Dolby B simulation
Reply #7 – 2013-06-06 00:25:06
It's not just thin-ness and high end boost, but the decay tails of cymbals and similar high-end transients tends to last considerably longer thanks to the dynamic range compression applied to the high-end (which the expander part of the Dolby B decoder reverses). Applying Dolby B is likely to tighen up the decay in a lot of hi-hats, cymbals and similar sounds. I guess that measurement of the hiss spectrum and level between tracks may also help to confirm whether Dolby B was turned on when digitized in comparison with known cases of Dolby B off and on (assuming the peak level of the loud audio is anywhere near full scale) I've been using someone else's Fostex X-18 cassette recorder/player/mixer recently to digitize some old band recordings and backing tracks (it can use both stereo tracks on side 1 of the tape as well as both tracks on side 2 effectively playing backwards, to record 4 tracks of audio on one side only of a cassette over half the marked duration), and it has Dolby B which cannot be turned off, as far I'm aware. (By zeroing the faders on channels 3 and 4, it can also be used as a 2-sided tape deck). I've previously used Tape Restore Live to reverse Dolby B encoding and adjust azimuth with good results, and used real Dolby B on my ancient Sony WM-36 Walkman (noted for decent reproduction when the EQ is set to zero, but lots of noise when non-zero)/ One of these days I must compare the WM-36 with Dolby B turned on to the same with Dolby OFF fed through Tape Restore Live.