題目是關於USB DAC與cable,
其中有篇回應 http://www.AudioAsylum.com/forums/pcaudio/messages/6/63932.html
這麼說
All cables sound different for various reasons. One of them is data rate, one noise interference from VBUS/GND, EMI/RFI radiated noise... etc...
If you have errors the THD goes up... if you have noise then you have other issues.
If you have errors the THD goes up... if you have noise then you have other issues.
還提到 http://www.AudioAsylum.com/forums/pcaudio/messages/6/63779.html
It's easy to see that the longer runs effect all devices. I have about 20 USB DACs and ADC's here the THD will go up on 24/96 and the Class 2 24(32)/192 stuff I have here when you go over 3M.
也就是說,問題是?
出問題的不在數位,數位出問題,protocol一定知道,
問題在類比!
畢竟這個應用是DAC啊~
而USB cable雖說是用來傳送數位訊號,別忘了,電源會和類比部份接在一起...至少ground會...
搞清楚問題的根源,才能夠對症下藥,
所以,Ayre用photo coupler隔開數位與類比部份~
那麼,電源應該也得做二組囉...
只是,不是說光電轉換這手法會引入jitter?這...豈不是兩難...
音響論壇254期談征宇的mz-CD3.1與mz-DAC3.1之間用的USB連接線,也這麼說
USB線要插確實,如果覺得二聲道不平衡或音場較窄,都要重新插線
二聲道不平衡這點...實在很怪啊...
同一條線(更仔細的說,同一根腳,同一條導體)傳輸二聲道,為何會造成不平衡?
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