Hi, guys!
I'm collecting classical CDs since the beginning of the CD era.
In my collection of ~ 5000 classical CDs I have discovered some 150 CDs with pre-emphasis so far (1 among ~33 - is this rare???).
Attention: It's often said that only recordings mastered before 1986 use pre-emphasis --> definitely
wrong !!!
Some labels do use it just
up to date (but not regularily) e.g. Erato and the Swedish label BIS (on almost
every second CD) !!!
In short (I can only tell about classical, though) - which labels are suspicious to use it more frequently than others?
I never found any CD by Universal (Deutsche Grammophon, Philips, Decca...), RCA (BMG) or CBS/Sony (but that's no guarantee)
EMI didn't use it after 1987 (but Maazel's Zeffirelli-Otello soundtrack has it - besides this one I only got some CDs from EMI Japan with pre-emph).
Pre-Emph is (still !) used frequently on Supraphon, BIS, Erato, New World Records and other smaller labels - especially from Northern & Eastern Europe.
( I believe you'll find it often, too on smaller jazz labels...)
So pre-emph still remains a serious problem for ripping (because most people simply don't know about it)!
Best puzzles are CDs with mixed pre-emph status (some tracks on the CD have pre-emph, others not!). For a long time I was quite sure such CDs wouldn't exist anyway - but meanwhile I have discovered at least 2 examples of
New World Records CDs with mixed status
There's a simple (but precise) free tool available developed by an acoustics engineer (Mr. Ahlersmeyer) to de-emphasize pre-emphasized audio data (so we could do compressing, converting, releasing - all we need afterwards).
It's just great, of course better than the often recommended WAVE 10 band equalizer Q10 - an equalizer can only give an approximation to the de-emphasis curve. Mr. Ahlersmeyer uses exactly the mathematics desribed in André's 3rd post above. You need the VB5 runtime libraries installed to your system. The tool is available as freeware here:
http://www.picosound.de/Waveemph100a.zip
Mr. Ahlersmeyer says that the tool wouldn't run under XP --> it does (you have to choose Win98 compatibilty modus though, else you would indeed get an overflow error).
Unfortunately the tool produces an overflow error, too, if the original CD data contains exactly 100% peaks. The only workaroung at the moment would be to normalize to 99% before using the tool...