debate on 24 bit - is it just audiophoolery?

[pacwin]

 

The Meyer Moran study is seriously flawed. Their own knowledge of the provenance of their musical sources is defective.

 

There are various threads on sa-cd.net concerning Meyer Moran

 

http://www.sa-cd.net/showthread/42987/42987/y

 

http://www.sa-cd.net/showthread/58757/58757/y

 

Some of which Moran has tried to defend his method.

 

If you cannot discrimate between 16bit and 24 bit audio (or now 32 bit) then perhaps your ears or your gear is falling short and another hobby might suit you better. Those of us who can are enjoying our DSD, DXD, and high resolution PCM data despite Meyer & Moran

 

For another study showing PCM discrimation try:

http://www.aes.org/e-lib/browse.cfm?elib=15398

 

or see this forthcoming workshop http://www.aes.org/events/128/workshops/?ID=2268

 

That having been said. Bit rate and resolution are only part of the story. Many of todays CDs originate from high or very high resolution sources and thus sound better than anything from say 10 years ago, causing people to question the value proposition of high resolution formats. ALso reissued analogue recordings now benefit from analogue to DSD or analogue to PCM processing (i.e Grimm converter) which extract maximal data from those tapes. Finally no matter the recording format if the performers, the recording venue, the microphones, cables, mixing desks, analoge to digital conversion and every other variable are sub-optimal so will the listening experience be.

 

The secret is to find high resolution recordings expertly played and expertly recorded.

 

[gordguide]

The premise of these listening tests is flawed.

 

First of all, the listeners themselves.

" ... With the help of about 60 members of the Boston Audio Society and many other interested parties, a series of double-blind (A/B/X) listening tests were held over a pe- riod of about a year. ..."

 

The Boston Audio Society has been around for a very long time ... they were around when I was selling audio in the 1970's. But, there is a significant consistency between the BAS of 1980 and 2010. They all believe that double-blind testing reveals everything there is to know about audio, and to an even greater extent, that any reasonably low distortion products all sound exactly the same.

 

They have been able to "prove" that no-one can tell the difference between a Dynaco 400 and a "Swartz 40" *, for example. Well, the listeners at the BAS couldn't, anyway.

 

They also proved no difference between a Shure V-15III and an AKG PE8S. In case readers are unfamiliar, these are Phono Cartridges costing roughly $150 each when they were available.

 

Not only that, but being quite familiar with both, I can assure you they could not be much different ... the P8ES has a notoriously rising high frequency curve, for example, and they pretty much epitomize the audio concepts of "recessed, laid back" vs. "bright, forward" ... although broadly speaking are of similar overall quality.

 

This is not an objective audience.

 

" ... Most of the tests were done using a pair of highly re- garded, smooth-measuring full-range loudspeakers ..."

 

I am familiar with what the BAS considers a "highly regarded ... loudspeaker". I personally do not hold their typical choices in such a high regard as they do. Interestingly, they do not mention the specific gear used, however they do offer some blurry photographs of the test gear. Have a look and come to your own conclusions.

 

If you do look at the block diagram of the test setup, you can see that this is really a test to see if any of the listeners can discern the insertion of two converters ... one A/D and one D/A. Due to the nature of the test setup, these converters are obtaining an analog signal from a CD recorder's internal D/A processor, then performing 16/44.1 A/D processing followed by a 16/44.1 D/A processing for one of the A/B test signals.

 

They use an ABX comparator invented by one of the authors of the study ... in 1977.

 

I'll leave it to the readers of Computer Audiophile as to whether this represents a good playback system and whether the listeners are discerning or ?

 

I can say this ... the average BAS member's sound system costs about $2~3,000. That in all likelihood includes the turntable and cartridge, and perhaps a tape deck. They spend a lot of time "proving" that anyone who spends more is a bona-fide idiot.

 

 

* " ... A 20 Watt per channel power amplifier with quasi-complementary ouputs built exactly to the five transistor per channel design in the RCA Transistor Manual. By the espoused standards of subjectivists, nothing should sound worse than this amplifier. ..."

 

Indeed.

 

** They never mention what resolution the source disks were, but the CD recorder's internal converter is performing the original D/A conversion.

 

More than anything else, this test setup and the participants reveal a great deal about where these people are, and where I'm not. And I'm not going to where they are anymore today than I was in 1977.

 

[firedog]

Bruce Browns thread at http://www.whatsbestforum.com/showthread.php?2938-The-Art-of-Listening-Hi-rez-music

 

is definitely worth investigation. One thread (the one with the link here) lets you compare redbook to 2 higher res versions of the same music. You can clearly hear the differences, as Bruce says below in the thread:

 

"Here is a file that we recorded at a native 24/352.8 It starts off with piano/drum. Do not listen to the music! Instead, concentrate on the sticks hitting the cymbal. Listen to the attack/transient of the initial hit. Listen to the tone and then the decay. Focus on just this one element.

Listen to the sound of the cymbals in the room. How big is the room? What kind of space is this drummer in? Listen to the tone of the cymbal.

Now... as you go down to 176.4, then 88.2 and finally 16/44.1, listen to these elements that I talked about above. Listen how the transient attack becomes more dull. Notice how the tone of the cymbal changes from crisp/pristine to dull and flat. Next, notice how the decay becomes shorter and shorter and the "room" becomes smaller and more dry with less reverb."

 

This goes right along with what Barry wrote in this thread about why (how) hi-res does sound better. To my ears, this is clear proof that the improvement with hi -res is audible.

 

[Paul R]

I just listened to those, and while yes, there is a difference, there was really nothing in the hi-res version I could not hear in the 16/44.1 version. I think the higher-res versions made it easier to hear everything, but after listening to each one 4 times, I learned to listen for each detail and could easily hear them in each sample.

 

So I begin to question if the clip might have been produced / mixed / engineered in some way that emphasizes the point? I honestly didn't like the clip- the drums seemed all over the place and very forward. The piano appeared to be coming from some nameless space behind the drums.

 

It sounded like listening to the input of several separate mics, and the drums and piano's could just as well have been in separate studios.

 

I repeated the experiment with headphones, and that made it even worse.

 

 

 

-Paul

 

P.S. - Repeated with a different amp and phones, and still the mix was a bit unpleasant for me to listen to.

 

 

[Kevin_O]

This was the master files to this album.

 

http://www.firstimpressionmusic.com/product_p/fimdxd079.htm

 

[Miska]

Now... as you go down to 176.4, then 88.2 and finally 16/44.1, listen to these elements that I talked about above.

 

For this kind of test, quality largely depends on the algorithm used for the conversion.

 

Even if the recording is made simultaneously at those different rates, with a modern ADC it will still be comparison of the similar conversion algorithm inside the ADC chip.

 

Same goes for playback chain, with any DAC there are most likely differences in converter properties at different rates.

 

Thus, it is actually really really hard to compare just the format and not the differences of specific components in the chain from ADC to DAC. However, the hires is mostly the easiest one the to get right through the chain.