Dr. AIX's POSTS TECH TALK Vinyl — 24 June 2018


The high-resolution challenge page had been pinged almost 1500 times and over 400 people have contacted me about downloading the files. Don’t worry if you haven’t yet downloaded the files, there’s still plenty of time to get in on the fun (yes, this is meant to be fun not a rigorous test or thorough survey!). I would encourage all participants to explore the option of using the ABX plugin for Foobar to do the evaluation. It elevates the rigor of the test a notch or two.

So what should we be listening for when experiencing these files? Is it the inclusion of the ultrasonic octave from 20-40 kHz that a real high-resolution file can capture? It’s highly doubtful that you or even a teenager would be able to identify any differences based on partials present in the highest range of the audio band — and beyond. I know my own hearing tops out at 15-17 kHz. And a really good set of audiophile speakers is unlikely to reproduce ultrasonic frequencies. Some headphones or speakers with supertweeters push the upper limit to around 40 kHz but if we can’t hear it, why bother? So why all the fuss about higher sample rates? The audiophile lexicon uses words like “air”, “transparency”, and “clarity” to describe recordings and systems that are exceptionally good at handling high frequency content. The wind chimes in the Laurence Juber “Mosaic” track (Tune_1_A) is a good example. Listen carefully at around 1:40. The inharmonic partials being produced by the wind chimes (made for a the tuning pins of a junked piano) are crystalline and clear — not mushy and crushed as they would be on vinyl or analog tape.

I’ve said before that increasing the sample rate of a PCM digital recording to 96 kHz more than covers all of the musical components coming from any instrument (especially acoustic instruments). It also pushes any of the dreaded digital “pre or post ringing” to near the Nyquist frequency (with 96 kHz that point is at 48 kHz – nobody is hearing that!) and insures that any “time smear” is relegated to the trash bin. There are very real technical reasons why moving the sample rate to 96 kHz makes sense. Going further is counterproductive and a waste of resources. We get 100% fidelity with a 96 kHz/24-bit PCM recording and that’s what we all want.

However, increased dynamic range in a recording is a very good thing and offers dramatically enhanced listening experiences. Moving from 16-bits to 24-bits increases the potential dynamic range of a recording from about 93 dB to over 120 dB (many authors get these numbers wrong because they don’t factor in dither which adds noise to the theoretical number of 96 dB). An article from about a month ago by my friend Jerry Del Colliano at AudiophileReview tweaked my interest when I read it and when I read the comments this morning. You can read it yourself by clicking here. Jerry is a publisher and not an audio engineer and thus can be excused for drifting into areas that he might best avoid. The focus of the article is that vinyl cannot match the dynamic range of digital — and that’s absolutely true. Only a hardcore digital denier would dispute that fact (surprisingly there are lot of comments from people that take that position). To believe that vinyl LPs are capable of capturing and reproducing the sound of live performance is crazy because the dynamic range of the very best vinyl LPs (direct to disc LPs) is about 60-72 dB. But Jerry a number factual errors in the piece.

“Perhaps your ears know best, but analog master tape, like what many of the most important recordings in the history of music were recorded on, can capture the 120 dB-ish range of an actual musical event.” This statement is not true. The best that analog tape — the multitrack 2″ machines that were used to make many of the classical albums from our past — can do with regards to dynamic range is about 72 dB NOT 120 dB! With each pass over the heads the oxide gets scraped away and is diminished, the high frequencies are attenuated, and the dynamic range reduced. That tape is then mixed to another analog tape — this time a two-channel master. The dynamic range is lowered again by 3 dB with each analog generation. The final mastered version is another copy so maintaining a dynamic range of 60 dB would be considered very good. But the mastering engineer uses dynamics compression and amplitude normalization to increase the apparent volume — at the cost of whatever dynamic range is left at his or her stage. The DR of an original analog master — probably the safety copy from which vinyl LPs were made — may have as little as 15-30 dB of dynamic range. In PCM digital terms this is less than 6 bits! That’s why I hammer at the myth of high-resolution regularly. The difference between what is possible and what is real is rather large.

And it doesn’t really matter whether you consume these recordings from vinyl LPs or CDs. The dynamic range of an actual performance isn’t maintained from recording sessions to distribution format. Yes, the potential of PCM digital to maintain every dynamic nuance present during the original performance is there. But it is almost never realized. The music business doesn’t want their releases to have real world dynamics. Jerry’s argument falls apart when you realize the realities of the music business model. He writes, “Obviously, you can’t get access to the VERY fragile and environmentally sensitive analog master tape of a recording, but what you buy music on current HD formats that are damn-near bit-perfect to that master tape. For $20 you get a meaningful recording with full 120 dB plus dynamics, no meaningful distortion from the playback source. The last line — where he says we’re getting “full 120 dB plus dynamics” — is false. But he’s right that the “high-resolution transfers” HDtracks and others offer represent the very best available digital version of whatever “master” tape was used during the digitization process. Could there be better versions in previous non-digital formats? Absolutely. Is it worth the elevated price to get a “high-resolution” download or stream — probably not. One reader buys old CDs — trusty 44.1 kHz/16-bit PCM — for $1 each at used record stores and loads them into his music server. The fidelity of the CDs are virtually indistinguishable from the high-resolution downloads at 25 times the cost.

What most writers — especially ones that have no experience engineering a record — get wrong is that the pathway from analog “masters” to “high-resolution” digital file doesn’t improve the fidelity of the original master — if done well, it maintains whatever fidelity (including the narrow dynamic range and limited frequency response) was present in the original master. This is the mantra of MQA supporters and the goal of its inventors — to minimize any sonic degradation due to the transfer from analog to digital. 96 kHz/24-bits can do this without any loss and without the overcharges associated with MQA’s licensing agreement. The 11,000 MQA albums on Tidal didn’t come from high-resolution sources so why all of the praise for a method that makes claims to produce high-resolution streams? It’s crazy. It’s why many of the high-end makers of DACs have decided to pass on MQA. They’re right.

Listen to the high-resolution challenge files with dynamic range in mind. The files from my catalog are unique in that they actually do maintain all of the dynamics associated with the original performance. When you experience the 16-bit file, the transients are quieter, the impact of a snare drum lessened, and the slap of Laurence playing his signature Martin guitar softer. That’s what dynamic range can really do and why real high-resolution audio has such great potential.

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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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