magnetic fields degrade signal purity. Okay. Whatever. Bottom line you play the tracks the system sounds better. 

The other method I use regularly is the Radio Shack Bulk Tape Eraser. Essentially just a really big powerful demagnetizer. Same as demagnetizing tape heads, you bring it close then take it slowly away. Use this on all the cables right up to the tone arm.  

This just leaves the cartridge. What about the cartridge? Good question. If you do what I just did there is only the last foot of phono lead and the fraction of an inch of moving coil left. How we gonna do that? 

Only by running a demagnetizing signal through it just like the XLO ones. Only one problem: its going through some very fine wires designed for only some fractions of a millivolt, not several millivolts. So if you have variable outs you can connect the phono leads to your CDP out and demagnetize that way.  

If you do, let me know. There's an awful lot of stuff I do all the time just to eke out that last little bit of sound- but crawling around plugging and unplugging just to get the last few inches of wire is where I draw the line. At least until someone comes along and tells me I'm missing out I tend to say.... not worth it.  

And sorry, but the shorting trick is nonsense.

^^^ I have a cartridge demagnetizer. When used, it does lower the noise floor somewhat. The problem is, the system sounds so incredible at this point, I forget to use it. Come to think of it, that would be a good project for today. Geeze, I’ve even stopped using my Radio Shack bulk eraser on my CDs. I’ll begin again. I’ll do the XLO test CD today too. Thanks for the reminder.

Frank

What happened with me, came to realize the improvement is definitely there. Not real huge or obvious but there. Then it gets worse, but very gradually and so slowly its hard to notice. There is for example a bigger difference between just turned on cold and hour later warmed up. Only instead of an hour its a week to a month getting magnetized.

Well this being the case it stands to reason if you only demag once in a while then you are going to be listening almost all the time to a dirty grungy system. So what I do, burn a disc with just the demag tracks and they repeat over and over again about a dozen times. This way, turn the amp on, hit play, go off do something else for half an hour by which time the system is nice and warm and demagnetized and ready to go.

You’re not fooling anyone by the way. Your system sounds so incredible because of the gate and mats and gray goo slathered all over the place. Which I know because, same here. Heh.

Not only is it not necessary, there are those that recommend against the practice as something that slowly damages the cartridge.  For example, A.J. Vandenhul (cartridge designer and manufacturer) is generally against the practice.  If you go to the Vandenhul website and go to the FAQ section, question 20 discusses the use of demagnefiers.  There are other cartridge designers who have voice some concerns, such as as Jonathan Carr of Lyra.

• "You’re not fooling anyone by the way. Your system sounds so incredible because of the gate and mats and gray goo slathered all over the place. Which I know because, same here. Heh."

Correcto Mundo, Mi Amigo. For those who didn't get on that train, too bad for you. :-)

Frank