Estupenda crónica de cuando el audio era un campo de batalla notorio y de primer orden en cuanto al desarrollo tecnológico.
The number of times out of 554 that the listeners correctly identified which system was which was 276, or 49.82 percent — exactly the same thing that would have happened if they had based their responses on flipping a coin. Audiophiles and working engineers did slightly better, or 52.7-percent correct, while those who could hear above 15 kHz actually did worse, or 45.3 percent. Women, who were involved in less than 10 percent of the trials, did relatively poorly, getting just 37.5-percent right.
...information about the signal chains and the source material within a couple of weeks of the article's publication on the Website of the Boston Audio Society, a venerable 37-year-old, independent non-profit organization, in which both authors have long been active. The equipment list included amplifiers from high-end manufacturers like Adcom, Carver, Sim Audio and Stage Accompany, and speakers from Snell and Bag End, as well as the oft-worshipped Quad ESL-989 electrostatics, which are supposed to have usable response up to 23 kHz — which is, of course, above the Nyquist frequency of the HHB recorder's converters. The subjects listened to discs that covered a wide range of material and included classical instrumental, choral, jazz, rock and pop, from audiophile labels like Mobile Fidelity, Telarc and Chesky.
Muy bien, siempre hay que dejar lugar para seguir evaluando y descubriendo "Does this mean that someone else couldn't do a similar experiment and end up with different results? Not at all."
But something is causing people to say they are hearing differences. If a double-blind test can't confirm those differences, then what's going on? For one possible reason, let's go back to Moorer's paper that I quoted earlier (called “New Audio Formats: A Time of Change and a Time of Opportunity,” which can be found on his Website,www.jamminpower.com). Later in the paper, Moorer noted that humans can distinguish time delays — when they involve the difference between their two ears — of 15 microseconds or less. Do the math, and you can see that while the sampling interval at 48 kHz is longer than 15 µs, the sampling interval at 96 kHz is shorter. Therefore, he says, we prefer higher sampling rates because “probably [my emphasis] some kind of time-domain resolution between the left- and right-ear signals is more accurately preserved at 96 kHz.” It's an interesting starting point for a discussion, but to my knowledge it's never gotten past that point — as a theory, it has never been expanded upon or tested. And judging from the results of Meyer and Moran's experiment, it doesn't seem to be a factor.
The Formula Dac is the first in the aqua - acoustic quality's production to show a proprietary D/A conversion system, that we name Optologic Dac. This conversion system follows the same multibit technology (already used in the previous world acclaimed dacs such as La Voce and La Scala) but with a discrete R2R resistors ladder instead of Burr Brown PCM1704 dacs. TechnologyGalvanic and magnetic isolations are implemented between the FPGA and the four branches of the R2R ladder converter. This creates complete isolation of all digital circuitry - including the clock - from the analogue section for a pure clean ground plane. It also plays the main role in the differential management of the R2R ladders, achieving perfect symmetry between the counter-phase halves. The result is the highest tonal contrast and naturalness never heard before from digital sources. The Formula Dac uses no digital filter or any other compensation, relying instead on maniacal attention to each sub circuit. The analog and digital power supplies are executed purely discrete by extensive use of BJT, Mosfet, Jfet and ultra-fast diodes. Passive parts were selected not just for the best sonic result but also for their top quality, longevity and reliability. With the exception of six superior quality electrolytics, all other caps are Tantalum, solid-polymer OS-CON and double-metalized MJP. The signal path itself is direct-coupled and free of all capacitors. The two output stages (one single-ended, one transformer-coupled balanced) use discrete BJT and JFet with metal-film resistors. All the electronics parts show an ultra low RF noise.