 I've had a number of reactions again on the review of the Fantastic Uptone Audio Ether-Region Audio File Ethernet switch, especially from people with knowledge of computer networks. They state simply put that if the sound differs the switch must have altered the data. I agree, but in what way? Before I get into the subject at hand, let me first try to explain what I consider to be my function in the audio universe. I'm no researcher nor designer. I'm a tech journalist and reviewer, specialized in audio. Like a motoring journalist, is no mobility researcher or car designer. His technical knowledge is clearly limited compared to these researchers and designers, but he does have a broad overview of all makes and types of cars. When a new technology is developed, the manufacturer invites journalists to a press meeting and have one or more technicians explain why the new technology is such a big improvement. And they almost always exaggerate. When then another brand organizes a press meeting, the journalist asks technicians of that manufacturer what they think of their competitor's new system. A good journalist listens carefully to the arguments in favor and against and then tries to see if he finds resulting behavior during test drives. Since he test drives dozens of cars a year, he is in a very good position to compare, especially if he has done this job for years. And a good motoring journalist is also able to explain new technologies to his audience comprehensively. He should tell his audience that more valves in a cylinder head in general increases horsepower as claimed in the advertisement, but that this often goes at the expense of torque. Unless a well-dimensioned turbo is added. And a good motoring journalist does not only drive cars in top gear sideways, but also reports on normal use, economics and so on. He does simple measurements like acceleration, top speed and fuel consumption, but far more important is the feel of the car and its practicalities like boot space. I consider myself in a more or less equal position as a decent motoring journalist. I do basic measurements just to check if something is wrong, get information from manufacturers or their technicians and if considered interesting report on it. But my added value is in test driving audio equipment, so judging by ear. If you don't agree with this, do what I do with TV programs I don't like. I don't watch them. And if you want to save the world for people like me, start your own YouTube channel. Okay, back to the subject. Can a switch have so much influence on the sound quality? In the end, the only way to establish this is to listen. Train listeners certainly don't need double blind tests if the stereo setup used has sufficient audiophile quality. See my few and double blind tests in a separate video. I was rather accepted when I heard about the sound of switches, so I approached AcuFox to see if I could have a review sample on loan. They were holding back a bit since they had negative experiences with some members of the press. But in the end, they sent me the AcuSwitch special edition. Watch my review and you'll see I was rather surprised by the improvement it brought. In retrospect, I even think I underplayed the outcome because of unbelief. When I reviewed the SOtM switch, I had accepted the influence of switches on the sound a lot more. So much more that I accepted the sound difference between a network cable and a fiber cable between the switch near the Intel NUC Roon server on the third floor and the SOtM switch in my living at ground level. Again, from a network specialist standpoint, fully ludicrous. Total cable length is 15 meters, slightly under 50 feet, even for CAD5 cable no problem at all. When I back up my video editing files of several hundreds of gigabytes from my editing computer to the big Synology NAS at the third floor, the files remain perfectly intact when copied back to the editing computer. So the connection is completely lossless and more than fast enough for audio. Even 384 kHz 24 bit files do only 18.4 Mbps, while modern networks do 1000 Mbps. I once had 8 streams running from the Roon server to 11 endpoints, without any problem. So why should fiber sound somewhat better than CAD6 cable? I think that we can agree that all data sent over a normally functioning network arrives unharmed. Switches are supposed to galvanically isolate each port by what is called a magnetics module. I wonder if the consumer grade switches I use confirm to this. I opened the Linksys SLM2008 and indeed had two four-port modules. I also opened the Sidecom LN120V1 that had four two-port modules. Since these were rather cheap switches, we might conclude that in general and certainly in my case, cheap switches offer galvanic separation. Remains the questions how well these high frequency transformers perform. I seem to recall that the SOtM did not use magnetic modules and you might wonder why. But the Ether region does use them. Perhaps here again, quality of the components play a role. The magnetics modules I found use center tap transformers for use with power over ethernet, abbreviated to PoE. Only a slight mismatch between two halves of the transformer windings might already cause a DC offset. That offset might even be within IEEE specifications for it won't disturb normal network use. I'll come back to this offset later on. All digital techniques work with stepped processes, like a mechanical clock that steps through a minute in 120 half second movements of the escapement. Digital techniques have a crystal oscillator as escapement, which makes sure that going through the steps happens at a regular interval. In this graph those intervals are drawn by vertical dotted lines and a digital signal then looks like this. At least in theory, in practice those intervals are not really as constant as we would like. That becomes visible when on an oscilloscope the traces are superimposed. This animation shows what happens. We see the vertical lines get wider since they vary in timing. Sometimes the vertical movement, both up and down, are earlier or later. This phenomenon is known as jitter. Within limits this is no problem for data transport. Even if it goes wrong and a bit is missed, the error correction is able to repair that bit or even more than one bit. And when the error correction is confronted with too many faults to repair, the receiving side simply asks the sender to resend the package. Up till now we have seen perfect square waves but these never happen for it would require unlimited bandwidth. They will at least have rounded corners but to explain the problem at hand I drew what can happen in a very exaggerated way. I have drawn two horizontal lines that indicate the threshold for the electronics to decide if there is a polarity change. The upper vertical line is for up-going voltage and the lower for down-going voltage. The vertical dotted lines show that the moment in time the voltage change is detected has moved to the right thus later in time. This again is no problem if it is as constant as shown here. The problem gets more serious when we combine the distorted waveform with phase noise. Now the detection of the fault exchange can be at the moment of the dotted vertical red line but just as good at the second red line and the difference in between them again shows the yitta. If we then add a less stable power rail you see that the waveform also vary in amplitude, the vertical axis. Because of the rounded shape of this waveform not only the variations in time domain, the horizontal axis but also the variations in amplitude, the vertical axis change the moment the fault exchange is detected. Still for data transport this would not be a problem if these errors are within the defined limits. Let's make the deviation more visible by copying the distances between the vertical lines to these green dotted lines and move them to about the middle of the jittered signal of the first half cycle. Now look at the other cycles and you see a nice stable clock is gone. And this is a relatively static representation. In real life all parameters can constantly change but normally this would not harm data integrity during transport or storage. So what can go wrong then? Jitter, for that is what we talk about, can only harm at two places in the audio chain, during analog to digital conversion and during digital to analog conversion. The analog to digital conversion is done in a studio and thus beyond our control. But the digital to analog conversion is, so let's see what happens there. The digital player, being a CD player, streamer, network bridge and the like, reads series of voltages that are registered on CD or in an audio file in binary form and renders these voltages to an analog signal. I use here a straight line as analog signal for educational reasons. Normally a straight line is most unlikely in audio. You can see that when the plotted voltages are connected by a line, it results in a perfectly straight line. This is the function of the reconstruction filter that evens out the voltage changes faster than a bandwidth of a half the sampling frequency rate would allow. Watch my video, digital audio posers are not real world, sine waves are, for more information. As soon as the timing is off, like so, the line is no longer straight. This is how jitter causes distortion in the analog signal. Depending on the spectrum of the jitter, at what frequencies the jitter modulates the digital stream, the impact of the sound quality will vary. If the jitter is at general consumer equipment level, harshness is quite common. Also deep lows can fully disappear. The stereo image is usually quite poor while the trenches sound rather disappointing. With streamers at the level of my setup too, harshness is clearly less to a level that it doesn't irritate anymore. Lowes are more defined, voices start sounding more natural with only sibilants being slightly audible. Digital sources at the level of my setup 1 have instruments and voices more separated and projected in a virtual space. Trenchings make, for instance, a picked guitar sound in front of the speakers and a piano sound far more dynamic. When there is no sound, there really is no sound. Described in the audiophile world as black background, this phenomenon is hard to explain other than it can shock people. I link this to time smearing, where the energy of a pulse is smeared over a longer time span. Quote, if the digital transport is so robust you can easily buffer it and all is fine. This is the common I frequently get from the digital inquisition, waving with the Malleus Nyquistum. If that was the case, how then can I hear the difference between digital sources? And I'm not alone. The digital inquisition can't hear a difference or often haven't even bothered. I've seen it all before in the 80s when we did not know about Jitta. Me and my colleagues clearly heard a difference but since it was not yet understood technically we were told we heard things that weren't there. L'histoire se répète. I'll give you possible reasons why buffers don't solve the problem but first a real-life example. I've used a fantastic CORT QDB76 HDSD digital to analog converter for years. It had a large buffer built in that could store up to 3 seconds of 44.1 kHz signal. I have extensively compared the buffer lengths offered by that DAC and didn't hear a difference. I did hear differences when changing the digital source though, regardless of the length of the buffer. How can that happen? This is what designers told me. After the buffer the signal has to be sent to the chip that does a digital analog conversion. During this transport Jitta can be introduced again. I already mentioned a noisy ground plane and varying voltages on the power rail. That is why the Ether region has the second side completely isolated from the primary side including the power supply. I'm also told that buffers can or will generate noise that can vary depending on how hard the buffer has to work. Logic introduced in the modulation distortion was also mentioned although I can't imagine how and where. Common mode noise on ethernet is mentioned too as cause for noisy ground plane. I sincerely hope that the research will find definitive answers although definitive answers don't seem to go together with serious audio very often. One of the reasons being that many researchers rather believe that theories are measurement gear than their ears. Those researchers with ears to trust often work at smaller companies that keep their findings to themselves since applying for a patent is far too costly, if possible at all. Only a very limited number of small companies are open about their products and designs. Optor and Audio being one of them. You don't need to trust my ears but please don't write me long comments without researching the phenomenon yourself. What you need is a proper stereo setup of at least €4,000. The better the setup, the easier it is to hear. If you do want to write a comment, start with a full list of equipment and the conditions you did your listening evaluation with. If you can't understand why a switch influences the sound quality to the degree I have described, I appreciate that. But any discussion is fruitless if you haven't researched it yourself. There is no use in fighting prejudice. I have seen that upturned audio allows for a 30-day return period so there is no excuse for trying and to those that reacted with hands-on reports on the reviews of audiophile network switches, I agreed completely. They are great. And that brings us to the end of this video. There will be a new video, as always at Friday, 5pm Central European Time. If you don't want to miss that, subscribe to this channel or follow me on the social media, sure you will be informed when new videos are out. If you like this video, give it a thumbs up. Many thanks to those viewers that support this channel financially. It keeps me independent and thus trustworthy. If that makes you feel like supporting my work too, the links are in the comments below this video in YouTube. I am Hans Beekhuyzen, thank you for watching and see you in the next show or on theHBproject.com. And whatever you do, enjoy the music.