Cornan Posted October 27, 2017 Share Posted October 27, 2017 11 minutes ago, R1200CL said: As I was staring to write you a long explanation, I suddenly understood I have no idea why I did ? As of cause ? these current leakage doesn’t care about what signal is traveling through either the DC cable, nor the Ethernet cable. Thanks for notice...(my stupidity) To defend you, I can say that I am all the same. An assumption is enough to get my brain working on high speed. I can tell you that all the things that pass through my brains nerve centers is not always that sensible! ? However, like Einstein said coriousity has it's own reason to exist! ? Link to comment
Popular Post Superdad Posted October 27, 2017 Popular Post Share Posted October 27, 2017 6 hours ago, 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. 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. 6 hours ago, R1200CL said: John .......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. No matter what so ever ? 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). Actually the LPS-1 already completely blocks low impedance leakage. And the SMPS grounding trick (I am now trying to source units that are already grounded--they exist--or get Mean Well to supply a custom version for us) is completely effective at shunting (getting rid of) the high-impedance leakage. Due to our use of transistors (instead of large, expensive, noisy relays) to alternate between banks of ultracaps, there is a very small amount of capacitance across power domains in the LPS-1 (less than 100pF) which is enough to allow some high impedance leakage through. To prove to everyone how effective the grounding trick is, here are 3 graphs--directly measuring leakage versus frequency. (do not try to compare these to anyone else's measurements--scales and units are different; and these are in dBM not dBV, that's 13dB difference right there). Here is the leakage (just up to 1KHz, John has done wider bandwidth measures as well) from a stock Mean Well GST40A: Here is the same Mean Well unit with its DC zero-volt ("ground") tied to the ground pin of its IEC320-C14 inlet this way: What you see remaining is all the low-impedance leakage. (Again this is the leakage measurement of just the grounded GST40A.) And here is the leakage (not output noise; these are all common-mode leakage tests which John can explain) from an LPS-1 being powered by the same modified Mean Well: You can see how all the low impedance leakage is now blocked. So yes, this is our admission that LPS-1, when used with an SMPS whose DC output is not grounded to AC mains, will let high-impedance leakage though (that's a different graph that I don't presently have from the same test set up). How did we allow this to happen? a) The test set up to see this properly was not made; b) Power supplies used during development may have been grounded units; c) We were not looking at high-impedance leakage or at these frequencies; d) We were concentrating on other aspects of performance: Isolation, ultra-low noise, ultra-low impedance; e) While John purposely chose transistors with the lowest possible capacitance, the spec sheets all specify capacitance only with the transistor in its "on" state, whereas in our application it is the capacitance of the part in its "off" state that is letting a little leakage through. (He has since built a special board/jig to measure these transistors, and while he found a couple of parts that have both a little lower capacitance and meet the various functional current/voltage requirements, there will always be some; Even if we cut the total capacitance in half the high impedance stuff can still get through; The ground/shunting solution is simpler and totally effective.) I hope this clears things up for those who are interested. And yes, I have egg on my face for all those months during which I insisted that the choice of "energizing"/charging supply would make zero difference to the output of an LPS-1. Of course noise, output impedance, and other aspects of our "floating" supply's isolation are not affected. But yes, based on our choice of bundled SMPS for charging, some leakage current gets through--unless you ground/shunt it. Too bad the Mean Well GST25A-07 we chose was not the sort that already was grounded in this fashion (no safety or emissions violations come from it as far as we can tell; and other certified SMPS units are already built that way). Happy Friday. Have a great weekend everyone, --Alex C. darkless, mozes, look&listen and 11 others 8 4 2 UpTone Audio LLC Link to comment
BigGuy Posted October 27, 2017 Share Posted October 27, 2017 1 hour ago, Superdad said: You are conflating frequency with impedance and that is not correct. In other words, there is high-impedance leakage and low-impedance leakage--and both have both high and low frequency components. Actually the LPS-1 already completely blocks low impedance leakage. And the SMPS grounding trick (I am now trying to source units that are already grounded--they exist--or get Mean Well to supply a custom version for us) is completely effective at shunting (getting rid of) the high-impedance leakage. Due to our use of transistors (instead of large, expensive, noisy relays) to alternate between banks of ultracaps, there is a very small amount of capacitance across power domains in the LPS-1 (less than 100pF) which is enough to allow some high impedance leakage through. To prove to everyone how effective the grounding trick is, here are 3 graphs--directly measuring leakage versus frequency. (do not try to compare these to anyone else's measurements--scales and units are different; and these are in dBM not dBV, that's 13dB difference right there). Here is the leakage (just up to 1KHz, John has done wider bandwidth measures as well) from a stock Mean Well GST40A: Here is the same Mean Well unit with its DC zero-volt ("ground") tied to the ground pin of its IEC320-C14 inlet this way: What you see remaining is all the low-impedance leakage. (Again this is the leakage measurement of just the grounded GST40A.) And here is the leakage (not output noise; these are all common-mode leakage tests which John can explain) from an LPS-1 being powered by the same modified Mean Well: You can see how all the low impedance leakage is now blocked. So yes, this is our admission that LPS-1, when used with an SMPS whose DC output is not grounded to AC mains, will let high-impedance leakage though (that's a different graph that I don't presently have from the same test set up). How did we allow this to happen? a) The test set up to see this properly was not made; b) Power supplies used during development may have been grounded units; c) We were not looking at high-impedance leakage or at these frequencies; d) We were concentrating on other aspects of performance: Isolation, ultra-low noise, ultra-low impedance; e) While John purposely chose transistors with the lowest possible capacitance, the spec sheets all specify capacitance only with the transistor in its "on" state, whereas in our application it is the capacitance of the part in its "off" state that is letting a little leakage through. (He has since built a special board/jig to measure these transistors, and while he found a couple of parts that have both a little lower capacitance and meet the various functional current/voltage requirements, there will always be some; Even if we cut the total capacitance in half the high impedance stuff can still get through; The ground/shunting solution is simpler and totally effective.) I hope this clears things up for those who are interested. And yes, I have egg on my face for all those months during which I insisted that the choice of "energizing"/charging supply would make zero difference to the output of an LPS-1. Of course noise, output impedance, and other aspects of our "floating" supply's isolation are not affected. But yes, based on our choice of bundled SMPS for charging, some leakage current gets through--unless you ground/shunt it. Too bad the Mean Well GST25A-07 we chose was not the sort that already was grounded in this fashion (no safety or emissions violations come from it as far as we can tell; and other certified SMPS units are already built that way). Happy Friday. Have a great weekend everyone, --Alex C. Sorry about conflating impedance and frequency and thank you for explaining more thoroughly. That being said, how does one block the low impedance component? I have already added the grounding umbilical to the output of the two LPS which I am using per John's guidance. Link to comment
Popular Post Superdad Posted October 27, 2017 Popular Post Share Posted October 27, 2017 18 minutes ago, BigGuy said: That being said, how does one block the low impedance component? I have already added the grounding umbilical to the output of the two LPS which I am using per John's guidance. Hi BigGuy: Can you be more specific? a) What power supplies are you using? b) What components are they powering? My post was only discussing SMPS (switch mode power supply) leakage and its relation to our UltraCap LPS-1. Our LPS-1 always blocks low-impedance leakage. And since LPS (linear power supply) units in general do not have much leakage current (high or low impedance), there is usually never a need to ground their outputs. There is the somewhat separate topic of Ethernet switches and grounding of a power supply feeding one. However, if one is feeding an Ethernet switch from an LPS (ours or someone else's), grounding of that supply's zero-volt leg is not useful--unless you are using a specific Ethernet switch (such as the NetGear FS105/108) that John tested and found to also block leakage coming in from other Ethernet devices (by grounding). As for blocking the low-impedance leakage component of SMPS units, for that you need to either use an UltraCap LPS-1 or ditch the SMPS. I defer to John as to if there are actually any low impedance leakage currents making it into a switch from other networked components. I suspect that the magnetics at every EN jack already blocks that. Sorry this is so confusing. --Alex C. gstew and SuperRoo 2 UpTone Audio LLC Link to comment
rickca Posted October 28, 2017 Share Posted October 28, 2017 3 hours ago, Superdad said: 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. This is promising. Is there an SMPS product line that's already grounded with a variety of volts/amps that might help me replace my other SMPS (the ones not powering an LPS-1). Since I don't do DIY and find iFi's $50 kit obscenely priced, this would be great. MikeyFresh 1 Pareto Audio AMD 7700 Server --> Berkeley Alpha USB --> Jeff Rowland Aeris --> Jeff Rowland 625 S2 --> Focal Utopia 3 Diablos with 2 x Focal Electra SW 1000 BE subs i7-6700K/Windows 10 --> EVGA Nu Audio Card --> Focal CMS50's Link to comment
BigGuy Posted October 28, 2017 Share Posted October 28, 2017 14 hours ago, Superdad said: Hi BigGuy: Can you be more specific? a) What power supplies are you using? b) What components are they powering? My post was only discussing SMPS (switch mode power supply) leakage and its relation to our UltraCap LPS-1. Our LPS-1 always blocks low-impedance leakage. And since LPS (linear power supply) units in general do not have much leakage current (high or low impedance), there is usually never a need to ground their outputs. There is the somewhat separate topic of Ethernet switches and grounding of a power supply feeding one. However, if one is feeding an Ethernet switch from an LPS (ours or someone else's), grounding of that supply's zero-volt leg is not useful--unless you are using a specific Ethernet switch (such as the NetGear FS105/108) that John tested and found to also block leakage coming in from other Ethernet devices (by grounding). As for blocking the low-impedance leakage component of SMPS units, for that you need to either use an UltraCap LPS-1 or ditch the SMPS. I defer to John as to if there are actually any low impedance leakage currents making it into a switch from other networked components. I suspect that the magnetics at every EN jack already blocks that. Sorry this is so confusing. --Alex C. Yes, this impedance issue IS confusing so I appreciate you and John having the patience to simplify so more of us can understand. To your questions... One LPS is an old desktop "brick" from HP used to power laptops where I am using the 5V tap to power the ADNACO Glass/USB device <http://www.adnaco.com/products/s3a/> The second is a DIY LPS designed by a member of our audio society. It is adjustable but I am using it to output 9V to a USB dongle similar in concept to the REGEN. Both LPS are AC powered from a PS Audio P300 regenerator. I recognize that John's grounding umbilical is more relevant to SMPS which by nature have more of an impedance issue than LPS but do remember him saying that it could/would help LPS as well. I figured what the hey. Having treated the high impedance component, I was looking to address the low impedance. Thanks. Link to comment
Popular Post JohnSwenson Posted October 28, 2017 Author Popular Post Share Posted October 28, 2017 3 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. 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 relm 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 S. Forehaven, gstew, Cornan and 10 others 6 4 3 Link to comment
lmitche Posted October 28, 2017 Share Posted October 28, 2017 John, WOW what a great explanation of the cause of the mysterious SQ changes we hear so frequently. I even get it. Many thanks! Larry gstew 1 Pareto Audio aka nuckleheadaudio Link to comment
asdf1000 Posted October 28, 2017 Share Posted October 28, 2017 2 hours ago, JohnSwenson said: 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 Hi John, epic explanation. Does this mean even the Intona fails to block high impedance components? gstew 1 Link to comment
Popular Post JohnSwenson Posted October 28, 2017 Author Popular Post Share Posted October 28, 2017 52 minutes ago, Em2016 said: Hi John, epic explanation. Does this mean even the Intona fails to block high impedance components? Yes, that is correct. John S. gstew and asdf1000 2 Link to comment
asdf1000 Posted October 29, 2017 Share Posted October 29, 2017 1 hour ago, JohnSwenson said: Yes, that is correct. John S. Thanks John. I guess the challenge now is how to shunt the high impedance components from a computer's non-grounded SMPS, before it gets to the Intona/ISO REGEN etc. Is the USB adapter that comes with the iFi Groundhog a good solution? Using that in the computer's USB port? Link to comment
sandyk Posted October 29, 2017 Share Posted October 29, 2017 6 minutes ago, Em2016 said: Thanks John. I guess the challenge now is how to shunt the high impedance components from a computer's non-grounded SMPS, before it gets to the Intona/ISO REGEN etc. Many Desktop PC's do have their SMPS grounded. How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file. PROFILE UPDATED 13-11-2020 Link to comment
asdf1000 Posted October 29, 2017 Share Posted October 29, 2017 Just now, sandyk said: Many Desktop PC's do have their SMPS grounded. Laptops with 2-pin plugs don't though (like my Macbook). Of course you can run off batteries but that can be impractical and add cycles to the battery. Link to comment
Popular Post gstew Posted October 29, 2017 Popular Post Share Posted October 29, 2017 John & Alex, Thanks for the great explanations & education on how AC power supply leakage works, how & why it was characterized, why that characterization missed the 'high-impedance' type of leakage, and what you can do to diminish its effects on our audio systems. The wealth of information you've both shared here (and embodied in your products) has made a world of difference in the sound quality of many audio systems, mine VERY much included. Please help me make sure I have understood all of this... First, linear AC-DC power supplies, have only the low-impedance type of leakage, though at various levels based on their 'different LPS implementation'**. AND all SMPSs, by nature of how they function, have both of the low-impedance & VERY high-impedance types of leakage. Uptone Audio LPS-1's (and similar non-AC connected supplies, such as pure battery supplies) do not pass the low-impedance leakage through the power supply feed, whether that leakage originates from an LPS or SMPS. Grounding the negative side of the output of SMPSs effectively eliminates the majority of the high-impedance leakage, preventing it from being passed through to the driven piece, whether to an Uptone LPS-1 or another piece of equipment, such as a network switch. AND grounding the negative side of the power input into one of the tested & confirmed switches (I won't list them here, that list may grow over time) ALONG with proper Ethernet cable connection (currently using alternating jacks, but that also may change over time) will prevent high-impedence leakage from being passed through the switch to downstream connected gear. Have I got it right so far? Next, a few questions. First, there are situations like my systems, where ALL upstream supplies (WiFi router, file server computer, switch, FMCs) and source supplies (player computer, interface cards, DAC, output stages) are linear supplies. AND in the case of the interface cards (RPi I2S isolator and reclocking cards) and DAC, those supplies are LPS-1s. BUT the amps I currently have in my systems are powered by SMPSs. In building / modifying / tweaking these amps several years back, I did find that having the negative output of the power supply grounded produced the best SQ, so they are all configured that way. IS there anything else I should be doing to reduce the effects of leakage currents in my setups? Is it worthwhile converting these amps to use linear supplies (where I can) or going to amps that already use linear supplies (where I cannot convert them)? Or can one not make a blanket statement here? Second, I assume that leakage currents are produced by the AC to DC conversion process in the supply, not anything afterwards. SO in gear that uses switching DC-DC converters (such as most computers, router, switches & FMCs out there), they are not producing any more leakage currents than ones that use linear regulators? (Though they MIGHT be producing more noise on the internal DC supply line, depending on the quality of the DC-DC converter and its implementation?) Third, grounding the negative output of a linear supply does nothing to diminish its low-impedance leakage currents, though it might be helpful in some situations such as when powering one of the recommended switches and using that grounding to block high-impedance leakage from upstream gear being passed to downstream gear, correct? Fourth, leakage from a linear supply and the sonic effects it has is separate and distinct from other qualities of the supply that impact SQ, such as low noise, broad bandwidth, symmetrical response, and wide-band low output impedance? (Which is why supplies such as your JS-2 & Paul Hynes well-regarded supplies still matter, correct?)* Finally, again, thanks for both the great information and great products! Greg in Mississippi *P.S. I wrote up one experience how some of those other quality factors of a linear supply can matter EVEN when energizing LPS-1's, due to how noise they can create can be transmitted via the AC power connection to other supplies in my post here: https://www.computeraudiophile.com/forums/topic/29313-discussions-of-alternate-quotenergizingquotcharging-ps-units-for-use-with-ultracap-lps-1-not-that-any-will-make-any-difference-to-output/?do=findComment&comment=691641 . Note that I heard these differences (and eliminated them) before I even hooked the supplies up to an LPS-1 in the system... they were just plugged into the same outlets as my other gear with nothing connected on their outputs. I just had a related experience, where by chance I received a discarded linear regulated AC-DC adapter that had been dropped and broken open. Looking at it prompted me to crack open up some of the 5V linear regulated adapters I'd purchased from Jameco and apply most of the same techniques I used to quiet my 4x LPS-1 energizing supplies, such as good Schottky diodes, John Swenson's transformer secondary ringing damping snubber, better DC filtering, and filtering on the AC input. What surprised me was the magnitude of the difference I heard replacing 2 stock Jameco 5v supplies (powering sending and receiving FMCs) in one of my systems with the modified ones. Of course, the changes I made should have reduced both the noise fed back to the AC line AND the noise fed to the powered equipment. Hmmm, given what I heard, I really need to try LPS-1's there! We really need a DIY forum on CA for things such as this. Modifying those adapters would not be an easy project for someone with no DIY experience, but a snap for someone who has done at least a little electronics DIY'ing. Alex, would you be ok if I started a separate thread on your sponsored forum to detail those mods? **P.P.S. John, can you point to or further explain what 'different LPS implementation' schemes produced different levels of leakage? Puma Cat and MikeyFresh 2 Everything Matters! 2 systems... Well-Tempered Refs->ET-2.5->DIY or Lounge LCR MkII phono stages Standalone digital Sony HAP Z1-ES or SDTrans384/Soekris DAM DAC Networked digital Zotac PI320-W2 LMS Server -> EtherRegen -> USBBridge Sig -> Katana / Ian GB / Soerkis / Buffalo-IIIPro DACs Passive S&B TX102 TVC or ladder attenuators -> BHK-250 -> Eminent Tech LFT-VIII / IV / VI ALL gear modified / DIY'd; cables MIT; all supplies DIY’d or LPS-1.2s w/HUGE Ultracaps; Audio gear on DIY AC filters + PS Aud P15s; misc gear on separate AC w/filters Link to comment
plissken Posted October 29, 2017 Share Posted October 29, 2017 On 10/27/2017 at 5:38 PM, Superdad said: 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. "Again this is not about measurements. I am under zero obligation to sell our products to hostile people who seek only to defame us." Is this a position you could find yourself climbing down from? Link to comment
Popular Post Superdad Posted October 29, 2017 Popular Post Share Posted October 29, 2017 1 hour ago, gstew said: Please help me make sure I have understood all of this... First, linear AC-DC power supplies, have only the low-impedance type of leakage, though at various levels based on their 'different LPS implementation'**. AND all SMPSs, by nature of how they function, have both of the low-impedance & VERY high-impedance types of leakage. Uptone Audio LPS-1's (and similar non-AC connected supplies, such as pure battery supplies) do not pass the low-impedance leakage through the power supply feed, whether that leakage originates from an LPS or SMPS. Grounding the negative side of the output of SMPSs effectively eliminates the majority of the high-impedance leakage, preventing it from being passed through to the driven piece, whether to an Uptone LPS-1 or another piece of equipment, such as a network switch. AND grounding the negative side of the power input into one of the tested & confirmed switches (I won't list them here, that list may grow over time) ALONG with proper Ethernet cable connection (currently using alternating jacks, but that also may change over time) will prevent high-impedence leakage from being passed through the switch to downstream connected gear. Have I got it right so far? Yes, you got it perfectly! And your clear summary stands well and very helpful alongside what John and I wrote. This sort of stuff should be preserved somewhere to be useful to others. 1 hour ago, gstew said: Next, a few questions.... All GREAT questions and ideas Greg! It's been a long day so answers and I-don't-knows will have to wait a day or so. As usual, you are on the right track. And we are waiting on photos of your wild web of PS wizardry! Happy Sunday my friend, --AJC Puma Cat, gstew and R1200CL 2 1 UpTone Audio LLC Link to comment
jabbr Posted October 29, 2017 Share Posted October 29, 2017 @JohnSwenson nice investigation Help a simple country boy out please: the term “high impedance leakage current” is making me a little dizzy as I try to drink my coffee on this Sunday AM. Impedance isn’t a term normally used to qualify a current so perhaps we should rename this before it takes on a life of its own — you mean “high voltage/impedance” = current ... what is a better term? Also these currents are going to be way more important at higher frequencies. I think if a circuit were made available to precisely illustrate the excellent point you are making here (this is all about parasitic capacitances and inductances) this frequency point will be better illustrated. (Yes— high impedance probes are essential when working with RF) Custom room treatments for headphone users. Link to comment
jabbr Posted October 29, 2017 Share Posted October 29, 2017 or is it this: the solid state “relays”/MOSFET switches in the power supply have very high impedance when “off” and connected to the input SMPS so transmit this leakage? yeah I think these are parasitic capacitances on the package, mosfets etc and really do pass much more current at higher frequencies — and grounding the SMPS does provide a low impedance path to ground. Custom room treatments for headphone users. Link to comment
BigGuy Posted October 29, 2017 Share Posted October 29, 2017 14 hours ago, sandyk said: Many Desktop PC's do have their SMPS grounded. IF the LPS or SMPS is grounded with a 3-prong plug, does this mean a grounding umbilical on the output is superfluous? Any electronic downside to using one even with 3-prong? Link to comment
gstew Posted October 29, 2017 Share Posted October 29, 2017 3 hours ago, jabbr said: @JohnSwenson nice investigation Help a simple country boy out please: the term “high impedance leakage current” is making me a little dizzy as I try to drink my coffee on this Sunday AM. Impedance isn’t a term normally used to qualify a current so perhaps we should rename this before it takes on a life of its own — you mean “high voltage/impedance” = current ... what is a better term? Also these currents are going to be way more important at higher frequencies. I think if a circuit were made available to precisely illustrate the excellent point you are making here (this is all about parasitic capacitances and inductances) this frequency point will be better illustrated. (Yes— high impedance probes are essential when working with RF) @Jabbr, Great minds question alike (except one of them hasn't finished his Dual Bank Floating Supercap Supply DIY board yet... hint, hint!). SO I asked pretty much the same question a few weeks ago: On 10/1/2017 at 10:57 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 AND John gave one of his textbook clear answers... even a DIY tech like myself understood: On 10/2/2017 at 2:19 PM, JohnSwenson said: 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. I hope that helps! Greg in Mississippi Everything Matters! 2 systems... Well-Tempered Refs->ET-2.5->DIY or Lounge LCR MkII phono stages Standalone digital Sony HAP Z1-ES or SDTrans384/Soekris DAM DAC Networked digital Zotac PI320-W2 LMS Server -> EtherRegen -> USBBridge Sig -> Katana / Ian GB / Soerkis / Buffalo-IIIPro DACs Passive S&B TX102 TVC or ladder attenuators -> BHK-250 -> Eminent Tech LFT-VIII / IV / VI ALL gear modified / DIY'd; cables MIT; all supplies DIY’d or LPS-1.2s w/HUGE Ultracaps; Audio gear on DIY AC filters + PS Aud P15s; misc gear on separate AC w/filters Link to comment
Superdad Posted October 29, 2017 Share Posted October 29, 2017 3 hours ago, jabbr said: or is it this: the solid state “relays”/MOSFET switches in the power supply have very high impedance when “off” and connected to the input SMPS so transmit this leakage? yeah I think these are parasitic capacitances on the package, mosfets etc and really do pass much more current at higher frequencies — and grounding the SMPS does provide a low impedance path to ground. MOSFETs where? There are none in the LPS-1. UpTone Audio LLC Link to comment
austinpop Posted October 29, 2017 Share Posted October 29, 2017 Would it be better going forward if we refer to it as “high source impedance” and “low source impedance” noise? My Audio Setup Link to comment
Superdad Posted October 29, 2017 Share Posted October 29, 2017 34 minutes ago, BigGuy said: IF the LPS or SMPS is grounded with a 3-prong plug, does this mean a grounding umbilical on the output is superfluous? No! Just because a PS may have a 3-prong (and actually have that pin connected on the primary side), it does not mean that it is also connecting that ground to its DC zero-volt output side. An example that is the 40 watt Mean Well I posted graphs and a photo of: Unlike the 25W series MW (okay the 7V version is labeled 22W) the GST40A units do come with their C14 AC input ground pin connected to the primary side. But they still need the mod (green wire in my photo or external accomplishment of the same) to shunt the high-impedance leakage back to ground as discussed. See also my overdue reply to @rickca in my next post. Puma Cat 1 UpTone Audio LLC Link to comment
jabbr Posted October 29, 2017 Share Posted October 29, 2017 12 minutes ago, Superdad said: MOSFETs where? There are none in the LPS-1. Haha are you sure? Of course there are What “relays” are you using? Solid state or mechanical? Hint: regardless, the parasitic capacitance in the “open” position determines your “high impedance” circuit Custom room treatments for headphone users. Link to comment
Superdad Posted October 29, 2017 Share Posted October 29, 2017 On 10/27/2017 at 5:49 PM, rickca said: This is promising. Is there an SMPS product line that's already grounded with a variety of volts/amps that might help me replace my other SMPS (the ones not powering an LPS-1). Since I don't do DIY and find iFi's $50 kit obscenely priced, this would be great. Hi Rick: Well the thing is, this is not something that any SMPS manufacturer specifies. And it seems to vary some even within a brand's offerings. So each one has to be tested (VERY easy: Just put a continuity checker across the ground pin--has to be a 3-wire unit of course--and the outer barrel of the output and hope for a beep.) I have bought a few brands through normal distribution but don't thing we can draw any conclusions about who does and does not offer what we seek. I confess that most of my sourcing research is focused on Chinese brands that have low cost models which meet our requirements (or for which the factory is willing to customize for us). I am looking for pieces for $8-15 in quantity, not $22-28 or more. But if anyone comes across units that display continuity (as above), please e-mail me with the brand and model. Even if you don't discover a brand whose whole line is correct for us, maybe there will be a model or two. It's worth knowing. MikeyFresh 1 UpTone Audio LLC Link to comment
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