[Ted Kendall]

At the time, most reputable tapes were very similar in bias requirement - divergences started with the introduction of low noise tapes on the domestic market.

With the general introduction of stereo equipment, setting bias at 10kHz instead of 1kHz became more common, as the overdrop was sharper and made channel matching easier. The sweet spot is pretty universally recognised - 1dB overdrop at 1k or 4-5 at 10k is the best compromise between output, distortion, noise, self-erasure and dropout.