Quote:
Originally Posted by TIMTAPE
Quote:
Originally Posted by Ted Kendall
...Record heads have a higher inductance than play heads - more turns, in other words, to ensure the tape can be saturated, whilst the number of turns on a play head has to be balanced against other losses.
|
Ted, I always understood it as the opposite: the record heads have a lower inductance (and impedance at the nominal frequency) relative to play heads. |
Tim - out of interest, these are the specifications for the Bogen heads used, e.g., by Brenell. I took them from an article on the Brenell deck in TR magazine by HW Hellyer - can't remember whether I transcribed or copied & pasted. They give specs for both dedicated Playback and Record heads (but see footnote), and suggest that Replay head has a higher inductance than Record head. These detailed specs are useful, 'cos I haven't seen them anywhere else.
BRENELL (BOGEN) TAPE HEADS
(
From: “Tape Recorder” magazine,
September 1967, article ‘Tape
Recorder Service’, HW Hellyer)
Recording head UK202, 2/2 track
Inductance - 120mH
Impedance at 1kHz – 780 Ω
DC resistance – 75 Ω
Bias at 100kHz - 23V at 1mA
Recording current (3-75 ips) - 120μA
Output at 2kHz (3.75 ips) – 2.4mV
Replay head UK200, 2/2 track.
Inductance - 550mH
Impedance - 3.5KΩ
DC resistance – 300Ω
Bias (1OOkHz) - 70V at 0.8mA
Record current - 50μA
Output at 2kHz (3 ips) - 5.8mV.
Erase head BL210, 2/2 track
Inductance - 2mH
Erase current - 55μA
Erase voltage - 80V @ 100kHz
[
Note: with appropriate circuitry, the
UK202 and UK200 heads can also
both be used as record/playback heads]