Dr. AIX's POSTS — 27 May 2016


The blurb at the top of the PS Audio page claims the fidelity of the collection of tunes on their audiophile compilation SACD disc is “nothing short of stunning”. My own description would be somewhat less generous. All of the tunes are very nice studio recordings, produced and recorded by capable engineers, and performed by talented musicians. But in spite of the 176.4 kHz 24-bit PCM specifications, the fidelity of all of the tracks is about equivalent to a standard CD and no better. As I’ve stated many times, well-done compact discs can sound terrific…and the files that I downloaded do sound very good. That’s the subjective assessment. How about the technical side of the picture?

Let’s start with a spectral plot. I opened each and every one of the tracks, selected the entire track, and performed a spectral analysis. The figure below shows a veritable rainbow of colors. Each color reflects the spectrum of one tune. I didn’t include all of the tracks on this plot…but they all show the same telltale pattern of DSD…there is a huge ultrasonic rise caused by the noise produced by a 1-bit encoding system. In order to improve the dynamic range beyond 6 dB (the amount 1-bit is capable of delivering), a process called “noise shaping” pushes the “in band” (20-20kHz) noise out in to the ultrasonic range where your ears won’t hear it. That’s great for your ears but your equipment will try to reproduce it! And that can be very problematic.


Figure 1 – The spectra of 6 of the tunes from ONE [Click to enlarge]

The files have a sampling rate of 176.4 kHz, which means that audio frequencies up to 88.2 can be captured and delivered. But look at what’s present just past the “audio band” in the analysis above…nothing but noise. Is it really beneficial or desirable to download a couple of hundred megabytes of data per tune when the majority of the ones and zeros contain nothing but noise?

There are a few tunes among the 10 that have musical content higher than 20 kHz but not by much.

Take a look at the spectra of the first tune on the album. This is the waveform and spectra in a different type of display.


Figure 2 – The spectra of “Quill Pen Feather” by Elephant Revival [Click to enlarge]

The big cloud in the middle of the plot is all noise that has been shifted out from the audio band. This is the fundamental problem with DSD…especially at 2.8224 MHz or DSD 64, which is the sample rate of the Sony Sonoma system used to produce most of these recordings.

The production of the tunes on the “One” compilation disc is excellent, the tunes are nice enough, and the musicians are wonderful. But the project doesn’t reap the benefits of high-resolution audio with regards to frequency or dynamic range. I’m tempted to downconvert the 176 kHz/24-bit PCM files to CD specs and let you take a listen. I doubt very seriously if you would be able to tell them apart. But I don’t want to distribute the intellectual property owned by others.

Tomorrow, I’ll take a look at the dynamic range of the collection.

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About Author


Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

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