EtherREGEN: The long development thread. [Some Gen2 dev. pics and update starting on page 92.]

[marce]

On 5/9/2019 at 6:16 AM, Superdad said:

 

Thanks.  And I forgot to mention that EtherREGEN is going to be on a 6-layer circuit board instead of a 4-layer. John is choosing to do it that way both for performance reasons and because he feels it will actually be easier to route everything. 

All this stuff is WAY above my pay/brain grade so I of course go along with whatever John says is best. 

Easier to control the impedance of the routes with 6 layers, there does seem to be a preference for running high speed LVDS as microstrip on the outer layers, having half the signal in air as a dielectric and slightly faster propagation does help. It's interesting to see as digital signals get faster, layout is using more and more techniques from high speed analogue rf/microwave. It wont be long before we have speeds where signals will have to be routed as co-planer wave guides or as pseudo co-axial structures, doable on a PCB with high density interconnect designs but expensive. Looking forward to seeing pictures of the boards, always interested in looking at boards! I do it every day. Like yours they show a bit of OCD in the symmetry, years of doing IC's or PCB's does that to you.😁

This is also the fun level of Ethernet, the physical level.

Agree on shields could add more problems, than it fixes. Interesting to think about cables, quite simple to produce, plug into an RJ45...the complexity from the connector to the Phy on a PCB is way more interesting, and almost invisible to most people. A look at some of the info out there such as "en562767.pdf" will illustrate the task ahead for John.

Have fun.

[marce]

On 7/9/2019 at 9:36 AM, struts said:

 

You couldn't just mount this part on the underside of these few boards?

Its SMD!!!

[marce]

I do double sided placement designs every day, no reason not to do it (though it does have an impact on cost and ease of assembly)... But unlike PTH components the pads for SMD components only exist on the outer layers of the PCB so you can't get to the pads from the opposite side, and you can't drill through the PCB without causing shorts.

A PCB is a 3D entity, with numerous layers of copper patterns forming the circuitry, the simplest usually having 4 these days, more complex ones 10-16 and very rarely up to 28 layers (the most I have ever done!), these layers connected by either standard plated through vias or HDI via's.

https://en.wikipedia.org/wiki/Via_(electronics)

https://en.wikipedia.org/wiki/Microvia

 

For fun the design I am doing has numerous power supplies, the fun part is getting rid of heat, heat sinks don't work very well in the vacuum of space and no convection currents to cool the PCB!!! In this instance the hot parts will have single sided placement with a metal assembly clamped to the opposite side of the board, lots of thermal vias to get the heat to where we want it...

[marce]

16 hours ago, LowMidHigh said:

 

1) Nice of you to presume that many folks don't understand clocks.  

2) It's been explained many a time that the BNC connection is built-in to the chip, so allowing external clock is trivial both in terms of cost and labor. Further, the competing product in the marketplace offers that same feature, so why not compete head-to-head, to the benefit of people like you, who do understand the value of an external clock? 

External clocks are not the best idea for domestic audio, the extra length of cable causes more issues than it solves.

[marce]

17 hours ago, Superdad said:

 

I think you are overthinking this.  Please refer to what I has posted previously.  Ours is the only switch to offer isolated dual-data/power/clock domains anyway, so it is not as if potential defeating of the isolation by introduction of "grounds" common to other external clock feeds would be a step further back than what is already normal for other products.

Also, you refer just to the galvanic isolation of the fiber connection.  Remember, the EtherREGEN provides true galvanic isolation of data/power/clock to the copper ports as well! (Any 'A' side to 'B' side crossing of the moat.)  Look again at the photo:

 

Sorry, clocks are science, not magic.  Ultimately low phase-noise at low frequency offsets, and low broadband phase-jitter performance are all that matter for these applications. The circuits of high-performance XOs are already quite low noise from a current draw standpoint, and decent frequency stability is a given.

 

Sorry, we will not be taking special orders for the external clock input to be set to other than 10MHz.  It does not make any sense to do so.  While the Mutec MC3+ is a fine product, it is not at the level of their REF10, and in fact the MC3+ has its own 10MHz input just for such. Mutec has never published phase-noise/jitter performance specs for the MC3+, and when you consider that and the cable I truly doubt the input of that to the EtherREGEN would be any better than our own internal "femto" clock.

 

Again, this emphasis on the clocks risks overshadowing more important aspects of the EtherREGEN's design.  So as interesting as the topic is, I ask that we move on.  Thanks. 

 

Hmmm how do you populate the board with so many chips devoid of text or pin 1 markers?😀

I agree on clocks, did a 64 channel phase array steerable wi-fi antenna, 64 channels with a master clock to sync them all, even on the same board, with total control it was fun! One of the first things as a young PCB designer you are taught though is keep clocks short, at the end of the day on any digital system they are the most important signal...

[marce]

3 hours ago, Foggie said:

Can you expound a bit on the cable length, as far as fiber is concerned (if it’s any issue)?  

 

I ran fiber to listening room (60ft) and to an area upstairs (100ft) using the two sfp ports in my managed switch in laundry room.

Nicely answered above, I was going to say similar, the DAC clock needs to be close, the DAC clocks supply if you want to get all microwavey should be under the oscillator so it only has to pass through the board, minimal interference. Any distributed clock should be LVDS. 

[marce]

3 hours ago, R1200CL said:

Those of us that have no alternative need a usb to SPDIF converter.

If you could make something better than the Singxer SU-1 or SU-6, it would help those of few of us that need an external converter. 
 

Maybe the marked isn’t big enough to defend a development of such a device ?

 

Or maybe it can be part of another future product 😀

I think you mentioned you and John has ideas that can keep you occupied for next three years, so whatever will come, I’m looking forward to it. 

So you de-code the USB audio to SPDIF via the adapter you want then feed SPDIF to the convertor or:

Your DAC de-codes the USB to I2C and feeds that to the converter.....

In both cases you are extracting audio data from the USB and re-transmitting it as a different digital format...

 

[marce]

On 8/10/2019 at 7:21 PM, kennyb123 said:

 

Looking at the specs Shunyata has published for their Ethernet cables, it appears the only difference is the number of CMode modules.  Venom has 0, Alpha has 1 and Sigma has 2.  The EtherRegen should lessen (or eliminate?) the need for any common mode filtering.  It’ll be interesting to hear if the differences between their three Ethernet cables vanish when used with the EtherRegen.

The Cmode filters are ferrite rings.

[marce]

1 hour ago, kennyb123 said:

 

Where did you get that information?

They look like ferrites and that's what you would use on Ethernet cable so you don't add losses and impedance mismatches for the signal. A basic common mode filter is passing the wires through a shared magnetic core of some sort. Pretty basic common practice.

Apologies just read the rest of the thread!

[marce]

On 8/17/2019 at 12:43 PM, octaviars said:

 

Just a thought when looking at the picture of the PCB the RJ45 port on the "B"-side it looks to be a Pulse Electronics J0G-0003NL with integrated magnetics will it be beneficial to actually have a ground connection to the streamer (lets say it is a streamer with AC voltage input and the chassi is grounded to the AC protectiv earth) in the LAN cable going from etherRegen to streamer? Just me thinking where the magnetics shunt away any noise on the "B"-side or is this not something to bother with?

 

 

 

the magnetic's provide an isolation transformer and a common mode inductor so they don't need any GND connection as such. The  RJ45 (shield) case is either connected directly to the board 0V direct, the boards 0V via a cap or many design have a separate chassis connection, the shield can be connected either directly to this or again by a cap.

Myself I wouldn't connect the screen of a Ethernet cable for domestic use, the wires are not that long and you never know what the RJ45 case is connected to in other devices so you can create an unintentional ground loop....

[marce]

On 10/14/2019 at 6:22 PM, Puma Cat said:

Its going to sound better. It was designed from the ground up by an engineer with 30+ years of industry experience to do this.  The AQ-Vox switch is a modification of an existing IT-based product, a D-link switch. 

 

And the EtherREGEN will cost ~30% less. 

I will second this, from what I have seen of the internal mods by Aqvox to the switch I would not touch it with a barge pole... For less money you get an Galvanicly isolated switch with the clocks done properly.... I know which I would recommend, the Uptone (and I'm a true heretic😁 and my view is based on technical appearance alone)  it really is a no brainer...