Here’s what Robert Stuart said about MQA at the end of the YouTube video introducing the technology:
“MQA is a revolutionary new British technology that allows us to capture the nuance and all of the detail of the original music performance but to put it in a file that is small enough to download or to stream today.”
You can check out the video yourself, although it’s pretty much a feel good piece lasting only a few minutes.
The innovation made possible by this new technology is the ability to deliver the benefits of high-resolution audio (96 or 192 kHz/24-bit PCM audio) in a container that is roughly the same size and has the same bandwidth of a CD. It’s easy to think of MQA as a data compression technology based on psychoacoustics but it’s much more than that. The researchers at Meridian have developed an encoding/decoding methodology augmented with metadata about the analog signal that can be used to deliver “lossless” audio at fidelity levels far beyond the specs of the sample rate and word lengths used. They’ve built a really smart end-to-end signal path.
The high-end audio world has moved aggressively towards high and higher sample rate thinking that they will bring improved sound quality. Recording at 96, or 192, or even 384 can result in audibly better recordings but an alternative benefit is the processing that is required to handle artifacts that come with digital audio. Here’s a quote from Robert’s AES paper called, “Hierarchical Archiving and Distribution”:
“It is now widely accepted that one key benefit of higher sample rates isn’t conveying spectral information beyond human hearing, but the opportunity to tackle the dispersive properties of brick-wall filtering. Wider-transition anti-alias and reconstruction filters directly shorten (proportionately) the impulse response and there is also more opportunity to apodize to remove extended pre- and post-rings.”
Another critically important factor (and one that I’ve failed to acknowledge in previous posts) is the resolution of human hearing in the time domain. There is new information that accuracy in the time domain is multiple times more important than the frequency domain. I’m not sure where the cutoff is for this level of accuracy but I’ve read and heard that 5 to 10 microseconds is the range. This requires a sampling rate of 192 kHz…according to this new information 96 kHz/24-bits is not sufficient.
The goal then is obvious. The audio world needs a way of getting the frequency, amplitude, and all important time domains provided by a sample rate of 192 kHz into a package that current bandwidth and storage capacities can handle. Meridian’s MQA does this by creating metadata about the time resolution (and other aspects of the analog signal) into a very low level signal (below the level of the noise) in a PCM file with a much lower sample rate. In a fashion similar to HDCD, the metadata is used to decode the MQA when the appropriate decoding equipment is sensed…otherwise the standard resolution PCM file is reproduced. How clever.
However, as important as this new technology is…it doesn’t make any changes to the original signal. It’s doesn’t reveal any additional nuances or fidelity in the original recording. The claims that it results in an improvement in fidelity over the source are misplaced. Here’s how one audiophile editor said it:
“I heard a wide range of music, from full-scale orchestral to voices to a very quiet piece by the Modern Jazz Quartet from the 1950s. I can still vividly recall the delicacy, ease, and resolution of the cymbals in the MJQ piece. I was also struck by the precision of their placement and how they appeared to float in the air against a completely silent background. The treble was totally unlike any other digital I’d heard, completely free from the metallic hardness and artifacts we assume are part-and-parcel of digital audio. Instrumental timbres were so naturally rendered to be almost eerie in their realism. Voices had a stunning palpability and immediacy that were all the more realistic for their compact image size and the sense that they were surrounded by a natural acoustic.”
What he heard was a standard definition analog sourced recording in MQA. The original source recording was limited by the technology of the 50s. To imagine that the recording suddenly had a “silent background” against which instruments floated or possessed treble that matches a new high-resolution PCM digital recording is hyperbole to be polite. There isn’t any “metallic hardness or artifacts” in a well done high-resolution PCM recording.
MQA is an important stepping-stone in the evolution of music delivery NOT a revolution is sound quality.
I’ll talk about how it’s done tomorrow.
I’m still looking to raise the $3700 needed to fund a booth at the 2015 International CES. I’ve received some very generous contributions but still need to raise additional funds. Please consider contributing any amount. I write these posts everyday in the hopes that readers will benefit from my network, knowledge and experience. I hope you consider them worth a few dollars. You can get additional information at my post of December 2, 2014. Thanks.