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.
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.
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