Misleading Measurements

[pkane2001]

1 minute ago, fas42 said:

 

... you do have those panzerholz headvices concreted in place, to guarantee the perfect alignment of the ear canals to the sound waves, of course ... ?

Of course! Made out of the best balsa wood, naturally.

[pkane2001]

3 hours ago, Teresa said:

 

WOW! Tons of equipment on three floors! You must be a millionaire.

 

We need a WOW button.

No, not rich, just many years of putting these together.

[pkane2001]

1 hour ago, Summit said:

 

You don’t need to name them all by model just your favorite source, DAC, amp and speaker.

 

Favorite = best measuring (ok or sounding).

 

Here's the current configuration (that does change frequently as I test and measure components):

 

My main source is a network RAID enclosure, connected to all the systems through WiFi. The main listening setup, in the basement, has a Windows 10 PC that I built about 5-6 years ago, situated in a separate room. The PC feeds a USB to Ethernet adapter that leads into the listening room over a 100ft Ethernet cable. No PCs in the listening room, player software controlled remotely over WiFi using an iPad or a laptop. The DAC is Holo Spring, balanced interconnects to Pass Aleph monoblocks leading to PSB Stratus Gold speakers. Room correction curve applied.

[pkane2001]

Just now, manisandher said:

 

Ooh... I used to own an Aleph 4 many moons ago. Didn't think you'd be into S-E output amps Paul. They certainly don't measure as well as P-P amps, you know? 🙂.

 

Mani.

 

Bought them when I was younger and more suggestible  I've had the monoblocks for about 25 years, and still like them. I do have a few other amps that are sometimes swapped in, when I want better measurements

[pkane2001]

8 minutes ago, manisandher said:

 

From another thread:

 

 

Yep. The two inputs were measured as being bit-identical. There seemed to be no consistent differences in the analogue outputs (admittedly with a non-SOTA ADC it transpired)... and yet... I could hear a difference.

 

Is it that our threshold of audibility is below the level to which we can measure THD/SINAD, etc., or... are we simply measuring the wrong things?

 

Mani.

 

Did you participate in Archimago's THD blind test? THD/SINAD are not the wrong thing to measure, they are a very simplified, average number approximating a much more complex non-linear behavior. As a first order approximation, these might be useful, but certainly not enough for a careful analysis of a device. Other measurements are required for that.

[pkane2001]

1 minute ago, semente said:

 

Oversimplification seems to be quite common. The Spinorama comes to mind.

 

It is among those who insist on a simple yes/no answer or a single number to describe a complex behavior. Even Chris was asking for a simple pass/fail answer

 

Spinorama is actually one of the more complex subjective audio experiments I've seen. There's nothing simple in the setup, the controls, or the analysis of the results.  The outcome of the experiment was then used to construct a predictive model that tried to estimate the subjective quality of a speaker among an average group of participating individuals, done by Sean Olive. The ASR "number" was designed to approximate Olive's model, and it is an over-simplification to my mind, just like THD is. Spinorama-type studies and measurements, on the other hand, represent much more than a single number and tell a much more complete story.

[pkane2001]

48 minutes ago, Confused said:

That is actually a very good point I think.

 

It does beg a question though.  To what measurements would you allocate a high weighting?

 

One way is through a mathematical/statistical analysis of a group of testers, correlating objective results to preferences. For example, here's what Sean Olive did to allocate "weight" to different objective parameters to come up with a subjective score for loudspeakers (I mentioned this in my previous post): 

 

https://www.researchgate.net/publication/332210798

 

(the PDF linked on this page is about loudspeakers, and not headphones as the page itself incorrectly claims!)

 

 

[pkane2001]

1 minute ago, fas42 said:

 

Oh dear ... the Thiels, which were a match made in heaven for the Pass, are consigned to the darker regions ... ?

currently doing duty in the video (5.1) system

[pkane2001]

10 minutes ago, fas42 said:

 

As is obvious to everyone who takes subjective SQ seriously - my current budget active speakers' biggest issue, so far, is their sensitivity to the mains quality - which has been a major part of the optimisation of every rig I've had ... something which no-one ever, ever measures  ...

 

Really? Mains interference is never measured? Maybe it's not something a THD or SINAD number by itself will reveal, but certainly distortion and noise floor plots will show it.

 

[pkane2001]

3 minutes ago, fas42 said:

 

Of course it can be measured ... but no-one actually does it ... give me a single link, to any online document, that has a specific measure of a particular component's performance in this one thing - no, "part of the overall picture" stuff, please!

 

I usually measure a component with a 60Hz (regular US mains frequency) and at 70Hz. If there’s any mains dependency in the component, it will show up as a frequency difference in the spurious tones in an FFT, or a change in the noise floor.

[pkane2001]

3 minutes ago, fas42 said:

 

Which is not measuring what I'm talking about - one way, out of many possible, of determining what I consider important is to inject a sweep of frequencies, starting from the mains frequency, to the mains plug of the component while it is powered up, and monitoring what happens to the noise spectrum.

It’s easier to just compare a component plugged into a wall outlet to one plugged into a power regenerator that has none of the junk. 

[pkane2001]

16 minutes ago, fas42 said:

 

And who has posted details of what they've found?

I have, and I’ve seen Amir post comparisons with a laboratory power supply with regeneration vs. just a wall outlet.
 

When testing one of the audiophile power supplies, I recommended to him  to use the 70Hz trick and he confirmed that the supply was leaking that frequency from its own power line.

[pkane2001]

.

[pkane2001]

1 minute ago, Audiophile Neuroscience said:

I don't trust Amir's measurements. They would need to be reproduced.

That’s  your prerogative, of course. Many of his measurements have been reproduced by others, including amateurs and manufacturers. While I’d certainly like to see more people posting the same measurements for verification, I’m not suspicious of his results.

[pkane2001]

6 minutes ago, fas42 said:

 

Any links?

These shouldn’t be hard to find, just look for his reviews that mention lab power supply 

[pkane2001]

11 minutes ago, fas42 said:

First thing I found was a post by Amir, where he said,

 

 

So, he has the assurance of knowing how all audio components behave, without even measuring ... 😉.

Keep looking  I also have one of the old PS Audio regenerators. The cool thing about it the ability to switch the mains frequency.

[pkane2001]

3 minutes ago, Audiophile Neuroscience said:

 

and that's your prerogative but you must realize that citing his measurements may be only convincing to the disciples. If those measurements have been verified it would be useful to specify this IF your aim is to convince others. It is otherwise just noise.

 

Not sure I get your point. For me, verifying measurements is part of an objective process of validating results, and not part of convincing the heathen. This is not a religious pursuit and not an act of faith, it's a simple process of confirming engineering findings.

[pkane2001]

Just now, Audiophile Neuroscience said:

My point is simple. If Amir's measurements are not trusted except by his disciples then the disciples are the only ones you will convince (without adding the verification)

 

So my statement that his measurements have been verified by independent parties means that the measurements can be trusted by more than his disciples, or am I still misunderstanding?

 

[pkane2001]

11 minutes ago, Audiophile Neuroscience said:

 

"his measurements" - do you mean all?

 

If referring to "I [you] have, and I’ve seen Amir post comparisons with a laboratory power supply with regeneration vs. just a wall outlet."

 

Then that is fine if you mean you have verified Amir's comparisons with a laboratory power supply with regeneration vs. just a wall outlet

 

🤪 I need a drink...

 

[pkane2001]

41 minutes ago, Jud said:

Might be interesting for folks discussing this topic to read the following Wikipedia article:

 

https://en.m.wikipedia.org/wiki/New_Coke

 

Thanks, Jud, but I meant something stronger than a Coke 😄

 

44 minutes ago, pkane2001 said:

🤪 I need a drink...

 

[pkane2001]

3 hours ago, Audiophile Neuroscience said:

Thanks. I can see the FFT for THD of the AD DAC is the same as in the data sheet but not sure (due to lack of technical knowledge) what small print gives away that the two FFTs Amir places side by side are not comparable.

 

So the fact that he didn't read a small print on a data sheet proves his incompetence or that he just wasn't paying attention? Or is it that his measurements of the device show that it has a very poor linearity, high jitter and starts to clip below 0dBFS? The latter is what I got out of it. We all seem to get what we want from measurements, I guess. I get information about the measured device, you -- information about the person.

[pkane2001]

16 minutes ago, opus101 said:

I missed the place where @Audiophile Neuroscience got information about Amir from this.

 

 

5 hours ago, Audiophile Neuroscience said:

example of "misleading measurements" and biased reporting rendering agenda-based measurements

 

[pkane2001]

13 minutes ago, opus101 said:

Ah that's not 'from this' - seems he brought that to the discussion prior.

 

Well, actually it was in response to your statement that "Amir misappropriated ADI's measurements of their DAC chip to malign Schiit", so mostly it was 'from this'. And how would you interpret the word "malign" if not as an accusation of malicious intent?

[pkane2001]

19 hours ago, fas42 said:

Another interesting bundle of thoughts I just came across, when someone asked for some noise making ideas ... https://www.eevblog.com/forum/projects/intentionally-injecting-noise-into-supply-rails/

 

As if he was reading this, Amir just posted measurements of an AudioQuest powerstrip, measuring its advertised line noise filtration capabilities. Apparently it does filter above 30kHz, but leaves all of the junk in the audio band. Who knows, it may actually be useful for some audio devices that don't have good filtration at the power supply.

[pkane2001]

14 minutes ago, fas42 said:

 

IME, all audio devices don't have good filtration at the power supply - that is, it's trivially easy to introduce some electrical noise making device or process into the environment, and hear the impact on the SQ ... just read the reports of companies struggling to get good sound in a show situation, and how they had to deal with the "lousy hotel power!"

Well, not all, as the JDS Labs Atom in the review showed no difference with filtered and unfiltered power, and Amir’s power line is pretty dirty.