03-16-2019, 07:48 PM
(Modification du message : 03-16-2019, 08:04 PM par a supprimer merci.)
Comme l'explique le texte que j'ai cité précédemment, entre une mesure de laboratoire et un flux audio "réel" les niveaux de bruits ne sont pas les mêmes - donc les mesures théoriques c'est une chose. De ce que je comprends, la capacité des DAC à filtrer certaines fréquences est limitée, et le bruit résiduel qui accompagne le signal "perturbe" le fonctionnement du DAC (horloges notamment) - mais je ne saurai en dire plus.
Beaucoup de fabricants de DAC l'admettent eux même - ils ne comprennent pas complètement les phénomènes en jeu. Voir un exemple ici: https://www.hifi-advice.com/blog/special...precision/
"CP: Do you know of a reason why Music Servers also differ in sound?
RP: I think the collective answer from the entire industry is that we don’t really know. Nobody knows exactly. Think back to when CD was first introduced. Audiophiles agreed that it didn’t sound very good in the beginning, but look how far we came and it’s pretty decent now. I think we will see a similar process for servers and streamers. There are just a few more things that collectively we have to do. We just have to eliminate layer for layer, what is causing the problem, and this takes time. We provide the receiver, the Renderer, and people can do what they like on the source side. We do get a lot of feedback from our customers, which gives us clues."
Encore une fois, ne pas tout comprendre ne veux pas dire que le problème de base n'existe pas, et ton test, à ce niveau, est hors sujet et ne te permets pas de dire que le résultat in-fine (en sortie du DAC) sera le même... On est d'accord sur ce point ?
Par ailleurs, ces mesures sont relatives, et on ne sait pas forcémment dire comment elles se traduisent à l'écoute. Tu peux penser que les mesures que tu viens d'évoquer sont "suffisantes", mais d'autres pas.
Pourquoi un DAC avec un S/N ratio de 140 db serait meilleur à l'écoute que celui à 120db si la différence est théoriquement inaudible...
Voici ce que Bruno Putzeys explique (ici: https://www.soundstageultra.com/index.ph...o-part-one)
"It is my experience -- confirmed by every new thing I do -- that when you get into really high measured performance, really low distortion, superlow noise, then the ultimate subjective sound quality starts improving and continues to improve in step with the measurements. At some point you will find that a product that measures absolutely perfectly under an extensive battery of tests will sound a lot better than a product with more typical high-end audio performance that has been tuned by ear for years. The upshot is that measurements do matter. The way you should translate this into a development process is not to listen and tweak your circuits, but rather to measure and adjust, measure and adjust, and then listen. If, at that point, something sounds off or is not quite working, that tells you something about what and how you measure. You calibrate by ear your set of measurements and the methods by which you measure, but you optimize your circuit by measurement. That is much more logical. You should take science to the absolute limit and crosscheck your scientific, technical procedures with what you are hearing, to make sure you’re not forgetting anything. The purely technical road in the end will yield a circuit that really sounds better than what you can get by mere philosophy and tuning parts. Start shooting for fantastically low distortion, fantastically low noise."
Beaucoup de fabricants de DAC l'admettent eux même - ils ne comprennent pas complètement les phénomènes en jeu. Voir un exemple ici: https://www.hifi-advice.com/blog/special...precision/
"CP: Do you know of a reason why Music Servers also differ in sound?
RP: I think the collective answer from the entire industry is that we don’t really know. Nobody knows exactly. Think back to when CD was first introduced. Audiophiles agreed that it didn’t sound very good in the beginning, but look how far we came and it’s pretty decent now. I think we will see a similar process for servers and streamers. There are just a few more things that collectively we have to do. We just have to eliminate layer for layer, what is causing the problem, and this takes time. We provide the receiver, the Renderer, and people can do what they like on the source side. We do get a lot of feedback from our customers, which gives us clues."
Encore une fois, ne pas tout comprendre ne veux pas dire que le problème de base n'existe pas, et ton test, à ce niveau, est hors sujet et ne te permets pas de dire que le résultat in-fine (en sortie du DAC) sera le même... On est d'accord sur ce point ?
Par ailleurs, ces mesures sont relatives, et on ne sait pas forcémment dire comment elles se traduisent à l'écoute. Tu peux penser que les mesures que tu viens d'évoquer sont "suffisantes", mais d'autres pas.
Pourquoi un DAC avec un S/N ratio de 140 db serait meilleur à l'écoute que celui à 120db si la différence est théoriquement inaudible...
Voici ce que Bruno Putzeys explique (ici: https://www.soundstageultra.com/index.ph...o-part-one)
"It is my experience -- confirmed by every new thing I do -- that when you get into really high measured performance, really low distortion, superlow noise, then the ultimate subjective sound quality starts improving and continues to improve in step with the measurements. At some point you will find that a product that measures absolutely perfectly under an extensive battery of tests will sound a lot better than a product with more typical high-end audio performance that has been tuned by ear for years. The upshot is that measurements do matter. The way you should translate this into a development process is not to listen and tweak your circuits, but rather to measure and adjust, measure and adjust, and then listen. If, at that point, something sounds off or is not quite working, that tells you something about what and how you measure. You calibrate by ear your set of measurements and the methods by which you measure, but you optimize your circuit by measurement. That is much more logical. You should take science to the absolute limit and crosscheck your scientific, technical procedures with what you are hearing, to make sure you’re not forgetting anything. The purely technical road in the end will yield a circuit that really sounds better than what you can get by mere philosophy and tuning parts. Start shooting for fantastically low distortion, fantastically low noise."