How does a Transport effect sound?


hi guys,

Been wondering about this: How does a CD Transport effect sound?  Isn't it just reading the disc and sending the 1s and 0s to the DAC.  Shouldn't every transport sound the same?

Thanks! 
leemaze
It should not. Bits are bits. However, noise from servo motors (reading the disk) can induce modulation distortion back through the power supply and create a jittery input to the internal DAC. There is also logic induced modulation that may affect the internal DAC. And then how the internal DAC does conversion. So in practice differences can be substantial listening to the analog out of different transports. If you are taking a digital feed from the transport then it is the jitter that is inherent in that digital signal which might affect whatever DAC is downstream. If you get a DAC with complete jitter rejection (below audibility) and then all transports played to that DAC will sound the same because as you said yourself, apart from clock timing (jitter), it is all 1s and 0s.
Actually it’s not 1s and 0s. It’s not 1s and 0s until the data gets to the A to D converter. The laser is simply reading ON and OFF depending on whether the laser beam is hitting a pit or land. Actually the laser reading process is an analog process, not digital. Also, the length of the lands, which are variable, helps determine what the actually digital data is.

There are several problems that make the reading of the “data” on the CD imperfect. One is wobbling of the CD due to out of round condition, various types of vibration and/or not being absolutely level during play. Another is background scattered laser light that makes its way into the photodetector. The photodetector is kinda stupid and can’t tell the difference. Yes, I know what you’re thinking, “But the Reed Solomon Error program is supposed to take care of all that.”