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發表於 2016-11-9 09:58:28
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本帖最後由 blau.vol 於 2016-11-9 14:26 編輯
Dear CheungTszCh,
actually, for Auralic Aries, which got 2 femto level clock , one for USB output and one for AES. we will use either one at anytime as we can't have USB and AES outputting signal in parallel .
and Femto clock controlled FGPA for output USB or AES, that is NOT really related to the DAC internal clock , as the DAC TCXO or femto clock is controlling the chipset.
Of course , if the digital signal sending from the source got less jitter , which is always better .
Many people ask , is it possible to sync the master clock btw the network player and the DAC chipset.... the answer is can't and should NOT . normally , they have different Master Clock frequency from Network Player(25MHz or 24MHz or 30MHz) with DAC chipset normally taking 22.5792MHz or 24.792MHz or 80MHz ~ 120MHz for ESS chipset (ESS chipset got diff sonic signature with diff Master clock Freq) ...
and some people ask , is it possible to sync the WORD CLOCK btw two, that is easier. however, the work clock generator need a protocol to talk between the Music Server with the Word clock generator ! as in CAS envirnment , we will play diff sample rate files (from 44.1 ~ 384KHz and dsd64x to dsd512x) , we need to have some kind of automatic system for handshaking btw Music Server with the Word Clock Generator.
or we have a USB Bridge (like HydraZ) ,rebuffer and analysis the USB input signal , and generate the WORD CLOCK from it and sync with the DAC. (HydraZ got WORD clock out, which change the word clock sample rate automatically). but you need to have a Fast CPU and a real good clock to govern the job.
So, a dac clock and the source clock (Network Player or Music Server) should works independently .... and actually , I did not mention if the DAC got another FPGA IC (normally got another clock freq) to do the pre-processing job and re-clocking all signal !
So, as the DAC is the one generate the analogue signal , the clock controlling the chipset or FPGA contribute most. ...
Cheers,
Blau
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發表於 2016-11-8 12:43:07
至於usb多唔多noise我就唔識，不過已經用埋jitter bug先落dac，效果係好左
長知識了