DAC IV stages
Reply #35 – 2013-02-22 17:17:17
Trouble is that in the real world, being disturbed by noise from the DACs is exceedingly rare... I understand the need for high quality low volume product offerings with far greater capabilities than the minimum that is required for the mainstream market. If nothing else they facilitate the creation of media with the required quality levels since a product can't be better than the means used to create it. These products need not be justified based on the needs of the mainstream market but can make sense even when they vastly exceed the minimum need. Yes, and yes. But let me bring this thread back to the question of detecting D/A converter differences in an ABX test. I believe the SNR performance of many common audio products, combined with the ubiquitous use of generous amounts of digital volume control is sufficient to expose detectable differences in an ABX test. This does not mean that the general public is dissatisfied with these devices, and it does not imply that the converter noise is objectionable, but it does indicate that converter differences should be detectable in an ABX test. In fact, this has been my experience. In the past, I posted the results of 2 ABX tests I conducted here at Benchmark: [a href='index.php?act=findpost&pid=0']ABX test - DAC1 vs MacBookPro via headphones[/a] [a href='index.php?act=findpost&pid=181']ABX test - DAC1 vs MacBookPro via speakers[/a] In the two above tests, truncation in the MacBook's digital volume control was a dead give-away and resulted in a perfect score in the ABX tests. The calculations I have presented in this current thread suggest that converter noise floor differences can also be sufficient to give away the identity of "X" in an ABX test (when using typical amounts of digital attenuation). SNR reduction and truncation are two distinct issues that can be caused by digital volume controls. When digital volume control is used, it takes more than 16 equivalent bits to reproduce a 16-bit noise floor (1 extra equivalent bit is required for every 6.02 dB of digital attenuation). Again this does not mean that the casual user will be dissatisfied with the audio performance. However, the casual user MAY be able to detect the difference between two D/A converters.