Tape heads: It all stops with a head when the audio is recorded on to the tape and starts with it on replay. Fortunately magnetic heads for audio recording are still manufactured by at least three companies across the World. Press Play > talks to two of them. In part 1, of this two-part podcast, to Peter Van Rompay, of AM Beligium http://www.ambelgium.be/en and in part 2, to Federica Galantino and Andrea Babuto, of Photovox Technology of Italy https://www.photovoxtech.it/. We talk head re-lapping, butterfly heads and toll machines on subways and roads.
In my conversation with Peter Van Rompay we spoke about the benefits of butterfly heads over standard "parallel" ones. Peter very kindly consulted his expert colleagues at AM Belguim who provided me with the following:
The generated magnetic flux generated in a record head is strongest at the head gap and decreases rapidly outward.
That is why magnetic heads have a circular profile: the leakage flux is severely weakened and it can only influence the tape very little.
Leaking flux is not welcome in audio recorders, because it will distort the recorded signal.
The ends of the core should be as far away from the tape as possible to avoid unwanted audio noise.
The first solution to overcome this is shape the magnetic core with extended ends and the vast majority of audio heads are made that way.
A second solution is to have the cores with extended ends, placed in V shape in the head.
In this way the ends are even further away from the tape you get a little less edge effect and a little more realistic sound.