jkeny wrote: > However, if you are struggling to understand what problems using > asynchronous USB solved then you really are dumber than I thought & > further strengthens my viewpoint that you are measurebators who twiddle > with your instrument but don't really know what it's for or how to use > it. Shameful
I've tried really hard to answer all of your attempts at tripping me up with nicely phrased replies and no ill intent but you continue to cast aspersions about my understanding of the technical issues in all of this USB hubbub. Here's what I know: The presence of jitter in digital audio is not a new issue and has been dealt with in various ways since the introduction of the compact disc back in the mid 1980s. However unless the CD player was really poorly designed and/or manufactured any jitter present was completely inaudible, either because the level of the jitter was well below the noise floor or because the jitter was in the pico second range. One thing that was true is that even in well designed and built CD players jitter was present and could be measured. As computer based audio and the of USB and USB DACs took off there was found to higher levels of jitter in the digital signal carried via a typical computer's USB port due the digital data being transmitted in a non-asynchronous manner. However, as in the case for the CD players, the vast majority of the USB induced jitter was inaudible since either the level of the jitter was well below the noise floor or because the jitter was in the pico second range, except of course for those really badly designed and poorly built USB ports, in which case the jitter might actually be in the nano-second range (a very, very, very, very rare occurrence). Now here is where it gets really interesting and the audiophile magic and voodoo kicks in. At some point several years ago some audiophile guru (I believe that it was one the "well respected" high end audio manufacturers, aka snake oil salesman) claimed to clearly hear (not just measure) jitter in the analog output of a USB DAC being fed digital audio data via USB from a computer. I don't know if the jitter in question was in the pico or nano second range but in either case anything in those ranges is completely inaudible to humans due the limitations of human hearing based on biological science. Apparently audiophiles have super human hearing capabilities. Now it was also known that by using an asynchronous USB signal instead of a non-asynchronous USB the jitter level could be greatly reduced and so the audiophile fixation on asynchronous USB was born. All of the above is a classic example of audiophile FUD (fear, uncertainty and doubt) in it full and mighty glory. A fake problem is introduced (audible jitter) and equally fake solution is introduced (asynchronous USB) and the money started rolling in as all good audiophile fell in line and waited in line to buy all those pointless asynchronous USBs. Absolutely beautiful and a required lesson to be learned for all future snake oil salesmen. By the way, if I got any of that wrong please let me with specific references and valid links to non-audiophile sites since any link to any audiophile site is as pointless as an asynchronous USB DAC. Living Rm: Transporter-SimAudio pre/power amps-Vandersteen 3A Sign. & sub Home Theater: Touch-Marantz HTR-Energy Veritas 2.1 & Linn sub Computer Rm: Touch-Headroom Desktop w/DAC-Aragon amp-Energy Veritas 2.1 & Energy sub Bedroom: Touch-HR Desktop w/DAC-Audio Refinement amp-Energy Veritas 2.0 Guest Rm: Duet-Sony soundbar Garage: SB3-JVC compact system Controls: iPeng; SB Controller; Moose & Muso Server: SBS on dedicated windows 7 computer w/2 Drobos 'Last.fm' (http://www.last.fm/user/jazzfann/) ------------------------------------------------------------------------ ralphpnj's Profile: http://forums.slimdevices.com/member.php?userid=10827 View this thread: http://forums.slimdevices.com/showthread.php?t=103684 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
