Low cost high quality excellent performing LPSU for audio.

[One and a half]

8 hours ago, guiltyboxswapper said:

The off-the-shelf medical grade PSUs  whilst have low leakage current, still can't compete subjectively with an OK grade linear PSU in practice.  

 

Hopefully Taiko Audio's switching DC-DC converter will start to put an end to the snobbery that prevents HQ SMPS (of low leakage) being developed for this application.  They too have designed their DC-DC switching frequency well out of the way of typical audio bands.

The main criteria for the power supply does the load require a tight or loose regulation of voltage. 

 

If you can get away with it,  a transformer,  rectifier caps will give you the same regulation for the mains ac supply, with the transformer regulation thrown in. Not precise calcs, this psu will be 5% of voltage out plus minus. That will be bare minimum of noise from the psu itself, since no IC or other chip does any regulation. A choke on the dc side will improve further opposing large sudden variations.

 

DC powered DACs should have some very basic regulation built in, obviating the need for the upstream device to be regulated.

 

Motherboards are a different story and AC powered dacs have their own reasons,  so best not to venture there too deep.

 

DC-DC supplies still switch, for MHz switching conducted noise could be filtered,  but introduces emitted noise from the switching devices and would need to be well shielded.

 

 

[Albrecht]

On 1/7/2021 at 4:30 AM, airguitar said:

Is there such a thing?

 

I truly believe that removing a standard SMPS is the way to go - in my own system it's very obvious listening to the benefit of using Auralic's own LPSU on an Auralic Mini for example. I use the spdif from the Mini into a Metrum Octave v2 DAC - the Metrum is super sensitive to upstream changes - the better the feed the better the sound (bad feeds result in a mushy flat sound in comparison) - so the Metrum is the perfect Canary in the Mine for testing these things out.

 

Some of these 'audiophile' LPSU's are so expensive though. 

 

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

 

Will something like this: https://www.ebay.co.uk/itm/LKS-Linear-power-supply-DC-5V-USB-5V-for-DAC-with-25VA-Talema-transformer-PSU-/272884127978

 

... be good enough? Not just to improve upon an SMPS - but to 'significantly' improve upon a SMPS! I see in audio circles that you can spend a ridiculous amount of money on some PSU's for audio systems - and I do recognise the fact that a quality PSU does make a positive difference.  But I'm looking for another less marketed solution that will be equally as good as well reviewed and well known alternatives if possible like in the example link above.

 

 

Hi,

Not in my opinion.

Simply put, you can’t cut corners. You have a great DAC, - what are your speakers & amp? IMO, - a much bigger difference would be had by replacing the Aurilic. Not sure what you mean be ridiculous, - but $500 is the going rate, and in a system where you have the excellent Metrum, - the differences will be significant. Again, - if you had a DAC like Schitt or something, - you likely wouldn’t need it. The Aurilic Aries Mini, - do you still have one that hasn’t broken yet?, - is a little worse than a Logitech SBT, but lower longevity. 

There are super cheap LPS “wall wort” power supplies that mostly max out at 1 amp for $11 on Jameco ... but... don’t get you much and IME don’t make much difference.

I have owned two Uptone LPSs, 5 Jamecos, 2 TeraDak LPSs, & 2 ZeroZone LPSs. As well as the ifi $50 non-linear. When used on a digital file player, - the TeraDaks and the ZeroZones don’t come any-where near the Uptones. 

IME, - your system and your AC in your home DO make a difference, so, - again, - if you didn’t have a Metrum, the conversation might change....

 

And, - I do think that it would be silly to buy a $500 LPS for a $500 digital file player, - (that sounds worse than any $400 Allo-Razberri Pi that you can buy). Finally, - DC cables are going to make a big difference.. it hurt to pay $100+ for a stupid Cardas DC cable, - but it made a very significant difference,- enough so, - that I found it to be a requirement.

The above only represents my opinion, with my gear, and other “friends” similar systems. Just to clarify as well, I have a lower performing system in my bedroom with Blue Circle integrated, Fritz speakers, a SBT, Chord Mojo, and a ZeroZone LPS. 

Good luck. 

[John769]

On 1/9/2021 at 4:04 AM, One and a half said:

On that ebay LPS-25-USB PSU. Where's the isolation voltage to earth and input to output voltage rating, overvoltage protection on the output? High quality parts mean squat when the basics are missing.

Are you able to notice any obvious anomalies with this one?  Limited viewing from the pics though.

 

https://www.aliexpress.com/i/32966779449.html

[One and a half]

4 hours ago, John769 said:

Are you able to notice any obvious anomalies with this one?  Limited viewing from the pics though.

 

https://www.aliexpress.com/i/32966779449.html

The Leo looks like a well made and neat unit. The R core transformer is a nice touch, these are not cheap. The overpressure level at 0.4V is really overVoltageProtection and that figure is useless unless it is accompanied by a time value (ms usually).

The regulation is 90% chance 3 terminal regulators which do a decent enough job, but since they don't mention LDO (low drop out) regulators, then they would be the standard 78xx model or LM317T. 

The specified use is a router, yes, good choice, but not for audio like a DAC or anything in the signal path, like USB fixer.

 

There's no data sheet or compliance plate fitted to the unit, so it would not comply to any IEC let alone country specific standards, therefore not recommended.

[John769]

@One and a half thanks!

[One and a half]

Often wondered what the differences were for the medical type grade EMC filter and the industry type, so here it is from TDK.

This filter has the built in switch and IEC320 male input as you find on appliances. The data sheet attached to this post.

The standard version has two caps after the choke, their centre point connected to earth (ground), whereas the medical filter does not so its leakage would be far less than the standard version.

Standard would remove quite a lot of Common mode noise, whereas the medical more suited to reducing differential noise. Same with some SMPS falling into the medical grade, how to have low leakage when connecting the two caps to ground is not effective. Need to point out that EMC filters typically reflect the noise back to the source, rather than absorb energy as is.

 

For all TN type AC systems (where the neutral is joined to ground) the E' and N' voltages are very close to one another, depends on how far away from the N-PE occurs. This means the cap from PE' to N' does hardly anything, since the voltage across it is so small. If the L to N were a 60-0-60 supply, then the cap N'-PE' would do a lot more work, this is the main reason for creating a balanced supply was created in the first place.

 

 

B84776.pdf

[guiltyboxswapper]

1 hour ago, One and a half said:

The specified use is a router, yes, good choice, but not for audio like a DAC or anything in the signal path, like USB fixer.

 

I take it you've not heard one in practice..... 

 

I had the revision before of the LEO in 19v format.  It was in a similar ballpark to the Farad Super3 of 19v (which everyone seems to adore on here) powering an Intel NUC, for approx half the cost.  

[One and a half]

2 hours ago, guiltyboxswapper said:

I take it you've not heard one in practice..... 

 

I had the revision before of the LEO in 19v format.  It was in a similar ballpark to the Farad Super3 of 19v (which everyone seems to adore on here) powering an Intel NUC, for approx half the cost.  

No I haven't listened, how to when there's no certificate of compliance? Hmm, that goes for Farad as well.

Anybody can build what they like, it will sound great and work for years, when it comes to conformity and build to rules, and then having it tested, well that's a different story and $$$.

[jabbr]

On 1/17/2021 at 2:35 PM, One and a half said:

The main criteria for the power supply does the load require a tight or loose regulation of voltage. 

 

If you can get away with it,  a transformer,  rectifier caps will give you the same regulation for the mains ac supply, with the transformer regulation thrown in. Not precise calcs, this psu will be 5% of voltage out plus minus. That will be bare minimum of noise from the psu itself, since no IC or other chip does any regulation. A choke on the dc side will improve further opposing large sudden variations.

 

DC powered DACs should have some very basic regulation built in, obviating the need for the upstream device to be regulated.

 

Motherboards are a different story and AC powered dacs have their own reasons,  so best not to venture there too deep.

 

DC-DC supplies still switch, for MHz switching conducted noise could be filtered,  but introduces emitted noise from the switching devices and would need to be well shielded.

 

 

 

This is an excellent point. The simple fact is that well designed digital devices have extensive on board regulation as well as power distribution. 

 

Consider applications that have objectively *extremely* tight noise requirements such as 100gbe NICs that run in bog standard PCs with bog standard ATX supplies. How is this possible? Obviously the NIC itself has an onboard power regulation and noise suppression. The reason to supply these cards with relatively tight voltage is that higher voltage increases the onboard dropout and hence heat.

[guiltyboxswapper]

12 minutes ago, jabbr said:

This is an excellent point. The simple fact is that well designed digital devices have extensive on board regulation as well as power distribution. 

 

 

They do, but they still prefer a cleaned voltage input to work from.

 

13 hours ago, One and a half said:

No I haven't listened, how to when there's no certificate of compliance? Hmm, that goes for Farad as well.

Anybody can build what they like, it will sound great and work for years, when it comes to conformity and build to rules, and then having it tested, well that's a different story and $$$.

Sure, which then renders most products out of scope if you play entirely by those rules. 

 

So what does an audiophile do your case, stick to SMPS only?  

[jabbr]

19 minutes ago, guiltyboxswapper said:

 

They do, but they still prefer a cleaned voltage input to work from.

 

Do they? Actually the devices need to operate with noise levels lower than you or I can measure ... they have this figured out!

 

You could spend $100K on power supplies alone and not achieve the low noise output of my  NIC. 

 

Quote

 

Sure, which then renders most products out of scope if you play entirely by those rules. 

 

So what does an audiophile do your case, stick to SMPS only?  

 

My audio area has a isolating transformer which prevents common mode noise from entering the audio area. The inputs to my audio area are a heavy AC power cable (hospital grade) which supplies my isolation transformer (in my case Equi-tech Q) and a beautiful yellow single mode fiber cable. Thats it!

 

I use fairly standard LPS to supply e.g. 12V to my digital devices. I don't worry too much about low voltage power supplies but use whatever is safe in your region. Many digital devices have a wide range voltage input so you can use *unregulated* linear supplies!

 

My servers, I don't worry about and use standard ATX. The output of these servers is fiberoptic. The fiberoptic NIC cleans the signal quite well. I have used many types of NICs in the past although currently using Mellanox/NVIDIA for most, minimum of 10Gbe because all these are low noise. My NAS has a ConnectX-3, one server a ConnectX-4 and the HQPlayer server a ConnectX-5 NIC. 

 

ConnectX-3 NICs are really really cheap. So are Solarflare and Intel for that matter.

[guiltyboxswapper]

5 minutes ago, jabbr said:

Do they? Actually the devices need to operate with noise levels lower than you or I can measure ... they have this figured out!

 

They can "function" with SMPS noise levels no problem, but you can hear it for sure, audibly, when fed with cleaner independent voltages.  Even lt3045's cant work miracles with noisy SMPS voltages being fed to it.

 

7 minutes ago, jabbr said:

My servers, I don't worry about and use standard ATX. The output of these servers is fiberoptic. The fiberoptic NIC cleans the signal quite well. I have used many types of NICs in the past although currently using Mellanox/NVIDIA for most, minimum of 10Gbe because all these are low noise. My NAS has a ConnectX-3, one server a ConnectX-4 and the HQPlayer server a ConnectX-5 NIC. 

 

ConnectX-3 NICs are really really cheap. So are Solarflare and Intel for that matter.

 

I use Solarflare too; great cards and v.high value no doubt.  But I can also confirm that servers benefit from good linear power too.  The noise makes its way over the fibreoptic NIC no problem it seems. 

 

Especially with HQPlayer I found this was true due to the sheer amount of data one ends up sending via NAA over the network - the effects of the network play a considerable part of the sound signature.  

[jabbr]

7 minutes ago, guiltyboxswapper said:

They can "function" with SMPS noise levels no problem, but you can hear it for sure, audibly, when fed with cleaner independent voltages.  Even lt3045's cant work miracles with noisy SMPS voltages being fed to it.

 

You can't hear the effects of SMPS on a server following a well designed fiberoptic network. By well designed I am using Mellanox NICs and Mellanox SN2700 switch to be exact. YMMV but if you can hear the effects of the server you are doing something wrong.

 

Quote

 

 

I use Solarflare too; great cards and v.high value no doubt.  But I can also confirm that servers benefit from good linear power too.  The noise makes its way over the fibreoptic NIC no problem it seems. 

 

You have a problem with your hardware. The noise cannot make its way across a correctly functioning fiberoptic NIC which is properly conformant see: "Stressed Receiver Test", you may have a counterfeit NIC is this is really the case. 

 

Here (note this was "new" in 2003!): https://www.lightwaveonline.com/optical-tech/article/16649441/10gigabit-ethernet-devices-stressed-by-new-test

Quote

 

Especially with HQPlayer I found this was true due to the sheer amount of data one ends up sending via NAA over the network - the effects of the network play a considerable part of the sound signature.  

 

Yes so you need a correctly functioning network.

[guiltyboxswapper]

1 minute ago, jabbr said:

You can't hear the effects of SMPS on a server following a well designed fiberoptic network. By well designed I am using Mellanox NICs and Mellanox SN2700 switch to be exact. YMMV but if you can hear the effects of the server you are doing something wrong.

 

Well designed fibre equipment can transport noise from the server that's powered from the SMPS.  A typical ATX PSU is operating with tolerances of 1% on their output rails.  A good linear rail even through a DC DC would be closer to 0.1% and more likely 0.01%.  

 

2 minutes ago, jabbr said:

You have a problem with your hardware. 

I wish it was that simple........ its not.

[jabbr]

4 minutes ago, guiltyboxswapper said:

Well designed fibre equipment can transport noise from the server that's powered from the SMPS.  A typical ATX PSU is operating with tolerances of 1% on their output rails.  A good linear rail even through a DC DC would be closer to 0.1% and more likely 0.01%.  

 

I wish it was that simple........ its not.

 

Its not simple but you are having an equipment problem., either that or a comprehension problem: you repeat that fiber can transmit SMPS noise: can you supply some actual measurements of your equipment which supports this? Or another measurement of noise? I don't think you understand the technology.

 

Unless you have something real to discuss, I can't keep arguing with unsupported assertions that go against not only my own experience, but an entire industry which has worked extraordinarily hard to reduce noise. 

[guiltyboxswapper]

1 minute ago, jabbr said:

Its not simple but you are having an equipment problem. 

 

So because I feed my equipment clean power and hear benefits, I have equipment problems?

 

Yeah, I'm done with you.

[jabbr]

2 minutes ago, guiltyboxswapper said:

 

So because I feed my equipment clean power and hear benefits, I have equipment problems?

 

Yeah, I'm done with you.

 

I have no idea what your setup is but it has been well demonstrated that SMPS can inject common mode noise through the AC power lines. Fiberoptic cannot carry common mode noise. You might very well have a "ground loop". That's why I have a very solid isolating transformer at the entry to my audio area, and keep my servers far away from the audio area, connected only by fiber. 

 

My statement that your noise problem is not due to a correctly functioning modern fiberoptic network stands.

[One and a half]

1 hour ago, guiltyboxswapper said:

 

They do, but they still prefer a cleaned voltage input to work from.

 

Sure, which then renders most products out of scope if you play entirely by those rules. 

 

So what does an audiophile do your case, stick to SMPS only?  

For my setup, I need 9V and 5V and both of these are provided by Acopian linear supplies which have accreditation. Not in the same leagues as Sean Jacobs or Paul Hynes as cost goes, they sure do sound better than the ifi smps they replaced.

[audiobomber]

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

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

I use a Teddy Pardo SuperReg 2A power supply with my exaSound DAC. I chose inexpensive Zero-Zone linear power supplies for my Playpoint and sMS-200 streamers, based on positive buzz at diyaudio.com. The cheaper one I use with the sms-200 beats the iPower SMPS for only about $20 more. 

 

While researching linear power supplies, I found advice in a couple of places (which I can't find now), that suggested  going about 15% above the SMPS rating when changing to LPS. The PlayPoint needs 3.3A, so I bought a 4A ZeroZone. The sms-200 calls for 1.5A, the Zero-Zone is 2A. 

 

If you are need to power more than one device in a system, you might also consider the Topping P50 or Allo Shanti.

[Superdad]

On 1/8/2021 at 1:36 PM, Miska said:

This is pretty good one! And doesn't cost much either.

 

https://www.meanwell-web.com/en-gb/ac-dc-medical-desktop-adaptor-output-5vdc-at-6a-ac-gsm60b05--p1j

 

100 milliVolts p-p DC output noise? No thanks.  (Just to give the lay folk perspective, the output noise of the Linear Technology LT3045 is a few microVolts; 100 milliVolts = 100,000 microVolts.)

 

Moreover, all the “medical” grade SMPS units do is reduce the low-source-impedance “touch current” leakage.  They do not at all reduced high-source-impedance leakage. (I can post measurements of such if people wish when I’m back in the office.)

 

Here is a long post on the subject that @JohnSwensonmade a bit over 3 years ago:

 

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 of,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 S.

================== 

 

 

Now besides all that, I will add these points:

 

a) Some of the better quality SMPS units can have lower output impedance—especially at low frequencies—than many of the cheap linear supplies we have seen. And low output broadband output impedance is VERY important for digital audio devices, given the very “bursty” nature of how they draw current.

 

b) Modern Class VI SMPS AC>DC adapters are required to comply with strict standards regarding what they put back into the wall mains. The harmonic switching noise they put back into the wall is extremely high frequency, extremely broadband (at those high frequencies), and extremely low in level. So I think the aversion to SMPS that some audiophiles have based on belief that they pollute the mains is unfounded.

 

c) Most conventional linear power supplies kick quite a lot of harmonics back to the wall—owing to their diode bridges—because they are not drawing current during more than 50% of the AC wave cycle time. This lack of “power factor correction” and the cumulative distortion of the mains is, aside from consumption inefficiency, part of the reason that governments have been trying to regulate out of existence the use of linear AC>DC power supplies.

[As an aside, using a large filter choke—besides making much easier the job of the output regulators—results in a “power factor corrected linear supply. Our own JS-2 is designed this way. Plug a conventional component/LPS into a Kill-A-Watt type device and you’ll see a power factor reading of about .5 (draw over just 50% of waveform); plug our choke-filtered JS-2 in and it will read about 0.97.]

 

Thus the main “evil” of an SMPS for audio is not their mediocre DC output noise nor the spread-spectrum ultrasonics they put into the wall. Rather it is the copious amounts of both high and low frequency leakage currents (common-mode AC traveling over DC connections throughout our audio systems).

 

—Alex C.

 

[plissken]

On 1/10/2021 at 2:49 PM, airguitar said:

The disadvantages of SMPS is they have significantly more noise than linear power supplies.

 

The problem is this is 100% bullshit. There are crap SMPS just as there are crap LPS's.

[plissken]

On 1/23/2021 at 10:35 AM, guiltyboxswapper said:

But I can also confirm that servers benefit from good linear power too.  The noise makes its way over the fibreoptic NIC no problem it seems. 

 

LOL. Oh  boy. The power supplies in servers are very well engineered and low noise. Now there are MANY DC rail direct options for servers and network switches were we have house DC in the data center. But this is to save $$ because AC/DC conversion is not a free process.

[plissken]

On 1/23/2021 at 10:45 AM, guiltyboxswapper said:

Well designed fibre equipment can transport noise from the server that's powered from the SMPS. 

 

It doesn't work that way. This is 100% wishful thinking. As long as the electrical to optical conversion has proper power nothing is going to make it to the other side of the link.

 

I've done muni-fiber with EX optics and we are talking 40km. This is all validated on $16K worth of Fluke.

[guiltyboxswapper]

3 minutes ago, plissken said:

 

It doesn't work that way. This is 100% wishful thinking. As long as the electrical to optical conversion has proper power nothing is going to make it to the other side of the link.

 

I've done muni-fiber with EX optics and we are talking 40km. This is all validated on $16K worth of Fluke.

 

Many on this forum can tell you otherwise.  Guess we all have "faulty equipment".  I can live with that :-) 

[plissken]

Just now, guiltyboxswapper said:

Many on this forum can tell you otherwise.  Guess we all have "faulty equipment".  I can live with that :-) 

 

I'll offer you the same $8000 to your $1000 that you can't tell the difference when blinded that I've offered to the many...