Low cost high quality excellent performing LPSU for audio.

[Superdad]

2 hours ago, Miska said:

Well, it doesn't have ground leakage because it doesn't have ground!

 

We never said ground leakage. Leakage is common-mode!

 

I have a whole series of leakage measurement graphs taken from a Mean Well GSM40B "medical" SMPS and for the form of high-source-impedance leakage John has been explaining, they are no better than any of Mean Well's non-medical models.

[plissken]

I'm naming my upcoming line of power supplies 'Olestra'

[Superdad]

.

[fds]

Have just become aware of the new ifi iPower Elite (which however seems not to be a LPSU):

https://ifi-audio.com/products/ipower-elite/

I had mixed experiences with ifi power products, very disappointing ones with the basic ifi iPower SMPS and surprisingly stunning ones with a couple of their AC Purifier plugs. Reading the forums, the iPower X seems to be quite good already. However, I really like that the new iPower Elite offers the possibility to use your favorite power cord with it.

[jabbr]

On 1/31/2021 at 2:09 PM, Superdad said:

Unfortunately it turns out that SMPS also include a high impedance component to their leakage, this is way above 1 Mega Ohms. The problem is that the existing test equipment and methodologies shunt this high impedance leakage to ground so they never see it. So nobody knew it was there. This high impedance leakage is significantly higher in intensity than the traditional low impedance leakage, so it can actually have a significantly larger affect on audio systems than traditional leakage, but nobody knew it was there.

 

The problem with inventing new terms for these things is that we forget to look at very basic electronics to analyze. This is common mode noise being discussed. Yes, common mode noise sourced from a power supply can "leak" back via the ground and so one type of common mode noise is also called leakage current, but essentially this is a common mode noise discussion for people familiar with electronics. 'leakage current" is defined and measured in the medical environment.

 

So lets look at > 1 Mega Ohm leakage currents , it is absolutely critical not to forget that these are currents, so at the nominal 5V (could be 3.3V) that we are dealing with a 1 Mega Ohm resistance path will have at most 5 nA current -- remember the handy V = IR equation folks!

 

Please explain using math how your statement that these high impedance leakage circuits could conceivably have "significantly larger" effects on audio systems when they are in fact probably buried in the background noise of the system.

 

Substitute "common mode noise" for "leakage currents" and this discussion will become comprehensible again.

[jabbr]

On 2/2/2021 at 5:42 AM, Miska said:

 

Well, it doesn't have ground leakage because it doesn't have ground!

 

 

 

This should be discussed as common mode noise ... common mode noise is transmitted over a twisted pair, but not over fiberoptic. The effects of shields are tricky at high frequencies e.g. 1 - 100 Gbe because the shield essentially forms an extension of the source ground plane. Not having shields on Ethernet cables does eliminate the typical "ground loops" that we get using lower frequency noise but the effect on higher frequency common mode noise is more complicated (whether this has an effect on the specific equipment is still subject to debate).

[jabbr]

On 2/2/2021 at 6:25 AM, asdf1000 said:

 

Noted but it's leakage currents will find it's way through USB DAC via USB ground most likely?

 

Whereas battery power supply will not have any leakage current at all - of any kind.

 

But then how well USB DAC deals with higher ripple of a powerbank, that's a different question of course.

 

Common mode noise can be transmitted through the USB cable twisted pair. D+/-. twisted pairs are useful to reduce differential mode noise.

[asdf1000]

48 minutes ago, jabbr said:

but the effect on higher frequency common mode noise is more complicated (whether this has an effect on the specific equipment is still subject to debate).

 

Can you expand on this? 

 

@Miska hinted he's not seen measurements of any leakage currents ("common mode noise") via UTP cable. 

 

Where is the debate with higher frequencies? And any measurements? 

 

[asdf1000]

@jabbr I'm also interested in this unshielded vs shielded ethernet cables you bring up, in the context of this common mode noise / leakage current discussion, in POE+ (30W) applications.

 

If we have the POE+ switch which uses SMPS (which produces leakage currents, despite being floating)

 

And this is powering RPi4 POE+ HAT with DAC with unbalanced RCA outputs to amp/s

 

Then with the UTP cable carrying power now in this POE+ application, can the leakage currents 'sail through' to the DAC's unbalanced RCA outputs and through amp/s etc ?

 

 

 

[jabbr]

APEC-2002.pdfslla057.pdfenergies-12-01984.pdf

 

This is a vastly discussed topic and these are but several papers which discuss. Henry Ott's writing are considered definitive. e.g. Henry Ott "Electromagnetic Compatibility Engineering" (textbook)

 

This is a brief discussion of differential vs common mode noise: https://techweb.rohm.com/knowledge/emc/s-emc/01-s-emc/6899

 

So essentially in POE, the twisted pair is serving as the power supply, and if the supply has high common mode noise, the common mode noise is transmitted to the receiver.

 

"leakage currents": every every every current travels in a circuit. The ground serves as a return path for common mode currents. All currents travel down the path of least impedance. As the frequencies become higher, the parasitic capacitances become more important because they provide lower impedance pathways. One of the reasons that  SMPS cause more common mode noise problems is that the higher switching frequencies increase the role of parasitic capacitances, also the small transformers used in such supplies tend to have higher capacitative coupling which allows common mode noise to sail through...

 

I use fiberoptic (and wifi) networks because there is zero capacitive coupling between source and destination so I don't need to worry about these issues. My audio area is fed by an Equi-tech transformer with very high common mode noise rejection, so I've greatly reduced the paths for common mode noise to enter my audio system. Differential mode noise is handled by the normal techniques e.g. XLR ... my headphone cables are balanced FWIW.

 

So, y'know I don't worry about what power supplies are supplying my servers nor ethernet switches (they all work).

[jabbr]

42 minutes ago, asdf1000 said:

Can you expand on this? 

 

@Miska hinted he's not seen measurements of any leakage currents ("common mode noise") via UTP cable. 

 

Where is the debate with higher frequencies? And any measurements? 

 

The common mode noise transmitted via an Ethernet cable depends on the common mode noise emitted by the switch. In sensitive applications e.g. a hospital ICU where a cardiac monitor may be placed into a heart via a catheter, there is a great need to eliminate a current traveling from the catheter tip and into the heart and back through the patient, ground etc. In such cases specialized isolating filters are used. Similarly isolating transformers are used to supply such equipment.

 

Whether any of this is audible in audio for noise in the gigahertz range I can't say.

[jabbr]

51 minutes ago, asdf1000 said:

@jabbr I'm also interested in this unshielded vs shielded ethernet cables you bring up, in the context of this common mode noise / leakage current discussion, in POE+ (30W) applications.

 

If we have the POE+ switch which uses SMPS (which produces leakage currents, despite being floating)

 

And this is powering RPi4 POE+ HAT with DAC with unbalanced RCA outputs to amp/s

 

Then with the UTP cable carrying power now in this POE+ application, can the leakage currents 'sail through' to the DAC's unbalanced RCA outputs and through amp/s etc ?

 

 

 

Shield coupling can cause the very common and clearly audible types of "ground loop" noise.

 

The effect of shielding on higher frequency common mode noise AKA "EMI" is more complicated. The little itty bitty transformers in the copper Ethernet PHY are more effective at blocking lower frequency common mode noise but given their parasitic capacitance do let higher frequency common mode noise "sail through"

[Superdad]

4 hours ago, jabbr said:

Substitute "common mode noise" for "leakage currents" and this discussion will become comprehensible again.

There is no disagreement here. John and I have always stated that leakage currents are common-mode AC (traveling over various nominally “DC” connections. We talk about them as “leakage” primarily because of their source, which is often overlooked.

 

3 hours ago, jabbr said:

One of the reasons that  SMPS cause more common mode noise problems is that the higher switching frequencies increase the role of parasitic capacitances, also the small transformers used in such supplies tend to have higher capacitative coupling which allows common mode noise to sail through...

 

I think a large part of the capacitive coupling letting that common-mode leakage noise through comes from the safety-mandated ‘Y’ capacitors positioned right across the (primary/secondary) of the transformers of nearly every SMPS in the world.

 

2 hours ago, jabbr said:

The little itty bitty transformers in the copper Ethernet PHY are more effective at blocking lower frequency common mode noise but given their parasitic capacitance do let higher frequency common mode noise "sail through"

Hence the reason our EtherREGEN uses (difficult to source) 12-core-per-port magnetics, whose center-taps are grounded—followed by our A>B side isolation “moat” consisting of differential isolators. No leakage gets past that moat. 

[R1200CL]

On 1/7/2021 at 1:30 PM, airguitar said:

I'm now on the hunt for an affordable yet no compromise (hopefully this isn't an oxymoron) 5V LPSU.

Not reading the whole tread. Where are you going to use it ? Amp requirement ? And is between 4 and $600 within your budget ?

Have you used quality DC cables?

[One and a half]

5 hours ago, jabbr said:

Common mode noise can be transmitted through the USB cable twisted pair. D+/-. twisted pairs are useful to reduce differential mode noise.

Any papers found on the transmission of common mode noise over USB? Don't need full blown thesis, but practical measured. I'm not in the industry, but have noticed few USB type medical sensors, even blood sugar monitors use IR for uploading data.

[jabbr]

12 minutes ago, One and a half said:

Any papers found on the transmission of common mode noise over USB? Don't need full blown thesis, but practical measured. I'm not in the industry, but have noticed few USB type medical sensors, even blood sugar monitors use IR for uploading data.

 

https://product.tdk.com/en/products/emc/guidebook/eemc_practice_02.pdf

 

 I've long believed (and have stated before) that the *only* way USB cable shields can make a difference in SQ is by modulating common mode noise transmission. Let me think again ... well if there is significant coupling you could affect the D+/- rise times ... so those two mechanisms.

[jabbr]

2 hours ago, Superdad said:

There is no disagreement here. John and I have always stated that leakage currents are common-mode AC (traveling over various nominally “DC” connections. We talk about them as “leakage” primarily because of their source, which is often overlooked.

 

 

I think a large part of the capacitive coupling letting that common-mode leakage noise through comes from the safety-mandated ‘Y’ capacitors positioned right across the (primary/secondary) of the transformers of nearly every SMPS in the world.

 

Hence the reason our EtherREGEN uses (difficult to source) 12-core-per-port magnetics, whose center-taps are grounded—followed by our A>B side isolation “moat” consisting of differential isolators. No leakage gets past that moat. 

 

Good, the issue I have with the "leakage current" concept is that folks are thinking that the only way you can get common mode noise is from the power supply. Of course a battery can generate common mode noise, RF/EMI when it powers a circuit that creates it. I'm assuming the issues we are discussing here have to do with power supplies for network gear and networked audio gear because that's the subforum we are in. So @asdf1000's questions are particularly apropos. I haven't used POE and have gotten away from copper Ethernet for these concerns : I don't know how much of an issue common mode noise transmission over Ethernet actually is for audio SQ, but I've eliminated this possibility, yet people still claim that the PSU matters ... and it may for copper equipment. Yeah it would be great to see how much of a measurable problem this is...

[plissken]

58 minutes ago, jabbr said:

Yeah it would be great to see how much of a measurable problem this is...

 

I heard a rumor, years old now, that there is going to be a white paper with a MoP that can be independently reproduced that shows this. As of right now we only have Archimago and Amir measurements to go off of. Neither have been debunked. 

 

Still think wireless is the best way to go for most people. I'm getting 400% more through put over my $56 TP-Link Omada AC1350 than some audiophile network gear.  The upshot is that the carrier modulation is 5GHz and not 125Mhz.

[asdf1000]

1 hour ago, jabbr said:

Good, the issue I have with the "leakage current" concept is that folks are thinking that the only way you can get common mode noise is from the power supply. Of course a battery can generate common mode noise, RF/EMI when it powers a circuit that creates it. I'm assuming the issues we are discussing here have to do with power supplies for network gear and networked audio gear because that's the subforum we are in.

 

But WiFi is an RF source and can be right next to potentially sensitive analogue source ?

 

Although like anything, with good Engineering the issues can be significantly reduced at the DAC/amp end by the designer.

[R1200CL]

I heard about an audiophile that only plays from buffers. The network cable is only used to fill up the buffer once in a while. After that the cable is unplugged. 

[plissken]

Just now, R1200CL said:

I heard about an audiophile that only plays from buffers. The network cable is only used to fill up the buffer once in a while. After that the cable is unplugged. 

 

I heard, whether Luddites realize it or not, digital, non-realtime, playback systems 100% play out of buffer and not off the wire directly like analog.

[One and a half]

14 minutes ago, asdf1000 said:

 

But WiFi is an RF source and can be right next to potentially sensitive analogue source ?

 

Although like anything, with good Engineering the issues can be significantly reduced at the DAC/amp end by the designer.

You raise a good point. 

Frequencies over 30MHz stay as radiated noise and can only be a problem when they become not radiated noise, but conducted noise (like through wiring (any type of wiring). This is very difficult though, since to be come conducted, the RF needs to be connected like an antenna, have the right components to tune to that frequency. That's how an AM radio works, jus hold one up to a computer and you can certainly hear the activities of a mouse and keyboard very clearly. An audio circuit is too low in frequency to induce these RF frequencies, since the components are very lossy to RF, and the RF would need to have lots of power and these devices are strictly regulated (except Russia where any thing goes I suppose).

 

Leakage currents, common mode noise exist in a conducted medium like a wire, and it's frequencies below 30MHz we should be worried about and keep them the hell out of a DAC or anything that is on the receiving end of USB, Ethernet, coax. Adding an SMPS is creating a common mode noise generator, NBG!

[One and a half]

8 minutes ago, plissken said:

 

I heard, whether Luddites realize it or not, digital, non-realtime, playback systems 100% play out of buffer and not off the wire directly like analog.

So does the buffer also playback the noise?

[R1200CL]

9 hours ago, One and a half said:

So does the buffer also playback the noise?

 

Maybe answer can be found here 😀

 

 

[sandyk]

 

24 minutes ago, R1200CL said:

Maybe answer can be found here 😀

Buffers are as only good for cleaning up a signal as the PSU area and Earthing in particular in the PC /server permits.

See this thread started by one and a half (Gary)

https://audiophilestyle.com/forums/topic/60381-hdd-to-case-bonding-uptick-in-sq/