markp@sri-unix (10/25/82)
I demagnetize the heads on my Nakamichi after every 8-10 hours of use. I have experienced NOTICEABLE degradation of frequency response, in particular increased midrange distortion, as a result of neglecting such maintenance. A friend of mine purchased a used deck some time ago, and it was almost totally unusable until we demagnetized the heads. It *is* possible to damage the heads of one's deck with a demagnetizer. First, one must be careful to NEVER *touch* the device to the heads. It is all to easy to scratch them! Second, the demagnetizer most *not* be turned on *or* off while in close proximity to the heads, as such action can cause permanent magnetization of the heads -- a stronger magnetization, in fact, than the demagnetizer can remove! These warnings should be prominent among the instructions for use of the demagnetizer. BE SURE TO REMOVE YOUR TAPES FROM THE SCENE OF THE ACTION!!! Unless you have a three-head deck, I recommend one of the demagnetizers housed in a cassette shell, such as the one made by TDK. Although these units are not as powerful as some of the hand-held manual ones, they are automatic and virtually eliminate both of the risks mentioned above. Also, their ease of use means that (if you're at all like me) you'll use the thing more often than you would a hand-held unit. If you require a hand -held, though, be sure to get one (like Nakamichi's) which boasts a vinyl -coated probe, to minimize any possible damage if you somehow manage to touch it to the heads. The TDK cassette-type unit sells for about $20, and the others anywhere from $12 to $35+. I use the Nakamichi hand-held (about $28) because it is the most powerful unit available (and because I have a three-head deck). I have been told that the heads become magnetized by the changing electric field generated by the moving magnetic fields of the moving tape. Perhaps someone out there knows for sure, or in more detail??? Sorry to be so long-winded... Mark R. Paulin ...decvax!teklabs!tekmdp!markp
markp@sri-unix (10/28/82)
Demagnetization can improve the performance of *both* record and playback. The person who owns a much-used car deck which has never been demagnetized may notice a *striking* difference in performance after demagnetization. Mark R. Paulin ...decvax!teklabs!tekmdp!markp