Demagnetizing tape heads should be a part of your regular maintenance routine when you own reel-to-reel recorders. Playing tapes causes the heads and guides to become magnetized due since the tape is magnetic. If the heads become over magnetized, your tapes may start to erase themselves, starting with the very high frequency signals. You may not notice this at first, but by the time you realize what is happening, you will probably will have done irreparable damage to the recorded material contained on the tape.
The frequency of demagnetizing will depend on the amount of work your tape recorder receives. When used on a regular basis in a professional recording studio, heads should be “demagged” once a week. The recommended demagnetizer is the “Han-D-Mag” by R.B. Annis Instruments, Inc.
CAUTION: NEVER turn the demagnetizer on or off directly in front of the heads…make sure you are at least 4-5 feet away. The machine should always be powered down during the demagnetizing process.
To properly perform the process, slowly bring the demagnetizer toward the head stack using a circular motion with the instrument coming close, but not necessarily touching and move over each head and guide. Only a few seconds are needed with each area of the tape recorder. Then slowly move the instrument away from the tape machine until you are at least 4 feet away prior to turning off the demagnetizer.
Keep the demagnetizer away from all tapes, credit cards and other items sensitive to magnetic fields.