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Audiophile grade Router with WiFi
#11
(18-Oct-2019, 11:10)David A Wrote: @thumb5 ,

I was thinking in terms of the clock phase error which some call jitter and which John Swenson believes accumulates to some degree from one data device to another along the transmission chain, even though the data is being carried in packets.

The idea of „accumulation“ makes sense to me given that the degree of deviation to the original signal changes within each step of the chain. Garbage in, Garbage out ...
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#12
(19-Oct-2019, 08:14)baconbrain Wrote:
(18-Oct-2019, 11:10)David A Wrote: @thumb5 ,

I was thinking in terms of the clock phase error which some call jitter and which John Swenson believes accumulates to some degree from one data device to another along the transmission chain, even though the data is being carried in packets.

The idea of „accumulation“ makes sense to me given that the degree of deviation to the original signal changes within each step of the chain. Garbage in, Garbage out ...

I can't understand that argument, particularly in the case of wi-fi.  What do you think is actually deviating from the original signal and accumulating during the transmission?  There is no timing information in the wi-fi packets, remember.
Roon (Mac Mini), Wilson Benesch Full Circle, Expert 1000 Pro CI, Kaiser Chiara
Warwickshire, UK
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#13
Copied below is something John Swenson posted on the AS EtherRegen thread.  Here I find myself in dangerous territory, I only understand this stuff in part, it is not my areas of expertise, which therefore leaves me venerable to believing technobabble.

On the one hand I think that John Swenson is a highly respected designer who knows far more about this than I do, so I should take note of his wisdom.  Plus, to be fair, some Swenson designed products have been shown to provide measurable improvements.

On the other hand, whenever I read posts like the one below, I do need to remind myself that he does have a vested interest as he gains financially from Uptone products, amongst others, so it is in his financial interest to promote the idea that there are all these little problem areas in digital audio that need fixing.

One question that I have regarding the idea of things like clock phase noise being carried over Ethernet packet data, is how does this noise make it's way through a FIFO buffer?  Or is it just electrical noise at this point?  It absolutely cannot be carried in the Ethernet data.  Anyone?

Anyway, copied below is what John Swenson had to say on the subject.

Also see link for similar:
https://audiophilestyle.com/forums/topic...ent-963599

Let me see if I can bring some clarity.
 
There are two types of "SQ degrading" influences the EtherRegen is designed to radically decrease: leakage, both high impedance and low impedance, and clock phase noise. The clock phase noise travels on the Ethernet signal itself (every edge coming out of any digital device caries the phase noise of the clock used to "clock out" that edge).
 
The very carefully chosen transformers on both sides play an important part in decreasing leakage. The active circuitry in the path across the moat adds a very major decrease as well. The result is that the leakage from A to B OR B to A is is decreased a huge amount. The decrease in leakage from one port to another on the A side is still quite significant but not nearly as much as when going from side to side.
 
The circuitry across the moat is designed to essentially eliminate the signal borne phase noise from one side to the other, it doesn't matter which direction, it works identically in both directions.
 
The circuitry between ports on the A side decreases these phase noise effects to some degree but not nearly as much as going from side to side.
 
There is ONE small difference between directions going across the moat:
The clock generator is on the B side, so the circuits on the B side get a "pristine" clock. The clock from the B side goes through a very special isolator to the A side. This isolator has extremely low additive phase noise, much lower than any other isolator I could find. (it aint cheap!) The clock on the A side has slightly worse phase noise than the clock on the B side because of this. Whether this is going to be audible, who knows. Remember all the decrease in leakage and external phase noise is still there.
 
Going from port to port on the A side should be better than any other switch out there, but going from side to side (either way) will be a whole new world.
 
Because the B side has a slightly lower phase noise clock it is usually better to have the B side port connected to the streamer etc.  But if you need to cross the moat the other way (such as using the SFP cage to drive optical into a streamer or DAC that has an optical input) that is also fine. The same decrease in leakage and external phase noise exists either way, the only difference is the slight increase in phase noise of the clock when going from B to A.
 
Because of this slight increase in phase noise when going from B to A, if you use a REALLY good external clock (such as a Ref10), you will only get the advantage of such a clock when connecting the B side to the streamer.
 
I hope this makes some sense.
 
John S.
1000 Pro - KEF Blade - iFi Zen Stream - Mutec REF10 - MC3+USB - Pro-Ject Signature 12
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#14
@Confused - thanks for that.  As I understand it, the (mooted) effect of the phase noise is to inject analog noise into the DAC due to changes in current used by the devices that recover clock information from the network signals.  This is not the audio sample clock but the clock for the bits carried on the network.  So although the clock phase noise could be described as jitter in the (Ethernet) clock, it is not related to jitter in the audio sample clock, since the two clocks are completely unrelated -- at least for Ethernet and asynchronous USB.  It seems quite reasonable to me that clock phase noise on the network/USB clock could cause noise in the DAC as John Swenson proposes (if I understand correctly) although it's obviously debatable whether that causes audible effects -- hard to generalise because it would depend very much on the specific hardware design.  But in any case that's not what audio people usually mean when they talk about jitter.
Roon (Mac Mini), Wilson Benesch Full Circle, Expert 1000 Pro CI, Kaiser Chiara
Warwickshire, UK
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#15
The only thing that matters in terms of clock is the clock of the last buffer.
So either you can imagine an electromagnetic way that other clocks are influencing that last clock (this is one theory for Ethernet which is electrically coupled and what fiber based solutions intend to avoid) or you have to imagine that the content of the buffer itself has an influence on the clock of that buffer, which is not impossible, but would be a very poor design IMHO.

Given the order of magnitude of the delay variation in a network (milliseconds to tens of them) compared to the jitter of even a bad clock, let’s say that I’m highly skeptical towards anything that is before the last network interface (by last I mean counting them from the source to the DAC).

Given how deceptive our brain can be, it would take proper ABX testing to scientifically determine the question.

My 2 cents,

Jean-Marie
MacBook Air M2 -> RAAT/Air -> WiFi -> PLC -> Ethernet -> Devialet 220pro with Core Infinity (upgraded from 120) -> AperturA Armonia
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#16
In addition to Confused’s quote; this one is from their product page:

https://uptoneaudio.com/products/etherregen

Quote:There are two types of sound-degrading influences the EtherREGEN is designed to radically decrease: Leakage—both high-impedance and low-impedance—and clock phase-noise. The clock phase-noise travels on the Ethernet signal itself and travels on power and ground planes. [Every edge coming out of any digital device caries the jitter/phase-noise of the clock used to "clock out" that edge; this shows up on the ground-plane and affects the threshold of chips’ clock inputs. This is an oversimplification of a complex subject; we intend to publish a short white paper and measurements to demonstrate this.]

Let’s hope they’ll publish this white paper soon as it should make these discussions easier. Though of course I can imagine that even if they’ll show effects in measurements some people will argue these differences are too small to matter.  Smile

For me the most important thing is the effect I’ll hear when it’s in my system, or not hear.  Wink
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#17
Quote:For me the most important thing is the effect I’ll hear when it’s in my system, or not hear.


@Antoine this is the way I think about it to I really dont care to much how it workes or does not work in any other system than my own.

Perhaps the etherREGEN is just a waste of time and money I really dont know and will this "phase noise" ever make it past the DAC to the analog side and can it affect the clock inside the DAC in any way? This will be so dependant of "your" system whats upstream of the DAC and how the DAC is built that it will be impossible to test every combination out there.

My TAD DAC will re-sample everyting that comes in on the inputs and clock it with a very good low phase noise clock mounted next to D/A chips. Will this be affected by the "phase noise" from up-stream equipment like my NUC with Roon ROCK and my dCS Network Bridge over AES? Again I dont know and perhaps I will never be able to tell any difference with or without the etherREGEN but still I cant know that without trying one and the cost of it is not that big and with a 30 day money back guarantee I can alway ship it back Smile
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#18
@octaviars and @Antoine - that's a good outlook, I'd say. It does look like a nicely-engineered item and (given that it's not mass-market) fairly priced. I'm tempted to try one myself, but perhaps when the hype has died down a bit.
Roon (Mac Mini), Wilson Benesch Full Circle, Expert 1000 Pro CI, Kaiser Chiara
Warwickshire, UK
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