SMPS and grounding

[BigGuy]

2 hours ago, rickca said:

So to use John's grounding technique, does this mean we now need two outlets for each SMPS (unless grounding multiple SMPS from the same wire)?  I'm impossibly dense about electrical things.

You and I are not dense...just uneducated on the topic.

 

I was pondering this 2 plug issue myself.  Can the two SMPS plugs be plugged into a power strip that  is modified properly and how could this be done?  I ran out of AC duplexes which are on the same master panel leg some time ago! 

[BigGuy]

15 minutes ago, rickca said:

@JohnSwenson how does one use something like this from Supra

https://www.madisoundspeakerstore.com/power-cables/supra-swf-10-earthed-mains-iec-320-plug/

Looks like a chassis-side connector for making your own power cord.

[BigGuy]

35 minutes ago, JohnSwenson said:

Hi Alex,

well you have now found the high impedance and low impedance part of leakage current. The 1 Meg shunts the high impedance part but doesn't do much for the low impedance part.

 

John S.

I'm up to speed on JohnS's previous recommendation of attaching a wire between the barrel connector of a SMPS using plug adapters such as these...

<https://www.amazon.com/dp/B01J1WZENK?psc=1>

to the grounding pin of a 3-pin AC plug  where both the SMPS and umbilical are plugged into the same mains outlet to deal with high impedance leaking current.  I have ordered supplies to construct these for LPS based on John's indication of potential improvement since I have no SMPS in the audio chain .

 

1) Looking forward to follow-up how-to on treating the low impedance leakage.

 

2) Now I am seeing more chat about inserting a resistor, e.g., 1Megohm (Voltage?), somewhere in the path.  Is this a "belt & braces" treatment of the high impedance like the grounding plug...or additional?

 

3) Where would the resistor be installed?

 

4) Being a novice at electrical/electronics I do not understand reference to "mains earth".  Perhaps a simple sketch would be helpful.

 

My apologies for being underinformed re these issues but I AM picking up increased understanding from the posts.  Thanks.

[BigGuy]

35 minutes ago, austinpop said:

A couple more questions:

 

Anyone have an Amazon link for this sucker?

 

And is that bare wire between the male and female DC terminal blocks?

Its all in the terminology used to search.

 

Here is source for 3-prong plug but lots of options...

<https://www.amazon.com/HiFiKing-PU-12-Audio-Connector-Hi-End/dp/B017NCPG8I/ref=sr_1_7?s=industrial&ie=UTF8&qid=1508170787&sr=1-7&keywords=ac+plug+connectors>

 

But I bought these so I know which are ground plugs...:-D

<http://www.hardwareandtools.com/cooper-wiring-bp3867-4gn-high-visibility-plug-fluorescent-green-efda-7490.html>

 

Source for DC power blocks but there are other less expensive sources, e.g., Ebay...

<https://www.amazon.com/dp/B01J1WZENK?psc=1>

[BigGuy]

58 minutes ago, d_elm said:

It is 14Ga house wire.  I put 3/4" heat shrink tubing over the assembly.

Bare wire would be fine assuming no chance for contact between + and - since kind of PITA to strip very short lengths.

[BigGuy]

2 hours ago, Cornan said:

 

You just need short wires between the + and - terminals of the plugs & socket, a long ground wire (long enough to reach the power strip where the SMPS in plugged into) from the - terminal to a normal AC mains plug where you connect the ground wire to the GND of the plug. Pretty straight forward and very well explained by John on the first post on this thread:

 

 

What ever you do. Be careful not to get it wrong!

 

 

 

REMINDER!  One of the screw connectors needs to be rotated 180deg so that the +'s and -'s line up.  When you do this, there will be quite an offset between the two connectors so I actually made an offset connecting wire to get them on same plane, e.g....

 

                    ________

                    |

       _______

 

I then used 3/4 inch shrink to make a neat package.

[BigGuy]

11 hours ago, JohnSwenson said:

Not really,

the shunt is to ground, that is what this thread is all about, the series has to be in series with the leakage, in this case it is the DC power, putting 100Mohm in series with the + and - of the power supply is not going to do any good, yep is will block the low impedance part, but you won't get any POWER through to run the device!

 

In some cases it is possible to block the low impedance part on SIGNAL connections, if the connection is all right with several K ohms in series. This is how the connection with a switch works, the transformers are 100 ohms impedance for the high frequency Ethernet signal, but in some cases can be significantly higher for the lower frequency leakage current, which is enough to block the low impedance leakage.

 

John S.

A bit confused now.  Understand the shunt to ground of the minus side of the DC power supply using the umbilical for the high frequency component of the leakage current for which you provided details previously.

IIRC. you mentioned that it was easy to get rid of the low frequency component as well but it needed to be done differently.  I, like others I am guessing, are looking for a DIY how-to for the low frequency.  I for one am not well versed in electronics so a "Betty Crocker" description of what parts and where to stick them (Uh, Uh!) ;-) would be helpful.

 

[BigGuy]

1 hour ago, Superdad said:

 

You are conflating frequency with impedance and that is not correct.  In other words, there is high-impedance leakage and low-impedance leakage--and both have both high and low frequency components.

 

 

Actually the LPS-1 already completely blocks low impedance leakage.  And the SMPS grounding trick (I am now trying to source units that are already grounded--they exist--or get Mean Well to supply a custom version for us) is completely effective at shunting (getting rid of) the high-impedance leakage.

Due to our use of transistors (instead of large, expensive, noisy relays) to alternate between banks of ultracaps, there is a very small amount of capacitance across power domains in the LPS-1 (less than 100pF) which is enough to allow some high impedance leakage through.

 

To prove to everyone how effective the grounding trick is, here are 3 graphs--directly measuring leakage versus frequency.  (do not try to compare these to anyone else's measurements--scales and units are different; and these are in dBM not dBV, that's 13dB difference right there).

 

Here is the leakage (just up to 1KHz, John has done wider bandwidth measures as well) from a stock Mean Well GST40A:

 

Here is the same Mean Well unit with its DC zero-volt ("ground") tied to the ground pin of its IEC320-C14 inlet this way:

 

What you see remaining is all the low-impedance leakage. (Again this is the leakage measurement of just the grounded GST40A.)

 

And here is the leakage (not output noise; these are all common-mode leakage tests which John can explain) from an LPS-1 being powered by the same modified Mean Well:

You can see how all the low impedance leakage is now blocked.

 

So yes, this is our admission that LPS-1, when used with an SMPS whose DC output is not grounded to AC mains, will let high-impedance leakage though (that's a different graph that I don't presently have from the same test set up).  How did we allow this to happen?  

a) The test set up to see this properly was not made; 

b) Power supplies used during development may have been grounded units;

c) We were not looking at high-impedance leakage or at these frequencies;

d) We were concentrating on other aspects of performance: Isolation, ultra-low noise, ultra-low impedance;

e) While John purposely chose transistors with the lowest possible capacitance, the spec sheets all specify capacitance only with the transistor in its "on" state, whereas in our application it is the capacitance of the part in its "off" state that is letting a little leakage through.  (He has since built a special board/jig to measure these transistors, and while he found a couple of parts that have both a little lower capacitance and meet the various functional current/voltage requirements, there will always be some; Even if we cut the total capacitance in half the high impedance stuff can still get through; The ground/shunting solution is simpler and totally effective.)

 

I hope this clears things up for those who are interested.  And yes, I have egg on my face for all those months during which I insisted that the choice of "energizing"/charging supply would make zero difference to the output of an LPS-1.  Of course noise, output impedance, and other aspects of our "floating" supply's isolation are not affected.  But yes, based on our choice of bundled SMPS for charging, some leakage current gets through--unless you ground/shunt it. Too bad the Mean Well GST25A-07 we chose was not the sort that already was grounded in this fashion (no safety or emissions violations come from it as far as we can tell; and other certified SMPS units are already built that way).

 

Happy Friday.  Have a great weekend everyone,

--Alex C.

 

 

Sorry about conflating impedance and frequency and thank you for explaining more thoroughly.

 

That being said, how does one block the low impedance component? 

I have already added the grounding umbilical to the output of the two LPS which I am using per John's guidance.

[BigGuy]

14 hours ago, Superdad said:

 

Hi BigGuy:

Can you be more specific?  

a) What power supplies are you using?  

b) What components are they powering?

 

My post was only discussing SMPS (switch mode power supply) leakage and its relation to our UltraCap LPS-1.  Our LPS-1 always blocks low-impedance leakage.

 

And since LPS (linear power supply) units in general do not have much leakage current (high or low impedance), there is usually never a need to ground their outputs. 

There is the somewhat separate topic of Ethernet switches and grounding of a power supply feeding one.  However, if one is feeding an Ethernet switch from an LPS (ours or someone else's), grounding of that supply's zero-volt leg is not useful--unless you are using a specific Ethernet switch (such as the NetGear FS105/108) that John tested and found to also block leakage coming in from other Ethernet devices (by grounding).  

 

As for blocking the low-impedance leakage component of SMPS units, for that you need to either use an UltraCap LPS-1 or ditch the SMPS.  

I defer to John as to if there are actually any low impedance leakage currents making it into a switch from other networked components.  I suspect that the magnetics at every EN jack already blocks that.

 

Sorry this is so confusing.  

--Alex C.

Yes, this impedance issue IS confusing so I appreciate you and John having the patience to simplify so more of us can understand.

 

To your questions...

 

One LPS is an old desktop "brick" from HP used to power laptops where I am using the 5V tap to power the ADNACO Glass/USB device <http://www.adnaco.com/products/s3a/>  

 

The second is a DIY LPS designed by a member of our audio society.  It is adjustable but I am using it to output 9V to a USB dongle similar in concept to the REGEN.

 

Both LPS are AC powered from a PS Audio P300 regenerator.

 

I recognize that John's grounding umbilical is more relevant to SMPS which by nature have more of an impedance issue than LPS but do remember him saying that it could/would help LPS as well.  I figured what the hey.

 

Having treated the high impedance component, I was looking to address the low impedance.

 

Thanks.

[BigGuy]

14 hours ago, sandyk said:

 

Many Desktop PC's do have their SMPS grounded.

IF the LPS or SMPS is grounded with a 3-prong plug, does this mean a grounding umbilical on the output is superfluous?

 

Any electronic downside to using one even with 3-prong?

 

 

[BigGuy]

20 hours ago, lmitche said:

John, WOW what a great explanation of the cause of the mysterious SQ changes we hear so frequently.   I even get it.  Many thanks!

 

Larry

+1  Starting to understand this whole issue of impedance noise and how to deal with it.

[BigGuy]

14 hours ago, charlesphoto said:

I will say, that the ground shunt trick has totally transformed my system. And even putting one on the Roku (which is powered on a different circuit from the hifi but lives next to it) I could swear the picture is brighter and sharper and the sound better. So far I've put them (ten in all) on most everything in the house that connects with the wired ethernet (Mac Pro, newer AE, and Xbox not included) and so I'm not particularly sure which is doing the most good, or if it's a cumulative effect. Whatever, it's almost like somebody delivered a bigger better system (esp the amp) to my house, for under $50 at that. Thank you John Swenson! 

charlesphoto's post raises a question for me.

I understand that the PS for a router should have DC grounded but is it important to go upstream to the modem as well?

 

IF so I need to get a power extender strip with a lot more outlets...or find a source for inexpensive grounded LPS of varying output voltages for all these accessories! 

[BigGuy]

35 minutes ago, thyname said:

 

Great explanation!

 

What about the scenario when no switch is involved (audio streamer connected directly to router), would grounding the router would take care of everything in the house, including another location that has a Switch? Or does this just work with the two FS105 and FS108 models you tested? Thanks!

 

16 minutes ago, charlesphoto said:

Interesting. I'm currently using a GS108NA with the ground shunt and powered by an "El Cheapo" Lps. It has other traffic on it though than just the hifi. I have an eBay FS105NA for $10 coming so will isolate the streamer and server on that with a ground shunt and see what happens.

 

As far as I'm concerned the grounding I did upstream hasn't hurt, esp as I had a bunch of extra adapters and it's really easy to do. I'm quite sensitive to EMF so getting the overall level down is always good. That said I wouldn't go out of your way or break the bank (i.e. silver wire nonsense) for these. But I do notice a difference when I unplug the ground shunt from the HDPLEX 160 which powers the downstream FMC and the LPS-1 and an iSPDIF Purifier for the TV. Shunts for all three run into the same socket which is plugged into a dedicated circuit along with the HDPLEX. Unplugged lots more sibilance.  

Great minds think alike!  I have cable service moden feeding a Linksys 1000 router that feeds my music server PC.

 

What is the purpose of a "switch" vs my Linksys router?

 

Do I just connect the switch between the existing router and PC?

[BigGuy]

11 minutes ago, lmitche said:

The purpose of the new Netgear switch, properly grounded, is filtering low and high impedance leakage currents from your music PC.

I see that there is a screw GND terminal on the back of the Netgear switch. 

 

Does that terminal need to be connected to ground using John's umbilical (modified with spade connector, etc.) IN ADDITION TO grounding the Netgear power supply?

 

At this point I think the only thing not grounded is me!  ;-)

[BigGuy]

10 hours ago, jamesg11 said:

Now that JS is closing shop on this epic investigation, for the time being I’ll at least assume, ... who is putting their hand up to write & post the summary/take-away?

 

Self-interest here, because I need to get someone more competent than me to implement, & they’re not going to wade all thru the extensive above.

 

I’ll start with locating one of those Netgear switches, pronto.

Definitely appreciate the patience shown by both John and Alex in answering our questions.

 

I too will be looking to purchase a Netgear switch, e.g., Fs105,  to insert between my router and PC but wonder how one knows if the switch is V5 or higher per John's recent post particularly buying onnline?

[BigGuy]

1 hour ago, BigGuy said:

Definitely appreciate the patience shown by both John and Alex in answering our questions.

 

I too will be looking to purchase a Netgear switch, e.g., Fs105,  to insert between my router and PC but wonder how one knows if the switch is V5 or higher per John's recent post particularly buying onnline?

Duh!  Its not V(er)5. 

[BigGuy]

Re John's comment re crosstalk between STP vs UTP ethernet cables, I had gotten this info from Blue Jeans Cable some time ago and decided against STP...

 

"The crosstalk would be between cables if you are running bundles of them over long distances.  This article (written by the owner of BJC) explains shielding in ethernet cabling in detail:

 

Shielding is, in most cases, not of much use on Ethernet cable.  The noise rejection characteristics of the pairs (common-mode noise rejection) are the most important consideration whether the cable is shielded or not, and there are all sorts of practical issues -- foil isn't a very low-resistance path to ground, and noise currents on the shield can sometimes hurt as much as they help. 

 

Performance-wise, the shield causes problems.  For one thing, the shield-to-pair spacing is hard to keep consistent, and it affects the pair impedance slightly; for another thing, a lot of the energy at these frequencies bounces off of shields, so internal crosstalk suffers for the benefit of alien crosstalk; and for a third thing, the nature of four pairs in a shielded bundle is such that the symmetry of the pairs is effectively disrupted by a shield which each conductor approaches, and then recedes from, with each twist (the other pairs don't affect this symmetry as profoundly because of the effect of different twist rates). 

The result is that if you take two patch cords: our Cat 6, and our Cat 6a, and test both of them both at Cat 6 and at Cat 6a standards, you find that both of them pass both standards, but the Cat 6 passes by larger margins than the 6a due to the effects of the shielding.  One might suppose that this means that the 6a should never be used -- but the difference is that in order to be certified the bulk cable must meet tests as well as the finished assembly, and Alien Crosstalk is tested only on bulk cable -- the Cat 6 would fail AXT, while the 6a passes it.  It's a design tradeoff -- deterioration in cable internal electricals in order to achieve external targets.

 

Now, that has some interesting implications in a home or small network environment; if the patch cables are deployed at work stations, rather than on patch panels, then they typically do not run close to one another in bundles.  Regardless of what the spec says, the Cat 6 patch would be better than the 6a in such a case, because the actual installation conditions make

alien crosstalk no longer a meaningful consideration.

 

But, more importantly, in most American network installations the backbone cable is unshielded.  What this means is that use of shielded cables in these systems can result in partial shield paths -- which can cause ground-loop problems and the like that can be rather hard to diagnose.  The best practice is, if the installed horizontal cabling is unshielded, to use unshielded patch cords, and correspondingly, if the installed horizontal cabling is shielded, to use shielded patch cords.  Either the entire system should be shielded, with shields tied to ground at patch panels, or none of it should be grounded.  This is one of those "how to tell the customers" conundrums -- we need, when we do make a shielded product available, to be sure that people understand that it really should only be used in particular environments, because the assumption tends to be "shielding = good" and this really does depend on the installation."

 

[BigGuy]

13 minutes ago, JohnSwenson said:

This and every other article on Ethernet shielding is talking about the differential signal between the two wires in the pair. Leakage is common mode, it is the same on both wires (NOT differential) thus the twistedness does not matter. Because it is common mode noise the twisted pair just looks like a weirdly shaped single conductor and makes a nice antenna.

 

I do NOT recommend shielded Ethernet in most cases, leakage will go through the shield, bypassing all things I have written about blocking it, none of that works if you have connected shields.

 

That is why I recommend using UTP and putting one of the grounded named swithces some distance away from the audio system, there will be nothing on the cable to radiate.

 

John S.

Sorry for my misunderstanding,  FS105 arriving tomorrow hopefully V3.

[BigGuy]

17 minutes ago, lmitche said:

I have lots of belden based bjc cat 6a cables and having re-terminated several, know that the cable is shielded but floating on both ends.

 

The internal structure of this cable is really something. I have no idea how they can cheaply manufacture something with this complexity.

Interesting re the bjc cat 6a cable since when I just inquired about STP ethernet, I was told they do not offer.

Is there a difference between STP and their 6a?

[BigGuy]

12 hours ago, lmitche said:

Yes, unconnected shield on bjc cat 6a cables.

IIRC, there was a much earlier post about the need to have the two ends of the shield connected to each other by an insulated wire otherwise the unconnected shield is just metallic sheathing.  Or does it serve a purpose even unconnected?

[BigGuy]

15 hours ago, JohnSwenson said:

Each Ethernet channel needs what is called the "magnetics package", this consists of a bunch of transformers and common mode chokes. You can either find these built into an RJ-45 jack or as a separate shielded box and a cheap jack with no magnetics is used. These magnetics boxes come in singles or duals.

 

The switches always use the separate magnetics boxes, they use duals as much as possible. For example an 8 port switch will have 4 dual boxes, a 5 port switch will have 2 duals and 1 single.

 

What seems to happen is that leakage will pass from channel to channel if the two channels use the same dual box. BUT (if the PS is grounded) the leakage gets blocked if the channels are on different boxes.

 

Thus for a common configuration where channels 1,2 are on the same box and 2,3 are on the same box etc, if one cable is on channel 1 you will not block leakage if the other cable is on channel 2, but you WILL get blockage if the other cable is on channel 3. IF one cable is on channel 2 and the other is on channel 3 you WILL get blockage because those two channels are on different magnetics boxes.

 

So the actual rule is somewhat complex, so to make it simpler, just make sure the cable going into the audio system has no other cable in a channel right next to it and you are guaranteed to be good. This guarantees that all other connections are on a different magnetics box from the one going to your audio system. The easiest way to do this is to have the cable going to the audio system on one end or the other on the switch, skip one jack, then you can use all the others for connections to the rest of your system.

 

John S.

Received my FS105 yesterday from B&H in NY and thankfully it was a V3.  Opened the hood to find out how the 2/2/1 boxes indicated by John were wired so that I could optimize IN/OUT connections.  From left to right I found the internal boxes as follows:  [1 2] [3 4] [5]   I  put IN from router to 5, using the other 2 for my PC OUTs with the server PC furthest from the input on [1 2].   Power supply and grounding are both plugged into adjacent outlets on a power strip figuring that pairs may actually be duplexes internally.

 

Not that I have that many ethernet connections but am using Blue Jeans UTP 6a cables which can be ordered in assortment of flavors which assists ID.

 

May have minimal inpact on SQ of system since audio is galvanically isolated with Adnaco Glass/USB system but, regardless, this all is a  "feel good" inexpensive tweak.

 

Glad I joined this thread!  Thanks.

[BigGuy]

Got to thinking about this while hooking up the FS105 y'day...

 

We have treated the noise generated by SMPS upstream of our computers using Netgear switches and grounding umbilicals and the noise generated by SMPS downstream between computer and DAC.

 

What about the noise generated by SMPS inside the computer feeding USB busses, aftermarket cards by SoTM and Adnaco, etc.?

[BigGuy]

38 minutes ago, mourip said:

 

CA got started by a series of articles that covered building a PC for dedicated audio use. In time most of these builds involved using system boards that could be run by an external DC linear power supply. There are some companies that sell music servers preconfigured. Also HDPlex makes great cases and LPSs for this purpose. So one big key to an electrically quiet PC is running it from an LPS. Add-on cards that allow for external powering also can help.

Definitely not interested in a custom or DIY build.  Have a Dell 3010 Pro machine in service as music server nor modifying it with an internal LPS unless that is something  "the average homeowner" can do.  ;-)  ( I DO have some electronic build skills.)

 

Would be interested in further details if only to be able to connect a grounding umbilical to the cable feeding my Adnaco board

[BigGuy]

16 minutes ago, lmitche said:

LOL, I have no idea.

 

56 minutes ago, Forehaven said:

I sent Ted the solid core, from my Bonsai work, it's 14g annealed.  Does the annealing process Larry make this particular solid core Cu less than ideal?

Google is your friend...

 

<https://www.thebalance.com/annealing-explained-2340013>

indicates one of benefits is improved conductivity! 

[BigGuy]

Just read about this alternative to wall warts...and maybe Gopherts tho' it is not adjustable.

 

https://ifi-audio.com/portfolio-view/accessory-ipower/

Wonder how it stacks up noise-wise?