The most important thing in remastering older material is to find the original master tapes. Unfortunately many classic albums have been digitally mastered to CD by uninterested engineers from tapes which are copies of the original. Maybe the original master tape has been lost or destroyed, or maybe cannot be accessed for some contractual or financial reason.
Some record companies simply dont appreciate the value of master tapes and the tape sent to the mastering facility is simply the first tape which came to hand - "Ah, thats the album we want, send them that tape."
The fact is, no matter how carefully a copy is made, be it analogue or digital, some quality can be lost. To confuse matters, it was common practice to make an "equalised production master" tape when an album was cut to vinyl. While such a tape may well have been superior to the original master in some ways it is still a copy; one generation away from the original master. It may also include adjustments made to cope with the restrictions imposed by the vinyl medium. Of course, in todays digital age such restrictions dont apply.
This was never more clearly demonstrated than with one job I did remastering an old and much loved album by 1960s group The Nice. Despite considerable searching the original master tape could only be found for one side of the album. That side sounded pretty much perfect and no eq whatsoever was needed; the problem was getting the other side to sound the same!
Some argue that a CD re-issue should sound exactly like the original LP release. This approach is, in my view, doomed to failure - a CD can never sound like an LP. The vinyl medium posesses many unique qualities, but the ability to imitate tape is not one of them! Cutting and pressing an LP is a mechanical process and the sound quality of the final result is dependant largely on geometry... As an LP side is played from beginning to end high frequencies diminish and distortion increases as the pickup moves towards the centre label. These qualities cannot be imitated by the CD, so, imitating the sound of a vinyl release is not achievable.
This often creates a dilemma for the mastering engineer and record producer, one which is particularly acute when dealing with singles from the 1950s and 1960s. Those old singles had a really hard, gritty sound, which got harder and grittier as records became worn down by repeated playing. This was the sound many people loved and grew up with and people feel so strongly about it that they continue their love-affair with vinyl to this day.
What's the answer; is CD simply too good? What is the philosophy we should adopt when remastering old classics to a digital format?
Dont get me wrong, I don't dismiss vinyl out-of-hand, Im simply saying it cant be imitated, but when remastering an old classic album listening to the vinyl version is still the best place to start because its the best evidence we have of what the artist and producer wanted, or at least approved at the time. The question I always ask myself when remastering vintage recordings is "Whats the best we can do today?" In other words, what would the producer and artist do now if this was a new release? The answer to that can often lead to quite different and clearly better results.
CD does not restrict us in the same way LP does. We have no imposed limitations on dynamics, phase or high and low frequency headroom, and as a result, 15+ years of listening to digital recordings means our expectations of sound quality are that much higher. In addition, sound engineers now have access to better, more sophisticated equalisers and processors which are better at dealing with the problems of poorer tapes and extracting detail from better ones.
The next problem we have is to resist the urge to make releases sound excessively loud!
Many 're-mastered CD releases have, in the past, been done with the aim of making the resulting CD sound as loud as possible, and this is almost always at the expense of the music.