The EtherREGEN thread for various network, cable, power experiences and experiments

MartinT · March 3

10 hours ago, Superdad said:

which will become EtherREGEN Gen2

Bring it on, Alex!

What news on expected readiness?

Superdad · March 3

17 hours ago, dbastin said:

What I have done (if you didn't notice on Page 121) is put the signal from the internet and router into ER via SFP, then across the moat to the server, and then back across the moat to Side A RJ45 towards the endpoint. So I am using the flip-flops twice.

Interesting set up. And of course you are welcome to utilize the EtherREGEN in whatever configuration pleases you.

But ultimately we are trying above all to benefit the DAC-attached endpoint (or Ethernet-input-equipped DAC) with the best signal. And for a variety of reasons that is generally always going to be the 'B' port.

17 hours ago, dbastin said:

Although I suspect it is the flip flops that really make the difference, I suppose you considered optical methods. I gather PS Audio has that in its new streamer.

Well it is our high-speed, low-jitter differential digital isolators which both effectively block common-mode leakage and allow for us to create the separate and very "quiet" 'B' side domain in which to utilize out special reclocking flip-flops. So both are needed.

As for the PS Audio steamer you mention, by which I assume you mean the AirLens:

They are not forthcoming with regards the topology of the design or in what data location they use isolators. Yet from PCB photos on the web it appears that they put the isolators on the final I2S lines coming off their big FPGA--just before their audio-rate circuits producing S/PDIF and I2S (LVDS over HDMI) outputs. Kind of standard--like what many DACs do with their USB>I2S signals at their inputs.

By the way, Paul McGowan officially confirmed that they are NOT using optical digital isolators in the AirLens. Good thing because those have terrible jitter. There are many forms of digital isolators: optical, RF (literally tiny RF transmitters narrowcasting across a gap), capacitive, GMR (giant magneto resistive; those are rather good). OEM cost can range from $1 to $25. speed capability varies, and performance ranges from crap (tons of jitter added) to quite good. But ALL isolators add some jitter/phase-noise and proper reclocking with flip-flops is needed for best performance. Sadly, that is a step often overlooked by designers implementing isolators. (I believe Ian Canada--with his various advanced DIY boards--is one of the few to get it right.)

kennyb123 · March 5

I think my new favorite technical term is “flip flop”. 😀

Superdad · March 5

1 hour ago, kennyb123 said:

I think my new favorite technical term is “flip flop”. 😀

They are cool--and highly effective. Especially the ones that we use. These buggers now cost us $15.50 each!

(Used to pay $8.50 when I ordered 3K at a time. Those days are gone. Even that big a buy now only gets us down to $12.50 each.) And don't get me started on the cost of Gigabit isolators or piles of LT3045/42 linear regulators...

kennyb123 · March 5

1 hour ago, Superdad said:

Those days are gone. Even that big a buy now only gets us down to $12.50 each.) And don't get me started on the cost of Gigabit isolators or piles of LT3045/42 linear regulators...

I figured you wouldn’t be able to hit the same price point for the Gen 2 given how much more expensive everything is. I have little doubt though that it will deliver a huge bang for the buck.

I’m thinking though that you should call the Gen 2 model the EtherFlipflop. 🙂

JohnSwenson · March 5

7 hours ago, kennyb123 said:

I think my new favorite technical term is “flip flop”. 😀

Floipflops have a very special place in my life. Fresh out of college(many decades ago) I was trying to get job in an Engineering glut. Every open position had hundreds of applicants applying. I had many interviews and I was told that I was something like 200 out of 800 applications, I was getting desperate. I went in for the interview at LSI Logic, they told me what they needed, which was a position that had never existed at any company, something brand new. I told them I was good at learning new things. Then they took me into a room with a big white board and said write down the timing equations for a flipflop. I had no idea what he was talking about, I mentioned that and thought I had just lost the position. He then said "well then derive it on the board". I took the marker and drew the schematic for a flipflop and started writing down all the timing paths, then consolidating them and finally had a simple set of equations. He said "that's it, nobody else has ever been able to do that, your hired!" I was there for 33 years and it all started with a flipflop.

John S.

dbastin · March 5

On 3/4/2024 at 4:55 AM, Superdad said:

ultimately we are trying above all to benefit the DAC-attached endpoint (or Ethernet-input-equipped DAC) with the best signal. And for a variety of reasons that is generally always going to be the 'B' port.

After 24 hrs of cable etc 'settling' (or whatever) and them another few hrs including a bit of tweaking and listening, I think that Side A server Side B towards endpoint is best ... but of course you will not be surprised. So extra reclocking doesn't seem superior to Side B.

On 3/4/2024 at 4:55 AM, Superdad said:

special reclocking flip-flops. So both are needed.

Both are needed to get the Side B result, but the point I was making is the flip flops are what sets ER design apart from typical isolation that doesn't.

On 3/4/2024 at 4:55 AM, Superdad said:

Paul McGowan officially confirmed that they are NOT using optical digital isolators in the AirLens

My mistake, I was sure I has heard or seen that they are. In a Youtube Paul 'vaguely' mentions RF . He also implies it is extremely rare for a streamer to isolate its output stage - maybe he hasn't seen Auralic, Aqua ...

2 hours ago, JohnSwenson said:

I was there for 33 years and it all started with a flipflop.

That's flipping amazing, you're a flopping genius!

Superdad · March 5

6 hours ago, dbastin said:

Both are needed to get the Side B result, but the point I was making is the flip flops are what sets ER design apart from typical isolation that doesn't.

Sure. But as far as I have seen, there are NO other switches on the market putting Ethernet through digital isolators at all.

audiophilac · July 21

@Superdad got a question to FMCs, are two clocks needed. one for the ethernet signal and another for the fibre optic transceiver or can a single clock work for both?

JayDog · July 21

single clock will work with isolated outputs. just make sure it is a quality clock.

R1200CL · July 22

I used a T. Can work. Must be 50ohm. Cause that’s what they offer.

Superdad · July 22

On 7/21/2024 at 1:46 AM, audiophilac said:

@Superdad got a question to FMCs, are two clocks needed. one for the ethernet signal and another for the fibre optic transceiver or can a single clock work for both?

Sorry, but your question is not clear to me:

a) Do you have FMCs that take an external clock? (If so what model?)

b) Or are you just trying to understand what clocks are internally used in an FMC? (You say: "one for the ethernet signal and another for the fibre optic transceiver...")

If you are asking about "b)" above, then I can explain this:

The actual fiber optic to electrical wire transceiver parts in an optical SFP module do not have any clock. The LVDS signals at the edge connector in the back of an SFP cage always feed into either an Ethernet switch chip or a Ethernet transceiver chip. Those chips will ALWAYS require a 25.0MHz clock of some sort (in typical FMCs that's just a $0.50 oval crystal.).

If you actually have an FMC that accepts a 10MHz external clock (then the FMC must internally synthesize that to 25.0MHz)--maybe it is just a switch that has SFP cages and takes external clock--then your question about using a single clock for two devices depends upon:

a) Is it one clock with two outputs--and are those outputs properly isolated?;

b) Is there some sort of isolation "moat" between the "ground" domains of the two devices you are wanting to use a single clock with? (i.e. is an EtherREGEN involved?)

c) What is the order and arrangement of connection between what you are calling the "FMCs?"

c) What are the power supplies in use--are they sharing DC side -Ve/zero-Volt "ground?"

As with so much in audio (and life), accurate answers are best obtained when the questions have context and detail.

Thanks,

--Alex C.

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