From Jack Theakston: "... Was real information about studio EQ published at
There were internal standards publications and test records that were shared
among the Victor studios however many record labels were in the record
player business and no doubt tweaked their curves for the benefit of their
own products. I'd guess that most used crystal cartridges with no other
playback eq. and their recording channels were probably aligned accordingly.
Around 1940 Victor began using what they called the Orthacoustic curve which
was pre-emphasis very similar to what would later become the New
Orthophonic/RIAA curve. This method had become SOP at NBC after some
experimentation during the mid '30s so the record division finally adopted
it. At the same time they dropped the mandatory use of an 8.5 kHz. low pass
filter that was much like the Academy Curve used in motion pictures.
Bob Olhsson Audio Mastery, Nashville TN
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