TEST FILES. How to verify the quality of your audio system and other audio tests.

[Soniclife]

OK, that answers my question.

If I was a 12 year old and wanted to troll this forum this is how I would do it.

 

[maty]

In the end the usual can not avoid personal disqualifications.

 

[flipflop]

If I was a 12 year old and wanted to troll this forum this is how I would do it.

I would take the sealioning approach popularized by @Audiojim and @Calexico

 

[Blumlein 88]

In the end the usual can not avoid personal disqualifications.

Can you give a good reason not to match levels?

 

[maty]

The most important: I did not generate the audios!

Surely you can differentiate between an mi and fa even if the levels differ slightly or not. Just differentiate, nothing more.

 

[Sgt. Ear Ache]

Instead of proving to the rest of the world I have golden ears, I'm going to prove the rest of the world has bad ears!

 

[maty]

Let us keep lowering the level of explanation.

Surely you are able to differentiate between A and B. And if the levels are not equal, in this example the size, it will be easier for you. A and B.

 

[Sgt. Ear Ache]

Can you explain in clear, easy to understand terms why you want us to tell you whether or not we can hear a difference between these files?

 

[Thomas savage]

I don't know , if any of you make me breakfast one day I need to trust you know the difference between a strawberry and a tomato else you will make a right royal mess of me fry up.

So take the maty test as that's what it seems to be about.

 

[solderdude]

When you take the red pill you get to keep your subjective powers and can always here substantial differences, even when there are none.
When you take the blue pill your subjective powers will be taken away and can never hear any differences in blind tests any more.... even if they are really obvious.

 

[Thomas savage]

When you take the red pill you get to keep your subjective powers and can always here substantial differences, even when there are none.
When you take the blue pill your subjective powers will be taken away and can never hear any differences in blind tests any more.... even if they are really obvious.

I vote we crush them up and snort them...

 

[Blumlein 88]

I vote we crush them up and snort them...

Thomas, ....I'm surprised. Don't you know a two alternative forced choice when you see one?

 

[daftcombo]

Hi,

I listened to all the clips yesterday night through AKG K701 EQ-corrected.
I think I can tell differences between a few clips, but no way I could identify them all. Perhaps I could pass an ABX for a few of them.
It is difficult.

 

[maty]

Thank you very much, you are the first!

The important thing is to detect that there are differences. I guess you need a more resolutive system to appreciate them without any doubt among those three DIY amps. I did it with my loved speakers in near field.

I liked the sound of the class A F5 Juma so much that I began to investigate. In addition to the transistors so difficult to find with respect to the original F5 from Nelson Pass, the key must have been the harmonic profile, with H2 predominant. But with a complex orchestration the sound is worse. The DIY speakers used with the amps probably have a lot to do with it too. Maybe H2 at -73 dB, I am not sure with F5.

 

[solderdude]

The differences between some of the files are so big that there MUST be audible differences so it is not weird that anybody trying this will hear differences. That only proves one thing. That considerable differences are audible.
This has nothing to do with bottlenecks or equipment being 'resolving enough'.

the key must have been the harmonic profile,

As can be seen the absolute phase is rotated and amplitude differs. Most likely that's what is really different.

 

[daftcombo]

It would definitely be interesting to have measurements of these amps to see what effect of FR and phase shifts have on the sound that we can hear in the clips.
I also think that FR is the most important thing, even if amps should be more or less flat in that regard.
Then phase or distortion.

 

[maty]

The phase shift is very important. It is a factor that almost nobody mentions. Everyone stays in the basics, in the flat frequency response.

The other day I did a test, I raised the response a bit to 23 kHz with a very limited bandwith in my BIG speakers, which have a supertweeter -inside the box- cut to 18 kHz. I was not supposed to notice the difference and less at my age but I did notice it. The only explanation I can think of is that of the phase. JRMC v24 and WiFi 24 bits.

 

[PierreV]

In the end the usual can not avoid personal disqualifications.

Well, you could, with a properly designed test...

Like many of us here, I own quite a few amplifiers and can compare them live. So why bother with sub optimal test files?

I don't hear or measure much difference between decent solid state amplifiers btw provided they are used in a reasonable configuration, sometimes obviously (comparing a cheap 2*20w to a 2*250w on large boxes) sometimes less obviously (ability to drive low impedance stuff). I do hear and measure differences with tube hybrids and also very cheap class D stuff.

As far as I am concerned anyway, I don't necessarily equate difference with better or worse. It all depends of what I am listening too, my mood, the time of the day, the room...

 

[solderdude]

The phase shift is very important. It is a factor that almost nobody mentions. Everyone stays in the basics, in the flat frequency response.

The other day I did a test, I raised the response a bit to 23 kHz with a very limited bandwith in my BIG speakers, which have a supertweeter -inside the box- cut to 18 kHz. I was not supposed to notice the difference and less at my age but I did notice it. The only explanation I can think of is that of the phase. JRMC v24 and WiFi 24 bits.

I can think of another much more plausible reason.. the tweeter does not have a very steep filter so when you raise the amplitude you also raise the amplitude of lower (audible frequencies)

About phase... substantial phase shifts within a very narrow bandwidth (speaker allignment etc) is audible.
A gradual and few degrees phase shift between 1kHz and say 20kHz or 20Hz is not that audible.
When considering phase shifts in amplifiers it concerns the latter.

 

[miero]

For a such testing a careful test preparation is required. And if it is done, results might not be so clear as here.

For example check this opamp listening test done by @pma
- http://pmacura.cz/opampshires.htm

And more links to interesting listening tests:
- https://www.diyaudio.com/forums/everything-else/330228-tell-original-file-tube-amp-record-test.html
- https://www.diyaudio.com/forums/eve...inyl-rip-digital-download-listening-test.html
- https://www.diyaudio.com/forums/everything-else/329440-tube-distortion-listening-test.html
- https://www.diyaudio.com/forums/everything-else/331257-listening-test-ii-tell.html