Dacs Audio GD (19th, NFB1, Master 7, HE7...)

[Ezel78]

(06-30-2017, 09:11 AM)VirtualFred a écrit : Salut,

En version Master 7 puis NOS 7 j'ai toujours eu une influence évidente de ce jumper PLL, pourtant toujours en I2S.
Je ne sais pas si c'est si simple, pour le NOS 7 j'ai lu sur Head-fi.org que ce jumper joue sur la fréquence à laquelle fonctionne la PLL et non le choix de l'horloge interne ou externe,  il en est peut-être de même pour les DAC19/M7 avec un choix en de moins 

C'est curieux Fred, ca sous-entendrait que Magna Hifi n'est pas au courant de ca ?
Voila ce que m'a écrit Magna Hifi récemment:

 didn't want to influence you with the NOS or standard mode but I agree with you. The 8x oversampling is for me also the best choice. Instruments are more separated and the sound is spatial. It's the magical effect I miss in NOS mode. But this is personal taste of course. 

PLL stands for Phase Locked Loop and in easy words it is a method to keep the source input in synch with the internal DAC. It can improve phase noise and reduce jitter. This will only have a benefit if the DAC works with an internal clock. Now its getting a bit complex but the Master 7 (and DAC19) does not have an internal clock on the I2S input at all. The PLL function is of no benefit. The SPDIF inputs are clocked and PLL might improve the sound.

The NOS 7 works completely different and is asynchronous. It uses an internal clock at a very high frequency and will clock incoming data. Because it works with a 4 times higher frequency compared to the source clock and roughly 32x higher frequency than the bit clock (at 44.1khz) of the I2S most of the incoming data will be clocked correctly. It will never be exact match like with the Master 7. This approach is similar to the Sabre ES dac chips by the way! Both methods have their advantages but in my believe, if you put all dots on the i, use very good source clocks (like Mano ?) etc, the results with synchronous technology (Master 7) will pass the asynchronous dac's (Like NOS 7 or NFB 7). This does not mean the NOS 7 isn't good, this is theoretical when everything is perfect. But I am not the only one who thinks like this https://www.lessloss.com/faq.html?q=asyn...reclocking

To complete the story: The Master 7 Singularity is different in this perspective and in Master mode it uses the source clock and I internal clocks are not in use when I2S input is used. In NOS mode it works as a NOS 7 or NFB 7. The difference with the Master 7 are the spdif inputs, they are clocked with matching clocks for both sample rate ranges (44.1 vs. 48)

To make a long story short: I would not use PLL with Master 7 and Mano. The jumper OFF is PLLturned OFF.


En d'autres termes: pas d'horloge sur les entrées HDMI (I2S) des M7 et DAC19.