View Full Version : Linear vs Switched mode PSU
I concur with Jez's metaphorical explanation, and was going to post it myself a while ago.
It can be taken further.
The outlet of the water tank can be seen to have a large diameter pipe and the water under the enormous pressure from the tall tank, this being parallel to the O?P of a PS being capable of delivering high current quickly, which will respond to large signals and big transients. (It's O/P impedance is low).
Although mains can be supplied at very high power, the I/P to the tank is in small pulses, those necessary to restore the tank to its 'full' point.
Expectation bias must apply to everyone and in all we do.
We bring to any situation a personal database of our experience which is a 'map' and a survival tool which prepares us.
But it has limits intellectually which in the case of our pursuit, made much worse by the pressure of advertising, which become apparent under scrutiny. Scrutiny also upsets us, often ruining our performance, at least I found this to be very true of me in examinations, the atmosphere of which increased my anxiety greatly.
A man on a gold course who has lost his ball sees a white piece of paper in the distance as his ball, expectation.
Yes we do hear a change most initially, and then we acclimatise, that is also in our biology.
If you put a clamp on your finger and wait, after a few minutes the feeling of it goes, or place your hand in some cold water, the same happens, but on returning to the normal temperature it will now feel hotter.
Entirely plausible...
One has to recognise that expectation bias works BOTH ways, so one can 'expect NOT' to hear a difference, and don't (due to being adversely influenced by one's objective belief system), even if perhaps one exists, just the same as one can 'expect TO' hear a difference (due to being adversely influenced by one's subjective belief system), even if perhaps one doesn't.
Therefore, objectivists don't get the sole right to play the expectation bias card, as ANY human being, no matter their belief system, can be fooled! ;)
Marco.
Nick Gorham over on AT posted this link a few days ago http://www.audio-talk.co.uk/phpBB3/viewtopic.php?f=9&t=6989#p148640 that would appear to back up Arkless own views and a perfect example of why any AB comparison will normally "show" there is no difference between two bits of kit, and so (for example) why all amplifiers sound the same.
Try and see. You'll be quite surprised of the results you get.
anthonyTD
26-07-2017, 09:39
Ahh good old NASA! :D
actually they have, and it wasn't easy
https://www.nasa.gov/sites/default/files/styles/full_width_feature/public/thumbnails/image/187_1003705_americas_dxm.png?itok=NWzaquaC
story here (https://www.nasa.gov/image-feature/nasa-captures-epic-earth-image)
PalsHuffMor
26-07-2017, 09:58
Nick Gorham over on AT posted this link a few days ago http://www.audio-talk.co.uk/phpBB3/viewtopic.php?f=9&t=6989#p148640 that would appear to back up Arkless own views and a perfect example of why any AB comparison will normally "show" there is no difference between two bits of kit, and so (for example) why all amplifiers sound the same.
Try and see. You'll be quite surprised of the results you get.
And Nick goes on to say:
But once you have "seen" it, its very much harder to not see it.
But the meaning (IMHO) of the video is that
Hearing a difference means there is a difference
Not hearing a difference is not proof of the absence of a difference.
I think most of us have been here before... and probably we all have entrenched views. It's illuminating that this thread is also running parallel with the 'myth busters' one.
A blind or double-blind A/B test is still subjective in the cases we are discussing as no test meters etc are involved - just one's ears.
I would suggest it is the only way to discern whether two or more pieces of equipment are different from each other in terms of SQ.
In terms of 'expectation bias' one must realise that scientists in the 'normal Baconian' methods don't show any at the start of the experiment -as they set up what is known as the 'null hypothesis', i.e. that there is NO difference between the two (or more bits of kit/processes etc). This is done as much to help in the inevitable stats test as not wanting to show bias; (yes, I'm aware that the mischievous will say that showing no bias at the start is in it's way a bias of sorts). Science, like democracy, is not perfect, but is the best (many would say only) method we have.
Although I have been 'a scientist' (and yes, research into the efficacy of antibiotics) I, when it comes to hi-fi, am much more of a subjectivist. How many of you have experimented with idiotic notions as: painting a green ring on the inside of CDs (to absorb stray red laser light) and sticking triangular black magnetic paper on two opposite corners of mains plugs (I can't recall the rationale for that)?
I do, however, despite what I have just written, prefer that any perceived, subjective, differences in SQ have some possible scientific explanations. Hardly a crime!
I seem to recall that this original thread was about power supplies and noise injected into the mains...Have we got any further on with that discussion? Are there any firm conclusions/ways forward?
BW
Richard
And Nick goes on to say:
But once you have "seen" it, its very much harder to not see it.
But the meaning (IMHO) of the video is that
Hearing a difference means there is a difference
Not hearing a difference is not proof of the absence of a difference.
Yes agreed but Nick goes on to further say:
Lets say B is actually a better less distorted (or in some way better sounding thing), if we hear A first, and then B, we think we have heard a improvement, so we say, ahh, that sounded better, lets go back to A again. But now we can't unhear the improvement, so now going back to A we still hear what we thought was a improvement going from A to B, and we begin to doubt or first thought. Now we go from A to B again, and still hear no improvement, the more we do it the more it becomes clear that we can't hear any difference, and our first thought of a improvement was false.
Nick Gorham over on AT posted this link a few days ago http://www.audio-talk.co.uk/phpBB3/viewtopic.php?f=9&t=6989#p148640 that would appear to back up Arkless own views and a perfect example of why any AB comparison will normally "show" there is no difference between two bits of kit, and so (for example) why all amplifiers sound the same.
Try and see. You'll be quite surprised of the results you get.
I laughed at this:
Eg,
I listen to amplifier A and it sounds good
I listen to amplifier B and it sounds more detailed "ooh, I haven't heard that triangle before"
I listen to amplifier A and now the triangle I hadn't heard on that amp is there, large as life.
I listen to amplifier B again and now it sounds the same as amplifier A - Bugger!
R
PalsHuffMor
26-07-2017, 10:28
We all hear the difference between A & B in the video on first play.
On subsequent plays, our brains trick us to believe that the difference is no longer there. But, of course, the difference is still there.
It doesn't mean that A/B testing is fundamentally flawed, just that we need to understand how our brains operate.
anthonyTD
26-07-2017, 10:34
:)
We all hear the difference between A & B in the video on first play.
On subsequent plays, our brains trick us to believe that the difference is no longer there. But, of course, the difference is still there.
It doesn't mean that A/B testing is fundamentally flawed, just that we need to understand how our brains operate.
RothwellAudio
26-07-2017, 11:53
Here's the link to the video mentioned above, just in case anyone doesn't want to follow a link to a link.
https://www.theatlantic.com/technology/archive/2014/06/sounds-you-cant-unhear/373036/
Yes, I had a demonstration of this exact phenomenon about 35 years ago and I've never forgotten it. It shows very clearly that judging things by simply listening isn't a simple matter.
Arkless Electronics
26-07-2017, 12:49
The "tragedy" of all this is , to me, that the whole idea of mains cables, fuses, spurs etc making a difference is ridiculous, ludicrous etc and one would have been laughed at for even suggesting any of these things could make a difference only a comparatively short time ago, and quite rightly! (my posts 173 and 207 should I hope convince rational people of this). We have now ended up in a situation where clever marketing, bought reviewers with advertising money to think of, slick salesmen etc have managed to convince the non technical audiophile that the ridiculous and impossible are real and worthwhile... you couldn't make it up! To go back to a medical analogy I used before, it has become so that the average patient has been "brainwashed" into thinking their illness is really caused by "the evil eye" or a demon and myself as "the doctor" is struggling to persuade otherwise rational people that it's actually high blood pressure, diabetes, heart disease or whatever:mental:
PalsHuffMor
26-07-2017, 12:58
The "tragedy" of all this is , to me, that the whole idea of mains cables, fuses, spurs etc making a difference is ridiculous, ludicrous etc and one would have been laughed at for even suggesting any of these things could make a difference only a comparatively short time ago, and quite rightly! (my posts 173 and 207 should I hope convince rational people of this). We have now ended up in a situation where clever marketing, bought reviewers with advertising money to think of, slick salesmen etc have managed to convince the non technical audiophile that the ridiculous and impossible are real and worthwhile... you couldn't make it up! To go back to a medical analogy I used before, it has become so that the average patient has been "brainwashed" into thinking their illness is really caused by "the evil eye" or a demon and myself as "the doctor" is struggling to persuade otherwise rational people that it's actually high blood pressure, diabetes, heart disease or whatever:mental:
So, in that case, anyone who hears a difference from different mains cables, running a dedicated radial etc...is what?
I agree there are some "slick salesmen" and "bought reviewers" out there but they do not attach themselves only to products that do not work...
The "tragedy" of all this is , to me, that the whole idea of mains cables, fuses, spurs etc making a difference is ridiculous, ludicrous etc and one would have been laughed at for even suggesting any of these things could make a difference only a comparatively short time ago, and quite rightly!
What good do you hope to achieve by laughing at people who simply disagree with you, Jez?
What do you think that's likely to solve? Do you think it's respectful to treat people that way, some of whom here may be your customers, and what do you think their reaction will be to your ridicule....? Does it make for creating friendly relations?
You need to stop being so selfish, as to only consider YOU, whilst not giving a damn about anyone else.
Marco.
anthonyTD
26-07-2017, 13:28
The test for me proves that we do actualy hear what we hear,
Ie; when we listen to a piece of equipment that we feel to be very revealing, we hear information within a recording that might otherwise be masked by an inferior version of the same equipment, If we had first heard the piece of equipment that we thought inferior in the begining of the test, then once we heard the better version, we would have realised what we were missing, that is what the test is actualy proving, even though you couldnt make out the words in the first version of the message, once you had heard the original, you could easily identify what was being said in the first version, this is what happens when you compare many things, not just Audio, so why the big deal ?:scratch: I am not sure what this test is meant to prove, all it proved to me is that I actualy do hear the diffrences between diffrent amplifiers, and other pieces of kit.
Here's the link to the video mentioned above, just in case anyone doesn't want to follow a link to a link.
https://www.theatlantic.com/technology/archive/2014/06/sounds-you-cant-unhear/373036/
Yes, I had a demonstration of this exact phenomenon about 35 years ago and I've never forgotten it. It shows very clearly that judging things by simply listening isn't a simple matter.
PalsHuffMor
26-07-2017, 13:33
I, and many others, disagree with Jez on the subject. Many others may, perhaps, agree with Jez. Positions are clear.
We could go round in circles...but, instead, how about a bake off? Switched vs Linear. Jez is invited, of course.
RothwellAudio
26-07-2017, 13:37
The test for me proves that we do actualy hear what we hear,
Ie; when we listen to a piece of equipment that we feel to be very revealing, we hear information within a recording that might otherwise be masked by an inferior version of the same equipment, If we had first heard the piece of equipment that we thought inferior in the begining of the test, then once we heard the better version, we would have realised what we were missing, that is what the test is actualy proving, even though you couldnt make out the words in the first version of the message, once you had heard the original, you could easily identify what was being said in the first version...
Yes, I'm well aware that that is what the demonstration shows. I didn't think it needed explanation.
...this is what happens when you compare many things, not just Audio, so why the big deal ?:scratch: I am not sure what this test is meant to prove, all it proved to me is that I actualy do hear the diffrences between diffrent amplifiers, and other pieces of kit.
It's meant to prove that the order in which you audition things makes a difference.
RothwellAudio
26-07-2017, 13:39
how about a bake off? Switched vs Linear.
Because a simple SMPS vs. linear test using just one piece of kit wouldn't be sufficient to draw general conclusions.
...but, instead, how about a bake off? Switched vs Linear.
Love to!
Just as soon as I can get someone to finish off my part built 'magic foo sounding' LPSU. Of course it needs to be done by someone who is a 'believer' so as to add the magic ingredient. :lol: :) Until then I'm an agnostic.
I, and many others, disagree with Jez on the subject. Many others may, perhaps, agree with Jez. Positions are clear.
We could go round in circles...but, instead, how about a bake off? Switched vs Linear. Jez is invited, of course.
That's a perfectly good suggestion, Chris, and one I'd personally be up for.
My point was that *no-one* here gets to laugh at anyone, simply because they think differently or have different experiences, and anyone who disagrees can find another forum to post on, as I simply won't permit that type of intolerant behaviour.
Marco.
RothwellAudio
26-07-2017, 13:45
... I simply won't allow that kind of intolerant behaviour.
You mean you're intolerant? :eyebrows:
Yes, intolerant towards 'intolerants'! ;)
Marco.
PalsHuffMor
26-07-2017, 13:47
Love to!
Just as soon as I can get someone to finish off my part built 'magic foo sounding' LPSU. Of course it needs to be done by someone who is a 'believer' so as to add the magic ingredient. :lol: :) Until then I'm an agnostic.
I imagine there are plenty of us who could bring along a Linear supply or two, but if you have the one with the 'magic foo' inside then we clearly need to wait...:lol:
RothwellAudio
26-07-2017, 13:54
It still doesn't address the fact that a limited scope test won't prove very much. It would be like comparing one pair of reflex loudspeakers with one pair of infinite baffle loudspeakers and then declaring that one type was better than the other.
Arkless Electronics
26-07-2017, 13:55
What good do you hope to achieve by laughing at people who simply disagree with you, Jez?
What do you think that's likely to solve? Do you think it's respectful to treat people that way, some of whom here may be your customers, and what do you think their reaction will be to your ridicule....? Does it make for creating friendly relations?
You need to stop being so selfish, as to only consider YOU, whilst not giving a damn about anyone else.
Marco.
I was pointing out the general consensus of professional informed opinion would, certainly, only 20 or so years ago, to find the idea of mains related issues affecting sound quality laughable. I agree with this and I have provided scientific argument to back my claims that it is impossible.
If my following scientific rigour rather than fairy tales puts off my customers then that's absolutely fine. If actually selling stuff was my main object I would jump on the bandwagon and start making mains cables, foo distribution panels etc etc. I would prefer to never sell anything than do this!
Arkless Electronics
26-07-2017, 13:57
Love to!
Just as soon as I can get someone to finish off my part built 'magic foo sounding' LPSU. Of course it needs to be done by someone who is a 'believer' so as to add the magic ingredient. :lol: :) Until then I'm an agnostic.
The offer still stands.... but it will always be that until I have it in front of me I can't say whether it will be one or six hours labour...
Arkless Electronics
26-07-2017, 13:58
Yes, intolerant towards 'intolerants'! ;)
Marco.
Same here.
Its all subjective folks.
You know, when comparing different kit the brain can be a funny thing? :)
https://www.theatlantic.com/technology/archive/2014/06/sounds-you-cant-unhear/373036/
PalsHuffMor
26-07-2017, 14:01
Because a simple SMPS vs. linear test using just one piece of kit wouldn't be sufficient to draw general conclusions.
I wouldn't want to get carried away with thinking that one bake off would demonstrate everything one way or another. More the start of expanding our listening experience and skills...
But, any process has to start, somewhere, and somehow. What would you suggest?
anthonyTD
26-07-2017, 14:02
Well, then I will have to disagree with that, a diffrence heard is still a diffrence, which ever version you hear first!
It's meant to prove that the order in which you audition things makes a difference.
Same here.
It's YOU who's the intolerant one here, no-one else., as no-one else is telling YOU how you should think!
If you want to post such anti-subjectivist views, then do it on your sticky thread, which is why you were given it. Do not pollute the rest of the forum with your arrogant, blinkered, objectivist bullshite!
Now I suggest you leave it there or you'll be out for a week, and that includes any back-chat from you to this post, which will simply be deleted, along with the immediate issuing of a one-week ban.
Marco.
RothwellAudio
26-07-2017, 14:29
I wouldn't want to get carried away with thinking that one bake off would demonstrate everything one way or another. More the start of expanding our listening experience and skills...
But, any process has to start, somewhere, and somehow. What would you suggest?
Good question. I'll have to give it some thought.
A couple of years ago on the HUG forum I argued with A.S. about AB comparisons as follows.
He argued that only under controlled level conditions of 0.1 dB could we be sure to validly hear differences, but I disagreed on the grounds that substantial differences, were audible on casual listening.
I cited a 1950s farmer going to 'the smoke' and calling into a Hi-Fi shop, sitting down and listening. On return to his home farm he said to his peers; "I 'eard one of them Oi-Fois yesterday, bloomin' amazing, I want one of them."
This was in the context of his life-long listening to MW.
The point is the degree of difference between the two under consideration; if large it can be heard casually, but as it tends to zero much more rigorous testing is required, and it must take into account the type of listener, because our experiences will affect our abilities.
I also think that sometimes when we listen casually we can hear more because we are relaxed, the process of intense analytical listening can sabotage our attempts to perceive, as in the anxiety of an interview compromising our performance.
I want to add that if a bake-off is arranged between two items, which items are chosen is of great importance.
I could include a linear supply with ten stages of pi C/L s, followed by a several stage stabiliser with a massive storage cap.
Someone could also supply a cheap SMPS costing a 20th for comparison. Would that be a fair comparison of technologies/
Since SMPS were I think evolved to cut cost, this is a difficult comparison.
I also think that sometimes when we listen casually we can hear more because we are relaxed, the process of intense analytical listening can sabotage our attempts to perceive, as in the anxiety of an interview compromising our performance.
I never listen for differences. My modus operandi is to make a substitution and just play some music. If there is a noticable difference (and one tha tis important to me), I will hear it whether I want to or not - it will just 'leap out'. I then have to decide if the difference is an improvement or not. If it is an improvement the item stays, but I will revert back to the original item after a week or so, just to make sure the improvement was genuine. There have been a few occasions when what I though was an improvement was not; it was merely a difference.
Arkless Electronics
26-07-2017, 14:48
I, and many others, disagree with Jez on the subject. Many others may, perhaps, agree with Jez. Positions are clear.
We could go round in circles...but, instead, how about a bake off? Switched vs Linear. Jez is invited, of course.
It seems that everyone has missed the fact that my ENTIRE ARGUMENT is that is not whether the DC voltage comes from a SMPS or linear supply that matters but how that voltage is dealt with AFTER it has left the PSU. If it's not "dealt with" at all ie no further filtering and no linear regulator after the PSU then I would expect a linear REGULATED supply to win every time unless the circuitry being powered had exceptional PSRR. It needs to be understood that provided the post PSU circuitry to filter and smooth (plus usually regulate) the voltage is done well it matters not one jot how "bad" or "polluted" etc the voltage from the PSU is.
AFAIK some of Alans Firebottle valve phono stages use SMPS actually internally and yet they are very well thought of;) Likewise Chord and some Linn gear.
I am not for one second saying that any SMPS will power any piece of hi fi equipment and give the same sound quality. What I am saying is that a well implemented use of a SMPS, with suitable filtering etc, will then equal a linear supply.
To answer the obvious question here, no you can't tell which pieces of equipment have suitable post PSU circuitry to make the choice of PSU irrelevant without suitable knowledge of electronics. An in-line unit betwixt SMPS and equipment being powered could be built to act as a suitable filter and could have a linear regulator inside. Jobs a gud 'n.
SMPS are vastly more complicated than a linear supply and designing a good one is a real "black art". However, once put into mass production on a big scale the lack of large quantities of copper and iron (vastly less used) and the lack of need for huge smoothing capacitors etc means they can be much cheaper than a linear supply.
Recall what I said about the non availability of anything but SMPS as wallwarts, and often in-line PSU's nowadays and all this becomes a big issue!
Consider something like a phono stage, active line stage (DAC's etc too but I don't make them) etc. It can be powered by a 24V 1A SMPS wallwart which I can buy for about £7-10... If a customer says "no I insist on a linear regulated supply" then I would have to build it from scratch. The parts would cost me say £30-60, a nice looking case another £20-30 and labour maybe £100 -£200. If this linear regulated supply was being made in China in the thousands then it could be only £30 compared to the £7 of the SMPS.... but it's not... and to have a suitable PSU hand built as a one-off by an engineer costs as outlined above....
So far, personally, the only time I've used a SMPS for any item of hi-fi equipment was for that buffer I built for Jerry a couple of months ago. I charged him £75 for this. It sounds great and there is no background noise from it. The alternative of a Linear regulated PSU would have made this more like £250 and it is doubtful whether any audible improvement would come from this in this case.
I myself developed and tested a SMPS for use inside a budget valve phono stage (actually a switch mode DC-DC converter but it's kind of the same thing) in exactly the same way as Alan has for his kit and if I was making a < £6-700 unit this is what I would use.
How do you think all the cheaper (and mainly Chi-fi) valve equipment powered from a wallwart works? As above!
Arkless Electronics
26-07-2017, 15:03
A couple of years ago on the HUG forum I argued with A.S. about AB comparisons as follows.
He argued that only under controlled level conditions of 0.1 dB could we be sure to validly hear differences, but I disagreed on the grounds that substantial differences, were audible on casual listening.
I cited a 1950s farmer going to 'the smoke' and calling into a Hi-Fi shop, sitting down and listening. On return to his home farm he said to his peers; "I 'eard one of them Oi-Fois yesterday, bloomin' amazing, I want one of them."
This was in the context of his life-long listening to MW.
The point is the degree of difference between the two under consideration; if large it can be heard casually, but as it tends to zero much more rigorous testing is required, and it must take into account the type of listener, because our experiences will affect our abilities.
I also think that sometimes when we listen casually we can hear more because we are relaxed, the process of intense analytical listening can sabotage our attempts to perceive, as in the anxiety of an interview compromising our performance.
I want to add that if a bake-off is arranged between two items, which items are chosen is of great importance.
I could include a linear supply with ten stages of pi C/L s, followed by a several stage stabiliser with a massive storage cap.
Someone could also supply a cheap SMPS costing a 20th for comparison. Would that be a fair comparison of technologies/
Since SMPS were I think evolved to cut cost, this is a difficult comparison.
They were originally developed for military and aerospace use and at the time would have been vastly more expensive than a linear supply. A linear supply is typically about 60% efficient (less if regulated) whereas a SMPS can be 90%+ efficient*. Combine this with it being possible to make a SMPS around ten times lighter in weight and similarly smaller in size and you can see why the military etc wanted them!
* BTW SMPS ARE regulated by their very nature but it's very poor regulation compared to a linear regulator. A linear regulator can be used after a SMPS as well as after a "linear" PSU of course.
PalsHuffMor
26-07-2017, 15:11
I am not for one second saying that any SMPS will power any piece of hi fi equipment and give the same sound quality. What I am saying is that a well implemented use of a SMPS, with suitable filtering etc, will then equal a linear supply.
Thank you for clarifying, Jez. I think that is very helpful.
To answer the obvious question here, no you can't tell which pieces of equipment have suitable post PSU circuitry to make the choice of PSU irrelevant without suitable knowledge of electronics...
Or we could use our ears :D
anthonyTD
26-07-2017, 15:49
:)
And from my own experience, and repairing kit that use SMPS over the years, equipment can sound and perform very well, As Jez has stated, what is after the raw DC element is very, very important, and where the biggest diffrences in sonics will be noticed, however; For me, my prefrence would still be with linear Supplies through out my system, and that is purely down to the aditional generation of noise Point.
It seems that everyone has missed the fact that my ENTIRE ARGUMENT is that is not whether the DC voltage comes from a SMPS or linear supply that matters but how that voltage is dealt with AFTER it has left the PSU. If it's not "dealt with" at all ie no further filtering and no linear regulator after the PSU then I would expect a linear REGULATED supply to win every time unless the circuitry being powered had exceptional PSRR. It needs to be understood that provided the post PSU circuitry to filter and smooth (plus usually regulate) the voltage is done well it matters not one jot how "bad" or "polluted" etc the voltage from the PSU is.
AFAIK some of Alans Firebottle valve phono stages use SMPS actually internally and yet they are very well thought of;) Likewise Chord and some Linn gear.
I am not for one second saying that any SMPS will power any piece of hi fi equipment and give the same sound quality. What I am saying is that a well implemented use of a SMPS, with suitable filtering etc, will then equal a linear supply.
To answer the obvious question here, no you can't tell which pieces of equipment have suitable post PSU circuitry to make the choice of PSU irrelevant without suitable knowledge of electronics. An in-line unit betwixt SMPS and equipment being powered could be built to act as a suitable filter and could have a linear regulator inside. Jobs a gud 'n.
SMPS are vastly more complicated than a linear supply and designing a good one is a real "black art". However, once put into mass production on a big scale the lack of large quantities of copper and iron (vastly less used) and the lack of need for huge smoothing capacitors etc means they can be much cheaper than a linear supply.
Recall what I said about the non availability of anything but SMPS as wallwarts, and often in-line PSU's nowadays and all this becomes a big issue!
Consider something like a phono stage, active line stage (DAC's etc too but I don't make them) etc. It can be powered by a 24V 1A SMPS wallwart which I can buy for about £7-10... If a customer says "no I insist on a linear regulated supply" then I would have to build it from scratch. The parts would cost me say £30-60, a nice looking case another £20-30 and labour maybe £100 -£200. If this linear regulated supply was being made in China in the thousands then it could be only £30 compared to the £7 of the SMPS.... but it's not... and to have a suitable PSU hand built as a one-off by an engineer costs as outlined above....
So far, personally, the only time I've used a SMPS for any item of hi-fi equipment was for that buffer I built for Jerry a couple of months ago. I charged him £75 for this. It sounds great and there is no background noise from it. The alternative of a Linear regulated PSU would have made this more like £250 and it is doubtful whether any audible improvement would come from this in this case.
I myself developed and tested a SMPS for use inside a budget valve phono stage (actually a switch mode DC-DC converter but it's kind of the same thing) in exactly the same way as Alan has for his kit and if I was making a < £6-700 unit this is what I would use.
How do you think all the cheaper (and mainly Chi-fi) valve equipment powered from a wallwart works? As above!
Apologies for going somewhat off topic....
..The Government has just announced the banning of diesel and petrol-driven cars from 2040 and thus we will all need electric cars to replace them. It takes at present about 8 hours to charge a car 'battery' and that this will take place mainly after the rush hour...ie in the evening when most of us, I assume, listen to hi-fi. Will the charging units be SMPS? Won't there be a significant drop in mains voltage? I wonder what effect, if any, it will have on SQ---always assuming that mains noise has a negative effect on SQ (!).
BW
Richard.
Arkless Electronics
26-07-2017, 16:15
:)
And from my own experience, and repairing kit that use SMPS over the years, equipment can sound and perform very well, As Jez has stated, what is after the raw DC element is very, very important, and where the biggest diffrences in sonics will be noticed, however; For me, my prefrence would still be with linear Supplies through out my system, and that is purely down to the aditional generation of noise Point.
I fully agree that it is preferable to have a linear supply. It's better to have very little noise in the first place than to have to go to all the time and trouble to filter it out. Also linear supplies are much more reliable than SMPS and vastly easier to repair if they go wrong. (SMPS generally best regarded as throw away if they go wrong unless an integral part of an expensive piece of kit)
However.... when we're talking £10 for the SMPS or £250 for the linear supply it is then quite an incentive to go to the time and trouble to filter and smooth the SMPS! And, if well implemented, the SMPS should then equal the linear supply for SQ.
The 60% efficiency of a linear (often less) V the 80-95% efficiency of a SMPS means we are increasingly finding SMPS the only choice, as the green bureaucrats increasingly get their way. Hence we will have to live with SMPS noise and get good at filtering it out well enough so it can match a linear supply.
:)
And from my own experience, and repairing kit that use SMPS over the years, equipment can sound and perform very well, As Jez has stated, what is after the raw DC element is very, very important, and where the biggest diffrences in sonics will be noticed, however; For me, my prefrence would still be with linear Supplies through out my system, and that is purely down to the aditional generation of noise Point.
What does 'additional generation of noise point' mean please?
I like to think pictorially and I found the block diagram in this article very useful (http://www.radio-electronics.com/info/power-management/linear-power-supply-psu/basics-tutorial.php) in understanding things (even though I imagine some here will object to some of the narrative). Are you saying that less noise is generated by the transformer in a LPSU vs. a switching PSU?
@Jez, from your explanation it would seem that an optimum audio PSU would be an SMPS but with well built smoothing and regulation most often found in LPSUs. Correct?
If so perhaps I can simply just take the output from my existing SMPS and route it via the Paul Hynes smoothing/regulators I have. thereby skipping the transformer I have. Not sure what the rectifier circuit on the board would do with a DC input. Rectify it to AC?
I'm hopeless in understanding all this but I'm trying. :)
anthonyTD
26-07-2017, 16:28
:)
I fully agree that it is preferable to have a linear supply. It's better to have very little noise in the first place than to have to go to all the time and trouble to filter it out. Also linear supplies are much more reliable than SMPS and vastly easier to repair if they go wrong. (SMPS generally best regarded as throw away if they go wrong unless an integral part of an expensive piece of kit)
However.... when we're talking £10 for the SMPS or £250 for the linear supply it is then quite an incentive to go to the time and trouble to filter and smooth the SMPS! And, if well implemented, the SMPS should then equal the linear supply for SQ.
The 60% efficiency of a linear (often less) V the 80-95% efficiency of a SMPS means we are increasingly finding SMPS the only choice, as the green bureaucrats increasingly get their way. Hence we will have to live with SMPS noise and get good at filtering it out well enough so it can match a linear supply.
Arkless Electronics
26-07-2017, 16:29
Apologies for going somewhat off topic....
..The Government has just announced the banning of diesel and petrol-driven cars from 2040 and thus we will all need electric cars to replace them. It takes at present about 8 hours to charge a car 'battery' and that this will take place mainly after the rush hour...ie in the evening when most of us, I assume, listen to hi-fi. Will the charging units be SMPS? Won't there be a significant drop in mains voltage? I wonder what effect, if any, it will have on SQ---always assuming that mains noise has a negative effect on SQ (!).
BW
Richard.
Yup they are already and will in the future be SMPS. VERY powerful ones! The cars themselves use switch mode control of the motors and do this at powers of 100KW+.... and as I've already mentioned many mains regenerators are SMPS and, in effect, a class D amplifier is a SMPS!
Then there is the SMPS that are used with domestic and industrial solar panels and wind generators to make DC or varying frequency AC into 240V AC and synchronise it with the grid.... at kilowatt and megawatt levels! They're everywhere!!
When properly designed though there is nothing to fear from them;)
anthonyTD
26-07-2017, 16:52
Hi Edward,
I meant the added noise generated by SMPS over a standard linear supply.
Sorry for any confusion.
What does 'additional generation of noise point' mean please?
I like to think pictorially and I found the block diagram in this article very useful (http://www.radio-electronics.com/info/power-management/linear-power-supply-psu/basics-tutorial.php) in understanding things (even though I imagine some here will object to some of the narrative). Are you saying that less noise is generated by the transformer in a LPSU vs. a switching PSU?
@Jez, from your explanation it would seem that an optimum audio PSU would be an SMPS but with well built smoothing and regulation most often found in LPSUs. Correct?
If so perhaps I can simply just take the output from my existing SMPS and route it via the Paul Hynes smoothing/regulators I have. thereby skipping the transformer I have. Not sure what the rectifier circuit on the board would do with a DC input. Rectify it to AC?
I'm hopeless in understanding all this but I'm trying. :)
Arkless Electronics
26-07-2017, 16:56
What does 'additional generation of noise point' mean please?
I like to think pictorially and I found the block diagram in this article very useful (http://www.radio-electronics.com/info/power-management/linear-power-supply-psu/basics-tutorial.php) in understanding things (even though I imagine some here will object to some of the narrative). Are you saying that less noise is generated by the transformer in a LPSU vs. a switching PSU?
@Jez, from your explanation it would seem that an optimum audio PSU would be an SMPS but with well built smoothing and regulation most often found in LPSUs. Correct?
If so perhaps I can simply just take the output from my existing SMPS and route it via the Paul Hynes smoothing/regulators I have. thereby skipping the transformer I have. Not sure what the rectifier circuit on the board would do with a DC input. Rectify it to AC?
I'm hopeless in understanding all this but I'm trying. :)
To hugely simplify things.. the faster the switching occurs the more noise it generates. The slower the switching the less efficient it will be. Linear supplies (we should really be calling them something else, such as conventional supplies, as they are far from linear! Linear regulator is accurate though) operate at mains frequency of 50Hz but switch at the top and bottom of each cycle so generate raw DC as pulses at 100Hz ie on and off 100 times a second. This is super slow motion in electronics terms! SMPS switch at around 100KHz ie 100,000 times a second and great effort is put into making each switching action as rapid as possible in order to get the best efficiency and the least waste heat.
Due to the above SMPS generate much more noise than a linear supply. However, it's at ultrasonic frequencies (above audibility unless you're a bat), whereas a linear supply generates noise at very audible frequencies.
I'm not saying that the "optimum audio PSU would be an SMPS but with well built smoothing and regulation most often found in LPSUs" no, but I am saying that with "well built smoothing and regulation most often found in LPSUs", correctly applied, they can be just as good as LPSU's.
Voltage regulators require a headroom of voltage above that wanted from their outputs. The minimum allowable being called the drop out voltage, as if it goes below this the regulator drops out of regulation. It will usually continue to give a voltage output but it will be all over the place! To use your existing SMPS you would have to be able to turn up its output to around 7-8V in order to regulate this down to 5V by a linear regulator. You would also have to bypass the rectifier as they only convert AC to DC, not the other way round. It could simply be removed and it's connections bypassed. If your SMPS can be turned up to 8V then it's easily doable but as you already have the mains transformer and case etc it makes sense to use it:)
To hugely simplify things..
<snip>
Sorry, yes I did mean 'well built .... as often found in LPSUs'.
No I was not actually suggesting I use an SMPS and direct its output to the Hynes regulators boards - just theorising for the purposes of understanding things. Your answer was yes so helpful.
So, if I may sum up in a simple way?
A PSU that is well built and most importantly has quality smoothing/regulation will be just the same as another PSU of similar quality build regardless if linear or switching mode. However in practice switching PSUs are often not as well built as linear PSUs leading to the general observation that linear PSUs are 'better'.
Perhaps that simplifies things too much for your taste but are those two sentences accurate as they stand?
Arkless Electronics
26-07-2017, 18:09
Sorry, yes I did mean 'well built .... as often found in LPSUs'.
No I was not actually suggesting I use an SMPS and direct its output to the Hynes regulators boards - just theorising for the purposes of understanding things. Your answer was yes so helpful.
So, if I may sum up in a simple way?
A PSU that is well built and most importantly has quality smoothing/regulation will be just the same as another PSU of similar quality build regardless if linear or switching mode. However in practice switching PSUs are often not as well built as linear PSUs leading to the general observation that linear PSUs are 'better'.
Perhaps that simplifies things too much for your taste but are those two sentences accurate as they stand?
Basically yes. It takes rather more thought and effort to get the SMPS as quiet as the linear supply but yes it can be done by suitable smoothing and filtering and especially by then adding a linear regulator after that.
Most applications for power supplies are nowhere near as sensitive to these issues as hi fi equipment and most are intended for generic universal use ie supplying 12V for a printer or phone or router or lights etc etc. Unless specifically designed for very low noise etc by the addition of the means above, a universal linear regulated supply will be much quieter and better regulated than a universal SMPS.
If the PSRR of the equipment being powered is superb then it may sound the same whether the horrible noisy SMPS is used or the super duper linear regulated one.
Many/most items such as DAC's phono stages, etc that have an external PSU will have a voltage regulator built in and at least a little smoothing, meaning that so long as the SMPS is at least a decent one it should give the same results as a linear one.
El cheapo gear without even an internal voltage regulator will be very sensitive to the PSU quality.
Unregulated linear PSU's, especially of the wallwart variety (no room for really big smoothing capacitor), are the noisiest of the lot and instead of the SMPS's 0.005V of 100KHz noise will often have a volt or so of very audible 100Hz noise!
So, if I may sum up in a simple way?
A PSU that is well built and most importantly has quality smoothing/regulation will be just the same as another PSU of similar quality build regardless if linear or switching mode. However in practice switching PSUs are often not as well built as linear PSUs leading to the general observation that linear PSUs are 'better'.
Perhaps that simplifies things too much for your taste but are those two sentences accurate as they stand?
Edward, you need to be careful that you have taken one persons opinion and turned it into a statement of fact.
Arkless Electronics
26-07-2017, 19:19
Edward, you need to be careful that you have taken one persons opinion and turned it into a statement of fact.
... 'cos obviously on the subject of electronics, the opinions of accountants, brick layers, bakers, solicitors etc etc who have read a few "Hi-Fi Answers" magazines and been on hi fi forums for a while are equally valid to those of electronic engineers specialising in audio electronics for decades who design and repair hi fi equipment professionally....:doh: I guess if you were ill you'd enlist the help of some bloke who saw the first 3 episodes of "Holby City" rather than a doctor?:D Obviously their opinions on medicine would be equally valid....
You couldn't make it up.
The thing is....
Not all EE's agree on the best way to do things. :)
Is there perhaps an element of 'art' in the Design that goes beyond raw specifications?
Is this where keeping an open mind (engineering curiosity!) advances the established current best?
No doubt all current EE theory is sound, but is there an additional 'art' to design that advances the state of the art?
Your 640P phonostage is maybe a good example of this?
For myself, an illustration might be in having a Haynes Manual for my Car does in no way convey what its like to own and drive it?
Theres an art to design that goes beyond specifications.
As one who does it professionally myself I've seen this in a lot of different walks of life, hifi included.
Just sayin' fella :)
RothwellAudio
26-07-2017, 21:12
The thing is....
Not all EE's agree on the best way to do things. :)
And neither do all doctors, but there tends to be a general consensus.
Is there perhaps an element of 'art' in the Design that goes beyond raw specifications?
Yes, there's an art to it whether you go beyond raw specifications or not. There are many ways to skin a cat and there are many cats to be skinned in an amp design. There are obvious ways to do things and less obvious ways. In adds up to art in my opinion. In fact, one of the classic electronics textbooks is called The Art Of Electronics (by Horowitz and Hill).
Edward, you need to be careful that you have taken one persons opinion and turned it into a statement of fact.
Oh, I did not realise I was making a statement of fact, just summing up my understanding in as few words as possible.
Anyway for me this discussion seems to have arrived at a point where my takeaway is that generally linear PSUs are 'better' than switching PSUs for audio stuff - because they are generally better built. So, perhaps, a LPSU will give me an improvement in sound?
Oh, I did not realise I was making a statement of fact, just summing up my understanding in as few words as possible.
Anyway for me this discussion seems to have arrived at a point where my takeaway is that generally linear PSUs are 'better' than switching PSUs for audio stuff - because they are generally better built. So, perhaps, a LPSU will give me an improvement in sound?
Avoid switchmode supplies if you can, in consumer level hifi they are normally built down to a price (or indeed, the whole feckin thing,...by committee)
As Jez said, it takes a lot of work to get a switchmode supply to sound good, so best to spend a wee bit more and hit the sensible middle ground.
I think engineering is an art, and there are some very good people who illustrate this; T. De Paravacini, and Nelson Pass for eg, both of whom 'push the envelope'.
Electronics uses science to innovate and implement designs, which, when they are demonstrably successful and good, become folklore as established designs and tend to become regarded as science.
Oscar Wilde said that all art is quite useless, and that anything which is useful cannot be art, and this I really take issue with.
Engineering solutions to me can have immense beauty in form and function.
Avoid switchmode supplies if you can, in consumer level hifi they are normally built down to a price (or the whole feckin thing by committee)
As Jez said, it takes a lot of work to get a switchmode supply to sound good, so best to spend a wee bit more and hit the sensible middle ground.
Ah thanks for that Gaz. Yes very happy to pay a wee bit more to hit the middle ground. Jez originally advised me that I would not hear any difference by moving to a LPSU. See post #1 of this thread. :)
Ah thanks for that Gaz. Yes very happy to pay a wee bit more to hit the middle ground. Jez originally advised me that I would not hear any difference by moving to a LPSU. See post #1 of this thread. :)
Jez knows his stuff for sure, and as he (rightly) has said before,,, power supply is important. :thumbsup:
The mains power supply is where your music comes from, dont compromise!
... 'cos obviously on the subject of electronics, the opinions of accountants, brick layers, bakers, solicitors etc etc who have read a few "Hi-Fi Answers" magazines and been on hi fi forums for a while are equally valid to those of electronic engineers specialising in audio electronics for decades who design and repair hi fi equipment professionally....:doh: I guess if you were ill you'd enlist the help of some bloke who saw the first 3 episodes of "Holby City" rather than a doctor?:D Obviously their opinions on medicine would be equally valid....
You couldn't make it up.
Being a scientist by profession I am well used to consulting with experts thanks.
In seeking an expert to design a good sounding bit of Hi-Fi for me, I would not turn to one who is incapable of hearing differences between mains cable or interconnects.
Other people may not be concerned by this, and that's their prerogative.
walpurgis
26-07-2017, 22:48
Surely a scientist would want to investigate the potentially unlikely scenario of mains cables making a difference?
southall-1998
26-07-2017, 22:59
You lot really crack me up sometimes!
S.
Infinitely Baffled
26-07-2017, 23:11
but, instead, how about a bake off? Switched vs Linear. Jez is invited, of course.
Great idea! Or what about this ... we could paint a door and all watch it dry.
For heaven's sake, listen to the music not the power supply.
IB
Arkless Electronics
27-07-2017, 11:30
Ah thanks for that Gaz. Yes very happy to pay a wee bit more to hit the middle ground. Jez originally advised me that I would not hear any difference by moving to a LPSU. See post #1 of this thread. :)
That is still my advice. The particular application you want to use it for is not even very sensitive to its power supply.
Arkless Electronics
27-07-2017, 11:38
Jez knows his stuff for sure, and as he (rightly) has said before,,, power supply is important. :thumbsup:
The mains power supply is where your music comes from, dont compromise!
IFthe processing after the PSU is good enough then no the mains power supply does not matter one jot. Remember it comes into the PSU as spikes of current in the first place!
If you are not in a position to know how resilient against PSU issues your equipment is, and also not in a position to do anything to improve the situation by adding filtration etc (as I guess most lay person hi fi users will not be) then yes get a good PSU.
If a SMPS is chosen at the design stage then suitable smoothing and filtration will be part of the design and it will work just as well as a linear supply;)
RothwellAudio
27-07-2017, 11:56
Great idea! Or what about this ... we could paint a door and all watch it dry.
For heaven's sake, listen to the music not the power supply.
IB
I agree. Don't let an obsession with minutiae get in the way of enjoying the music.
Due to the above SMPS generate much more noise than a linear supply. However, it's at ultrasonic frequencies (above audibility unless you're a bat), whereas a linear supply generates noise at very audible frequencies.
Just a thought but could this not be the reason why users swapping to linear supplies from SMPS report an improvement in sound quality? That is to say the introduction of noise in the audible bandwidth from the linear is generating a perceived improvement in sound quality?
For example It has been postulated that so-called 'grounding boxes' by Entreq and others actually improve subjective sound quality by picking up RFI and introducing it into the signal path.
Reducing noise and distortion may be the path to High Fidelity but higher noise and distortion can subjectively improve the listening experience. (c.f 'vinyl vs digital').
What Jez isn't talking about is how ultrasonic frequencies can cause modulation effects (IMD), which can fold down into the audio band. I do believe his own gear would be immune to such things.
Interesting related read here:
https://www.resolutionmag.com/wp-content/uploads/2016/02/Noise-in-power-supplies-Part2.pdf
MrRadish
27-07-2017, 12:46
My experience is that high frequency noise affects digital equipment the most and is probably why there's been a revival in vinyl formats (not the only reason admittedly). I've heard too many digital systems with messed up treble (including my own for a while) for it to be coincidence, and the background noise of vinyl is much easier to live with. Now I've filtered it all properly my digital gear sounds much cleaner, sweeter and purer than my record player. As soon as I stick a poor SMPS (such as my router's wallwart) into the same power zone it all goes to pot.
For a long time my iphone and other portable digital gear sounded vastly better than my big rig, just because it ran off batteries.
Arkless Electronics
27-07-2017, 13:54
Just a thought but could this not be the reason why users swapping to linear supplies from SMPS report an improvement in sound quality? That is to say the introduction of noise in the audible bandwidth from the linear is generating a perceived improvement in sound quality?
For example It has been postulated that so-called 'grounding boxes' by Entreq and others actually improve subjective sound quality by picking up RFI and introducing it into the signal path.
Reducing noise and distortion may be the path to High Fidelity but higher noise and distortion can subjectively improve the listening experience. (c.f 'vinyl vs digital').
A voltage regulator after the raw supply removes all the 100Hz from the linear supply. It is far less good at removing the very high frequencies from a SMPS and these are much better dealt with by passive L-C-R filtering. Going a touch off topic here but high quality discrete "super regulators" can be orders of magnitude better than the cheap 78xx series and LM317 etc 3 pin regulators found in most equipment. The latter work great at mains frequencies but are falling off in performance by 1KHz or so (still very useful out to 10-30KHz) whereas the best super regulators will work fine to 100KHz+ and still give useful performance out to a MHz or so. They also have much lower noise etc. The penalty being cost... An LM317 can be about 20P but a good discrete regulator more like £50! The best discrete super regulators can offer lower noise, lower output impedance and better regulation than even a lorry battery!
Probably in some cases there is a genuine improvement when going over to a linear regulated supply because the SMPS in use was a crap one and the circuitry being powered had poor PSRR. I'm sure that in many other examples it will be good old expectation bias though...
To try and bring all this to some sort of conclusion, I am not a fan of SMPS but they can give results just as good as a linear PSU under the right conditions. For sensitive low level audio this means usually that the equipment is designed to use a SMPS and has suitable filtration, smoothing etc to render the HF noise irrelevant. Some applications such as computers, routers, hubs, and most digital applications will be fine with a SMPS as they are inherently pretty immune to the noise anyway. They also themselves generate noise of a similar nature to that from SMPS!
Power amps can often give better results with a SMPS than with a linear PSU as in most cases, due to the high powers involved and the expense of building a regulator for such power levels, power amps tend to use unregulated PSU's and a linear one will have a volt or more of 100Hz mains interference and fairly poor regulation. A few power amps which do use proper linear regulated supplies are Naim NAP250 and similar models in the range, Quad 303 and a few Radford SS amps from late '60's early 70's such as the SPA50. The "worlds best power amps" Halcro power amps use SMPS!!
It needs to be said also that SMPS vary hugely as to how good they are! The wallwart one I used for that buffer a short while measured as having only 3mV of noise. An excellent result! Some others may have 100mV. Caveat emptor... Take your oscilloscope along when buying one:D
Arkless Electronics
27-07-2017, 14:29
My experience is that high frequency noise affects digital equipment the most and is probably why there's been a revival in vinyl formats (not the only reason admittedly). I've heard too many digital systems with messed up treble (including my own for a while) for it to be coincidence, and the background noise of vinyl is much easier to live with. Now I've filtered it all properly my digital gear sounds much cleaner, sweeter and purer than my record player. As soon as I stick a poor SMPS (such as my router's wallwart) into the same power zone it all goes to pot.
For a long time my iphone and other portable digital gear sounded vastly better than my big rig, just because it ran off batteries.
My advice is the exact opposite of everything said above. Remember all PC's are powered by a hefty but cheaply made SMPS anyway! Also digital electronics produce just about as much noise as a SMPS does! Digital electronics have huge "noise immunity" by virtue of it working as 1's or 0's. The greater the voltage difference between a 1 and a 0 the greater the noise immunity. Typically the noise immunity will be around 2V or so meaning an interference "spike" or random noise/whatever would need to be 2V or greater for a false 1 to be caused where a 0 should be.
MarginWalker
28-07-2017, 18:15
Has this thread changed anyone's opinion? It reads exactly the same as every 'do cables make a difference' and 'are all DACs the same' thread I have ever read and it all seems an it pointless to me
Has this thread changed anyone's opinion? It reads exactly the same as every 'do cables make a difference' and 'are all DACs the same' thread I have ever read and it all seems an it pointless to me
I don't think it is a question of opinion. What I took away was that SMPS are fine, even superior in some situations, 'linear' better in others, it's complicated and it depends on other, external factors. I didn't know that before. Plus good power supply rejection and regulation is important for sound quality. Which I did know before but not in a technical way.
I don't think it is a question of opinion. What I took away was that SMPS are fine, even superior in some situations, 'linear' better in others, it's complicated and it depends on other, external factors. I didn't know that before. Plus good power supply rejection and regulation is important for sound quality. Which I did know before but not in a technical way.
Same here, my takeaway is that both SMPS and LPSUs have their uses for different applications and probably does not make much difference for SQ, assuming high quality materials being used.
But I'm still curious to try things out and as I have all the stuff for a high quality LPSU build will likely still go ahead. This probably means I will just do it myself - need to learn to solder though! Can't be that hard surely? :mad: :)
Powered by vBulletin® Version 4.2.3 Copyright © 2026 vBulletin Solutions, Inc. All rights reserved.