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UpTone LPS-1 Linear Power Supply Review and Measurements

RB2013

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Who in their right mind would buy this piece of crap? From the looks of it a real room heater - any Thermal Room Heating specs you'd like to spec here
img_01.jpg
 

RB2013

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Makes the 25,000uv Meanwell energizer/LPS-1 look like a bargain in comparison...then again a $25 LT3045 + R-Core DC-30W (with some nice Nichicon HW caps) would be an infinitely better solution (0.8uv -76db PSRR@1Mhz).
 

Mivera

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Who in their right mind would buy this piece of crap? From the looks of it a real room heater - any Thermal Room Heating specs you'd like to spec hereView attachment 8331

Yes shows the extent of your knowledge judging a supply for it's shape alone. Sorry douchebag, but all it takes is a couple nice regulators after that supply to take it to the best standards of power supply possible circa 2017. Those LT3045's own noise becomes the bottleneck. However ripple noise is only 1 issue. Everything else is over your head. Better do some more Google cut and paste's and learn a bit more.
 

RB2013

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Quit pretending to know what big numbers mean and stick to your vinyl.
Blizard-Wizard (or what ever you call your self these days) you had me ROLTF LMAO with your LT3045 - "Hey look at what I found folks" post. Right after posting about the old school TI You are such a loser - do people really buy that WAY overpriced crap you make. Such a joke.


Yes shows the extent of your knowledge judging a supply for it's shape alone. Sorry douchebag, but all it takes is a couple nice regulators after that supply to take it to the best standards of power supply possible circa 2017. Those LT3045's own noise becomes the bottleneck. However ripple noise is only 1 issue. Everything else is over your head. Better do some more Google cut and paste's and learn a bit more.
Oh Blizzard-Wizard or should I say the 'Ice-King'. You can do better...er...maybe you can't...but weren't you the one who posted the Ebay link to the LT3045 - now you're saying it's a 'bottleneck'?




download.jpg
 
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RB2013

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Anyway back to the MeanWell/LPS-1. Someone mentioned that Alex recommends that buyers just use the MeanWell as an energizer...and even if the LPS-1 does not pass the noise this beast creates 64,000uv-297,000uv of AC leakage noise back to the mains - doesn't this effect your DAC and other digital chain devices? Without proper AC filtering of course so.

Now he even brings up the issue of the MeanWell brick as a major source of EMI/RFI noise - that can capacitively couple to your IC's (and power cords?). Maybe they should include a nice Faraday Mu Metal cage for it!

Not what you'd expect for $395 - and limited to 1A. Now you need to spend another $100 on a cheap LPS to act as an energizer to min the AC leakage.

$495 for that solution?

And as Amir has shown - it looks like there maybe some capacitive coupling to the power supply from components on the LPS-1 circuit board.

Not to mention - as Alex has told me numerous times - those FPGA's are a large source of noise and jitter.

Interesting quote from your buddy Amir (s/), John Kenny on his Ciunas website about the supercaps.
https://www.ciunas.biz/other-faq?utm_campaign=7dac611fcb-EMAIL_CAMPAIGN_2017_08_24&utm_medium=email&utm_source=Daily+Blog+of+my+News&utm_term=0_7ccdad00ed-7dac611fcb-39550633

"How do batteries compare to supercapacitors?
Supercapacitors are capable of delivering very high currents at low noise but they have some drawbacks. The main one is that they are found mostly in 2.5 voltage versions. To output 3.3V, two supercapacitors in series are required plus baancing circuitry & a voltage regulator needed on the output. Our experience is that balancing circuits & voltage regulators are inferior sounding compared to direct battery power."

So maybe that advanced circuity to make the supercaps work - is generating noise itself. Would be interesting to the DC output noise of the LPS-1.
 
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OP
amirm

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Welcome to the forum. Balanced power is not compliant with code in US for the many reasons he mentions. I have to think about it more but for now, I think it might work. But so does using a linear supply.
 

RayDunzl

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I have an Equitech 1.5 RQ.

It has ETL certification, both Input and Output Breakers, and the outlets are GFCI protected.

Example:

upload_2017-8-25_19-29-18.png


Here is something of a Technical Specification:

http://www.equitech.com/support/BPSpecs.doc

---

I am still alive.
 
OP
amirm

amirm

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They are approved for commercial installations where it is expected that an engineer will determine fitness for the application.

http://www.equitech.com/support/647.html

"647.3 General. Use of a separately derived 120-volt single-phase 3-wire system with 60 volts on each of two ungrounded conductors to a grounded neutral conductor shall be permitted for the purpose of reducing objectionable noise in sensitive electronic equipment locations provided that the following conditions apply.
(1) The system is installed only in commercial or industrial occupancies.
(2) The system's use is restricted to areas under close supervision by qualified personnel.
(3) All of the requirements in 647.4 through 647.8 are met."

Fortunately Ray, you qualify. :)
 

RayDunzl

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Fortunately Ray, you qualify

Thank you...

I was busy formulating some kind of reply like "Busted again" but hadn't read the last line yet.
 

Superdad

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Gentleman:

John Swenson and I have been busy with many other things (management, production, measurement, and new product development), but we have recently begun addressing the issues at the root of evil of SMPS units, and presenting both our findings and explanation about pernicious leakage issues. These posts directly intersect with the measurements Amir took of the analog output of a DAC fed by a device (either ISO REGEN or microRendu) which was powered by an our UltraCap LPS-1--when it "energized"/charged by a stock Mean Well GST25A07-P1J 7.5V/2.93A/22W tabletop SMPS brick.

Neither John or I hang out here at ASR, but I will now past below copies of a couple of recent posts we made in an active thread about SMPS and grounding.
https://www.computeraudiophile.com/forums/topic/37034-smps-and-grounding/ John's discovery about high-impedance leakage lead him to start that thread with an easy trick to shunt it to ground--and was a byproduct of a specialized test circuit that he designed to more readily detect it, even between equipment connected only via Ethernet switches (not all of which are created equal in this regard, but that's all discussed over there).

Anyway, here is the post of mine I wanted to share. (I'll past John's deeper follow-on separately.)


From this post:
https://www.computeraudiophile.com/...-and-grounding/?do=findComment&comment=734822
-------
On 10/27/2017 at 8:06 AM, BigGuy said:
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 replied:
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.

On 10/27/2017 at 8:15 AM, R1200CL said:
.......and even if we use a LPS-1 and shunt it we won’t get rid of the low impedance ?
(using a FS105/8 before your AE. )
I think yes, cause in another thread you have stated the shunt applies to all SMPS including the LPS-1.
Tough in that posts high and low impedance leakage was not discussed.
So yet no final solution how to get rid of both impedance components is such an application ? ( only those two switches used as AE).


I replied:
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:

MW40_1khz_0929.gif


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:
MW GST40 grounded copy.JPG


MW40_1khz_internalgnd_0929.gif

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:

MW40_1khz_internalgnd_lps1_0929.gif


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 at the time;
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.
UpTone Audio LLC
 

Superdad

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And here is the very long post of John's that I wanted to share. None of this is rocket science by any stretch, but AFAIK, very few engineers (in audio at least) have looked closely at this issue:

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


To which John did an exemplary job explaining in lay terms much of the issue. BTW, some of what he hints at may actually be pointing the finger at the real reason why so many people report hearing differences with all the stuff (like Ethernet and power supplies) where the differences in theory should be too small to be of sonic consequence. For everything we share, there is a whole bunch of stuff (circuit techniques he is working on for our new products) that we elect not to discuss. It is not our goal to tip off other firms of our product directions or to publicly explain the completely new methods we intend to utilize. We already drop enough breadcrumbs.

----
From John Swenson, October 28, 2017
Leakage current has been around since AC power went into houses. All AC power supplies have it in some form, including linear supplies. In the 60s a couple engineers actually measured and modeled leakage current in audio systems. Given the time frame it was all from linear supplies, SMPS were a long way in the future. Different LPS implementations turn out to have significant differences in the leakage they produce.

In the audio realm the effects of leakage that were important concerned generating voltages across loads and sources, even with tube circuits these are usually significantly less than 1 Mega Ohm, thus in what I am calling the "low impedance" range.

This analysis of leakage current became quite important in the emerging medical instrumentation business (heart monitors etc), since electrical equipment was being deliberately connected to human bodies it was very important to know if this leakage current could be dangerous to humans. Since they are worried about mA range of current the leakage that was important had to be fairly low impedance to generate significant current. Thus a LOT of leakage analysis, testing tools, testing standards etc were focused on low impedance leakage. It was not specifically decided to ignore high impedance, but the effects of interest could only be produced by low impedance leakage, so that is what was studied.

The result of this was that all leakage testing was done with circuits and test equipment that was designed to work at 1 Mega Ohm or less. With linear supplies this was perfectly sufficient.

Then along came SMPS. It turns out that SMPS are very different with regard to leakage then LPS. First is frequency, linear leakage is power line frequency related (60, 120, 180 etc), but SMPS have a huge range of frequencies due to the switching nature of their operation. They ALSO include the traditional 60, 120, 180 etc.

SMPS have been extensively tested for leakage, but it has been done with all the existing test equipment and methodologies, thus focusing on low impedance leakage.

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.

Do not confuse the high impedance with high frequency. The SMPS contains high and low impedance components at all frequencies. Thus even at 60 Hz, there are both high and low components. This MUST mean that there are at least two different mechanisms contributing to the leakage simultaneously. One with a high impedance and one with a low impedance. The same thing happens at the higher frequencies. That amplitude ratio between high and low impedance varies with frequency (this is varies radically from one model to another), but both components seem to exist across the frequency range.

Currently I do NOT know what these mechanisms ARE, just that they must exist due to the behavior of the leakage. So please don't ask what is causing this, I don't know.

If you have leakage from a source (PS), it can show up in several ways. One is direct flow to earth ground. If the PS that is the source of the leakage has an electrical path to something that is grounded (such as a DAC, preamp, poweramp etc), maybe an interconnect, USB cable, Ethernet cable etc, the leakage current will create a voltage across the impedance of the cable, frequently the "ground wire" or shield of the cable. This can add noise to the intended signal. This is how leakage current has traditionally shown up in audio systems, as low frequency "hum or buzz" at the preamp or poweramp, because they were grounded.

Another way leakage can get into systems is through a DAC, the leakage current can go through the ground plane of the DAC PCB, that current creates a small voltage which modulates the oscillators(s) producing the clocks in the DAC, adding jitter to those clocks. Even if the leakage doesn't get to a preamp or power amp it can add jitter to the clock in the DAC, thus subtly distorting audio output.

This leakage from a computer through a DAC has been particularly important in computer audio since most computers are powered by SMPS.

In both the above cases the leakage here is composed of both the high impedance and low impedance components.

The leakage current does not have to go directly to an earth ground, it can also go from one power supply to another power supply, even if both have two prong plugs. This is what I have called a leakage loop. I have already written extensively about leakage loops so I am not going to go into it here.

So how do I know high impedance leakage exists and how do I measure it? A couple months ago I was looking into leakage current and was trying out several different detector circuits and started seeing very strange results that didn't make any sense. I ran a whole bunch of tests on different SMPS models and had a hard time coming up with correlations, things just were not making any sense.

I was trying to figure out what could be causing this. After many weeks of trying different things it started to look like the leakage might be very high impedance (over a hundred Mega Ohms). A few simple tests confirmed that this was in fact true. (I still didn't know it was BOTH high and low at the same time). But that presented a quandary, how in the world do you measure that. All my test equipment maxed out at 10 Mega Ohms which make it impossible to properly measure such high impedance signals. It turned out I couldn't even buy test equipment for this (at least not that I had any chance of affording) so I had to build my own. That took a little while to design and build, but I finally had a differential probe with around 10 Giga Ohms input impedance, AND very low noise.

With this tool I could now properly measure this very high impedance leakage. Unfortunately it was STILL doing really weird things. Another round of tests revealed that the leakage was composed of both a high impedance and low impedance part at the SAME frequency. Wow that was something I had not anticipated. I devised a series of tests to check this and sure enough, the results clearly showed both a high impedance and low impedance component at the same time from the same supply.

Unfortunately this makes dealing with leakage way more complicated than I had ever imagined. All the methods I had been using and discussing for getting rid of leakage were all focused on the low impedance component, which work for that, but frequently don't touch the high impedance components.

So how do you deal with leakage now that we know about both the high and low impedance components? It turns out that there is no single method that works well for both, so you have to come up with different methods, one for high and one for low and figure out how to apply them together.

There are two broad categories of how to stop leakage:
1) series block
2) shunt

Series block sticks something in series with the leakage path which prevents the leakage from going through. But in order to be useful it has to let whatever the signal is go through. This manifests itself with various isolation schemes that have been tried over the years. These work by increasing the impedance to the leakage, but still letting the signal go through. These work fairly well for the low impedance components, but the rise in impedance for the leakage is not nearly high enough to block high impedance components, they sail right through these isolation mechanisms.

This is where the shunt comes in. It turns out it is very to get the high impedance components to shunt around your sensitive components, instead of trying to block them, you just make them go somewhere else. The easiest way to do this is to shunt them to ground and the power supply itself. It CAN be done in other parts of the system, but shunting to ground at the source is the easiest way to deal with it.

Unfortunately the shunt does not deal with the low impedance part. So you need to do BOTH the shunt to ground and the series block. THAT will get rid of it all.

The series block is going to be different depending on what the "signal" is. For a power supply the "signal" is DC power. So just sticking in a resistor is not going to work, it will block the leakage but it also blocks DC. SO you need to get more creative. A magnetic circuit that passes DC but blocks 60Hz and up would work, but that is very large, heavy and expensive. This is where the LPS-1 comes in, it blocks all low frequency leakage, but does not block the very high impedance leakage. So use either an LPS to drive it or an SMPS whose output is grounded to shunt the high impedance component.

For high frequency signals such as Ethernet the existing transformers are sufficient to block the low impedance components of leakage. Leakage even from SMPS is still significantly lower in frequency than Ethernet signalling so a properly designed transformer will have a high enough impedance at the lower frequencies to block the low impedance components, but NOT the high impedance components. SO you still need to shunt the high impedance components and the transformer will take care of the low.

Theoretically you could do the same with USB, BUT USB is not just AC, it requires DC connectivity through the data pair, so a transformer will not work. This has made series blocking very difficult to deal with. There are a few solutions, but none of them block the high impedance components, so you still need to shunt the all the high impedance source before they get to the USB cable if you want to stop ALL the leakage from getting through to a DAC.

Stopping the low impedance leakage from getting through an audio interconnect is a difficult task. The leakage and the audio are in exactly the same frequency range so you can't separate them that way. The only known way to do this is with a balanced system. In many cases the leakage will be the same on both signal wires, but the audio will be differential, a proper differential input can block the leakage. BUT most implementation will NOT stop the high impedance component, so you STILL need to short it out before it gets there. Unfortunately not all balanced system are created equal. There are several implementations that do the differential input in such a way that it still doesn't block low impedance leakage. So a differential input MAY block low impedance leakage, it may not. Its best to get rid of it before it ever gets to the audio section in the first place.

Wow that was a lot longer than I thought. I hope this makes sense and is useful to people.

John Swenson

============
 

watchnerd

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And here is the very long post of John's that I wanted to share. None of this is rocket science by any stretch, but AFAIK, very few engineers (in audio at least) have looked closely at this issue:

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


To which John did an exemplary job explaining in lay terms much of the issue. BTW, some of what he hints at may actually be pointing the finger at the real reason why so many people report hearing differences with all the stuff (like Ethernet and power supplies) where the differences in theory should be too small to be of sonic consequence. For everything we share, there is a whole bunch of stuff (circuit techniques he is working on for our new products) that we elect not to discuss. It is not our goal to tip off other firms of our product directions or to publicly explain the completely new methods we intend to utilize. We already drop enough breadcrumbs.

----
From John Swenson, October 28, 2017
Leakage current has been around since AC power went into houses. All AC power supplies have it in some form, including linear supplies. In the 60s a couple engineers actually measured and modeled leakage current in audio systems. Given the time frame it was all from linear supplies, SMPS were a long way in the future. Different LPS implementations turn out to have significant differences in the leakage they produce.

In the audio realm the effects of leakage that were important concerned generating voltages across loads and sources, even with tube circuits these are usually significantly less than 1 Mega Ohm, thus in what I am calling the "low impedance" range.

This analysis of leakage current became quite important in the emerging medical instrumentation business (heart monitors etc), since electrical equipment was being deliberately connected to human bodies it was very important to know if this leakage current could be dangerous to humans. Since they are worried about mA range of current the leakage that was important had to be fairly low impedance to generate significant current. Thus a LOT of leakage analysis, testing tools, testing standards etc were focused on low impedance leakage. It was not specifically decided to ignore high impedance, but the effects of interest could only be produced by low impedance leakage, so that is what was studied.

The result of this was that all leakage testing was done with circuits and test equipment that was designed to work at 1 Mega Ohm or less. With linear supplies this was perfectly sufficient.

Then along came SMPS. It turns out that SMPS are very different with regard to leakage then LPS. First is frequency, linear leakage is power line frequency related (60, 120, 180 etc), but SMPS have a huge range of frequencies due to the switching nature of their operation. They ALSO include the traditional 60, 120, 180 etc.

SMPS have been extensively tested for leakage, but it has been done with all the existing test equipment and methodologies, thus focusing on low impedance leakage.

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.

Do not confuse the high impedance with high frequency. The SMPS contains high and low impedance components at all frequencies. Thus even at 60 Hz, there are both high and low components. This MUST mean that there are at least two different mechanisms contributing to the leakage simultaneously. One with a high impedance and one with a low impedance. The same thing happens at the higher frequencies. That amplitude ratio between high and low impedance varies with frequency (this is varies radically from one model to another), but both components seem to exist across the frequency range.

Currently I do NOT know what these mechanisms ARE, just that they must exist due to the behavior of the leakage. So please don't ask what is causing this, I don't know.

If you have leakage from a source (PS), it can show up in several ways. One is direct flow to earth ground. If the PS that is the source of the leakage has an electrical path to something that is grounded (such as a DAC, preamp, poweramp etc), maybe an interconnect, USB cable, Ethernet cable etc, the leakage current will create a voltage across the impedance of the cable, frequently the "ground wire" or shield of the cable. This can add noise to the intended signal. This is how leakage current has traditionally shown up in audio systems, as low frequency "hum or buzz" at the preamp or poweramp, because they were grounded.

Another way leakage can get into systems is through a DAC, the leakage current can go through the ground plane of the DAC PCB, that current creates a small voltage which modulates the oscillators(s) producing the clocks in the DAC, adding jitter to those clocks. Even if the leakage doesn't get to a preamp or power amp it can add jitter to the clock in the DAC, thus subtly distorting audio output.

This leakage from a computer through a DAC has been particularly important in computer audio since most computers are powered by SMPS.

In both the above cases the leakage here is composed of both the high impedance and low impedance components.

The leakage current does not have to go directly to an earth ground, it can also go from one power supply to another power supply, even if both have two prong plugs. This is what I have called a leakage loop. I have already written extensively about leakage loops so I am not going to go into it here.

So how do I know high impedance leakage exists and how do I measure it? A couple months ago I was looking into leakage current and was trying out several different detector circuits and started seeing very strange results that didn't make any sense. I ran a whole bunch of tests on different SMPS models and had a hard time coming up with correlations, things just were not making any sense.

I was trying to figure out what could be causing this. After many weeks of trying different things it started to look like the leakage might be very high impedance (over a hundred Mega Ohms). A few simple tests confirmed that this was in fact true. (I still didn't know it was BOTH high and low at the same time). But that presented a quandary, how in the world do you measure that. All my test equipment maxed out at 10 Mega Ohms which make it impossible to properly measure such high impedance signals. It turned out I couldn't even buy test equipment for this (at least not that I had any chance of affording) so I had to build my own. That took a little while to design and build, but I finally had a differential probe with around 10 Giga Ohms input impedance, AND very low noise.

With this tool I could now properly measure this very high impedance leakage. Unfortunately it was STILL doing really weird things. Another round of tests revealed that the leakage was composed of both a high impedance and low impedance part at the SAME frequency. Wow that was something I had not anticipated. I devised a series of tests to check this and sure enough, the results clearly showed both a high impedance and low impedance component at the same time from the same supply.

Unfortunately this makes dealing with leakage way more complicated than I had ever imagined. All the methods I had been using and discussing for getting rid of leakage were all focused on the low impedance component, which work for that, but frequently don't touch the high impedance components.

So how do you deal with leakage now that we know about both the high and low impedance components? It turns out that there is no single method that works well for both, so you have to come up with different methods, one for high and one for low and figure out how to apply them together.

There are two broad categories of how to stop leakage:
1) series block
2) shunt

Series block sticks something in series with the leakage path which prevents the leakage from going through. But in order to be useful it has to let whatever the signal is go through. This manifests itself with various isolation schemes that have been tried over the years. These work by increasing the impedance to the leakage, but still letting the signal go through. These work fairly well for the low impedance components, but the rise in impedance for the leakage is not nearly high enough to block high impedance components, they sail right through these isolation mechanisms.

This is where the shunt comes in. It turns out it is very to get the high impedance components to shunt around your sensitive components, instead of trying to block them, you just make them go somewhere else. The easiest way to do this is to shunt them to ground and the power supply itself. It CAN be done in other parts of the system, but shunting to ground at the source is the easiest way to deal with it.

Unfortunately the shunt does not deal with the low impedance part. So you need to do BOTH the shunt to ground and the series block. THAT will get rid of it all.

The series block is going to be different depending on what the "signal" is. For a power supply the "signal" is DC power. So just sticking in a resistor is not going to work, it will block the leakage but it also blocks DC. SO you need to get more creative. A magnetic circuit that passes DC but blocks 60Hz and up would work, but that is very large, heavy and expensive. This is where the LPS-1 comes in, it blocks all low frequency leakage, but does not block the very high impedance leakage. So use either an LPS to drive it or an SMPS whose output is grounded to shunt the high impedance component.

For high frequency signals such as Ethernet the existing transformers are sufficient to block the low impedance components of leakage. Leakage even from SMPS is still significantly lower in frequency than Ethernet signalling so a properly designed transformer will have a high enough impedance at the lower frequencies to block the low impedance components, but NOT the high impedance components. SO you still need to shunt the high impedance components and the transformer will take care of the low.

Theoretically you could do the same with USB, BUT USB is not just AC, it requires DC connectivity through the data pair, so a transformer will not work. This has made series blocking very difficult to deal with. There are a few solutions, but none of them block the high impedance components, so you still need to shunt the all the high impedance source before they get to the USB cable if you want to stop ALL the leakage from getting through to a DAC.

Stopping the low impedance leakage from getting through an audio interconnect is a difficult task. The leakage and the audio are in exactly the same frequency range so you can't separate them that way. The only known way to do this is with a balanced system. In many cases the leakage will be the same on both signal wires, but the audio will be differential, a proper differential input can block the leakage. BUT most implementation will NOT stop the high impedance component, so you STILL need to short it out before it gets there. Unfortunately not all balanced system are created equal. There are several implementations that do the differential input in such a way that it still doesn't block low impedance leakage. So a differential input MAY block low impedance leakage, it may not. Its best to get rid of it before it ever gets to the audio section in the first place.

Wow that was a lot longer than I thought. I hope this makes sense and is useful to people.

John Swenson

============

Isn't it just easier to avoid the problem entirely by using a different system architecture?

This whole issue seems rooted in generation 1 computer audio, where interfaces are connected directly to a computer.

As opposed to current architectures with network-native endpoints connected to servers/streaming services via networking interfaces (Wifi, Ethernet).
 

Jinjuku

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Alex, if you never understood my frustration with you before and the entrenchment you represented, I think you understand it now.

And I can't say thank you enough for finally switching the stroke of your oars and realizing that people aren't out to get you. I prompted you in a post, I think last year, that instead of swimming against the stream of Amir, BE17, Don, sorry if there is anyone else that I missed, that you instead sit down and speak with them. That you were getting free engineering advice.

I understand there may have been difficulty in changing your mindset but it's a breath of fresh air in this industry to see your change.
 

extracampine

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So......what is the answer then? Where are we at? Is there a better power supply that should be used with the LPS-1, or should a different linear power supply be used?
 

Superdad

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So......what is the answer then? Where are we at? Is there a better power supply that should be used with the LPS-1, or should a different linear power supply be used?

Here is an example of a suitable SMPS that already internally shunts its zero-volt output ("ground") to its AC mains ground pin--eliminating all high-impedance leakage through the LPS-1 (the LPS-1 already blocks all the low-impedance leakage) and resulting in measures as clean as the last graph I posted a few posts up:
https://www.mouser.com/ProductDetail/CUI/SDI30-12-UC-P5
 

extracampine

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Many thanks superdad. While you are here, would you agree with the emerging consensus on this particular forum/thread that at best (with the LPS properly implemented) the Microrendu does not affect SQ when compared to direct connection of the DAC to the PC?

Also - the link you gave says this about the product: "Product available only to OEM/EMS Customers. Product is not shipped to consumers in the EU." I'm in the UK - any suggestions?
 

Superdad

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Many thanks superdad. While you are here, would you agree with the emerging consensus on this particular forum/thread that at best (with the LPS properly implemented) the Microrendu does not affect SQ when compared to direct connection of the DAC to the PC?

Sorry, but given the skepticism of this forum, your question--even it was not intended as such--reads like one of those YES/NO "Do you still beat your wife?" sort of things. ;) I see that you just joined today, so I'll assume you are not just throwing bait into the waters. Still, I'm not going there.

Also - the link you gave says this about the product: "Product available only to OEM/EMS Customers. Product is not shipped to consumers in the EU." I'm in the UK - any suggestions?

Arrow Electronics also has stock and offices in the UK. Here is a link to the version that is not coming with a USA plug, so they ought to sell it:
https://www.arrow.com/en/products/sdi30-12-u-p5/cui-inc
 

extracampine

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Thanks. That link seems to be a USA distributor also. I'll have a look around.

Regarding my question, you had previously inputted into this thread so I thought that you might be able to clarify regarding my question. I'm not sure what you're saying with your wife beating analogy o_O
 
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