Over the years a variety of record equalization practices emerged and there was no industry standard. For example, in Europe recordings for years required playback with a bass turnover setting of 250300 Hz and a treble roll-off at 10,000 Hz ranging from 0 to 5 dB or more. In the US there were more varied practices and a tendency to use higher bass turnover frequencies such as 500 Hz as well as a greater treble rolloff like 8.5 dB and even more to record generally higher modulation levels on the record.
What was the industry standard on equalization practices?
there was no industry standard