Tag Archives: digital audio

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Hidden treasures

A master recording captured on 30-year-old magnetic tape won’t sound as good as it once did, but that is not true of virgin vinyl LP’s or digital audio of the same age.

Of all the virgin vinyl ever produced there was one that was head-and-shoulders better than any other: Direct-to-Disc recording. Many of us will have fond memories of the Sheffield and Crystal Clear Direct-to-Disc recordings of the 70s and 80s. These rare treasures were an extraordinary challenge to make but, done right, there were few examples of recording art better than they.

For those unfamiliar with this lost art here’s how it worked. An artist or band would perform music live in a studio, often with little more than a stereo pair of microphones fed directly into a mixing board. The output of that board was fed into a cutting lathe where the mastering engineer would follow along with the musical score, making on the fly adjustments to the lathe to compensate for dynamic range challenges (as opposed to doing the same on the mixing board which limits that range). These were true works of art—one of a kind and never duplicated because it was live, the stamping master capable of producing only so many copies before it was exhausted.

The results were often extraordinary: Dynamic to the point of the needle sometimes jumping out of the record groove. The first time you played one of the albums would be the best and each successive play just a little less exciting (as the playback needle polished the grooves into submission).

What made the magic wasn’t the technology of Direct-to-Disc because digital was (and is) far better in every respect. It was remarkable because of what didn’t happen: the mastering engineer couldn’t screw it up with limiters, filters, equalizers, and all the trappings that today rob the life from reproduced music. The impossibly difficult process had to be live and without hindrance to qualify as Direct-to-Disc.

Imagine what we could do with live music on good microphones fed directly into a DSD recorder with the hands of the mastering engineer kept off the bells and whistles available today.

Oh man, those treasure would be remarkable.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Getting something for nothing

We all like the idea of getting something without having to pay a penalty: that free sample at the market, a kind gesture, a door being opened when your arms are full. Closer to home, more digital audio information than we started with.

When we upsample a 44.1kHz 16-bit file to a higher rate and depth, like 96kHz 24 bits, we typically get better sound quality. And since the magic of upsampling just sort of works at the touch of a button, we seem to be getting more for nothing. After all, the file size is considerably bigger. There must be more there. Right?

So, how does that work? How can a program know what went missing from the original recording so it can add it back in?

There are actually two things going on. The first, and least important, is interpolation. Interpolation is a mathematical process that adds more data points through intelligent guesswork and statistical analysis. Simply put, if our steps are moving in a predictable pattern: 1, 3, 5, 7 then it’s likely we can add the missing steps: 2, 4, and 6, as additional data points so we wind up with 1,2,3,4,5,6,7.

Perhaps more important is the choice of filters. With standard CD rates of 44.1kHz we need to have a fairly steep filter so we don’t run into trouble above 22kHz. By increasing to 96kHz we can apply a much gentler and better sounding filter to our digital data and this, in my experience, is responsible for the majority of what we might consider better sound from upsampling.