Sunday, September 27, 2015

MQA Reconsidered

Having read the introductory articles in The Absolute Sound, I like the look of the thinking behind MQA, Meridian Quality Assured.

In it's full encoding and decoding, when possible from an analog source, it preserves fantastic temporal response, so that tiny pulses are tiny pulses without the pre and post echo.

It does this by using more than one sampling rate, with the higher sampling rates having fewer bits because the greater resolution is not needed.

I was thinking about that sort of thing in my previous 'information" arguments against DSD and Delta Sigma in general.  Only a few times, if ever, I have noted my reservation that most of this "information" that DSD (and to a lesser degree, multibit delta sigma modulators) is at barely audible if at all frequencies.  So maybe I've been making a mountain out of a molehill.  I haven't known how to account for this before, but Meridian discusses this very issue (in their terms) showing that the information needed is a diagonal curve.

DSD's errors fall roughly in this range, but as I have noted before, the use of noise-shifting means the upper frequencies aren't really linear and accurate.

Meridian can achieve better quality, fully up to the required diagonal, in fewer bits than 44.k uncompressed.  Better than HD quality such as 192/24 they say…since they have better pulse accuracy still.

It sounds possible.  It certainly sounds better to me than DSD, and likely my older secret decoder ring, HDCD.

I'm a big fan of HDCD and I've always sought out HDCD versions and HDCD compatible players.  I have a way of transcoding HDCD into 24/96 by analog resampling, which sounds better to me than digital conversion, and I've heard experts say that.

While I was willing to pay the nickel for better sound, I wondered if others would balk (and, well, they did in the sense that HDCD became a very small player in the market) to pay the nickel.  Then, if you didn't have HDCD capability, you'd get a version that not only had less resolution than the encoded version, it might have an altered dynamic envelope.  So, ,in effect, a low-fi version in the unquestionably audible way.  That in effect makes it a secret decoder ring you must have to get the real music, which can be seen as  a kind of extortion.

Of course Dolby, Dbx, and other encoding schemes have been based upon those same principles.

And regards compatible SACD's…there has been much speculation that the CD layer is a different mastering, or dumbed down from true 16 bit quality.

And this even gets to audiophile releases…in many cases the main reason why they may sound different is different mastering.  And so too with LP's.

So ALL these are using the same extortive system as Meridian would be.

It's hard to pull these things off.  Dolby dominated cassette, though I was not happy with most dolby playback (except Nakamichi), done properly, it gave a nicer recording, though sometimes I preferred making my own recordings without dolby, especially if meant to be played on non-Nakamichi cassette decks.  I felt it was a useful but highly flawed system.  Actually back in the heyday, I hated Dolby B.  Now I'm inclined to use it consistently on my Nakamichi RX-505.

Elsewhere, I don't think Dolby was as successful, but I heard the claim they put a lot of pressure on producers to use Dolby products when the producers didn't feel it improved the products, or preferred others, such as Dbx.

I was glad that Meridian won the rights for DVD-Audio with MLP knowing that Meridian is, well I've generally had more respect for their thinking than Dolby.  I heard that DVD-Audio was held up by a battle between Dolby and Meridian.  I'm glad Meridian won.

And I glad and very surprised to hear that the "Dolby True HD" audio on Blu Ray is basically MLP.

So know the geniuses at MLP have given us a really really true HD format.  If it's anywhere as good as it sounded in the pages of The Abolute Sound, I wish them luck, and I am interested in getting the magic.

Sadly everything in my main systems must be converted to 44.1 to 96 kHz.  So I'm not sure I could even approach using MQA as intended, but I can get a version downsized to 24/96.  Or I can resample from the analog outputs, as I do with SACD, HDCD, and mostly DVD-Audio.

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