CD - DAT 15/50us EIAJ deemphasis plugin.

When transferring digitally old 16 bits DAT tapes or CD recorded with 15/50us preemphasis, it would be nice to have a plugin or at least an EQ filter preset in Nuendo to apply the correct deemphasis curve.

It is necessary because the digital stream is not deemphased when going digitally out of the DAT or CD player. So if a deemphasis is not applied with a digital filter in Nuendo, there is too much treble.

I had this problem transferring an old DAT tape. It’s possible to approximate the curve using an EQ plugin, but it would be better to have a dedicated solution to precisely mimic the analog de/preemphasis filters used with those CDs and DATs.

A dedicated deemphasis plugin that we could put in the control room external input inserts or on a track would be nice.


Some informations i did find about 15/50 us pre/deemphasis :

http://forums.stevehoffman.tv/threads/cd-dat-with-pre-emphasis-how-to-de-emphasize-correctly.88541/

In a nutshell: to generate the correct target 15/50µs EIAJ de-emphasis (or pre-emphasis) curve for CD/DAT use the following equation:

DE(f) = 10log(A/B)-10.4576
PRE(f) = 10
log(B/A)-0.9684

DE(f) - de-emphasis output in dB at a frequency of f Hz
PRE(f) - pre-emphasis output in dB a frequency of f Hz

Where:
f = frequency in Hz
A = 1 + 1/(H x H)
B = 1 + 1/(L x L)
H = (2 x pi x f x t(H))
L = (2 x pi x f x t(L))
t(H) = high freq. time-const (15 µs = 0.000015)
t(L) = low freq. time-const (50 µs = 0.000050)
pi = 3.1416