Quote:
Originally Posted by Restoration73
The reason for the moving heads is the two coils on each erase and bias head are always in circuit in series, i.e. no switching is involved...
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Yes and the series setup in the bias head mean individual record bias adjustment for left and right tracks was not possible. You had to hope that the bias was equal. The only other method was fractionally tilting the bias head after loosening its two mounting screws........................... But again the fundamental problem of Xfield bias wasn't just its increased complexity but its exaggeration of momentary high frequency sound dropouts, often due to dirt on the tape surface. With conventional bias, any dirt on the tape oxide surface lifted the tape off the record head leading to some dropout. But since the bias was also reduced, there was at least some compensation due to some reduction in "over bias". Xfield bias reversed that, further over biasing the tape which was the last thing you needed. The system had an inherent tendency to record level instability. Fortunately, playback was unaffected.