A possible conclusion
Contents
First, let’s ask the question again:
Does a switch affect the clock in a streamer or dac?
Yes: 100%. We have now demonstrated that, we may hope.
Then the question:
Is the influence of a switch on measurements – and playback – large?
That’s harder to answer. Because in terms of overall jitter, it’s not that much if we’re honest. Certain areas do get affected more, but that may require more research.
However, in terms of phase noise, we find 10 dBc/Hz quite significant. Thereby, the audible influence is also quite significant between a free, provider-tier, router compared to a decent Netgear or Dlink. And the step then to a ‘real’ audio switch is also considerable we may say. How the various ‘audiograde’ switches compare to each other, we dare not say. That could be another test.
To briefly summarize this long story about the influence of network switches on clock jitter: our measurements have shown that especially phase noise decreases with a decent switch that does not transmit much (common mode) low-frequency noise to the streamer. We see in our measurements a direct relationship between low-frequency noise from the network port and phase noise on the clock.
Is this audible? Yes: we conclude that it is audible. As far as we are concerned, the listening tests show that switches with a lot of noise from the port do not sound as good. And now that we have been able to establish the relationship between this noise (especially so low-frequency) and phase noise on a clock in a streamer, we think it is also proven, frankly.
More elements
By the way, we have now only measured the influence of a network switch on the clock in a streamer. (And for this story, that was enough). Know, however, that we have in fact measured the influence of an external noise source on an audio circuit. If we look at it from a meta-view, we see the influence of an external noise source on the streamer’s power supply which in turn affects the clock circuit.
So you might well extend these results to other areas in that device. In fact, this noise affects other crucial areas as well. Think of an output stage of the dac. So it always makes sense to use clean components. However, in this case we wanted to show that even network switches can affect your audio system. And that has NOTHING to do with data integrity!
Hi Jaap,
really interesting test!
What surprises me is that there is no clear correlation between phase noise and jitter – since they are just two sides of the same coin.
I believe that the Pura the AMMONITE switches perform well because they have better phase noise in the Ethernet signal by using the OXCO clocks. That would at least be a coherent explanation that would also agree with John Swenson’s thesis. Then we would have two things affecting the sound: common mode noise and phase noise.
Have you found a dependency regarding the frequency range of the common mode noise to worsen the streamer clock – I would be interested. I could not clearly assign this in the measurements.
Best regards,
Eric
Hi Jaap,
really interesting test!
What surprises me is that there is no clear correlation between phase noise and jitter – since they are just two sides of the same coin.
I believe that the Pura the AMMONITE switches perform well because they have better phase noise in the Ethernet signal by using the OXCO clocks. That would at least be a coherent explanation that would also agree with John Swenson’s thesis. Then we would have two things affecting the sound: common mode noise and phase noise.
Have you found a dependency regarding the frequency range of the common mode noise to worsen the streamer clock – I would be interested. I could not clearly assign this in the measurements.
Best regards,
Eric
When you compared switches, does noise peaks appeared the same frequency points on each switches and how big was the general noise floor levels on them? It would be nice to see spectrum analyzer screen shots from each switches how then behaved.
If you login via Patreon, you can see all the measurements.
When you compared switches, does noise peaks appeared the same frequency points on each switches and how big was the general noise floor levels on them? It would be nice to see spectrum analyzer screen shots from each switches how then behaved.
If you login via Patreon, you can see all the measurements.