Misleading Measurements

[The Computer Audiophile]

Just now, pkane2001 said:

 

Hi Chris,

 

USB cables introduce a lot less variability into the overall playback chain than the DAC, the analog stage, the amp, and especially the transducer, speakers or headphones. Usually this is well below the threshold of audibility. I've seen a few broken USB cables that caused obvious errors, but a cable that conforms to USB spec should just work.

I hear what you're saying, but a DAC that measures below the threshold of human hearing must also be in that "should just work" category correct?

[pkane2001]

16 minutes ago, The Computer Audiophile said:

I hear what you're saying, but a DAC that measures below the threshold of human hearing must also be in that "should just work" category correct?

 

Correct. But there are many more opportunities to mess up a DAC than a USB cable.

[Summit]

Threshold of human hearing is only significant if actually measured after the transducers.

[Qhwoeprktiyns]

8 hours ago, The Computer Audiophile said:

I hear what you're saying, but a DAC that measures below the threshold of human hearing must also be in that "should just work" category correct?

 

I think you already know the answer to that question.

 

Unless you have already heard a DAC that "does just work". 

 

The audio industry thrives on things that don't "just work". You could say it is part of the fun of the hobby (not my point of view, but that's not important).

 

 

[kumakuma]

9 minutes ago, fas42 said:

 

not how many high end setups operate - they frequently make recordings impossible to listen to; the level of distortion being added in the playback is far too unpleasant to tolerate, for any extended period.

 

So how can many here spend hours each day listening to their "setups"?

 

 

[John Dyson]

On 7/1/2020 at 7:30 PM, pkane2001 said:

 

Sorry, Frank, but that's false. Not just from books, but from my own experience. If you've not heard a properly instrumented 3-D audio with HRTF adjustment and head tracking, you should try it. There's no comparison to your "imagined" soundscape.

You really do seem like a measure twice, cut once type person, and that is good.   Tweak tweak tweak, on the other hand, wastes a lot of potentially productive time.  None of us has lots of time to spend tweaking, when there might be good alternatives.  Some situations REQUIRE tweaking, but no-one should seek out the circumstance -- because,  in worse-than-trivial situations, becomes a game of frustrating whack a mole.   At first, 'whack a mole' can be fun, but after trying to deal with more than a few variables, the multi-dimensional optimization -- where dealing with analytical/complex math -- the optmization starts being less and less intuitive, VERY QUICKLY.

 

I'd suspect that people with experience using both general techniques would counsel people to try to 'measure twice', which at first requires a little more learning and study, but the results are well worth it.

 

A good analogy is Thomas A Edison (some really old, exploitative, but persistent guy that one of my first bosses knew and worked for), where he spent huge amounts of time 'tweak tweak tweak', but this little guy named Tesla blew Edison away once technology required some actual intellectual study and learning.   If Mr 'tweak tweak tweak' Edison had his way, then electrical power distribution would have been deployed with generation stations on every several city blocks, and NO power distribution in the countryside.   Edisons weak, tweak tweak tweak technique was fortunately deployed only in limited situations before being replaced.   Edison's intellectual arguments consisted of electrocuting animals.  :-).   His economic arguments were done by his early supporter, JP Morgan.  Thank goodness, brute force, force-of-will and hard-core financial might did NOT win in this case.

 

Tweak-tweak-tweak works okay in primitive situations -- but in more complex multi-dimensional situations (almost all EE/DSP stuff is like that), can become a misguided allocation of time.  A little learning/planning ahead of time, in many simple applied technology cases (home audio systems) are well worth the investment.

 

Many of you know that I am in tweak tweak tweak hell right now -- and I would never counsel any friend of mine to use the design-by-tweak technique for any complex project at all.

 

John

 

[fas42]

4 minutes ago, John Dyson said:

Tweak-tweak-tweak works okay in primitive situations -- but in more complex multi-dimensional situations (almost all EE/DSP stuff is like that), can become a misguided allocation of time.  A little learning/planning ahead of time, in many simple applied technology cases (home audio systems) are well worth the investment.

 

Many of you know that I am in tweak tweak tweak hell right now -- and I would never counsel any friend of mine to use the design-by-tweak technique for any complex project at all.

 

John

 

 

Why the "tweak-tweak-tweak" method works in the audio game is because the core engineering is good - to use your analogy, Tesla did all the crucial research as well as what was needed - but, he was a bad 'finisher' ...it needed an Edison to come along and finesse the solid design elements already in place; tidy up the loose ends.

 

Which is why "turds can be polished" - the keys parts are good enough to do the job, but require extra, additional, knowledge driven refinement to bring out what is inherently possible - the end result can easily outperform, subjectively, an unfinished "Tesla effort" ...

[pkane2001]

20 minutes ago, John Dyson said:

You really do seem like a measure twice, cut once type person, and that is good.   Tweak tweak tweak, on the other hand, wastes a lot of potentially productive time.  None of us has lots of time to spend tweaking, when there might be good alternatives.  Some situations REQUIRE tweaking, but no-one should seek out the circumstance -- because,  in worse-than-trivial situations, becomes a game of frustrating whack a mole.   At first, 'whack a mole' can be fun, but after trying to deal with more than a few variables, the multi-dimensional optimization -- where dealing with analytical/complex math -- the optmization starts being less and less intuitive, VERY QUICKLY.

 

I'd suspect that people with experience using both general techniques would counsel people to try to 'measure twice', which at first requires a little more learning and study, but the results are well worth it.

 

A good analogy is Thomas A Edison (some really old, exploitative, but persistent guy that one of my first bosses knew and worked for), where he spent huge amounts of time 'tweak tweak tweak', but this little guy named Tesla blew Edison away once technology required some actual intellectual study and learning.   If Mr 'tweak tweak tweak' Edison had his way, then electrical power distribution would have been deployed with generation stations on every several city blocks, and NO power distribution in the countryside.   Edisons weak, tweak tweak tweak technique was fortunately deployed only in limited situations before being replaced.   Edison's intellectual arguments consisted of electrocuting animals.  :-).   His economic arguments were done by his early supporter, JP Morgan.  Thank goodness, brute force, force-of-will and hard-core financial might did NOT win in this case.

 

Tweak-tweak-tweak works okay in primitive situations -- but in more complex multi-dimensional situations (almost all EE/DSP stuff is like that), can become a misguided allocation of time.  A little learning/planning ahead of time, in many simple applied technology cases (home audio systems) are well worth the investment.

 

Many of you know that I am in tweak tweak tweak hell right now -- and I would never counsel any friend of mine to use the design-by-tweak technique for any complex project at all.

 

John

 

 

You're right John. I dislike tweaking. I do it out of necessity, when I need to understand some puzzling behavior, I guess you could call it "experimenting". Then, I tweak, sometimes randomly, until I figure out the cause and the reason for why it works the way it does. Once I understand the real fix, I discard the tweak. It'll keep gnawing at me if I find a tweak that  I can't understand or explain, and I'll have to keep digging, sometimes for weeks, into one particular issue until I get the answer.

[jabbr]

1 hour ago, John Dyson said:

You really do seem like a measure twice, cut once type person, and that is good.   Tweak tweak tweak, on the other hand, wastes a lot of potentially productive time. 

It’s more than that, often the first cut is the cleanest, and refitting just frays the edges. 
 

The saying: the enemy of good is perfect is apropos.

[John Dyson]

1 minute ago, jabbr said:

It’s more than that, often the first cut is the cleanest, and refitting just frays the edges. 

I am DEFINITELY not arguing against doing some tweaking, and sometimes intuition really does work.  I do basically agree with your sentiment also, because if something is so complex where multiple variables need to be tweaked, then the complexity probably grows not just exponentially, but probably some aspect of factorial also.   A tweak, or a few simple tweaks -- no arguments, no big loss.  The risk is when the 'design' consists primarily of tweaking.

 

A quick tweak -- no one really needs to argue about that.  My major argument is about the risk of wasting a lot of effort on tweaking, then investing oneself so much into the tweaking and result, that perhaps there might be some bias developed from hope, expectation or perhaps even aural accommodation.

 

Tweaking (in a plural sense), if the goal is the 'result', can be a real pain in the b*tt.  Instead, if the hobby is about the joy of tweaking -- then the victim (or perpetrator) of the technique will likely be able to spend LOTS of time on the hobby.  I don't even wish that on a rival or even enemy, unless they really like sitting and tweaking, trying to find the 'right' sound.  (I HATE incessant tweaking myself...  My life/project right now is cursed with 'tweaking' -- not fun, but it is important to do.)

 

John

 

[Audiophile Neuroscience]

12 hours ago, pkane2001 said:

12 hours ago, The Computer Audiophile said:

I hear what you're saying, but a DAC that measures below the threshold of human hearing must also be in that "should just work" category correct?

 

Correct. But there are many more opportunities to mess up a DAC than a USB cable.

 

Hold the phone, is not the number of opportunities to mess up irrelevant? If in fact the DUT measures below the threshold of human hearing it "should just work" in that range below the threshold of human hearing, isn't that the assertion? So why report it is the question being asked. Things like price, aesthetics, build quality, and performance in the audible range are independent factors that people can use to guide purchase.

[pkane2001]

3 hours ago, Audiophile Neuroscience said:

 

Hold the phone, is not the number of opportunities to mess up irrelevant? If in fact the DUT measures below the threshold of human hearing it "should just work" in that range below the threshold of human hearing, isn't that the assertion? So why report it is the question being asked. Things like price, aesthetics, build quality, and performance in the audible range are independent factors that people can use to guide purchase.

Already answered all of that.

[Audiophile Neuroscience]

29 minutes ago, pkane2001 said:

Already answered all of that.

 

Sorry, I missed this bit....

18 hours ago, pkane2001 said:

 

 As long as the consumers are aware that there's no audible difference, they can concentrate on other qualities that matter to them.

 

Hi Paul and yes I do agree. I already said something similar too 😜

 

The crucial part, as you say, is that the (allegedly) inaudible part not be represented as a better performance marker. So, If the measurement is offered and not specifically stated as irrelevant it may well be misleading to those less technically inclined readers. Presumably @Archimago provides this interpretation in those cases.

 

In either case it would be nice to hear from @Archimago as he was specifically mentioned by the OP.

[bluesman]

13 hours ago, John Dyson said:

Tweak tweak tweak, on the other hand, wastes a lot of potentially productive time. 

But it’s an excellent way for many to get critical education and experience.  Those who just want to listen need easy, efficient, transparent aids to optimize their systems.  But to those for whom knowledge about what’s in the boxes and how it all works enhances their audiophilic enjoyment, tweaking can be a valuable and pleasurable learning experience.

 

If you’re learning from the effort (or just enjoying it), it’s productive time well spent.

[Jud]

On 7/2/2020 at 8:50 AM, pkane2001 said:

 

Correct. But there are many more opportunities to mess up a DAC than a USB cable.

 

Though there are plenty of opportunities to introduce noise into a system involving a number of boxes and cables that include both of these. I would love to see more work done on system topology, components and cabling and how all of these affect system noise. I've seen a few articles about topics like grounding, but I haven't had good luck finding detailed and precise information on how to configure a system and then how to measure the results in easy to digest form for the audio layperson (i.e., non-electrician).

[pkane2001]

1 hour ago, Jud said:

 

Though there are plenty of opportunities to introduce noise into a system involving a number of boxes and cables that include both of these. I would love to see more work done on system topology, components and cabling and how all of these affect system noise. I've seen a few articles about topics like grounding, but I haven't had good luck finding detailed and precise information on how to configure a system and then how to measure the results in easy to digest form for the audio layperson (i.e., non-electrician).

 

A USB cable has a very simple design and the USB spec defines the parameters of what it has to be able to accomplish, and to what tolerances. Anything else the cable is doing is superfluous or possibly detrimental to its purpose of carrying data.

 

If you want to know how anything in the chain is affecting noise in the audio system -- measure the output of the system. The output of a DAC is what is fed into an amp. If the noise is not detectable there, then it's either non-existent, or it's properly filtered out by the receiver circuits.

 

Unlike the claims by Frank and others, I usually test a large portion of my system all wired together. Sometimes including two PCs (one is a Mac), attached RAID storage, a Wi-Fi network, a USB-to-Ethernet converter, a couple of USB and ethernet cables (one is 100ft long), a DAC, and sometimes even an amp with a simulated load. All in one shot. If this doesn't introduce any measurable additional noise into my system compared to, say, a Lush^2 cable feeding the same DAC directly from a battery-powered PC, then I'm not worried that anything is introducing unwanted noise. 

[sandyk]

4 hours ago, pkane2001 said:

All in one shot. If this doesn't introduce any measurable additional noise into my system compared to, say, a Lush^2 cable feeding the same DAC directly from a battery-powered PC, then I'm not worried that anything is introducing unwanted noise. 

 Why a  Lush^2 USB cable ?

 Are you admitting that some specification meeting USB cables may result in audible differences , even if not obviously measuring differently ? 😋 

[Jud]

4 hours ago, pkane2001 said:

 

A USB cable has a very simple design and the USB spec defines the parameters of what it has to be able to accomplish, and to what tolerances. Anything else the cable is doing is superfluous or possibly detrimental to its purpose of carrying data.

 

If you want to know how anything in the chain is affecting noise in the audio system -- measure the output of the system. The output of a DAC is what is fed into an amp. If the noise is not detectable there, then it's either non-existent, or it's properly filtered out by the receiver circuits.

 

Unlike the claims by Frank and others, I usually test a large portion of my system all wired together. Sometimes including two PCs (one is a Mac), attached RAID storage, a Wi-Fi network, a USB-to-Ethernet converter, a couple of USB and ethernet cables (one is 100ft long), a DAC, and sometimes even an amp with a simulated load. All in one shot. If this doesn't introduce any measurable additional noise into my system compared to, say, a Lush^2 cable feeding the same DAC directly from a battery-powered PC, then I'm not worried that anything is introducing unwanted noise. 

I was thinking along the lines of practical tutorials like "OK, you've got a ground hum. Here's how to find what's responsible and eliminate it." 

 

Even better, since I think hum and noise that isn't consciously audible may subconsciously affect enjoyment (cf. the Iowa gambling task experiment), what is the equipment and what are the measurements to take to determine noise levels when there's no audible hum or noise?

[The Computer Audiophile]

Just now, Jud said:

I was thinking along the lines of practical tutorials like "OK, you've got a ground hum. Here's how to find what's responsible and eliminate it." 

 

Even better, since I think hum and noise that isn't consciously audible may subconsciously affect enjoyment (cf. the Iowa gambling task experiment), what is the equipment and what are the measurements to take to determine noise levels when there's no audible hum or noise?

As my friends and I used to say, with Spectral the added hum is a feature :~)

[John Dyson]

8 hours ago, bluesman said:

But it’s an excellent way for many to get critical education and experience.  Those who just want to listen need easy, efficient, transparent aids to optimize their systems.  But to those for whom knowledge about what’s in the boxes and how it all works enhances their audiophilic enjoyment, tweaking can be a valuable and pleasurable learning experience.

 

If you’re learning from the effort (or just enjoying it), it’s productive time well spent.

A few tweaks are okay, but tweak tweak tweak isn't instructive.  Studying a bit of technical background and learning why the attempt at 'design' requires so many tweaks, is MUCH MUCH more important.

 

Tweaking doesn't create learning -- ask Mr Edison about that.  I doubt that 100yrs of Mr Edison tweaking would have created Tesla's new ideas.   Tweaking is an intuititve physical activity -- it is only an adjunct to the more important learning.   Or, most ideally -- a finishing touch.

 

John

 

[pkane2001]

29 minutes ago, Jud said:

I was thinking along the lines of practical tutorials like "OK, you've got a ground hum. Here's how to find what's responsible and eliminate it." 

 

Even better, since I think hum and noise that isn't consciously audible may subconsciously affect enjoyment (cf. the Iowa gambling task experiment), what is the equipment and what are the measurements to take to determine noise levels when there's no audible hum or noise?

 

I won't be any good at writing a testing and measurement guide, but these do exist written by others. What I do is simply use a quality ADC to measure a test signal at the output. Software like REW and others (including DeltaWave) let me measure distortions, compare waveforms, check phase, and measure harmonic distortion. With DeltaWave, I can use any audio track as the test signal. Occasionally I use a digital storage oscilloscope to check for what goes on well above audible frequencies. That's about it. You can do quite a bit with just REW.

 

[pkane2001]

56 minutes ago, sandyk said:

 Why a  Lush^2 USB cable ?

 

Because I tested one.

[fas42]

6 hours ago, Jud said:

 

Though there are plenty of opportunities to introduce noise into a system involving a number of boxes and cables that include both of these. I would love to see more work done on system topology, components and cabling and how all of these affect system noise. I've seen a few articles about topics like grounding, but I haven't had good luck finding detailed and precise information on how to configure a system and then how to measure the results in easy to digest form for the audio layperson (i.e., non-electrician).

 

I would suggest looking at posts by member jneutron in the diyAudio forum for some good insights, if you are not familiar with him  - his bread and butter is making circuits in research facilties where huge currents are involved work properly, so has real world knowledge of what is needed. An example of his thinking, https://www.diyaudio.com/forums/the-lounge/348308-john-curls-blowtorch-preamplifier-iv-post6086931.html

 

[fas42]

6 hours ago, pkane2001 said:

 

If you want to know how anything in the chain is affecting noise in the audio system -- measure the output of the system. The output of a DAC is what is fed into an amp. If the noise is not detectable there, then it's either non-existent, or it's properly filtered out by the receiver circuits.

 

How I detect noise is by listening ... it's trivially easy for me to make a tiny adjustment to the electrical environment of the home in which one is listening, and hear the variation in SQ. Whether one wishes to call this noise is up to the individual, but what it really says is that the playback chain is not sufficiently robust to reject this input - why you should want to measure such I don't quite see; but if you want to make it really obvious, in some numbers, just hook up, say, a working arc welder into a nearby socket - that will give you plenty of juicy data to work with, 😁.

[sandyk]

42 minutes ago, pkane2001 said:

 

Because I tested one.

Other than a Subjective check  , are you able to post some of your measurements, including it's measured impedance, which is possibly the most critical for a high quality USB cable , which could illustrate why so many members favour this cable over most generic USB cables ?