Introduction of my new Antipodes K50 Music Server
- Thread starter shakti
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EtherRegen has been debunked by hyper-precise measurements at the DAC output by Audio Science Review (the comparison between $20 switch and $640 ER).
I read it somewhere and it engraved in my memory forever. I usually distill out the summaries of advanced thinkers in audio, like these Antipodes ones:
Ethernet is preferable over USB (when it is not noisy).
No filters on the signal path should be present, otherwise the bandwidth will be further constrained constrained (think EtherRegen etc.).
If bandwidth is infinite, no matter how much noise is there (must be less than 50%), there will be no jitter.
If bandwidth is constrained, even when the noise is zero, there will still be jitter.
Ah so you haven’t graduated high school yet. Hopefully you’ll soon learn the scientific method - and how conclusions can be drawn only if the test procedure is capable of producing results.
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Ok, Cracker, I'll draw it for you. Once upon the time, the concept of jitter misled people into thinking that all you need in a digital signal is the correct bits (which is relatively trivial to transmit) with great timing (low jitter), and so all you need was a great clock. This simplistic view was highly misleading. At least three things matter - the clock, noise and bandwidth. In the image of a perfect square wave, the horizontal axis is time and the vertical axis is voltage. We will assume the clock is perfect – ie. the vertical signal lines occur at perfectly spaced intervals (the bit rate). When the signal is representing a binary 0, it is at 0v. When the signal is representing a binary 1, it is at 1v. And we will assume that the receiver of this signal decides that the transition between a 0 and a 1 has occurred when the signal rises through the 0.5v level, and that a 1 has transitioned to a 0 when the signal falls through the 0.5v level. Now imagine that there is noise added to the signal. If the frequency of the noise is below the bitrate then this perfect square wave swims on top of a longer and smoother wave. The interesting point is that the timing between the data transitions (where those vertical lines pass through 0.5v) is unchanged. So no problem, yet. If the frequency of the noise is above the bitrate then the horizontal lines get fuzzy. And if we combine the low frequency noise with the high frequency noise the effect is combined. Again, the interesting point to note is that the timing between the data transitions (where those vertical lines pass through 0.5v) is unchanged provided the noise is not extremely high. So, again, no problem. Noise, on its own (as long as the deviations caused are materially below 0.5v) is not a problem. The reason it is not a problem is those vertical lines, because noise does not change the space between them.
Now imagine there is no noise. Zero noise is impossible, but something else that is impossible is the vertical line on the square wave, since it requires infinite bandwidth. The vertical lines imply the signal can achieve 0v and 1v in more or less the same instant. Whatever tools we have to transmit a signal, the demands of high bit-rate signals are way beyond what the available tools can deliver. Think about how your analog cables can mess with sound up to around 20kHz, and then think about the enormously wider frequency range required of a digital cable (and, optical cables just have a different set of problems, mainly related to reflections). The higher the bit rate the harder it gets. When we allow for constrained bandwidth, instead of transitions being instantaneous, the signal goes up a slope when transitioning from 0v to 1v, and down a slope when transitioning from 1v to 0v. If the bandwidth was the same as the bitrate then the signal would be a sine wave. To reasonably square out the signal you need to add several harmonics of the bitrate (say 7 or more) above the bitrate, and that is a lot of bandwidth - even more for higher bit rate signals. By adding harmonics, the sine wave begins to square out. Interestingly, in both of these constrained-bandwidth examples, the transitions through 0.5v are still perfectly spaced – even with the sine wave. So still no problem.
But as I mentioned, a higher bitrate signal (if you think high bitrate files must always sound better) requires even more bandwidth to square out the wave, and so in a system that has a finite limit on bandwidth, a lower bitrate signal will be more accurately represented than a high bitrate signal. On top of that, if you ask anything in a music server to work faster, it will work with less precision and this is a key trade-off to be aware of when you assume higher bit rates must be better, just because the numbers are bigger. These examples only allow us to conclude that there is no problem if we can achieve zero noise or infinite bandwidth. But each of those goals is unattainable, and the problem becomes apparent when there is both noise and constrained bandwidth. So what happens if we add a low frequency noise component to a frequency-constrained digital audio signal? All of sudden, the 0.5v points are shifted right or left by the addition of the low frequency noise that lifts or drops the signal between bits. Shifting the slopes up or down shifts the 0.5v points left or right. The greater the amplitude of the noise, and the greater the bandwidth constraint, the greater is the effect on timing (jitter).
Now if we add high frequency noise to a frequency-constrained signal you can see that the transition timing at precisely 0.5v is now hard to discern for any digital receiver. If the signal is vertical at the transition then noise does not affect it. But as soon as the transition is not vertical then noise changes the transition point. It is the combination of constrained bandwidth and noise that inevitably creates jitter (variation in data transition timing), regardless of how great the clock is. All kudos to Amir from Audio SCience Review for measuring all of this and debunking EtherRegen and alike.
What should happen when the hypothesis fails to produce results is that a new hypothesis should be formed and a new test constructed. That didn't happen. "Hyper-precise measurements" are worthless if they aren't measuring the right things. Science tries to find an explanation. It doesn't "debunk" broadly. That's not science. It's biased pseudo-science masquerading as science.
Lastly "debunking EtherRegen and alike" isn't something someone who cares about science would ever draw from test results. As such I won't respond any further as I know it will be a waste of time.
Lastly "debunking EtherRegen and alike" isn't something someone who cares about science would ever draw from test results. As such I won't respond any further as I know it will be a waste of time.
I admired your patience and good will
I admired your patience and good will
Sorry for allowing things to veer off-topic.
Abracadabra, ha ha ha. Some scientist. Let me guess: you are into alchemy and horoscopes, now am I right?
noun
noun: science
the intellectual and practical activity encompassing the systematic study of the structure and behaviour of the physical and natural world through observation and experiment.
Now, Cracker, tell us what is "observation" and "experiment". Ok, Jack? Tell us that and we go from there.
Any chance we can get back to the discussion on the new antipodes...
Well...I cited Mark, the creator, the founder of Antipodes. If he cannot be in the discussion of Antipodes, then nobody can. Capisco?Any chance we can get back to the discussion on the new antipodes...
From Antipodes Audio support:
"It is true that S/PDIF and AES3 outputs have limited bandwidth compared to the full-bandwidth available with USB, Ethernet and I2S. However, there are downsides to having Ethernet and/or USB receivers in the DAC. Both introduce noise into the DAC. USB has the effect of adding a trace of ‘sizzle’ at the edge all sounds, creating some listener fatigue. Ethernet has the effect of rounding the edge of all sounds, diminishing the tension and urgency of real music. The extent of these problems depends on how well these inputs are implemented in the DAC. If you compare these outputs to our S/PDIF and AES3 outputs you will hear the benefits in naturalness and musicality for yourself."
and
"The manufacturer of my DAC says the Ethernet input is the best sounding. What are my best options?
You cannot take such claims literally. Your DAC manufacturer is, at best, making a generalisation, because comparing Ethernet with other inputs includes comparing the player engine and app in the DAC with the player engine and app in the Music Server. If a DAC manufacturer has not compared their inputs using a K50 then they are making a generalisation that you should not accept blindly. In our experience most DAC manufacturers are assuming you will use a standard computer as your music server.
We cannot know that the player engines in Antipodes products are better sounding than those in all DACs ever made, or still to be made, so we won’t make any generalised claims. The same goes for doubting DAC manufacturers’ generalised claims.
But there is also the question of the player apps, and they have a significant impact on sound quality. As an example, with an Antipodes Server/Player you can choose from player apps that are superior to the player apps used in DACs. Most of our customers wish to use Roon Server to manage their music and streaming services, with good reason. But this will generally mean you have to use the Roon player within the “Roon Ready” DAC. With an Antipodes, you can use the superior sounding Squeezelite or HQPlayer Embedded as the player app."
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In my humble opinion this entire discussion is an irrelevant hypothetical. The DAC's design and execution of each of the 3 inputs in combination with the digital source construct is the only meaningful determinant. Discussion outside this context is silly. Mark has confirmed this to me unequivocally. Comments regarding the digital output from the server (or transport) can't be taken in isolation. Particularly with some of the work being done on all 3 types of Dac inputs.
Don't feed the trollAny chance we can get back to the discussion on the new antipodes...
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