Q.: With so many different formats of recorded music to choose from (mp3, vinyl, CD, AAC, FLAC, .WAV, .AIFF), how do I know which one sounds closest to what the artist originally intended?
A: This question has been with us ever since recorded music became available in multiple formats. The answer requires a quick trip down memory lane, and a look at the dark art of mastering. First, the history:
The first time multiple formats with differing sounds were seriously available to consumers was in the 1970s. The advent of 8-track and cassette tapes was the first time a format other than vinyl gained a foothold with the buying public. Between those two, 8-track actually was the superior sounding format, but both tapes and the players were technically unreliable. The free market spoke, and the convenient little cassette won the day.
The problem was, it sounded terrible. Slow tape speed and the small tape width meant there was a tremendous amount of “tape hiss.” Various tape formulations and schemes for noise reduction were developed to combat the problem. But if you didn’t have a deck that took advantage of them, or you didn’t know how they worked, your cassette most likely sounded WORSE than it would have without any of the fancy technology. All of that to say while vinyl and cassette ruled the day commercially in the ’70s and ’80s, there was no debate as to which format sounded better. If you were serious about your sound you listened to vinyl. And that’s the format that recording professionals cared about.
That all started to change with the advent of the compact disc. Suddenly the evils of cassette tape hiss, and vinyl pop and crackle would be a thing of the past! Digital playback would save us all from unwanted noise in our recordings! A great plan, however, there were still two problems: The first was that vinyl continued to out-sell CDs for some time, which meant that it still ruled the audio roost. The second was that recording studios continued to use analog equipment, and they discovered that despite the promise of digital audio technology, early digital recording systems in fact did not sound better than the old analog tape machines they’d been using for decades. (A situation that would continue for various reasons until the early 2000s.) But in the consumer world, CDs staged a takeover.
1988 marked the first year that compact discs out-sold vinyl. The free market had spoken again, and the recording industry listened. Vinyl was no longer the king of the record store. That meant a whole new approach to the final step of the recording process: Mastering.
For those who don’t know, mastering is the last stop a recording makes before heading to the printing plant, or the web, for public consumption. The original job of the mastering engineer was to transfer the audio from the recording format (analog reels of tape in the old days), to a consumer format (vinyl, cassette, CD). “It’s also your last chance to tweak the sound of your product in the overall aspect,” says Grammy award winning mastering engineer Robert Hadley, “Adjust high end, or low end. As you would on your stereo except in much more detail. Once we’ve got it to the consumer format,” says Robert, “we give the client a reference print to take home and listen. Then they can say, ‘Cut 4 sounds a little dull in comparison to Cut 3,” and we’ll go back in and make an adjustment.” In addition, mastering is the stage at which the sequence of songs is finalized, fade ins and outs are tweaked, as is the time between each song. The mastering engineer will also make sure all of the songs on an album play back at a similar volume to one another, so you don’t have to adjust your player’s volume between each song. But most important to our discussion, mastering engineers make sonic decisions to maximize the sonic potential of each format.
So now that we know the history, and have some idea what mastering involves, we can look at our current situation. These days there are 4 common ways we listen to music: Vinyl, compressed digital files (mp3, aac, FLAC files), high resolution digital files (.wav, .aiff), and CDs (which are also a form of digital audio). The question of which one sounds the closest to the artist’s intent lies in how the final mixes were mastered.
Despite the popularity of mp3s and other compressed digital files, mastering engineers very rarely attempt to optimize an artist’s final masters for that format. Why? Well, these days compressed digital files are the modern equivalent of the cassette tape in terms of quality. Assuming your vinyl playback system is in decent shape, they are on average the worst-sounding format available. In order to keep file sizes small, and give you room for more songs on your digital playback device, these files are compressed from higher resolution digital files, then decompressed as you listen. This process degrades the sound quality. The smaller you want your files, the more they have to be compressed. And the more file compression, the worse the sound quality. Since the mastering engineer can’t possibly predict all of these variables, trying to optimize for this format is nearly impossible. “MP3s and AACs are all born from CD quality audio,” says Robert, “So the better the file sounds that you have to make the compressed files from, the better they’ll sound.” And that includes those created for sale by your favorite online digital music store.
High resolution digital files share a similar issue. Although in this case, their increased resolution allows for a level of audio nuance that would be totally lost on a lower-quality format. Which means those listeners might miss out on important details of the recording. High-resolution digital isn’t nearly as popular as compressed audio because of the much larger file sizes, so mastering specifically for this format doesn’t make sense from a commercial standpoint, though some artists and labels will have a separate mastering job done to maximize this format’s sonic advantages. Robert tells me, “We’ll relax the level, and take the digital limiting off to take advantage of the greater detail and dynamic range.” That said, high resolution mastering jobs aren’t common, and never the only mastering job done for a project.
CDs sit somewhere in the middle. They have higher audio quality than compressed digital files, but lower quality than high resolution files. And while many audiophiles debate the sonic quality of the compact disc, for the vast majority of us a well-produced and mastered CD sounds excellent. So this is the format most often favored during the mastering process. Higher and lower quality files are created from these masters. While you may hear more detail in the higher resolution files, the mastering engineer will have made his or her audio decisions based upon the sound of the CD-quality files. “Honestly,” Robert says, “I don’t see CDs going anywhere anytime soon. There’s just too much hardware out there. More than there ever was for cassettes.”
In today’s music world, vinyl is the outlier. The modern process of mastering a final mix for distribution on vinyl is very different from that of the digital formats,  and there are a number of time and audio limitations involved. For instance, very low frequencies that are more common on digital formats can actually pop the needle out the groove of a record. The maximum time per-side on an LP record is 17 minutes. That can be increased by reducing amount of volume (level) to decrease the width of the groove; but at a cost to the overall sonic quality of the music. Vinyl also can’t take the same level common on most modern digital masters. And of course, the substance itself brings its own patina to the sound of the music, which the mastering engineer must account for. Robert will actually make a digital “cutting master” using the same EQ and analog limiter settings as he originally did for the CD master; but without the digital limiting, and with a more relaxed level overall. Very similar to making a high resolution digital master. He’ll then use that file to create a lacquer master (which are what get sent to be reproduced at a record plant – similar to vinyl, but much more fragile), and make whatever further sonic adjustments are necessary based on the sound of the lacquer master.
All of that means music that’s optimized for vinyl during mastering will sound significantly different from music optimized for CD, or for low quality digital formats. So the question of which format most closely resembles the artist’s original intent really centers around which format they’ve chosen to have their music mastered for. And if they’ve chosen to have it mastered for multiple formats, then it’s actually which one they like best! But in the end, the real question is which one you like. Because what artist’s want MOST is for you to hear their music!
 For you techies out there, CDs have a sample rate of 44.1KHz, and a dynamic range of 16 bits. High resolution audio files can reach as high as 192KHz/32-Bit, but are most often available at 96KHz/24-Bit.
 Robert points out that in the early days of CD, the mastering job for vinyl and digital was the same. That changed over time, as mastering engineers were asked to take advantage of the higher volume digital technology allowed.
Will Kennedy is a record producer, engineer, and mixer living in Los Angeles. His credits include O.A.R., Michael Franti and Spearhead, and The 88. You can find him at http://www.willkennedyproducer.com
Plagued by an audio question and don’t know where to turn? Email Will a question for this column at [email protected]