There are two camps in this -
Some say that with time the head gets magnetised from the tapes (leading to drop in sound quality) and a demagnetiser removes this.
Others say that the bias current and recording (if used) takes care of magnetisation and there is no need for demagnetiser.
I was in the first camp and then shifted to second after trying demagnetiser a few times with no audible effect on sound quality.
Which demagnetizer you are using. Please write a post about your experience and conclusion.
Still I am in love with cassettes and Cassette decks. During my school / college days atleast I used to play two cassettes per day on my BPL system and not enen done a single time demagnetization in my life and still using (more than 20 years) many of those tapes.
I would like to put another one point to debate.
As per my understanding the current flow direction of the magnetic head coil might be in opposite direction during playback and recording and therefore the magnetic flux direction also be in opposite. This might be do demagnetization by natural...
I think the one I have is an Akai AH-15. It was donated to me by FM wlg.
I had used a magnetized screw driver for head alignment, and had increased tape hiss as a result. Using this reduced it back to original levels. During normal use, the noise levels don't increase as much, and the improvement is not as obvious - Doing an A/B is not possible
Want to see if it can make a big difference for others, hence looking for folks who want to try it on their decks.
PS. it works. If I turn it on with the deck on, it is detected.