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Misleading Measurements


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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.

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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21 hours ago, fas42 said:

 

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

 

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.

 

We are going off in many tangents.  IMHO the OP was pretty much about what do you do when a device measures well and you THINK you don't like the sound or when it measures terribly and you THINK you love the sound.

 

Might the measurements be misleading, asks the OP?

 

Of course not. What should you do? Well, what the audio enthusiasts have been doing all this time. Buy based on other factors. Some will rationalize and try to make it about audio, others will happily admit they just wanted the object of desire.

 

That's it. Close the thread. I will be going over to a music discussion forum.  EVERYTHING is subjective on that matter, so at least having the endless discussions, flame wars, arguments via logical fallacies make more sense to me...

 

 

v

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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.

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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20 minutes ago, fas42 said:

 

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.

 

 

 

Injecting noise... well that IS definitely a test case. Remember the part about thresholds and tolerances?  some devices will pass or not based on least or more stringent conditions - it all depends on the pass/fail criteria defined by the designer and course will reflect the design philosophy. Human hearing? not part of formal testing.

 

OF COURSE, things escape the testers, or maybe devices are not tested at all. Or the test plan is badly designed. Or the device  is shoddily built. Or there is a manufacturing QC problem.  But that does not mean we should discard formal measurements and go by ear. 

 

v

 

 

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35 minutes ago, vmartell22 said:

OF COURSE, things escape the testers, or maybe devices are not tested at all. Or the test plan is badly designed. Or the device  is shoddily built. Or there is a manufacturing QC problem.  But that does not mean we should discard formal measurements and go by ear. 

 

v

 

 

Nobody here is suggesting that we should.

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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7 hours ago, MarkusBarkus said:

...I would just add that there would also be a few assumptions underlying the test/QA plan, that might constitute "normal usage/conditions." 
 

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?

 

Of course - problem is that listening is in the "ear of the earholder"- I might declare a device as ok but some other person might say is crap. Then you add biases - I am pretty sure there could be listeners that will declare anything over $10K as super fantastic no matter what...

 

So yeah let's is ok to listen - is just not reliable.. by definition...

 

v

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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.

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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If measurements were the "be all, end all" there would be no need to make further improvements other than cosmetic, or replacement units due to old age .

You guys keep forgetting that virtually  everything designed by engineers is made for the Consumer/end user who will make a Subjective  evaluation of just how good the original engineering actually was,

( unless perhaps they are ASR members 😜) and choose another product from a different manufacturer or designer if the product doesn't perform as well as claimed, or is found to  be unreliable. 

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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On 11/20/2020 at 5:34 PM, fas42 said:

 

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.

 

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?

 

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22 hours ago, fas42 said:

 

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.

 

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 ;)

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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, 😉?

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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Just now, fas42 said:

 

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, 😉?

 

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 😜

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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 ...

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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Just now, fas42 said:

 

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 ...

 

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.

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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 ... 😉.

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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@pkane2001 we have heard tales from the dark side of neighbors welding, and its effects on the "rig."

 

...and @sandyk I agree that manufacturers assume consumers will make their decisions based on subjective evaluation. You and a few others here have the kung-fu to measure a device to see if it

matches the spec sheet, and act accordingly. 


Most of us (me for sure) are only using our ears, however defective they are, in our rooms, however defective they are.

 

I get your point, and would add that manufacturers are also making decisions about price point, and the number of units they need to, or expect to, sell.

 

Honestly, I am fascinated by the business model that supports the creation of five or ten thousand dollar cables. I would love to see the BOM and "forecasting.xls" and be in those meetings!

 

For me, in the end, it's mostly all good. Cable company workers have mortgages and kids too. I only get fired up if they're lying to consumers, which they probably sometimes are.

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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.

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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30 minutes ago, MarkusBarkus said:

 we have heard tales from the dark side of neighbors welding, and its effects on the "rig."

 

...and @sandyk I agree that manufacturers assume consumers will make their decisions based on subjective evaluation. You and a few others here have the kung-fu to measure a device to see if it

matches the spec sheet, and act accordingly. 

 I have seen the effects of this on DTV reception from a workshop a couple of hundred metres away at a previous address , but it wasn't audible through my system where I have gone to a lot of trouble with earthing and PSU areas.

 

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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22 hours ago, sandyk said:

If measurements were the "be all, end all" there would be no need to make further improvements other than cosmetic, or replacement units due to old age .

You guys keep forgetting that virtually  everything designed by engineers is made for the Consumer/end user who will make a Subjective  evaluation of just how good the original engineering actually was,

( unless perhaps they are ASR members 😜) and choose another product from a different manufacturer or designer if the product doesn't perform as well as claimed, or is found to  be unreliable. 

Alex, you are banned from this topic. You can’t follow rules, so there are consequences. 

Founder of Audiophile Style

Announcing The Audiophile Style Podcast

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22 hours ago, pkane2001 said:

 

Neighbors welding is nothing compared to me doing an hour-long telescope CCD exposure in my back yard in the middle of the night only to be ruined at the very end by a restless neighbor turning on their flood lights less than 100 yards away. 

 

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

Custom room treatments for headphone users.

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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.

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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3 minutes ago, fas42 said:

 

That article is 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 in clear SQ variation - playing with ideas in PS noise reduction, mere observation is enough to confirm the value of what is being tried.


Dark frames are used to remove uneven response from the CCD pixels due to slight differences in their thermal noise response. Somewhat analogous to DSP to flatten out speaker response, except at the level of thermal noise, well below any audibility.

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