View Full Version : Mythbusters does Hi-Fi.
Arkless Electronics
20-07-2017, 19:20
Or at least this mythbuster, singular, will:)
First somewhat of a lengthy introductory preamble to "set out my stall".... It was suggested in a thread a few days ago that I put my "foo fighters" hat on and set straight some of the myths in hi fi. This being a "subjectivist friendly" site I presumed Marco would not wish me to go ahead with this here on AOS.... but I have exchanged PM's with Marco on the matter and he's all for it!
Hi Fi is a vast subject which encompasses many engineering disciplines such as analogue electronic engineering, digital electronic engineering, mechanical engineering and acoustics etc. My own area of expertise is analogue electronic engineering, and it is within this field that most of my "lecture" shall be aimed. "Lecture"? Well yes.. rather than a debate as such this is me offering information, fact and a smidgeon of opinion based on decades of professional EE experience, so if you feel the need to add that you tried a "foomaster MkII green pen" on your CD's and it "literally transformed" the sound quality then please don't bother...:D
Once upon a time hi fi was a mainly technical hobby. Back in the '50's and '60's many people built their own gear from kits, or from scratch based on articles in the likes of "Wireless World " and "Practical Wireless" etc, and people tended to have a much greater knowledge of electronics than in today's much broader based hobby.
The likes of Donald Aldous, Angus Mackenzie and Stanley Kelly ruled the roost in hi fi reviewing and were highly competent engineers in their own right. Anyone suggesting that fuses, mains cables etc could effect the sound would have been dismissed as a lunatic as swiftly as someone claiming to speak to fairies at the bottom of the garden....
Today the majority buy "black boxes" and form a system from them in which everything beneath the covers is regarded as "here be dragons".
Electronics is a complicated subject.... and not a particularly intuitive one to many people. This makes it fertile breeding ground for myth and suspicions to be put in the minds of the largely non technical end users of hi-fi equipment. Many of these can be traced back to specific marketing ploys in the dim and distant past.. some not so distant! Many others to people adding 2+2 and making 5 and then telling enough people about it...
In these days of forums and the internet, Chinese whispers can travel very quickly and unfortunately become entrenched until they become "common knowledge" and even "accepted wisdom"... despite in many cases being QUITE WRONG.
It has sadly come to the stage where, if I may make a clumsy medical analogy, we were once in an age of enlightenment where scanners were coming into use, computers making a difference, new and effective drugs coming into use on a monthly basis... and then we get to where we are now... where due to Chinese whispers on the internet etc, lay people have once again started to believe in "unbalance of choleric and melancholy", "the evil eye" or "demons needing releasing" to such an extent that an experienced doctor telling them this is just old wives tales is regarded as a quack by his patients!
I shall, if readers will indulge me, attempt to bust a few of these myths, explain where others are true but only in certain cases, some true but likely to have such a small effect as to be unnoticeable, some wrong other than in a very specific case etc etc.
As promised elsewhere earlier I shall start with switch mode V linear regulated PSU's...
Wakefield Turntables
20-07-2017, 19:33
Great idea but I still feel that there are those of us that are prepared to listen and ponder your musings to try and understand our hobby (that's me), those that don't give a shit, and those that will say your theories are incorrect and they are in fact correct. Sounds like you've a hard gig coming up. I think your barking completely up the wrong tree if your trying to flog more gear, personally I wouldn't bother and just let your equipment do the talking.
Hurrah!
Have at it Jez. Pleased you've started this thread.
I see it as welcome relief from mains cable n fuse threads and as one of laymen of which you speak, if I learn a bit tech then all the better.
Arkless Electronics
20-07-2017, 20:04
Great idea but I still feel that there are those of us that are prepared to listen and ponder your musings to try and understand our hobby (that's me), those that don't give a shit, and those that will say your theories are incorrect and they are in fact correct. Sounds like you've a hard gig coming up. I think your barking completely up the wrong tree if your trying to flog more gear, personally I wouldn't bother and just let your equipment do the talking.
I'm certainly not going it to flog gear!! How very dare you:D Just not something I would do;) Many of the myths came about from people wanting to shift more kit in the first place! From techno babble marketing people etc.... If anything I'll be risking treading on the toes of those who continue propagating certain myths for financial gain I suppose:eek:
A hard sell well yes.. The biggest problem maybe that if the myths came about from peoples lack of technical knowledge then they probably won't understand the rebuttal of the myth... and/or if myth came from technobabble then the myth may sound as plausible to the lay person as the rebuttal does!
Arkless Electronics
20-07-2017, 20:06
Hurrah!
Have at it Jez. Pleased you've started this thread.
I see it as welcome relief from mains cable n fuse threads and as one of laymen of which you speak, if I learn a bit tech then all the better.
Oh don't think fuses and mains cables won't be tackled :D
walpurgis
20-07-2017, 20:24
Oh don't think fuses and mains cables won't be tackled :D
Ah. You'll have some nice fancy upmarket ones to recommend then? ;)
Floyddroid
20-07-2017, 20:44
Slightly unfare methinks especially when there are other desingners/manufacturers out there who spot vitriolic shite whilst infering their designs are superior to others. I think this article by Jez i a cool one. I for one will be following it.:D
Great idea but I still feel that there are those of us that are prepared to listen and ponder your musings to try and understand our hobby (that's me), those that don't give a shit, and those that will say your theories are incorrect and they are in fact correct. Sounds like you've a hard gig coming up. I think your barking completely up the wrong tree if your trying to flog more gear, personally I wouldn't bother and just let your equipment do the talking.
Oh don't think fuses and mains cables won't be tackled :D
I expect nothing less..
Floyddroid
20-07-2017, 21:04
Speaking as one with very little knowledge of electronics apart from the most very basic elements and one of the gulable fools who in the past spent silly money on mains cables, interconnects and their likes i welcome the wisdom of someone like Jez who in the past has worked for one of the largest UK Hi-Fi manufacturers and walked due to having a consience. Start of a good thread is this.
Wakefield Turntables
20-07-2017, 21:14
Slightly unfare methinks especially when there are other desingners/manufacturers out there who spot vitriolic shite whilst infering their designs are superior to others. I think this article by Jez i a cool one. I for one will be following it.:D
No! Have you actually properly gone through my post? I support Jez and if I didn't care I wouldn't post.
willbewill
20-07-2017, 21:45
Thanks for the thread - looking forward to the myths getting busted.:goodthread:
Looking forward to having some myths busted. Also hope Jez you will give some hints as to what does improve sound.
Sent from my SM-N910F using Tapatalk
walpurgis
20-07-2017, 22:35
Thanks for the thread - looking forward to the myths getting busted.:goodthread:
Or verified? :)
Thanks for this thread Jez, I will be following it with great interest.
Often wondered whether there was any truth in a lot of the"tweaks" you mentioned so am glad someone like you has taken up this challenge.
Arkless Electronics
22-07-2017, 12:51
After some thought I have decided that before going into the subject of SMPS, the bigger picture of power supplies in general needs tackling. I often see all sorts of confusion, false assumptions and 2 + 2=5 going on regarding power supplies (PSU's) so going back to basics is probably a good start. Some foundations are required before heading off in any specialised areas...
narabdela
22-07-2017, 14:42
Fantastic idea Jez!
Put your hard hat on and go for it, it's going to be a bumpy ride. :clap:
Arkless Electronics
22-07-2017, 17:23
Sorry if this is patronising to many but to begin with I'll assume zero knowledge on the part of the reader...
So what is a power supply and what qualities do we want from it?
Everything powered by the mains needs a PSU (power supply unit) and even in the case of battery power, the batteries are then the power supply. A PSU is NOT only an external box which supplies power to another piece of equipment. It will often be built into the equipment and even in the case of an external PSU there will often be more circuitry associated with the power supply within the main unit.
The perfect power supply will give a precise DC voltage which does not vary under any circumstances and has zero noise superimposed on the DC.
Imagine a perfect 10V DC PSU. The 10V output would not vary with time, temperature, incoming mains voltage (if it's mains powered of course) and most importantly it will not vary with the current being drawn from it by the load.
This last quality is known as a PSU's regulation. All PSU's, even batteries, have as one of their characteristics their regulation but this is not the same thing as having a voltage regulator... other terms such as the "stiffness" of a supply, its internal resistance, source resistance or source impedance all refer to basically the same thing. The perfect supply has 0% regulation, meaning infinitesimally low internal resistance. This means it would maintain exactly 10V whether it had no load on it or 1000 Amps being drawn from it. Think of the 10V being 10 foot of rope. It should stay 10 foot exactly even with 1000kg weight hanging of it. (I shall use analogy here and there to try and make things easier to grasp so apologies for the clumsiness of some of them! In this case the less than perfect rope would stretch to more than 10' but the less than perfect supply "sags" under the load and gets to be less than 10V...)
Why is it so important that a PSU be "stiff", have excellent regulation etc?
Imagine an amplifier with 3 stages of amplification, typically that means that at it's most basic we have 3 transistors (or valves) each with a particular gain (amplification factor). Lets say each has x 10 amplification so in total we have 10x10x10 = 1000 x amplification of the input signal.
Now the problem is that an amplifier has more inputs than just the one labelled "input"... The point where each of the 3 stages takes its power from the PSU is also an "input", of much less sensitivity than the actual input but present nonetheless. Imagine that a 1mV signal in the form of a kick drum beat from a cartridge is the input. This will be amplified 1000 x and appear at the output as a 1V kick drum beat. The final stage obviously has the biggest signal as it's amplified by 10 by each stage and to give this 1V signal out the final stage must draw the most current from the PSU.
If the PSU has poor regulation, ie is not "stiff" and has a high source resistance, then the 10V from the PSU will drop to lets say 9.9V in sympathy with the drum beat... The first stage is being powered from the same PSU and so it also experiences this drop down to 9.9V. The original 10V minus the drop to 9.9V gives us in effect another signal to the first stage of 10-9.9=0.1V or 100mV, 100 x more than the 1mV actual input from the cartridge! This will mainly appear at the output of the first stage, forgoing its x 10 amplification but still then being amplified by 100 x by the two following x10 stages.... In a severe case such as the example given we get "howl round" in the same way as a mic too close to the speaker in a PA system, but of course all happening in the electrical domain rather than via sound. (it would most often be at an ultrasonic frequency beyond even bat hearing in practice).
Noise on the DC Voltage gets into the circuitry by the same method.... Note. In electronics "noise" refers to anything present which should not be there but is not related to the signal. So we mean mains hum at 50Hz, the frequency doubled rectification products at 100Hz, clicks pops, hiss etc etc
Now, depending on circuit topology, real amplifier stages vary hugely in how susceptible to the above problems they are... in the degree to which their power input is also a signal input if you like. This gives us a figure called Power Supply Rejection Ratio, or PSRR. As a brazen generalisation, the simplest "purest" circuits with the fewest parts tend to have the worst PSRR (with the exception of a simple triode valve stage, which can have a useful degree of PSRR inherent to it. Still not that good in this respect though) and much more complicated circuitry is needed to give better inherent PSRR. Op amps tend to have extremely good PSRR.
At the two extremes a very simple purist input stage for a very high gain circuit like a phono stage could require a really superb PSU to even work without obvious mains hum, hiss and pops and a state of the art PSU to sound really good. whereas at the other extreme some op amp circuitry could be powered by a really crap PSU with poor regulation and loads of noise and yet be impervious to it.
It is important at this stage to point out that even in the case of the super sensitive phono stage example, if it had an external PSU as it often would, this PSU may not need to be particularly super-duper as filtering and smoothing , followed by a voltage regulator, would usually be inside the main phono stage and, if well implemented, can remove the noise and add the "stiffness" and excellent regulation we need at Point Of Load (POL) ie at the actual place we need it and often as physically close to this point as possible. An alternative but not good practice method used by some designers is to make the external PSU super duper good and forgo the filtering and regulation at POL. Now it can probably be easily seen that in the first case the quality of the external PSU is completely uncritical and could be expected to make little or no difference to sound quality or anything else.... In the second case the quality of the external PSU would be absolutely critical!!
I guess the concept of obtaining good regulation by means of active voltage regulation using a voltage regulator circuit (or IC) needs tackling next... and unfortunately the concept of dynamic source resistance ie source impedance will also have to be dealt with, which I'm not looking forward to trying to explain!:eek:
Sorry to technical types for all the ifs, buts, caveats etc I've glossed over or not mentioned but this is aimed at the layman.
I'll let folks absorb that and answer any questions arising, things needing clarification etc before moving on:)
anthonyTD
22-07-2017, 17:37
Good start Jez :)
A...
Arkless Electronics
22-07-2017, 18:02
Good start Jez :)
A...
Ta. It ain't easy as an EE to know just how much to simplify it, which areas people have the most difficulty understanding etc. This was really brought home to me the other day round at a mates house. He has a pair of Heybrook HB3's of mine on "permanent" loan and had placed some tapes on top of one. I pointed out that there are magnets on the backs of the speaker drive units and it may damage his cassettes. Now this mate of mine, who is a VERY clever chap but knows nowt about electronics, said to me "but aren't they only magnetic when the amps switched on and playing music"..... That's what I'm potentially up against!:eek:
anthonyTD
22-07-2017, 18:11
:eek:
Mind you, in the old days, with mains energised types,[or to put it correctly, types that used the smoothing choke as the magnet] he'd have had a point!:D
Ta. It ain't easy as an EE to know just how much to simplify it, which areas people have the most difficulty understanding etc. This was really brought home to me the other day round at a mates house. He has a pair of Heybrook HB3's of mine on "permanent" loan and had placed some tapes on top of one. I pointed out that there are magnets on the backs of the speaker drive units and it may damage his cassettes. Now this mate of mine, who is a VERY clever chap but knows nowt about electronics, said to me "but aren't they only magnetic when the amps switched on and playing music"..... That's what I'm potentially up against!:eek:
I think I'm following so far.
Agreed! Looking forward to Part II. :)
Arkless Electronics
22-07-2017, 19:13
Agreed! Looking forward to Part II. :)
Yer a bleedin' EE yerself IIRC you don't need it explaining Barry!
Arkless Electronics
22-07-2017, 19:14
Added another paragraph to that first bit.
Infinitely Baffled
22-07-2017, 19:17
Very good, Jez! A scorching start. You must have done this before?
I have a Q: in your example the " sag" in power supply stiffness had the effect of introducing a false signal of 0.1v at the first of the three amplification stages. Given that all three amplification stages run off the same power supply, they will - as you mentioned - all be experiencing the same sag. Does that mean that stage 2 and stage 3 will also be introducing their own false signals, compounding the one introduced at stage 1? And those false signals all get amplified in each subsequent stage they pass through? It's a wonder there is any audible music signal left!
IB
Sorry if this is patronising to many but to begin with I'll assume zero knowledge on the part of the reader...
So what is a power supply and what qualities do we want from it?
Everything powered by the mains needs a PSU (power supply unit) and even in the case of battery power, the batteries are then the power supply. A PSU is NOT only an external box which supplies power to another piece of equipment. It will often be built into the equipment and even in the case of an external PSU there will often be more circuitry associated with the power supply within the main unit.
The perfect power supply will give a precise DC voltage which does not vary under any circumstances and has zero noise superimposed on the DC.
Imagine a perfect 10V DC PSU. The 10V output would not vary with time, temperature, incoming mains voltage (if it's mains powered of course) and most importantly it will not vary with the current being drawn from it by the load.
This last quality is known as a PSU's regulation. All PSU's, even batteries, have as one of their characteristics their regulation but this is not the same thing as having a voltage regulator... other terms such as the "stiffness" of a supply, its internal resistance, source resistance or source impedance all refer to basically the same thing. The perfect supply has 0% regulation, meaning infinitesimally low internal resistance. This means it would maintain exactly 10V whether it had no load on it or 1000 Amps being drawn from it. Think of the 10V being 10 foot of rope. It should stay 10 foot exactly even with 1000kg weight hanging of it. (I shall use analogy here and there to try and make things easier to grasp so apologies for the clumsiness of some of them! In this case the less than perfect rope would stretch to more than 10' but the less than perfect supply "sags" under the load and gets to be less than 10V...)
Why is it so important that a PSU be "stiff", have excellent regulation etc?
Imagine an amplifier with 3 stages of amplification, typically that means that at it's most basic we have 3 transistors (or valves) each with a particular gain (amplification factor). Lets say each has x 10 amplification so in total we have 10x10x10 = 1000 x amplification of the input signal.
Now the problem is that an amplifier has more inputs than just the one labelled "input"... The point where each of the 3 stages takes its power from the PSU is also an "input", of much less sensitivity than the actual input but present nonetheless. Imagine that a 1mV signal in the form of a kick drum beat from a cartridge is the input. This will be amplified 1000 x and appear at the output as a 1V kick drum beat. The final stage obviously has the biggest signal as it's amplified by 10 by each stage and to give this 1V signal out the final stage must draw the most current from the PSU.
If the PSU has poor regulation, ie is not "stiff" and has a high source resistance, then the 10V from the PSU will drop to lets say 9.9V in sympathy with the drum beat... The first stage is being powered from the same PSU and so it also experiences this drop down to 9.9V. The original 10V minus the drop to 9.9V gives us in effect another signal to the first stage of 10-9.9=0.1V or 100mV, 100 x more than the 1mV actual input from the cartridge! This will mainly appear at the output of the first stage, forgoing its x 10 amplification but still then being amplified by 100 x by the two following x10 stages.... In a severe case such as the example given we get "howl round" in the same way as a mic too close to the speaker in a PA system, but of course all happening in the electrical domain rather than via sound. (it would most often be at an ultrasonic frequency beyond even bat hearing in practice).
Noise on the DC Voltage gets into the circuitry by the same method.... Note. In electronics "noise" refers to anything present which should not be there but is not related to the signal. So we mean mains hum at 50Hz, the frequency doubled rectification products at 100Hz, clicks pops, hiss etc etc
Now, depending on circuit topology, real amplifier stages vary hugely in how susceptible to the above problems they are... in the degree to which their power input is also a signal input if you like. This gives us a figure called Power Supply Rejection Ratio, or PSRR. As a brazen generalisation, the simplest "purest" circuits with the fewest parts tend to have the worst PSRR (with the exception of a simple triode valve stage, which can have a useful degree of PSRR inherent to it. Still not that good in this respect though) and much more complicated circuitry is needed to give better inherent PSRR. Op amps tend to have extremely good PSRR.
At the two extremes a very simple purist input stage for a very high gain circuit like a phono stage could require a really superb PSU to even work without obvious mains hum, hiss and pops and a state of the art PSU to sound really good. whereas at the other extreme some op amp circuitry could be powered by a really crap PSU with poor regulation and loads of noise and yet be impervious to it.
Sorry to technical types for all the ifs, buts, caveats etc I've glossed over or not mentioned but this is aimed at the layman.
I'll let folks absorb that and answer any questions arising, things needing clarification etc before moving on:)
Yer a bleedin' EE yerself IIRC you don't need it explaining Barry!
My post was in support of what Anthony said.
Yes, I spent 30 years working at an electronocs research laboratory, but my work there was in the design of microwave components (mostly filters) for radar and communications systems. My understanding of electronic circuitry is somewhat basic, and is largely what was taught to me for my undergraduate physics degree.
Arkless Electronics
22-07-2017, 19:28
My post was in support of what Anthony said.
Yes, I spent 30 years working at an electronocs research laboratory, but my work there was in the design of microwave components (mostly filters) for radar and communications systems. My understanding of electronic circuitry is somewhat basic, and is largely what was taught to me for my undergraduate physics degree.
Aha a plumber:eyebrows:
Aha a plumber:eyebrows:
Not necessarily, though my first filter design was about 5' long and had to handle a peak power of 1 Megawatt. My second design though required a microscope for assembly! ;)
Arkless Electronics
22-07-2017, 19:35
Very good, Jez! A scorching start. You must have done this before?
I have a Q: in your example the " sag" in power supply stiffness had the effect of introducing a false signal of 0.1v at the first of the three amplification stages. Given that all three amplification stages run off the same power supply, they will - as you mentioned - all be experiencing the same sag. Does that mean that stage 2 and stage 3 will also be introducing their own false signals, compounding the one introduced at stage 1? And those false signals all get amplified in each subsequent stage they pass through? It's a wonder there is any audible music signal left!
IB
Yes that's spot on Gary:) Then it it's stereo and all stages are working from one supply.....
I'll throw a spanner in the works by saying that it all happens at t'other end of each stage as well... ie where each stage goes to earth... which is why good grounding practice is critical in hi fi and sometimes regarded as a "black art"... but that's for another day and the pub is beckoning me right now:D
Arkless Electronics
22-07-2017, 19:41
Not necessarily, though my first filter design was about 5' long and had to handle a peak power of 1 Megawatt. My second design though required a microscope for assembly! ;)
Yeah such a different field of electronics it makes the brain hurt that they're part of the same subject... I recall hand tuning interdigital microwave filters on Duroid whilst monitoring S parameters on a VNA in a previous life but I wouldn't pretend any design expertise in that field:)
PalsHuffMor
22-07-2017, 19:51
I am a mere 'consumer', so I won't be attempting to 'follow'. I will never have the breadth or depth of knowledge, or practical experience required to comment authoritatively about the technical merits of a component, so I will leave that to 'the experts'. True, some designers / manufacturers may impress me more than others when communicating their philosophy, but that's as deep as I go. Going by some of the stuff I have read online, applying just a little knowledge to some people is akin to 'activating an idiot'. I don't want to fall into that trap myself and I would rather we didn't create any more of them.
My 'skill' in this area is knowing whether something sounds 'right' to me, and only, of course, compared to what I have heard before. Hearing as many different bits of gear as possible is therefore my aim. In addition to perceived sound quality, the other issue I care passionately about is value for money. Does component quality and sound quality justify the price being charged? 'Mythbusting', for me, is about debunking the marketing BS and rip-off pricing that afflicts so much of the hifi market. I welcome anyone who can help with that...
I am a mere 'consumer', so I won't be attempting to 'follow'. I will never have the breadth or depth of knowledge, or practical experience required to comment authoritatively about the technical merits of a component, so I will leave that to 'the experts'. True, some designers / manufacturers may impress me more than others when communicating their philosophy, but that's as deep as I go. Going by some of the stuff I have read online, applying just a little knowledge to some people is akin to 'activating an idiot'. I don't want to fall into that trap myself and I would rather we didn't create any more of them.
My 'skill' in this area is knowing whether something sounds 'right' to me, and only, of course, compared to what I have heard before. Hearing as many different bits of gear as possible is therefore my aim. In addition to perceived sound quality, the other issue I care passionately about is value for money. Does component quality and sound quality justify the price being charged? 'Mythbusting', for me, is about debunking the marketing BS and rip-off pricing that afflicts so much of the hifi market. I welcome anyone who can help with that...
Oh I'm sure there will be plenty to say about that! :D
montesquieu
23-07-2017, 00:51
Good stuff Jez. Will there be a test at the end?
And an NVQ in Foo-bashing?
I am a mere 'consumer', so I won't be attempting to 'follow'. I will never have the breadth or depth of knowledge, or practical experience required to comment authoritatively about the technical merits of a component, so I will leave that to 'the experts'....
Neither will I but it doesn't mean I don't want to learn. The saying 'A little knowledge is a dangerous thing' is only applicable if you are going to jump in feet first and do something practical. Having a basic grasp of how something works is desirable, not something to be avoided.. I have never understood why people want to walk around with blinkers on. If you want to understand what is bullshit in hi-fi - and yes there is a lot of it - how can you do that if you don't have a scooby how it really works?
To paraphrase something I read on another forum, 'People either assume hi-fi electronics is much more complex than it really is, or assume it is much simpler than it really is, and that is the problem.'
If you want to understand what is bullshit in hi-fi - and yes there is a lot of it - how can you do that if you don't have a scooby how it really works?
By using your ears and experimenting with all manner of different equipment and ancillaries over the years, in different contexts, trying different things often dismissed as "foo", to ascertain whether they work or not, and learning from your mistakes, thus amassing sufficient experience, enabling you to 'sort out the wheat from the chaff', or rather determine what's "bullshit" or not... ;)
That seems to have worked rather well for me!
Seriously though, I totally *get* where you're coming from and agree, but the problem is you can't MAKE yourself become interested in something that bores you to tears... I've tried getting into the technical side of hi-fi, and whilst some of the basic stuff has stuck, most of it is too much hard work to fathom. Quite simply, my brain doesn't really work that way.
That's why I leave most of the 'techy stuff' to the experts whom I trust to make my equipment, and simply concentrate on enjoying the fruits of their labours, and most importantly, the effect it has on my appreciation of recorded music. However, that doesn't mean I can't sometimes question their decisions or have some input in what they do.
At the end of the day though, we're all different people, with different talents and skill sets, and none of us in this hobby are required to be technically knowledgeable in order to have a valid opinion or be considered as 'worth listening to', especially when discussion topics are of a subjective nature. Most importantly, no-one should feel 'inadequate' simply because they don't know one end of an oscilloscope from another.
The reality is that ALL of us here has something to offer, based on what we've learned from the practical experience we've gained over the many years we've been into this hobby - and in the process may have learned things that some experts haven't! :eyebrows:
In short, we can ALL learn from each other, by sharing our experiences, whether we're technically minded or not.
Marco.
By using your ears and experimenting with all manner of different equipment and ancillaries over the years, in different contexts, trying different things often dismissed as "foo", to ascertain whether they work or not, and learning from your mistakes, thus amassing sufficient experience, enabling you to 'sort out the wheat from the chaff', or rather determine what's "bullshit" or not... ;)
.
Aye, but that can also become just wandering round in a maze, covering the same ground over and over again, and spending a lot of money in the process, without actually getting where you want to be. Agree that as a layman the best thing to do is listen to a lot of different approaches/kit, you can't replicate that sort of experience with book-learning.
For me, at least, it helps with that process if you have at least some grasp as to why amplifier A sounds rubbish in your system and amplifier B doesn't, whereas in a different set-up it is the exact reverse. How many times have you read 'Don't buy that amp, I had one and it is rubbish' only for the next post to be ' I have that amp and it is fantastic, buy one now.'?
Aye, but that can also become just wandering round in a maze, covering the same ground over and over again, and spending a lot of money in the process, without actually getting where you want to be. Agree that as a layman the best thing to do is listen to a lot of different approaches/kit, you can't replicate that sort of experience with book-learning.
Precisely. Book learning isn't the be-all-and-end-all, especially when you don't build equipment, and therefore require no formal training. That, however, doesn't preclude you from having a valid opinion on hi-fi.
You have to remember that not all of us learn from self-directed study. It simply depends on how your brain works, therefore you choose a learning methodology based on how new information 'sinks in' most effectively for YOU!
After all, we're not all 'geeks'... ;)
In terms of the first bit you've written above, you're absolutely right, and unfortunately hi-fi forums are littered with folk who come into that category, but it's also possible to adopt the learning method I've suggested, and if you have good ears and judgement, succeed more than you fail :)
Marco.
Surely the whole point of formal study is to gain the knowledge and insights that have been established over years of human endeavour, and to benefit from that gained knowledge and experience.
This we hope, is 'objective knowledge'.
Our own everyday experiences are valid, but interpreting what is going on, and causes of phenomena are really quite difficult, and I cannot embrace a subjective stance in isolation, rather I superimpose it on my 'objective knowledge' and try to evaluate my experiences.
We may think of food as a purely subjective choice, but actually our preferences are often formed by our early experiences and formation, which are 'culturally' subject to a narrow range of exposure. I was seduced by my Great Aunts into sucking American gums in my early years, my being taught that they were a luxury. In fact they gave me cavities, and later acquisition of objective knowledge showed that sucrose directly causes cavities because of one particular high energy bond which it contains. I have not eaten 'popuist' sweets since '75.
I accept that gaining objective knowledge is, or can be hard, but it is worth the effort both for practical purposes, and because it enhances the mental facilities; most such challenges do.
If you want evidence of just how far from real understanding a purely subjective anecdotal life can be, and how it can lead us into a fantasy world, look at TV advertisements, and the inferred, if not stated 'realities' that they portray.
PalsHuffMor
23-07-2017, 10:28
The saying 'A little knowledge is a dangerous thing' is only applicable if you are going to jump in feet first and do something practical. '
...or if you are going to jump in keyboard first and tell people what kit is 'right' and what is 'wrong'.
Fantastic thread! Thanks for sharing your knowledge Arkless!
PalsHuffMor
23-07-2017, 11:31
Surely the whole point of formal study is to gain the knowledge and insights that have been established over years of human endeavour, and to benefit from that gained knowledge and experience.
This we hope, is 'objective knowledge'.
Our own everyday experiences are valid, but interpreting what is going on, and causes of phenomena are really quite difficult, and I cannot embrace a subjective stance in isolation, rather I superimpose it on my 'objective knowledge' and try to evaluate my experiences.
We may think of food as a purely subjective choice, but actually our preferences are often formed by our early experiences and formation, which are 'culturally' subject to a narrow range of exposure. I was seduced by my Great Aunts into sucking American gums in my early years, my being taught that they were a luxury. In fact they gave me cavities, and later acquisition of objective knowledge showed that sucrose directly causes cavities because of one particular high energy bond which it contains. I have not eaten 'popuist' sweets since '75.
I accept that gaining objective knowledge is, or can be hard, but it is worth the effort both for practical purposes, and because it enhances the mental facilities; most such challenges do.
If you want evidence of just how far from real understanding a purely subjective anecdotal life can be, and how it can lead us into a fantasy world, look at TV advertisements, and the inferred, if not stated 'realities' that they portray.
Marketing BS is just as harmful as 'deaf adherence' to measurements. 'This beats everything at up to ten times the price' style reviews and advertorial should set off alarms, as one example.
It remains that the test of objective measurement (and other areas of technical design) is subjective listening, not the other way round.
Surely the whole point of formal study is to gain the knowledge and insights that have been established over years of human endeavour, and to benefit from that gained knowledge and experience.
This we hope, is 'objective knowledge'.
Our own everyday experiences are valid, but interpreting what is going on, and causes of phenomena are really quite difficult, and I cannot embrace a subjective stance in isolation, rather I superimpose it on my 'objective knowledge' and try to evaluate my experiences.
We may think of food as a purely subjective choice, but actually our preferences are often formed by our early experiences and formation, which are 'culturally' subject to a narrow range of exposure. I was seduced by my Great Aunts into sucking American gums in my early years, my being taught that they were a luxury. In fact they gave me cavities, and later acquisition of objective knowledge showed that sucrose directly causes cavities because of one particular high energy bond which it contains. I have not eaten 'popuist' sweets since '75.
I accept that gaining objective knowledge is, or can be hard, but it is worth the effort both for practical purposes, and because it enhances the mental facilities; most such challenges do.
If you want evidence of just how far from real understanding a purely subjective anecdotal life can be, and how it can lead us into a fantasy world, look at TV advertisements, and the inferred, if not stated 'realities' that they portray.
I don't disagree with the points you've made, Dennis.
However, at the end of the day, you are who you are, and some of us simply aren't predisposed to a solely academic way of learning. We learn in other ways (through practical experience), which can be just as beneficial and rewarding, particularly depending on how you live your life and/or make your buying decisions.
Also, as true as what you say is about living in a "fantasy world", there also comes a point where you must have the confidence to trust your senses and gut instincts, and simply go with that 'feels' right, and then make your own mistakes or not, or forever be a slave to certainty.
This continual 'fear of being fooled', in the absence of proof to confirm what we experience as real, which some folk seem to suffer from (often those of a scientifically minded bent), for me doesn't equate to having a healthy state of mind.
I prefer to act like a human being, no matter how fallible my actions are, and be in touch with my senses and emotions, than as some notionally 'perfect robot', programmed to function solely on serving 'scientific facts'.
Marco.
...or if you are going to jump in keyboard first and tell people what kit is 'right' and what is 'wrong'.
Well yes, if you end up giving incorrect technical advice then that could certainly cause someone to waste time and money. Otherwise the hobby already has plenty of people saying 'My way is best', and most of them have no technical knowledge at all, so I'd argue that those two things are completely independent of each other.
PalsHuffMor
23-07-2017, 12:28
Well yes, if you end up giving incorrect technical advice then that could certainly cause someone to waste time and money.
And one might be able to correctly recite electrical theory but still have no genuine understanding or experience of how to implement it.
RothwellAudio
27-07-2017, 09:58
The perfect supply has 0% regulation, meaning infinitesimally low internal resistance.
Shouldn't that be 100% regulation? The perfect supply would have 0% voltage drop on full load as compared to no load - that would be 100% regulation, in my language at least.
Arkless Electronics
27-07-2017, 11:23
Shouldn't that be 100% regulation? The perfect supply would have 0% voltage drop on full load as compared to no load - that would be 100% regulation, in my language at least.
Nope... if you look at a specification sheet for a transformer it will give a figure for regulation in % and this gets bigger for smaller transformers..
RothwellAudio
27-07-2017, 11:52
Nope... if you look at a specification sheet for a transformer it will give a figure for regulation in % and this gets bigger for smaller transformers..
Yes, I remembered this after I'd posted. Still, I think when they say a transformer has 20% regulation they're being a bit lazy with their language and they're actually saying it is 20% off perfect regulation, ie 80%, or the full load voltage is 80% of the no load voltage.
Regulator manufacturers specify the same way, eg the specs for the LM317 say the load regulation is 0.3%, but it would make more sense to me to call it 99.7%.
Still, I doubt my argument will convince the entire world of electronics to revise its wording :lol:
Marco, I don't think we have any conflict of views here.
Whilst I believe in the 'objectivist' philosophy to the extent of validating the established criteria, I also accept that they are not, and cannot, give an exhaustive account of reality.
I also accept that subjective listening is essential and central to audio, and that some objectivists may be so biased and bigoted in their belief in the objectivist stance, that without listening they could design something on figures alone which would sound abhorrent.
Science does not rule out human perception, in fact it relies heavily on it, but it also entails massive amounts of work via 'subjective' empirical testing as a part of the process to arrive at a hypothesis, then thesis, and then theory. This may last for years, but sooner or later a better model will be arrived at and adopted as 'truth'.
When we look at a voltmeter, we are each subjectively seeing a needle on a scale, and reading a value, which we then regard as an objective measurement.
I might be convinced by the subjectivist argument if there was an example where an instinctive reaction managed to prove the physics wrong. Or rather the interpretation of the physics in that context. I have asked this before and have not been given an example. Here is a hypothetical situation. Someone says cable risers improve the sound quality of their speakers. A scientist says this cannot be true because the physics says it is impossible for the sound to change just by lifting the wire. Later another scientist does an experiment where he discovers that the impedance of the cable changes when it is raised off the ground. He finds an effect, and proves it scientifically, that previously was thought to be impossible. In this case the subjective judgement leads to a change in the scientific understanding. Obviously this is a made up scenario, but has it ever happened in reality?
anthonyTD
28-07-2017, 11:46
I am a great believer that every perceived change' that is witnessed by at least more than one person can be explained, if we know what to look for; as far as measurement and test, there is no Magic implied by those of us who do actualy believe in what we are hearing,we just need to look further into things that we currently perhaps dont associate with such changes.
I might be convinced by the subjectivist argument if there was an example where an instinctive reaction managed to prove the physics wrong. Or rather the interpretation of the physics in that context. I have asked this before and have not been given an example. Here is a hypothetical situation. Someone says cable risers improve the sound quality of their speakers. A scientist says this cannot be true because the physics says it is impossible for the sound to change just by lifting the wire. Later another scientist does an experiment where he discovers that the impedance of the cable changes when it is raised off the ground. He finds an effect, and proves it scientifically, that previously was thought to be impossible. In this case the subjective judgement leads to a change in the scientific understanding. Obviously this is a made up scenario, but has it ever happened in reality?
Good thread idea Jez, I have really enjoyed your "teaching" so far and am looking forward to the next chapter (althought I doubt much will "stick" between my ears)
Andy
I would imagine that in the early days of hi-fi people were ' accidentally' discovering all sorts of stuff. Later the physics would explain what was happening. But back then when all was new probably no one bothered arguing about the physics of it. And of course the cynicism wouldn't have been there because the snake oil salesmen hadn't put people on their guard. It's more recent examples im interested in.
I wonder whether any myth busting was actually required prior to the advent of two channel?
In post 50 Andrew you have chosen an example which is patently untrue to validate an assertion.
But what you describe in principle is exactly what happens in scientific discovery; a subjective assertion is made, and someone with patience works at it and discovers an underlying principle, or more usually nothing.
Surely the scientific process was prompted by the human need to understand his environment in order to better control it for his survival. Even a snapping twig in the forest near a tribal home, prompts enquiry.
Having recently seen some 'hosepipes' raised on 'electric rail supoorts', which were all massive, I take it that you are ignoring the direct acoustic effects in your example.
I'm a little confused by your response Dennis. I'm not making an assertion, just using an invented scenario as a way of describing a potential example where the science ends up proving a subjective assertion. I realise in this case the science has not done so, who knows it might in the future, but is typical of the kind of situation that leads to argument. I'm not completely opposed to a subjective argument just wary of statements that appear to fly in the face of all logic or science. My interest is genuine, l would like to know about recent discoveries where a subjectivel assertion that appears to defy all scientific logic is then proven to be scientifically correct. When you say direct acoustic effects do you mean the behaviour of sound waves in the room being altered by the raising of the cable?
Arkless Electronics
28-07-2017, 16:52
Thread abandoned.
But we haven't got to the good stuff yet. I wanted you to disprove cable lifters, damn it all.
anthonyTD
28-07-2017, 16:59
???:scratch:
Thread abandoned.
walpurgis
28-07-2017, 16:59
But we haven't got to the good stuff yet. I wanted you to disprove cable lifters, damn it all.
Can you use those with headphones?
If I'm part of the reason you've abandoned this thread because of drift then I apologise and promise not to be a distraction in future if you want to reconsider. I was looking forward to learning more of the science.
Thread abandoned.
Aw shucks. :rolleyes:
Or do you mean you will start a new thread?
Jez, if we promise to be good will you reconsider?
Bigman80
28-07-2017, 18:20
I was actually trying to follow this. C'mon Jez, don't abandon us!!!
Sent from my EVA-L09 using Tapatalk
anthonyTD
28-07-2017, 18:40
Probably gone to the pub now!:D
Yes I did Andrew, hence the exaggerated sizes. (Hose pipes and electric rail supports).
I do not think that anyone has been disrespectful to the pursuit of truth, off thread,or impolite.
RothwellAudio
30-07-2017, 20:50
On the subject of power supplies and voltage regulators, here's something that bugs me: regulators located remotely from the audio circuit. It's wrong!
Here's an example from another forum:
http://audiokarma.org/forums/index.php?threads/boozhound-deluxe-build-from-kit.780338/
You can see one box contains a transformer, rectifier, smoothing caps and a voltage regulator. There's a cord connecting the power supply to the audio circuit - in this case a phonostage. All looks neat and tidy, but the regulator regulates the voltage at its output with respect to its local 0V reference. It can't compensate for any resistance in the wires to a circuit located remotely, so the sensible thing to do is have the regulator right next to the audio circuit. Why put it in a box at the other end of a long piece of wire?
Arkless Electronics
30-07-2017, 23:21
On the subject of power supplies and voltage regulators, here's something that bugs me: regulators located remotely from the audio circuit. It's wrong!
Here's an example from another forum:
http://audiokarma.org/forums/index.php?threads/boozhound-deluxe-build-from-kit.780338/
You can see one box contains a transformer, rectifier, smoothing caps and a voltage regulator. There's a cord connecting the power supply to the audio circuit - in this case a phonostage. All looks neat and tidy, but the regulator regulates the voltage at its output with respect to its local 0V reference. It can't compensate for any resistance in the wires to a circuit located remotely, so the sensible thing to do is have the regulator right next to the audio circuit. Why put it in a box at the other end of a long piece of wire?
As I've said many times before..... and as is accepted good practice.... though not always adhered to as you rightly point out.
I would have got to this if there hadn't been several pages of conjecture and debate before I even got to part 2
I was actually trying to follow this. C'mon Jez, don't abandon us!!!
Sent from my EVA-L09 using Tapatalk
+1
Thank you for trying to do this Jez, do hope you continue for the ones of us that were silently following. I am always looking to learn something new and this thread had me really interested.
Well there are potential outcomes from him continuing.
He could provide very clear and accurate information showing most of us how ignorant we are, and may feel good after doing so.
He may reveal his own limitations, which itself will be of use to all, and maybe even to him if he receives corrections.
Just possibly, through debate, clarification of issues may result.
I wonder if it would be helpful to Jez if we made a list of phenomena that we found difficult to justify from a scientific view?
e.g.:
1. 'Electrons only flowing in one direction down a copper wire' - those cables with arrows on them to denote which way round they should be connected between two pieces of equipment.
2. The whole mains debate (silver-plated fuses/plugs/cables/chokes/'smoothers' etc). (I hasten to add that I can understand the logic behind shielding cables).
3. Are bits just a series of '1's and '0's? Do 'digital' cables have an effect? The possible effect of jitter.
4. The effect of different isolating feet on amps, CD players, DACs etc.
...just an idea...?
Thanks,
Richard.
anthonyTD
01-08-2017, 10:54
I am sure Jez will come back to this at some point,
Meanwhile, I will add my own 2 pence worth as far as the next step in power supplies, which Jez Started.
Outboard power supplies, and when' if ever they are necessary.
As can be see from what Jez has already explained in the first instalment, Stiff, low impedance power supplies are the goal we should all be aiming for, therefore; it is very important, especialy where high current is concerned to keep the power supply, and its regulation as near as posible to the circuits its supplying, and its something I have always tried to do in all of my own designs, however; where it can be a juggling act is when your dealing with low level signals such as phono-stages, where its always going to be a comprmise between keeping the power supplies as near as posible to the circuit, while maintaning enough distance between the mains transformer and the sensitive gain circuitry' to keep noise, and hum to a minimum.
Even then you should always keep the final regulation as near as posible to the signal circuitry.
A...
RothwellAudio
01-08-2017, 13:05
Ok, I'll add a further two pence worth on the subject of the stiffness of a power supply.
Firstly, I think it always makes sense to consider the circuit which the power supply will be supplying power to. For example, a 100W power amp might draw only 100mA when it's idling but draw several amps at full tilt. On the other hand, a class A preamp might draw only 10mA - and it will draw only 10mA whether it's idling or at full tilt. So for the preamp there's no point in designing a power supply that will maintain the same voltage at 1mA current drain and 4A current drain because it will never see those variations.
However, although the preamp's current drain is constant 10mA averaged over time its current drain is modulated by the signal it is amplifying. That means looking at "stiffness" slightly differently. The power supply must be able to supply the demands of the preamp's modulated current requirements while staying stable, and that means if the preamp is amplifying a 50Hz signal the current will be modulated at 50Hz, and if the preamp is amplifying a 20kHz signal the current will be modulated at 20kHz. Stiffness at DC isn't really an issue - it's stiffness at audio frequencies that matters.
A crude unregulated supply would be a transformer, rectifier and smoothing capacitor. The obvious "audiophile" approach to improving this would be to simply have a bigger transformer, bigger rectifier and bigger smoothing capacitor, but examining the power supply's output voltage while it feeds a preamp which is amplifying a 10kHz signal might soon show you that you have just spent a lot of money for very little improvement. A much smarter approach would be to add a voltage regulator - the design of which is a topic for another day.
The point I'm trying to make is that it's more useful to consider power supplies not so much as "good" or "bad", but rather "suitable" or "unsuitable" for the circuit they will be paired with. What's good for a power amp isn't necessarily good for a preamp.
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