SMPS and grounding

[One and a half]

5 hours ago, jamesg11 said:

/& so safety cut-out required downstream of secondary ...

In fairness, Cornan's drawing doesn't show any protection systems.

 

The whole idea of grounding one of the secondaries is for safety, the other(s) are:

- Common mode noise is not introduced again. 

- Floating the neutral creates a voltage between earth and the neutral which equipment may not be appreciative of

 

Here's a white paper from Powervar explaining the causes of neutral to earth voltages of interest.

Their ground guard device is an isolation transformer, so common mode noise is knocked on the head, and one secondary is tied to ground (earth). This keeps the voltage of the neutral very close to ground, but , and but again, does not cause current to flow in the ground, the return current goes to the transformer where it originated.

 

 

- 

Powervar Neutral to Ground Voltage causes and cures wp202.pdf

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A quick measurement today revealed that if the host PC is grounded, the frame of an iMicroUSB3.0 is also grounded and the USB shell is as well input and output. 

This of course doesn't mean that the 0V is grounded, and it isn't unless 'forcefully' connected at the power source, but at least the shield is connected to ground/earth.

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For those of you have the Groundhog, a similar principle applies to the 0V connection and the frame of a microUSB 3.0. When the switch is down, the resistance from the frame to 0V is 56 Ohms, and the other way is 28 Ohms, not quite 0 Ohms. Also IIRC, the regen had a smaller resistance of 3 Ohm from a 0V, caused a colour change in versions. Seems that there's a deliberate impedance quite different to AC power technology where the neutral and ground is hard bonded with 0 ohms on the secondary of transformers. If the noise needs to travel a certain path, this is one to achieve with a higher than 0 but less than 60 Ohms...

 

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9 hours ago, Cornan said:

 

This means that you use shielded USB cables right?

In my case I'm using JSSG (floating shields with drain wire connected to both shield ends) starquad on both USB cables and DC cables. The AC mains cables is unshielded starquads.

Different setups probably gives different end results.

Yes, I always use shielded cables everywhere, AC, signal, the lot. The shields channel the noise where it's under control, rather than out of control. Ideally, but will never happen in domestic audio equipment, the shield should be bolted to the chassis of the source and the receiver as in the photo. This would work for XLR, forget it for RCAs. Then install a 6mm or 10AWG +  bonding earth wire between the source and receiver. Like you do in countless badly noisy industrial environments for the last 20-30 years for digital signals.

 

 

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1 hour ago, jamesg11 said:

Not that there aren’t things to bother about - a tweaker friend, who I tuned into the js grounding idea & who ordered some of the plugs etc for such, was told by an electrical engineer that the tweak was ‘illegal’ in Oz.

 

Go for it. <=24Vdc is Extra Low Voltage, do what you like, no licensing required.

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1 hour ago, JohnSwenson said:

Hi guys, I was going to post on this, but these recent posts are just what I have wanting to talk about.

 

I've been doing a bunch of measurements on both Ethernet and USB cables. This has to do with leakage being common mode, radiation from cables may be very different than commonly assumed.

 

Ethernet:  leakage current is common mode, the same on both data wires.

    UTP:  No shield, common mode leakage it radiated very well from the twisted pair. Twisted pair makes no difference, both wires have   the same thing

  STP: Shielded cable, metal connectors at each end, shield connected from box to box. Leakage goes right through shield, the shield makes a great antenna radiating the leakage.

 STP: shield is not connected to either end. Provides a little bit of attenuation of radiation due to leakage current.

 STP: JSSG, a single wire connect both ends of shield, ends of shield NOT connected to boxes. Since the shield is not connect to the boxes leakage cannot flow through shield. The wire connecting both ends of the shield does a very good job of blocking the radiation from the leakage current.

 

So for a system that DOES have leakage going through the Ethernet cable, all but the last will be radiating low frequency noise from the cable which can be picked up by normal audio cables and devices.

 

USB cables have a similar situation

 

Normal cable: shield connected at both ends, leakage flows through shield, radiating leakage.

Un-shielded cable. Leakage flows through ground wire and also VBUS and data. Due to geometry of cable and how leakage gets into data pair, does not radiate as good as UTP. less radiation that regular cable. May be why some people like un-shielded cables.

Un-shielded just data pair. With no ground wire and VBUS wire, leakage through just data pair is quite a bit less, producing significantly less radiation than normal cable.

normal cable, but JSSG, shield NOT connected between boxes. The JSSG shield blocks a very large amount of the radiation from leakage. Still has full ground, VBUS and data wires, without leakage radiation.

 

This leads me to think that a lot of systems are actually picking up noise due to radiation from leakage flowing through the Ethernet and USB cables. This may actually be why some people like some weird configurations of cables.

 

Note that this has absolutely NOTHING to due with the actual data going through the cable, it is just due to leakage from power supplies going between between boxes through the digital cables.

 

Note that this is from leakage, if you stop the leakage from flowing through the cable, all this cable stuff above makes no difference.

 

Just some more food for thought.

 

John S.

 

Great post!

 

These findings tell me the amount of leakage is dependant on the frequency of the leakage. It's not DC, so anything other than DC, OK.

 

Cabled shields attenuate higher frequencies. The solid wire between equipment is to lower the potential differences between the source and the receiver, so the (higher frequency) leakage current sees the solid cable as opposition. This makes sense to me, since it's industrial practice and the systems seem to work OK.

 

So earthing the 0V line drops the common mode node reference, so any leakage current hasn't a chance to return?  

[One and a half]

Ahem. Earthing 0V supplies on systems that are designed for 5V, has nothing to do with 230V systems. 

 

Now I need to make up bonding wires.

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2 hours ago, sandyk said:

 

 What  if we have a breakdown between Primary and Secondary sides of a 5V SMPS supply ?

Are they completely immune to such things due to their design ?

Just asking.

If there's a complete breakdown,  then the 0V being earthed will blow a fuse or breaker and the downstream circuit is wrecked.  

This could happen with a flashover from primary to secondary,  but this would be caused by the primary shorting (massive collapse of the field)  and protection devices would work again in that case.

 

Transformers are very reliable if they are selected for the right duty and don't get hit with any direct lightning strikes. 

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1 minute ago, sandyk said:

 

 That is my main concern about using a direct earth instead of something like a low value 0.25W resistor (e.g.22 ohms or a little higher) which would very quickly go o/c and hopefully protect the downstream circuit.

A resistor of that value should be just as effective as a direct earth given the very high impedance leakage source.

Restricted earth fault, you would need to work out if the resistor passed enough current to activate an overvoltage protection, or out of balance system.

[One and a half]

Information on the ifi Galvanic 3.0 construction. The input USB 3 connector's shell is insulated from the output's shell and the case. The output USB A connector's shell is connected to the case. So the shell casing is not continuous and is created. I thought to bond the case to the source computer's case, but this would 'short circuit' the design, and didn't go ahead with the bonding. I thought that could alleviate audible ticks generated by the ifi Galvanic 3.0 which recently surfaced. The solution to that problem was to remove the  ifi Galvanic 3.0 and replace it with an Intona. 

 

I did bond the ifi Micro USB 3.0's case to the source computer's case with a short 17cm 10 AWG wire. An improvement, perhaps a little cleaner, really splitting hairs though. The next step is for a 9V linear power supply for the ifi Micro USB 3.0 instead of the supplied iPower. The Acopian LPSU is working out well for the Icron Ranger, made a big difference to the noise lowering, with the 0V solidly grounded.

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On 11/13/2017 at 4:58 AM, Superdad said:

 

Of course I am biased, but I own both the above devices, so I can suggest to you that the most musical solution might be to replace both with an ISO REGEN!   Don't know that you have ever tried one Gary.

--Alex C.

Hi Alex,

 

I have not tried an ISOREGEN, since it needs also needs LPS-1, JS-2 (forget the AC unfriendly Meanwell) to work with it, plus quite a few connecting cables, USB connectors of the inverting kind and now shorting to ground links. When you elected to build the units this way, there was little/no choice to include them in the one box, I did ask at the time of the release of the ISOREGEN. That's why there's been no order to Uptone and went to ifi instead, since their one box uses USB3.0 bus power, one cable in and out.

 

What I would appreciate though is to use Uptone technology inside a DAC as a joint venture, where all the cables are hidden and paths are short.

[One and a half]

1 hour ago, Superdad said:

Wow!  If you were to evaluate an ISO REGEN, I would ask that you do so with the removal of 12(!) items (devices, cables, PS) from your present chain.  

So you see, we ARE trying to simplify things...

 

Cheers to you,

--Alex C.

 

On the USB Chain, I would like to clarify, since ridicule and ignorance befuddle the intent to overcome USB limitations. The Icron and associated gear stays, to isolate an electrically and noisy computer from the listening room.

The USB chain changes from day to day, sometimes less even to the barest bones, so it is under constant review.

 

It appears that the ifi Galvanic3.0 won't be the saviour, due to either design or manufacturing flaws, we'll see. Certainly after your post Alex, a ISORegen won't be on the shopping list either. Daniel from Intona is working on a newer model USB Isolator, so will definitely put this design on the short list. It may take some time, there's lots of music to listen to.

 

Cheers,

 

[One and a half]

@Speed Racer, thanks for the breakdown of your system using Ethernet. When the xRendu were available, I compared Ethernet to USB, the the fixes and components are much the same, much more if FOC is involved. The relentless provisioning of power supplies and their leakage paths are the same for USB components, and I already have USB parts to use, why complicate things even more.

 

At the moment, the configuration is without the MicroUSB so PC | Intona | Icron | DAC.

[One and a half]

9 hours ago, Superdad said:

Also I notice that you have the ICRON Ranger USB extender at the far end--as the last piece into your DAC.  From the standpoint of sonics I am convinced that is holding your entire system back and that with the ICRON as the last element you will never realize the benefits of improved USB signal integrity, impedance match, or clocking.  Might I suggest that you put a nice USB regenerator AFTER your ICRON--as the last piece before your DAC?  You should achieve a better result.

Best,

--Alex C.

 

No apology required.

 

The Icron is transparent, it shows all the attributes, good and bad of USB, warts and all.

It is NOT the routeable device from PSAUDIO, the Icron Ranger 2214 is a 'straight' USB extender with a linear PSU (0V grounded), have it for about three years now. 

If I added a USB fixer closer to the DAC, the PSU is a major drawback as to where it's sourced from as I don't have any more cabling between the computer and the listening room left. 

Been through all combos of using Ethernet cable for AES3 without the Icron from MC3-+USB direct to DAC, all sorts. The DAC works better using USB.

[One and a half]

12 minutes ago, sandyk said:

 

 Use Power Boards with VDR's in them. They are cheap enough, and should give you quite a bit of protection.

A Topaz/Elgar/Xantech isolation transformer will to a better job and a VDR leaks (JS quote).

[One and a half]

Just now, sandyk said:

 

 We can't always do what we would like to do in this area,. when renting.

The leakage of a VDR may be insignificant compared with transformer efficiency losses ?

John was quite specific in ruling out any power strips with surge suppression devices like Vdr, since they are usually connected to earth and they don't have gigohms resistance.  So there's leakage from them which then spreads. 

 

A 'large' isolation transformer can be hidden behind the equipment rack, about the size of a shoebox. 

Two of them would create a great base for a turntable,  they can weigh up to 30kg. Kinda ugly but functional.

[One and a half]

Just now, rickca said:

I better go back and review John's post.  I missed that point, thanks.

Have a look here:

 

 

[One and a half]

1 hour ago, sandyk said:

 

That's a bloody good question  !

 Perhaps Garry can answer that one ?

None really. Take this situation. A 9V, 12V, 7V power supply each driving different devices. Join all three 0V together and then one cable to ground, done.

Some power supplies (rare event) have 0V bonded to the chassis of the PSU. If the bond is made again, no big deal, even if the PSU has a three pin AC plug, also no big deal, but those rotten 2 pin AC switchmodes, essential to ground the 0V.

[One and a half]

8 minutes ago, sandyk said:

 

 None would have been my answer too, but rickca is saying he has a problem.

It doesn't make much sense to me .

No, really struggling to think why the Protection LED is on and grounding the output. If it were a short circuit, the SMPS shuts down. Some protection LEDs are always on, to tell you it's active, others it's a fault, so RTFM s'pose.

Or there's a cap to ground that's shorted perhaps on the input side, but now we are looking at equipment failure, can be anywhere now.

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57 minutes ago, MrDerrick said:

Would this product be useful?

SFE_SNR (2).pdf

not until the manufacturer publishes an attenuation versus frequency curve....

[One and a half]

4 minutes ago, MrDerrick said:

Is this adequate?

MANUAL-SNR.PDF

Thanks for the manual which has the curves. Hmm. Don't make much of an impact below 100kHz do they?

The money is better invested in a LPS for audio purposes.

[One and a half]

On 11/21/2017 at 4:35 PM, octaviars said:

 

My Asus router runs on 19V.

 

I use 5V to ISP, 19V to router, 12V to switch and 19V to NUC with Roon ROCK. 

 

For each 0V of each power supply, bring them to a common point, and from that common point, ground that connection, if you haven't completed this already.

[One and a half]

10 minutes ago, octaviars said:

 

I dont think I will do that I will only ground the 12V to the GS108 switch and keep the other ones floating as the PSU is linear and the only place I need a ground is at the switch to shunt away leakage on the ethernet. 

 

I talked to Paul Hynes about connecting all -0V to ground and he thougt that was not something he recommend as all groundplanes from the equipment would be shared and also noise from each component could spill over to another. 

 

I also think @JohnSwenson wrote somewere that only grounding at one place could be a good thing. And as I have no SMPS the only ground I need is at the switch to shunt out leakage from the ethernet.

 

So my HD Plex will get one grounded output to my switch GS108 and the other 3 outputs will be floating. 

 

My Paul Hynes SR4 feeding my SOtM SMS Ultra will also be floting.

 

Understand where you are coming from. If all the 0V are tied to ground at one point, the 0V are guaranteed to be the same potential. If any load creates an impedance leakage (high or low), that current returns to the source that's supplying it. Each current from the 19V or 5V supply will always travel back to the source, that's the way it works. There won't be a spill from one component to the other, of course if everything floats, now spill is a very likely event.

 

The main problem is, to treat each component, a switch, DAC, power supply, PC as an island and look at the specs to say, there's no noise from these, must be somewhere else. In today's complex connected spaghetti, the island concept needs a serious going over and it shouldn't be up to the end user to figure it all out. Resolution down to very small levels is measurable and listenable these days especially for a DAC, so every effort to stop leakage currents needs more attention than the music itself  Less noise = more signal but getting there is a LOT of work.

 

For example, my Internet is not working, so I can't control Jriver, so I listened to CDs of the same music I've been playing from Jriver lately. Wow, where did the bass come from, and the depth. For a CD player, paths and power supplies are short and linear. For a computer playback system they are a dog's breakfast (all over the place), no wonder noise gets in via unshielded power cable, DC unshielded, SMPS, low cost high noise switching regulators, filters...that's just the power supplies, haven't begun to grapple the mess from a computer where power supplies are multiplied by 20.

[One and a half]

8 minutes ago, Em2016 said:

 

 

Your CD player isn't a normal one though Gary !  

 

That wonderful Playback Designs SACD transport/DAC is quite special

 

 

 

Too true.

A good sound out of computer audio is just getting harder, the spend is limitless Very, very tempted to toss the USB Chain and DAC and end up with a streamer to analog converter (STAC ) , like a Pioneer N-70A,  Lumin D2,  Chord Code X (along those lines) and be resigned to accept with what comes out of it, end of story. No need to route through a switch(es), there's a direct wired CAT5e, direct from a computer than can be used. Another topic though!

[One and a half]

18 minutes ago, sandyk said:

 

Which country are you in ?

Have you checked another wall socket ?

Middle East perhaps. Interesting the hot is looped, but the neutral isn't. Very suspect though. Still most systems have earth fault detection of some kind,  provided there's an earth to connect to in the beginning.