SMPS and grounding

[Superdad]

5 hours ago, rickca said:

So that's different than grounding the downstream USB input, right?  

 

No.  The ground (outside of DC barrel) of the ISO REGEN's power input and the shell/ground of the ISO REGEN's USB output jack (and hence the same on the DAC's USB input jack) are common to one another (use a continuity checker and you will see).

So running a wire from the ISO REGEN output/DAC USB input to AC mains ground is the same thing as connecting the ISO REGEN's DC "ground" to AC mains.

[gstew]

On 9/24/2017 at 5:44 PM, JohnSwenson said:

Remember the leakage from an SMPS contains both high impedance and low impedance components, the ground shunt gets rid of the high impedance components. The low impedance components are still left. These components are usually still greater in amplitude than many linears, but some linears might be a bit more.

 

BUT since what is left is the low impedance components, they CAN easily be blocked.

 

You can do the same thing with linears, which gets rid of THEIR high impedance components, just leaving the low impedance components, which are REALLY low.

 

I'm putting together another post in the next few days that shows how this works with network systems (I'll post that in the thread on the Sonore forum).

 

John S.

John,

I don't understand the context & meaning of 'high impedance and low impedance components' of the SMPS noise.

 

I've never heard of noise having an impedance.

 

Can you provide some background and definition on that?

 

TIA!

 

Greg in Mississippi

[sandyk]

Greg

 John will correct me on this if I am wrong, but HF noise from an SMPS would be coupled into the secondary side ( the other side of the HF transformer) via the obligatory low value, and high voltage, capacitors that are connected between primary and secondary to meet FCC RF/EMI standards. This would be a high impedance source.

Incidentally, I have been looking at the high voltage leakage from my DTV STB as it connects into my TV and main system.

It hovers around 100VAC from the STB chassis to mains earth, but when the STB is connected via HDMI to the TV it is reduced to Zero.

I have disconnected the STB's  Antenna and coax SPDIF leads to verify this.  The interesting thing is that with nothing else plugged into the TV except the HDMI plug , and even when the TV's  2 wire mains plug is removed from the mains socket, the leakage STILL remains at Zero volts !

This shunting obviously is a good thing , but I am at a loss to see how this can happen.

 

Alex

 

[gstew]

27 minutes ago, sandyk said:

Greg

 John will correct me on this if I am wrong, but HF noise from an SMPS would be coupled into the secondary side ( the other side of the HF transformer) via the obligatory low value, and high voltage, capacitors that are connected between primary and secondary to meet FCC RF/EMI standards. This would be a high impedance source.

Incidentally, I have been looking at the high voltage leakage from my DTV STB as it connects into my TV and main system.

It hovers around 100VAC from the STB chassis to mains earth, but when the STB is connected via HDMI to the TV it is reduced to Zero.

I have disconnected the STB's  Antenna and coax SPDIF leads to verify this.  The interesting thing is that with nothing else plugged into the TV except the HDMI plug , and even when the TV's  2 wire mains plug is removed from the mains socket, the leakage STILL remains at Zero volts !

This shunting obviously is a good thing , but I am at a loss to see how this can happen.

 

Alex

 

Alex,

 

Thanks for the response. Very curious if that's it or if something else is involved. I DO think I understand the need for very high impedance probes to measure it. AND also likely that the high impedance is part of why shunting it to ground works so well. 

 

Also curious about your DTV STB & TV puzzle. My 1st thought are some high-ohm (50k-1M) resistors across the HDMI inputs to ground in the TV and that this is sufficient to dissipate the  high-impedance leakage in the resistors. 

 

Curious what John has to say on these questions/puzzles.

 

Greg in Mississippi

 

[agladstone]

I’m going to attempt to build a few of these DC grounding devices. 

My question is this (which was briefly mentioned previously but not detailed), I have about 6 SMPS devices (all on a separate AC circuit than all of my other audio equipment) and they’re all plugged into the same Furman PST-8 AC strip. 

I only have 2 remaining open plugs on the strip. 

If I where to build one or two of these with 3-6 Green wires coming out from the ground of a DIY plug, would it be okay to have that one plug provide the ground for anywhere between 3-6 SMPS devices (since I don’t have space for more than 1or 2 of these plugs on my power strip)? 

Also, if I followed this thread carefully enough, it seems like for my LPS-1 that powers my ISO Regen, I would want to have the ground wire going to the DC input of the ISO-Regen and NOT the DC input of the LPS-1, is this correct? 

Also, If I’m clear, in addition to one going to input of ISO-Regen, another ground wire should also go into the input of the LPS-1 from the meanwell SMPS that is powering the LPS-1? 

Thanks in advance for helping me with this prior to me starting to build these little devices:) 

[ElviaCaprice]

Why not just cut off the original adapter off going into the component from the smps?  Then just add a single correct size CCTV barrel connector for the component running the additional ground wire out?  In fact, do this for all the LPS-1's plugged into the same strip and attatch to the same plug the grounds.

 

Could also just bare out a spot on the DC negative and solder on a ground wire.

[sandyk]

1 hour ago, gstew said:

Also curious about your DTV STB & TV puzzle. My 1st thought are some high-ohm (50k-1M) resistors across the HDMI inputs to ground in the TV and that this is sufficient to dissipate the  high-impedance leakage in the resistors. 

 

Hi Greg

 I can't understand how this can happen where the TV is SMPS powered , and the 2 wire mains plug has been unplugged.

There shouldn't be ANY connection to mains earth at all.

 

Regards

Alex

 

 

[gstew]

21 minutes ago, sandyk said:

 

Hi Greg

 I can't understand how this can happen where the TV is SMPS powered , and the 2 wire mains plug has been unplugged.

There shouldn't be ANY connection to mains earth at all.

 

Regards

Alex

 

 

Alex,

 

I'm just musing that with at least some of the components of the leakage being super-high-impedance, a high-impedance resistance across it may not ground it, but in effect short it out.

 

You could try 1M resistors across the signal pins to ground at the end of the HDMI cable... I can't imagine that would hurt anything, but could demonstrate a possible mechanism.

 

Later!
 

Greg in Mississippi

[Superdad]

15 hours ago, agladstone said:

Also, if I followed this thread carefully enough, it seems like for my LPS-1 that powers my ISO Regen, I would want to have the ground wire going to the DC input of the ISO-Regen and NOT the DC input of the LPS-1, is this correct?

 

With the present topic, no, you would just ground the DC of the supply that you have feeding your LPS-1.

 

Quote

Also, If I’m clear, in addition to one going to input of ISO-Regen, another ground wire should also go into the input of the LPS-1 from the meanwell SMPS that is powering the LPS-1? 

 

Grounding of the ISO REGEN (its DC input jack is already and always common to its USB 'A' output shell and consequently your DAC's USB input ground) is only necessary in cases where you experience ticks or disconnects (caused by EMI charge build up with the Silanna chip having no place to "drain" to).  Otherwise, doing that is not advised--and there is even a chance you will introduce a ground loop (though it should be harmless since on that, the downstream side of the isolation,  only the ISO REGEN and your DAC-onward are involved; upstream, computer-side is of course isolated).

 

Hope that all makes sense.  Experiment and do what sounds good.

 

--Alex C.

[ElviaCaprice]

I had some spades laying around about the right size, cut six lengths of wire, attached them to the ground on the same plug, soldered the spades to the opposite end.  Attached to 4 LPS-1s and two HDPlex LPSU DC inputs.  All plugged into the same power strip powered by a Topaz. 

Verdict???  My sound was already very good, maybe some further clarity on extreme highs and lows.  I'll have to try listening for a few days and pull one of the grounds from time to time.

[agladstone]

12 hours ago, Superdad said:

 

With the present topic, no, you would just ground the DC of the supply that you have feeding your LPS-1.

 

 

Grounding of the ISO REGEN (its DC input jack is already and always common to its USB 'A' output shell and consequently your DAC's USB input ground) is only necessary in cases where you experience ticks or disconnects (caused by EMI charge build up with the Silanna chip having no place to "drain" to).  Otherwise, doing that is not advised--and there is even a change you will introduce a ground loop (though it should be harmless since on that, the downstream side of the isolation,  only the ISO REGEN and your DAC-onward are involved; upstream, computer-side is of course isolated).

 

Hope that all makes sense.  Experiment and do what sounds good.

 

--Alex C.

Thanks for helping to clarify!! Now I’m clear, and will give this experiment a try:) 

[Forehaven]

On 9/25/2017 at 6:52 PM, JohnSwenson said:

I've been experimenting with some ways to make the SMPS a little easier or applicable to a broader range of equipment. First off is a way to use it with equipment that does not have a 5.5x2.1 barrel jack.

 

I found another I had on hand, in this case the 7.5V Mean Well, this was exactly the voltage my switch took, IT plugs into the adapter, then a 5.5x2.1 to something else is used to plug into the device. In this case it was one of the adapters that came with the iPower. This works great. Using this technique I was able to ground the power to a bunch of different devices that had different plug sizes.

 

Both Amazon and Ebay have kits of these adapters available which include many different plug types.

 

Next up is an interesting kit from iFi called the Groundhog. It has a gounding system and several adapters to ground equipment in various ways. The one most appropriate is this:

 

This kit is unusual, it contains an IEC SOCKET, not a plug, you plug in a standard IEC power cord for your country. Most of you will already have several of these in your cable drawer. It doesn't matter what the country is, the IEC end is the same so they will plug right into the Groundhog. They call the adapter I show plugged in the "DC Spade", it is actually a little clip designed to clip onto the barrel of a 5.5 plug, thus grounding it. Clip it onto the barrel, then just plug it in.

 

This replaces the adapter shown in the first post with an off the shelf system you can buy, you don't have to build anything yourself. It is not dirt cheap, ($49), but for those that don't want to deal with building the adapter it is a nice alternative. It does exactly the same thing - it grounds the negative DC output of a power supply.

 

I hope this makes it a bit easier for people to try this approach.

 

John S.

ok, i give up.   what the hell is the dc adapter with pin outs??

[JohnSwenson]

1 hour ago, Forehaven said:

ok, i give up.   what the hell is the dc adapter with pin outs??

Read the very first post in this thread. This covers how to build a grounding power adapter which grounds the negative wire coming from the DC output of an SMPS.

 

This adapter will only work if the existing connector is a 5.5x2.1 plug (many are).

 

The linked post covers a way to do this for a plug that is not 5.5x2.1.   In addition it covers a commercially available product that lets you do this grounding without having to build anything yourself.

 

John S.

 

 

[JohnSwenson]

On 10/1/2017 at 8:57 AM, gstew said:

John,

I don't understand the context & meaning of 'high impedance and low impedance components' of the SMPS noise.

 

I've never heard of noise having an impedance.

 

Can you provide some background and definition on that?

 

TIA!

 

Greg in Mississippi

Any electrical signal (useful or noise) has a "source impedance". You can think of this as a resistor the signal has to go through before it gets to where you are looking at it. It is an impedance because it can vary with frequency.

 

As a concrete example, lets say your source has an impedance of 1k ohms, if you apply that to a 1k ohm resistor to ground, the signal level will be cut in half. That is actually how you usually measure output impedance, run the input through a known resistance to ground and measure the level across the resistor, the output impedance acts as a voltage divider with the known resistor, from the resulting voltage you can calculate the source impedance.

 

For any given "noise source" there is at least one mechanism generating that noise. The mechanism will have a particular impedance associated with it. In many cases more than one mechanism is involved with generating noise, each of these mechanisms may have a different output impedance. There may also be different frequency response issues with the different mechanisms.

 

This seems to be the case with SMPS, there seems to be at least two different mechanisms that cause the leakage and they seem to have very different impedances. I don't know what those mechanisms ARE, i have not spent time in figuring that out, I'm not really interested in building my SMPS so I don't really care what actually causes it, especially since it will take a LOT of work to find out and I would much rather spend my time working on other things.

 

Leakage current causes issues in audio systems when it flows through a conductor, creating a voltage across that conductor which causes something to not behave the way you would like it. In some cases this is just directly creating noise on the shield of an interconnect and the receiving circuit sees this as noise. In a DAC this can show up as noise developed on a ground plane that can modulate an oscillator causing increased jitter on the clock.

 

There are two ways you can attenuate the leakage noise, you can put a resistance in series with it, or you can shunt it. Lets cover both of the separately.

 

The series resistor form works like this: you have the source impedance and you stick a resistor in series. Lets look at some possible values and outcomes. Say 100 ohm output impedance and you put 1 mega ohm in series, that is going to attenuate the noise drastically. But what if the source is 100 mega ohms, then that 1 mega ohm resistor is not going to do very much (a VERY slight attenuation). So for high impedance series resistor works good for lower impedance source, but not well for high impedance source.

 

The shunt form works by shunting the source around your source around the "test point", frequently to ground. Say you have the 100 ohm source and you shunt with 1 mega ohm, nothing happens, but of the source is 100 mega ohms, that 100 mega ohm shunt will dramatically decrease the amplitude.

 

I know the output of the SMPS is a combination of impedances by running a bunch of these shunt and series tests with different values and seeing what I get. The only way to get the results I saw is if the source consists of both high impedance and low impedance components at the same time.

 

The upshot is that it takes BOTH methods to get rid of the noise, both a shunt and a series.

 

John S.

 

 

 

 

[Forehaven]

33 minutes ago, JohnSwenson said:

Read the very first post in this thread. This covers how to build a grounding power adapter which grounds the negative wire coming from the DC output of an SMPS.

 

This adapter will only work if the existing connector is a 5.5x2.1 plug (many are).

 

The linked post covers a way to do this for a plug that is not 5.5x2.1.   In addition it covers a commercially available product that lets you do this grounding without having to build anything yourself.

 

John S.

 

 

oh for god's sake, I'm so sorry i missed that!  so embarrassed!  Thanks John! 

[sandyk]

This morning, with a Teac  HDB850 STB working at 240V AC (approx.) I measured an average of 90V AC from the "earth" side of it's output jacks to Mains Earth with nothing else connected.

 With a 1 megohm "bleed resistor" connected from the "earth" side of it's output jacks to mains earth, it only dropped to an average of 50V AC, which is still way too high. 

 

Alex

[rickca]

@JohnSwenson how does one use something like this from Supra

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

[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.

[JohnSwenson]

15 hours ago, sandyk said:

This morning, with a Teac  HDB850 STB working at 240V AC (approx.) I measured an average of 90V AC from the "earth" side of it's output jacks to Mains Earth with nothing else connected.

 With a 1 megohm "bleed resistor" connected from the "earth" side of it's output jacks to mains earth, it only dropped to an average of 50V AC, which is still way too high. 

 

Alex

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.

[genjamon]

I'm really interested in what conclusions are forthcoming about this issue with regards to the LPS-1.  I'm currently running my UltraRendu from an LPS-1 powered by a Meanwell SMPS on a completely different circuit than the audio system.  Will shunting the Meanwell output to ground benefit in this arrangement?  

 

And if so, what about pegging the (-) side of DC output to ground on a different circuit than the audio system?  Am I just creating a new pathway for ground noise on a different circuit of the house to enter into my audio system?

[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.

[Adyc]

4 hours ago, genjamon said:

I'm really interested in what conclusions are forthcoming about this issue with regards to the LPS-1.  I'm currently running my UltraRendu from an LPS-1 powered by a Meanwell SMPS on a completely different circuit than the audio system.  Will shunting the Meanwell output to ground benefit in this arrangement?  

 

And if so, what about pegging the (-) side of DC output to ground on a different circuit than the audio system?  Am I just creating a new pathway for ground noise on a different circuit of the house to enter into my audio system?

 

 

+1. I think UpTone should provide some offshelve solution rather than letting their customers doing this DIY grounding.

[sandyk]

4 hours ago, JohnSwenson said:

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.

 Hi John

 Back in 2006 Silicon Chip magazine did similar experiments , and their version used a 22nF 275VAC X2 capacitor connected from the case to earth via a separate mains plug. They called it a " Tingle Terminator" . In  a later issue (October 2007) they did a series of tests using both SMPS powered and transformer powered CD/DVD players, where they published scope shots of the waveforms across a 100 ohm resistor connected from case to earth, with and without, the "Tingle Terminator."

 

Regards

Alex

[agladstone]

A couple additional questions as I get ready to order supplies to make some of the AMPS grounding devices:

1. What gauge ground wire should I use? 

I plan on trying to have several ground wires connected per plug at once (creating multiple leads out to multiple SMPS’s), so I want it to be as thin as possible, but large enough to be sufficient. (Most of my DC cables are 20AWG) 

 

2. Does the wire cover actually have to be Green? 

 

3. Another idea I’ve had was that I could also make a similar DIY device and have the ground wire go to the RG6 splitter for my Cable Box and Cable Modem? Would this work and would provide any benefit? 

[ElviaCaprice]

On ‎10‎/‎2‎/‎2017 at 12:36 AM, ElviaCaprice said:

I had some spades laying around about the right size, cut six lengths of wire, attached them to the ground on the same plug, soldered the spades to the opposite end.  Attached to 4 LPS-1s and two HDPlex LPSU DC inputs.  All plugged into the same power strip powered by a Topaz. 

Verdict???  My sound was already very good, maybe some further clarity on extreme highs and lows.  I'll have to try listening for a few days and pull one of the grounds from time to time.

After further listening, plugging in the ground plug and unplugging, my observations are that on my system this DIY grounding has no noticeable effect.