"Dave Plowman (News)" wrote

The use of Dolby B (domestic) would be very unusual at 30 ips. As really
would be Dolby A. The main use of 30 ips was to get the best noise figures
without any reduction systems - and even then they had other
disadvantages.


Dolby licensing prohibited the use of Dolby B on 15 and 30 ips tapes. The
"high-speed" (3.75, 7.5 and 15 ips) version of the series 75 Ferrograph with
Dolby B was required to disable the Dolby circuitry when 15 ips was
selected. And I agree the main reason for using 30 ips was to avoid using NR
at all.

David.