"Dave Plowman (News)" wrote in message
...
In article ,
Paul Stamler wrote:
The second is that it was written fifty-plus years ago, and things have
changed a lot. Modern tapes respond a lot differently from the Scotch
111 that was the norm in 1957. For example, Burstein suggests that if
3% THD is considered the overload point, 0 VU should be 6dB below that,
and will have about 1% THD. Older tapes did work like that: distortion
increased steadily until they hit the commonly-accepted overload point
of 3% distortion. Modern tapes have much lower distortion until just
below the overload point, after which the distortion level shoots up
quickly. "Harder clipping" in the modern vernacular. Modern tapes also
do a lot better at avoiding high-frequency saturation, and of course
have much greater dynamic range.

Indeed - the 'BBC' way I was taught on setting bias in the early '60s was
to increase the bias until the level peaked (using 1kHz tone) then carry
on 'till it dropped by 1 dB. Which was a reasonable compromise for the
standard tape the BBC used in those days.


Later, a 10kHz tone was used, and bias set at 3dB over peak.
This was recommeded by AGFA for PEM468.