What did you do for controls, Stefan? Unless you controlled for level and experienced all of this double blind, it is likely that you are experiencing placebo effect on some of these, particularly those changes where the squeezebox or transporter is doing the final retiming and conversion.
Bits are bits. If you keep the Squeezebox fed and are feeding it the same format, it should not care where the bits came from. After all, the BBC makes it all the way to you from the UK with a second of latency and maybe 0.1 second of latency jitter. Squeezecenter can buffer it and spool it to Squeezebox which has yet another jitter buffer. Squeezebox reconstructs and retimes the sample stream. All the jitter in the world (well until the buffer runs dry :) never reaches your ear, just that introduced by the Squeezebox itself. With this understanding, moving your music library from an internal disk to a NAS should have no effect on the sound coming out of the Squeezebox or Transporter. Some of the other changes such as SPDIF to TOSLink may. SPDIF is notorious for its jitter. But again, we are filling a buffer and regenerating the timing. I can see a difference resulting if the jitter is so bad that a bit is lost every now and again. This would cause actual errors or dropouts in the sample stream. The way around this is to use "forward error correction" by using Hamming coding or one of the newer forward error correcting techniques like those used in disk drives. Even if a bit is lost every now and again, the bit-stream can be recovered. I don't really know the details of SPDIF, only that it dates back to the beginnings of digital audio production equipment and is obsolescent. Bit jitter should not have a big effect on playback as long as all of the bits can be recovered correctly off the SPDIF waveform. The bit stream can always be buffered and retimed. The last device to buffer and retime the bit stream determines the pitch accuracy and sample jitter. What happens along the way is not seen unless the pipeline goes dry. Sample jitter is interesting. From my introduction to digital signal processing in college, jitter (non-uniform sampling in geek speak) introduces noise in the reconstructed audio. A classmate did his masters thesis on the subject deriving the effects of nonuniform sampling. My recollection is that he concluded that the noise was Gaussian for the sample jitter distribution that he examined. This would show up as a raised noise floor in the playback. It would be hard to notice a tiny amount of jitter on most program material. FLAC and Apple Lossless do give you back the original bits. Folks have verified this. I ripped an CD to one of each, loaded into Audacity, and played the tracks. I couldn't hear a difference. There can be a difference if you are not normalizing the levels or you are using different play back level management schemes. These can cause the levels to differ enough to fool you. I demonstrated placebo effect to myself some years ago. I bought some Nordost cables (the modest ones) to replace some way too long monster cable that came with my trusty DQ-10's in the early days of Monster. The difference was dramatic after the change. The next day, things were back to normal. I expected a change and, by Jove, I heard one. I'm not so quick to form opinions about a change after that experience. Interestingly, the woofer surrounds failed and I never noticed. I had a local pro audio shop renew the surrounds and the DQ-10s are still going strong at 30 years young. It has been 13 years so I've forgotten what prompted me to take the front panels off to look. My rig: SB3, Conrad Johnson PV-1, Gas Ampzilla, Dhalquist DQ-10s. Computer audio: Presonus 1394 and Monsoon Audio planar desktop speakers. -- dlhamby ------------------------------------------------------------------------ dlhamby's Profile: http://forums.slimdevices.com/member.php?userid=12801 View this thread: http://forums.slimdevices.com/showthread.php?t=57449 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
