Misleading Measurements

[fas42]

The audio game just swims in confounders - being so-called objective about it is often just pretending that these confounders don't exist in the situation, or that they have been "taken care of" - oh, if life could always be so, umm, rational ... 😉

[fas42]

Unfortunately, changes in SQ that matter a great deal to the subjective experience don't lend themselves to being measured easily - I group the factors under a general umbrella of "integrity" - my first really good system, decades ago, and the current active speakers, have had nothing done to them to change their characteristics, in any conventional sense - all the tweaking applied to both should have had close to zero impact to all the things normally measured. But what has been done to both is to track down, yes, the 'confounders' which play such a great part in the perception of the playback - their integrity as functioning systems, and robustness against external interference mechanisms were worked on a great deal - and the listening shows the benefits.

 

There is no magic to this - no more than there is magic to, say, SpaceX getting their rockets to perform reliability - not have too many RUDs - Rapid Unpredicted Disassemblies ... us normal folk call these, spectacular explosions, 😉. There's a mighty big difference between having a RUD, and not having a RUD - which could be down to someone rushing the last bit of checking, or being distracted while assembling something ... now, how do you measure that ... ?

[fas42]

As being discussed, observation is the start of achieving understanding - unfortunately, philosophical as well as ego factors cause some to downplay, or ridicule other people's observations ... and science is always the loser here. Insistence on measurement is used as a weapon by one side, in the hope that 'uncomfortable' observations can be made to go away ...

[fas42]

7 minutes ago, sandyk said:

Will somebody please point me to the conforming posts that I must have missed, as I would really like to see some examples of Misleading Measurements instead of the philosophical discussions  currently . 

  

 

Measurements are misleading, if they are used to 'prove' that the performance of whatever is beyond reproach - in audio, it doesn't work this way; the ear/brain can easily detect anomalies in a complete system, during playback of a recording - it ain't pleasant to listen to  🙂.

 

Of course, some then turn around and say, "Well, it's a crappy CD you're playing!"  - now, you can't get more objective than that, as a reason, can you? ... 😝

[fas42]

And here's a thread on ASR, from yesterday, that absolutely nails the ugliness of the people who post there ... https:// www.audio “science” review /forum/index.php?threads/paul-says-you-must-lift-speaker-cables-of-the-floor-for-better-sound-quality.17681/

 

Paul from PS Audio says very matter of fact things about the cable lifting question - but that doesn't stop the crowd from lamming in, with full force - all doing a Trump, hurling abuse at the spawn of the devil icon who has been evoked ... and some here wonder why there is a 'thing' about the ASR crowd ... 😁.

 

[fas42]

33 minutes ago, pkane2001 said:

 

Yawn. Boring, Frank! Got anything interesting to share? Like some objective evidence that cable lifters produce audible differences, perhaps?

 

 

Nicely edged out to slips 🙂 ... okay, I've got something better - do you reckon it would be possible to get objective evidence that having a working, heavy duty arc welder plugged into a socket next to that feeding an audio system could produce audible differences?

[fas42]

7 minutes ago, pkane2001 said:

I got one, eh, two. They do make a very nice audible difference. Will arc weld all day long into a short. Made by Nelson Pass.

 

Nicely edged away again ... always easier, if one doesn't answer the question ... 🙃

[fas42]

6 minutes ago, pkane2001 said:

That was a direct answer. Maybe not the one you were looking for?

 

 

The reference was to, how do we know that an audio system is 100% impervious to all types of electrical interference that can manifest in the area - just say, "The engineers who designed this should know what they're doing!", perhaps ... ?

[fas42]

Well, I've just discovered something quite juicy, https://en.wikipedia.org/wiki/Cucking_stool - got to read the bit about the origin of the name, 😉.

 

Now, where can I order one, over the Net ...

[fas42]

Just now, pkane2001 said:

Umm. Measurements, perhaps? Just a guess on how any engineer would approach it.

 

And where on the spec sheet for some consumer audio gear would I find that?

[fas42]

Just now, pkane2001 said:

Why ask me, I don’t make audio equipment. Ask the manufacturers.

 

So, if I want to confirm that there is no possibility of electrical noise causing any audible differences to my playback, I should ring the manufacturers, and ask to talk to the engineers who designed my kit - to ask them how they tested it?

 

Sounds like a very advanced, first world country, solution, to me ...

[fas42]

10 minutes ago, pkane2001 said:

Measurements, Frank. Measurements.

 

So, you know, say, that your own rig is fully competent in every area that matters - because you have a full set of Measurements that you can quite quite easily reel off ... ?

[fas42]

18 minutes ago, pkane2001 said:

No joke, Alex. I don’t measure for ‘total immunity’. I measure for my own use, in my own house, for my normal application.
 

What I find to be a joke is manufacturers that develop products claiming full immunity while having no measurements to back this up. I can’t imagine the process of developing an electronic product to perform a specific function while having no way to confirm that the product actually does what it’s designed to do.

 

Right, so you measure for your own use, to meet your standards of acceptability - so, poor ol' Joe Blow, who hasn't got your expertise and equipment, and who perhaps has higher standards - Heaven Forbid! - has no hope of knowing whether what he has is up to standard ... except, except, except, he uses his ears to assess what he's got ... oh dear, did I just hear the Laws of Physics crumple and crash to the ground ... 🙂.

[fas42]

Just now, pkane2001 said:

but I have no problem with that, just use your ears properly! ;)

 

 

Define, "properly".

[fas42]

8 hours ago, pkane2001 said:

properly adverb (CORRECTLY)

 

Hmmm ... "Correct listening" ... something which one is required to do in places like China 🙂.

 

The battery on the tongue analogy now can come back into play - you use this to determine whether there is any significant charge in the battery - this is, an observation ... actual measuring of it may, or may not, be useful.

 

You listen to a system, and it exhibits distortion, anomalies in the SQ - again, an observation. From then on, it's pointless to extract numbers; all activity is devoted to resolving what is causing the misbehaviour.

 

It's easy to see why the thinking in most audio circles is so lopsided - the fascination is with, "making things better". "Correct thinking", rather than worrying about "correct listening", is what allows one to first pinpoint the presence of flaws in the playback sound, and second to locate and eliminate the causes.

 

Which brings us back to the cable lifting thing - a highly resolving rig makes it easy to hear the audible effects of static noise interference; lifting off the carpet, say, is a quick workaround to attenuate these sort of parasitic behaviours. A well engineered playback chain will have all parts sorted so no anomalous effects occur - it's all actually very straightforward stuff.

[fas42]

24 minutes ago, pkane2001 said:

Lifting off the carpet does what now? Are you talking about static electrical charge inducing audible noise in a speaker cable? Care to explain how this happens?

 

It introduces electrical noise into the playback chain - and parts of the circuitry which are not sufficiently well engineered to isolate from this then produce audible anomalies. So, either 'improve' the physical construction of the cables - which is why the vast market of cables of all persuasions exists - or make the circuitry good enough so it "doesn't care"; or use workarounds of separatings parts of the chain that may otherwise cause static.

 

How does this happen? Triboelectricity can kill circuits, stone dead - I used to work on computers covered with stickers threatening anyone who dared to touch them in the "wrong place"; or make them misbehave - there was a printer that regularly went nuts; they spent eons of time and money trying to fix this; ended up being a buildup of static as the cause - solution: spray mists of water into the air, regularly. In audio, much, much more low level - but enough to sneak its way in, and cause audible differences.

[fas42]

11 minutes ago, sandyk said:

 Bear in mind too, that there may also be mains wiring directly underneath the floor where the speaker leads lay, which may induce noise into them. With the prolification of SMPS devices these days, there is also the slight  possibility that RF/EMI from them may get back into the negative feedback area of an amplifier via the speaker leads .

 

Yes, the feedback loop in conventional amplifiers is a mighty easy way to disturb audio quality - dump some RF into the output stage, the feedback loop attempts to correct, but does so very badly; because the bandwidth is not there to do it - QED, degraded SQ.

[fas42]

5 minutes ago, vmartell22 said:

 

It would be on the design document - from there, after a risk analysis,  a test plan is created. Part of the test plan is functional testing.  Whatever you are aiming for, like 100% noise rejection, there will be a test case for that. The test case will specify thresholds, tolerances, etc. Data points will be taken using... measurement devices, not by ear. And pass/fail will be determined.

 

That's it.

 

v

 

Yes, that's how it should work ... so why do all real world audio components then fail ... ? It's trivially easy for me to inject some real world electrical noise into the environment of the replay setup, and hear the SQ degrade ...

 

Meaning, that the test cases, if used, are not strict enough - engineering of audio circuitry doesn't cut the mustard; and therefore the consumer then has to complete the work that should have been done in the factory.

[fas42]

8 hours ago, MarkusBarkus said:

 

Perhaps the test case: "Turn on arc welder on adjacent power feed..." would not constitute a normal test case. And that exception wouldn't likely appear in consumer documentation: Warning, do not run device while neighbor is arc welding." Although the the caveats that do appear sometimes read as if written for consumers new to the planet.

 

Not that we're voting, but may I cast one for measure and listen?

 

One can do quite a good job with DIY - some time ago I designed a noise filter for the mains feed - test scenario: parallel to that socket I had an extension cord, with light globe plugged in; by easing its plug part way out of the extension socket I could make the globe flicker - there was a mini arc welder thing going on inside the plug socket combination. Which made nasty, spluttering noises emerge from the speakers - without that filter. With filter inline, it was dead quiet ... no measurements, but my ears told me that what I had done was effective.

 

Using extreme test cases gives one a good margin, for feeling confident that progress has been made - observation is enough to assess the value of the change.

[fas42]

1 minute ago, pkane2001 said:

 

Sure, static electricity discharge can kill electronic circuits. How many people do you know that had their speakers destroyed by static electricity from cables simply laying on a carpet?

 

 

Which is why I made the point, " In audio, much, much more low level ..." - typical symptoms of static interference are a loss of sparkle and life in the playback; it has a boring quality about it - and you have to resort to "good recordings" 🙂 to retain interest in keeping listening ... sound familiar, 😉?

[fas42]

4 minutes ago, pkane2001 said:

 

I don't know too many audiophiles with arc welders plugged in and operating while they are listening, but maybe I just don't know enough people ;)

 

If you live in a unit, and next door they operating some electrical devices which is sparking badly inside, because it's on the way out - then your SQ could be stuffed, 🙂.

 

Best solution is to make your own rig highly robust, to prevent suffering from interference - then you never have to worry about what's going in the local area.

 

On the home front, I'm still irked because I can't stop what's happening electrically in the house from impacting my low cost active speakers setup - close, but no cigar; in spite of the layers of filtering I've already got in place ...

[fas42]

9 minutes ago, pkane2001 said:

 

The "typical symptoms" seem to be exactly the same as for all the other ills you ascribe to audio reproduction chain, from friction-based connectors to volume pots to arc welders on the same AC line. Not very useful for troubleshooting purposes, I must say 😜

 

Yes, because all of these factors generate noise - which the components are not well enough engineered to ignore. Troubleshooting? Pretty easy, actually - for a volume control, just refresh the contact, by moving the dial - did the SQ change? For external electrical interference, just shut down the house - is it better? Then start switching things on, one by one - do you lose SQ with a particular device now operating. Next door? You know the story - the best listening is late at night, when everyone has gone to bed - no crap from the neighbours infesting my power ... 😉.

[fas42]

6 minutes ago, pkane2001 said:

 

So does one of the PS Audio regenerators fix this nasty problem? Not that I have any neighbors operating arc welders, but just asking just in case.

 

Possibly. The regenerator becomes part of your replay chain, effectively - think of it being an extension of the power supply circuitry in your components - and then it may help or hinder, depending upon everything. The typical story I hear is that the treble is improved, but bass goes flat - which makes sense: the ability of the unit to deliver clean current at peak demand from the power amplifier's power supply may not be good enough - and the subjective experience is a mixed bag.

[fas42]

47 minutes ago, jabbr said:

 

And doing this you can judge the value of various power supply noise reduction techniques. 

 

e.g https://academic.oup.com/jmicro/article/67/suppl_1/i123/4855799

 

That article is a good, visual, parallel to the business of evolving a technique to detect whether changes made to an audio system and its environment, is beneficial. In the visual field, you use dark, reference images to see if the impact of noise can be countered - in audio, you use a 'reference' recording where noise impact is quite easily observable, manifesting as clear SQ variation - playing with ideas in PS noise reduction, mere observation is enough to confirm the value of what is being tried.

[fas42]

An interesting new thread in that 'other place' is developing, https://www.audio “science” review/forum/index.php?threads/making-very-small-distortions-errors-audible-with-music-signals-some-examples.20886/

. This is refining a method for finding meaningful differences in all those things which are "unmeasurable", and therefore "inaudible" 😁 ...

 

Will be interesting to see how this develops - hopefully, to some degree countering all those "misleading measurements", 🙂.