Pressing Matters

It is my sincere hope that this blog provides entries of interest to music lovers, musicians, and audio enthusiasts, as well as folks who make records.  A few previous entries, such as Can you hear what you’re doing? (Part 1) and Can you hear what you’re doing (Part 2), were aimed specifically at those setting up studios in order to make records, among whom there are a great many musicians.  Of course, it has been my hope that others would find these of interest as well.  So it is with the current entry.  While it is intended primarily for those who make records, if I’m lucky, those who purchase and listen to records will also find something of value herein.

With audio mastering completed for the new Work of Art album entitled Winds of Change (first mentioned in the August 22, 2014 entry of this blog, also called Winds of Change), and with the album artwork approved, it was time to contact the CD replicator in order to get the “pressed” versions manufactured.  Actually, CDs are not pressed like vinyl records.  They are made using an injection molding process, but the term pressing seems to have endured in common use.

Those familiar with my label, Soundkeeper Recordings, know that we release each album in several different formats.  In addition to the regular CD, we offer six custom burned formats, including CD-R and five formats with higher resolution than a CD can provide:
–   Music-only DVD-R with 24-bit, 96 kHz audio, playable in most regular DVD players
–   24-bit, 96 kHz .aif files-on-disc
–   24-bit, 96 kHz .wav files-on-disc
–   24-bit, 192 kHz .aif files-on-disc
–   24-bit, 192 kHz .wav files-on-disc

For more about the different resolutions, see the May 22, 2014 entry in this blog, Is “too much” not enough?

As far as standard, 16-bit, 44.1 kHz CD resolution, the reason Soundkeeper Recordings offers our releases in CD-R format, and the true subject of this entry, is something I’ve said since I heard the finished product for the very first CD I mastered, back in January of 1983—CDs made at different plants all sound different from each other and none sounds indistinguishable from the master used to make it.  This may sound strange in view of the marketing that has accompanied the CD format from the beginning, primarily in the form of the slogan “Perfect Sound Forever” and the widely accepted idea that nothing can change once the signal is in a digital format.

Imagine my surprise then, when I first started mastering CDs and found that the same digital U-Matic tape (the format used at the time to send CD masters to replication facilities) sounded different depending on which side of the Sony DAE-1100 editor I used to play it.  The DAE-1100 was commonly used at the time to assemble CD masters.  The unit controlled tape machines for the ¾” tape cartridges that comprised the U-Matic format.  One or two machines could be used on the Playback side and another machine was used on the Record side.  The CD master was assembled on a U-Matic tape in the machine connected to the Record side of the editor.

Early on in my experience with this system, I wanted to compare a tape that was copied from another, just to hear for myself that a digital copy was indistinguishable from the original, as we’d all been told.  Unfortunately, the test never got that far.  What I found was that the original tape, played from the Playback side of the editor sounded better than the copy.  Something was getting lost on the copy, as it seemed coarser and less well defined than the original.  I don’t recall what made me try it but I decided to swap the tapes, listening to the copy from the machine attached to Playback side of the editor and the original from the machine attached to the Record side.  To my surprise, now the copy sounded better (i.e., more like the analog source tape I was using) than the original digital conversion.  When heard from the Record side of the editor, the original digital tape now sounded coarser and less well defined than the copy!  Clearly, there was something else going on.

Perhaps it was this experience that diminished the surprise when the finished CDs for that first CD mastering project came in and I compared them with the CD master used to make those discs.  Here the coarseness was even greater than what I’d encountered on the different sides of the DAE-1100 editor.  The finished CDs almost sounded “out of focus” compared with the CD master, such was the extent of the loss of clarity and fine detail.

Things got more interesting when I created CD masters for albums where large sales were expected.  In those days, there were fewer CD plants than there are today and they were all working at capacity.  In order to accommodate expected demand for the big sellers, the CD master would be cloned and those clones were sent to multiple replicators in order to get back sufficient numbers of finished discs to meet the demand.  This was an education in that I discovered that CDs from different plants all sounded different from each other.  Sometimes CDs from different lines within the same plant sounded different from each other.

So much for “Perfect Sound Forever”.  The format has been claimed to deliver perfect copies of the master.  Logic would demand that if this is the case, all those perfect copies would sound indistinguishable from each other and they’d all sound indistinguishable from the masters from which they were made.  But they weren’t then and they still aren’t today.  (There is an exception that I’ll get to shortly.)

Having sent CD masters to plants all over the world and all over the USA, I’ve had the opportunity to compare a lot of finished product to the masters from which said product was made.  Happily, the days of U-Matic tapes are long gone and the advent (long ago) of computer workstations made for many improvements.  Still, even with the most sophisticated CD mastering tools, the reality from the replication facilities remains—the finished discs don’t sound like the masters.

In my experience, a slow-burned CD-R made directly from the computer-based CD master, sounds more like that master than any pressed CD, even the best in my experience.  This is why Soundkeeper Recordings offers our releases in CD-R format as well as replicated CDs.  But how then, to select a CD replicator?  If they all produce discs that sound different from the CD master, how does one find the most faithfully made discs?  This is the question that was on my mind when I started the label.  Knowing that a lot of folks just prefer a factory-made disc to a burned version, even if the latter is more faithful to the master, I needed to find a replicator for Soundkeeper CDs.  My whole reason for starting this label was to avoid the compromises I feel are too often part of the record making process.  I wanted a no-compromise replicator — if such a thing existed.

I reached out to contacts at most of the plants I’d sent masters to over the years.  I told them about my concept for the label and that I needed the most faithful to the master, highest quality discs.  All but one of them told me essentially the same thing.  They said their CDs were perfect replicas of the CD master.  Since my own experience consistently told me something quite different, I could only conclude they were not hearing it the same way I was.  Or they just weren’t listening and were simply repeating the received mantra.  I thanked each in turn and moved on to the next person on my list.

Out of all the replication facilities, only one person at one facility told me, with no prompting from me whatsoever, “Oh the finished CDs will never sound like the CD master.”  I wanted to hear more but knew by then that I’d found my CD replicator.  Here at last, was someone who appeared to actually be listening.  It turned out, this replicator took an unusual approach to making their finished CDs too.  Where many plants increased their throughput – and hence, their income – by speeding up the process, this plant kept with the slower methods.

The first step in manufacturing a CD involves cutting what is called the glass master.  The CD master from the mastering facility is fed into a Laser Beam Recorder (LBR), where a laser is used to create the pits in a photoresistant coating on a glass disc.  This disc is used in the subsequent steps of CD manufacturing.  Most plants cut the glass master at high speed.  Some will cut the glass master in real time, at additional cost.  Many folks have found real-time glass cutting to result in finished discs that sound closer to the original CD master.  The person at this plant told me they cut all their glass in real time, at no additional cost.  It is just how they do it.

In addition, most CD replicators have moved to shorter injection molding cycles.  The faster the cycle, the more finished discs that can be produced in a given day.  Typical injection molding cycles for CDs are now about 4 seconds long.  The person at this plant told me they use a slower cycle, closer to 9 seconds long.  This makes for better formed pits on the finished discs, making it easier for the laser in the CD player to read the discs and minimizing the incidence of playback errors.

Whether the real-time glass cutting and slower injection molding cycle are the reasons or whether some other factors might be involved, I don’t know.  What I do know is that when I master an album, I listen to it so many times that I become intimately familiar with all the details of its sound.  Often, when I hear the finished CD that comes back from the replicator, it takes only a few seconds to hear the typical loss of focus and fine detail.  Something like a chord strummed on an acoustic guitar becomes a loose mélange rather than the six discrete, individual string sounds heard on the CD master.  With CDs from this replicator, the sound is so much closer to the CD master, I need to synchronize playback of the finished disc with the CD master in order to discern the remaining differences.  (Still not as close to the master as the CD-R but closer by far than I’ve heard from other CD plants.)

Now earlier on in this entry, I mentioned an exception.  In fact, I wrote about this in the February 23, 2014 entry in this blog, entitled Listening to Tomorrow.  Basically, what I’ve found is that what I’ve written about in the current entry comes into play when the CD is played in a CD player or via a CD transport.  This has been my experience regardless of the player or transport, or its price.  However, when the CD is properly extracted to a computer, the audible differences do go away.  To date, after 31 years of the CD format, it is only via computer that I’ve heard the audio from a CD disc sound indistinguishable from the master used to create that CD.  Still, those listening to computer music servers with CD or better resolution (as opposed to mp3 or other reduced formats) are in the minority.

Most of the music lovers I know of who purchase CDs will listen to them in CD players or via a separate CD transport feeding an external digital-to-analog converter (DAC).  In order to provide these folks with a CD that truly represents the CD master approved by the artist and producer, selection of the replicator is critical.  To this end, I feel very lucky to have found Bryan Kelley and the folks at GrooveHouse Records, who I have been recommending to mastering clients since my first conversation with Bryan, and who, as far as I’m concerned, are the official CD replicators for Soundkeeper Recordings.