Story Time With a Valuable Lesson

Robert Katz Leave a Comment

This is a cautionary true story from the naked city.

Yesterday I mastered an acoustic music album for a fine instrumental artist who tried to do it right the first time. He went to a recording studio to get it done (I think it was a “project studio”), and then went to one of the best-known mastering houses (lots of gold records on the walls) to get it mastered.

The artist was dismayed. The master which came from from this top-notch mastering house was (in the artist’s own words) “to my ear, the tone seems “cold” and somehow less compelling than what is available even on the mix-studio ref. In some cases there seems to be a loss of “presence”. It is not clear if the problem stems from the method of transfer, or from the method of dithering.”

As you can see, this artist has educated himself on the vagaries of digital. He even asked the mix house to supply 24-bit AIFF files on CD ROM from Cubase. He asked me to consult on this and see what I could find. I listened to the mix reference CD and compared it to the master. I agreed that the master was grainy and unresolved—I agreed that even the original mix reference CD sounded clearer and more real than the master he had received. I concluded that something had gone wrong in the mastering.

Ironically, very little was done in the mastering, according to the artist, who attended the session, no limiting, no compression, simply EQ (the artist thinks a 1 dB high shelf at 10K, which in most cases he decided he didn’t like) and (I think) UV-22 dither. I am not sure if it was digital or analog EQ. Clearly this is a purist project done by an artist with good ears and by the way, the mastering engineer involved has a good reputation with acoustic music.

So, at his request, I began to remaster his project. I put up two of the songs on the original 24 bit AIFF files. The first thing I discovered is that all 8 bottom bits of the 24 bit mix (source) files are ZEROs! (looking at my bitscope). So, that means that the original mix house truncated the Cubase mix output somehow when making the AIFF files. That’s loss number one which can never be restored without a remix, automatically his mixes have some unwanted grunge and loss of depth due to the truncation to 16 bit. Even though it was in a “24-bit container”. A bitscope really helps weed out the problems.

I applied very simple digital eq (1/2 dB boost at 20 kHz Q 1.0), some other subtle processing, and 16-bit dither with a shape that sounded good. And I believe the sound that I got is more open, livelier, even clearer, and no colder, even warmer than the original. I’m not sure if what I did was any different than the previous mastering house. But we should consider these questions:

1-The original mastering house could have noted and alerted the artist that his source mix files were really 16 bits masquerading as 24. This might have been correctable at that time at the mix stage while the mix engineer still had his session, if the mix engineer had used his workstation incorrectly.

2-Why did the original mastering house not carefully compare its master with the original and make sure that the master sounded at least as good as and no worse than the original, even with minimalist processing? What aspect of the minimalist processing was shrinking the sound of the original?

I’m not perfect (far from it). If at some time you work with me and you find that one of my masters sounds worse than the source you sent me, please CALL ME and tell me about it. Maybe I made a mistake that could easily be avoided. One slip of the mouse in this digital world…. I accept constructive criticism (usually :-), and I promise I will listen to you. Anyone can get hit with the dreaded “digital bug”. As you can see from this precautionary tale, it can happen to anyone.

Should I have called up the first mastering engineer and let him know about his problem?
I do not know him well, and I felt it was not my place to call him. But maybe he’ll see this message and check his gear with a few tests to make sure that a bug has not crept into the digital system. I hope he finds his problem! We’ve all been there at some time.

Bob Katz

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