Bit-identical playback CAN sound different

[manisandher]

10 minutes ago, yamamoto2002 said:

That 19kHz noise may be inductor whine, move microphone to close to any switching power supply or DC-DC converter (PC, network switch, monitor display, graphics board etc) and see what device emit the noise :)

 

The mic remained totally static for both captures. Why would there be more noise in one than the other, the second recorded literally seconds after the first finished?

 

Mani.

[yamamoto2002]

17 minutes ago, manisandher said:

 

The mic remained totally static for both captures. Why would there be more noise in one than the other, the second recorded literally seconds after the first finished?

 

Mani.

 

network traffic, background tasks, power state vary in time. computer display noise varies when drawing content is different.

 

 turn off room lights and computer monitor (set 1 minute timeout), and disconnect network, and use battery powered laptop. Insert several minutes of silence track before test signal and play

[pkane2001]

27 minutes ago, manisandher said:

 

The mic remained totally static for both captures. Why would there be more noise in one than the other, the second recorded literally seconds after the first finished?

 

Mani.

 

What is interesting, as well, is if you listen to the difference between the two. It sounds like a very quiet reverb/reflection rather than the original sound, almost like an echo. But it is true that it's more of the high frequency sound (much lower than 19kHz, but like you describe, the leading edges are most pronounced):

 

https://app.box.com/s/had70geer8z8jkkzd5idijah1ddjrrh0

 

Mani, are you sure you didn't move between the two takes? Even a small repositioning could change the reflections when they reach the mic, especially if you were not far away.

 

Note: I've increased the level by 15dB to make this easier to hear, otherwise this is the difference directly from DeltaWave, after removing clock drift and aligning time and level for both files.

 

The sound at 32 seconds is something dropping or door slamming, I doubt this came from the speakers.

 

[pkane2001]

deleted

[PeterSt]

28 minutes ago, yamamoto2002 said:

network traffic, background tasks, power state vary in time. computer display noise varies when drawing content is different.

 

You realize that it is all about exactly that, right ?

(but the taming of it by various means and in various base states (statuses))

[manisandher]

34 minutes ago, yamamoto2002 said:

network traffic, background tasks, power state vary in time. computer display noise varies when drawing content is different.

 

4 minutes ago, PeterSt said:

You realize that it is all about exactly that, right ?

(but the taming of it by various means and in various base states (statuses))

 

We need to distinguish between the optimised audio PC connected to the DAC and the regular desktop PC connected to the ADC. I think Peter is referring to the former and how it might affect the output of the DAC (and therefore indirectly the output from the speakers), and yamamoto2002 is referring to the latter and how it might affect what the mic is picking up directly.

 

40 minutes ago, yamamoto2002 said:

turn off room lights and computer monitor (set 1 minute timeout), and disconnect network, and use battery powered laptop. Insert several minutes of silence track before test signal and play

 

Yep, will do.

 

Mani

[PeterSt]

4 minutes ago, manisandher said:

and yamamoto2002 is referring to the latter and how it might affect what the mic is picking up directly.

 

Oh, he surely may refer to that. In that case ...

But (and he may speak for himself), I don't think he does. Mind you, there's all the logic in the world that your led lights etc. may influence. But in the end it is all about that (too). So without that all eliminated, some things won't work out at all. Remember the struggle for Windows 8 (and AmirM never responding -hahaha), this ended up with this (my sig) :

 

 

Maybe I said it too clumsy, but without these things sufficiently arranged for, all is moot (too much electrical noise to even start doing things well).

Btw, @yamamoto2002, you are one of the best out there. So as a matter of fact all comments are appreciated. I mean, aren't we all still learning ... for the good cause ? I sure am. Mani is too.  Actually we all are. Audiophiles you know...

 

[manisandher]

1 hour ago, pkane2001 said:

What is interesting, as well, is if you listen to the difference between the two. It sounds like a very quiet reverb/reflection rather than the original sound, almost like an echo. But it is true that it's more of the high frequency sound (much lower than 19kHz, but like you describe, the leading edges are most pronounced):

 

https://app.box.com/s/had70geer8z8jkkzd5idijah1ddjrrh0

 

Thanks Paul. Very interesting.

 

1 hour ago, pkane2001 said:

Mani, are you sure you didn't move between the two takes? Even a small repositioning could change the reflections when they reach the mic, especially if you were not far away.

 

I was seated at my desk ~1m immediately to the left of the mic and remained as still as I could throughout. Only my hand/arm really moved to control the mouse/keyboard.

 

1 hour ago, pkane2001 said:

The sound at 32 seconds is something dropping or door slamming, I doubt this came from the speakers.

 

No doubt my wife or one of the boys.

 

I'll try to do any retakes when they're all asleep 🙂.

 

Mani.

[manisandher]

2 hours ago, pkane2001 said:

Note: I've increased the level by 15dB to make this easier to hear...

 

I actually find it more instructive to listen to it without the 15dB increase. Playing it against the two original files, the difference between them becomes immediately apparent. As I've been saying, listen to difference in the leading edges of the guitar plucks and the sibilance in his voice.

 

Mani.

[fas42]

What's amusing, of course, as Peter points out, is that the differences could be due to all those little electrical doodahs going on - which we will have to eliminate to try and make the measurement correlate ... but, of course(!!), our subjective hearing abilities can't possibly be picking this up, can they now ... ??

 

It's really very funny, 😁 ...

 

[Superdad]

7 hours ago, manisandher said:

Our front drive is a few meters away from a main road and it may well be that a lorry just happened to have passed by during one of the takes.

 

Most every place else in the world we call them "trucks" Mani!  

(But don't worry, I am not much into either type of football...)

[Rexp]

7 minutes ago, Superdad said:

 

Most every place else in the world we call them "trucks" Mani!  

(But don't worry, I am not much into either type of football...)

Well American English is more common. 

[sandyk]

6 hours ago, manisandher said:

 

Listen for the following differences between the two tracks:

1. the leading edges of the guitar plucks

2. the sibilance in his voice

 

One track is slightly softer (easier to listen to) in both cases... to my ears.

 

Mani.

Is this as you originally found in the tests with Mansr after the aborted start ? IOW, a little cleaner sounding overall .

[March Audio]

On 3/22/2021 at 3:19 AM, manisandher said:

DeltaWave shows the main difference between the two mic captures as lying between 16-20kHz:

 

 

This is just one data point of course. At some point, I'll take a number of captures at both settings to see if there is a consistent difference.

 

Mani.

Hi

 

Just stumbled across this.

 

Am I correct in saying you are using a microphone to capture the speaker output?

[March Audio]

Sorry I got interrupted.

 

If that is the case then with the greatest of respect Im afraid that methodology is going to be extremely insensitive and inconsistent for checking for differences.

 

You will be lucky to get a 60dB signal to noise ratio when you need to be looking more like 120dB+.  The room has far too much (and inconsistent noise).  Your speaker and microphone add distortion.

 

A far better way would be to just use the audio interface in loopback feeding the output back to the input and recording that.  You have one source of noise and distortion then which will stay consistent and you will achieve an SNR that will allow you to look for very low level differences.

[manisandher]

6 hours ago, March Audio said:

You will be lucky to get a 60dB signal to noise ratio when you need to be looking more like 120dB+.  The room has far too much (and inconsistent noise).  Your speaker and microphone add distortion.

 

Agreed. And this will probably come to nothing as a result.

 

6 hours ago, March Audio said:

A far better way would be to just use the audio interface in loopback feeding the output back to the input and recording that.

 

Have done this many times already, but cannot find any consistent differences between recordings. And yet, I hear differences during playback (9/10 in blind ABX, etc.). That's why I thought I'd try a mic, just to see what comes up...

 

Mani.

[fas42]

Had a look myself using DeltaWave - there definitely appears to be something going on; in the high frequency content, there is a regular mismatch of the waveform, the difference waveform shows this quite clearly.

 

But to be more sure of this, a controlled recording of something like 3 successive versions needs to be done, in quick succession: setting 1; then setting 2, then setting 1 again. This would hopefully rule out changes in the environment over time, any warm up variations; and, show consistency of the playback, recording chain.

[March Audio]

On 3/26/2021 at 3:35 PM, manisandher said:

 

Agreed. And this will probably come to nothing as a result.

 

 

Have done this many times already, but cannot find any consistent differences between recordings. And yet, I hear differences during playback (9/10 in blind ABX, etc.). That's why I thought I'd try a mic, just to see what comes up...

 

Mani.

If you are up for it we can try a little experiment next week.

 

You will need foobar and its ABX plugin.

 

https://www.foobar2000.org/getfile/foobar2000_v1.6.4.exe

 

https://www.foobar2000.org/components/view/foo_abx

[PeterSt]

2 hours ago, March Audio said:

If you are up for it we can try a little experiment next week.

 

I hope I am allowed to say that it is totally beyond me what you are trying to achieve or prove ? 🙂

 

On 3/26/2021 at 1:09 AM, March Audio said:

Just stumbled across this.

 

So yes, you did.

 

On 3/26/2021 at 2:01 AM, March Audio said:

You will be lucky to get a 60dB signal to noise ratio when you need to be looking more like 120dB+.

 

The only thing you could be stating here is that it is super easy to hear differences beyond 120dB (of differences), am I right ?

No, I am not right, but this is because you missed the gist of this "experiment".

 

Bit perfect playback for two different situations, means

- the data arriving at the DAC is 100% the same.

 

Still perceiving differences audibly means

- Something in-DAC happens to change the sound.

 

This is actually all.

But what you missed is that this is incurred for. By voodoo or other means.

- What you can hear, can be recorded by microphone.

- What you can hear for differences should be able to be recorded by microphone.

And that is what happened. At least so far it seems so.

Note : That these differences can be incurred for is nothing new to me (and my software users) because the software was made to do that from day one (2006 or so).

 

Also see next post.

[PeterSt]

That this would happen (record it by microphone and you will be able to "see" it), is something I predicted the other day (in an other thread) and is probably why Mani conducted the test like this in the first place. My explanation of why this means would work out, while recording the output directly at the output of the DAC by means of an ADC does not work out at all, is this:

 

All what occurs for differences at the output of the DAC are so minute that they will disappear in the noise of everything digital. You may think that amplifying all with 20dB+ may unveil differences, but since you'd be amplifying the noise just the same ... no.

Still the differences *are* there.

 

Amplify all through the power amp, put t through some speakers and all, say, "resonances" of the differences because audible, thinking that the room too is a huge amplifier. Thus we can easily hear what's hard to record at the output of the DAC (output of the power amp probably still the same issue).

But as said, what we can hear in the room obviously can be recorded. By noisy microphone environment or not.

 

The gist of the thread is also about being under 70dB loud kitchen hoovers, and still being able to pick 10 out of 10 the differences.

That easy it is.

[yamamoto2002]

Here it is acoustic noise emitted from the power supply (?) of my sonically noisiest 27inch computer display (built-in speaker is muted)

 

AKG C414 → RME Babyface Pro → Asus UX31E laptop to record

 

Worst case (Very audible)

 

 

Best case (slightly audible from 1m distance)

 

 

Display switched off

[March Audio]

14 hours ago, PeterSt said:

 

I hope I am allowed to say that it is totally beyond me what you are trying to achieve or prove ? 🙂

 

 

So yes, you did.

 

 

The only thing you could be stating here is that it is super easy to hear differences beyond 120dB (of differences), am I right ?

No, I am not right, but this is because you missed the gist of this "experiment".

 

Bit perfect playback for two different situations, means

- the data arriving at the DAC is 100% the same.

 

Still perceiving differences audibly means

- Something in-DAC happens to change the sound.

 

This is actually all.

But what you missed is that this is incurred for. By voodoo or other means.

- What you can hear, can be recorded by microphone.

- What you can hear for differences should be able to be recorded by microphone.

And that is what happened. At least so far it seems so.

Note : That these differences can be incurred for is nothing new to me (and my software users) because the software was made to do that from day one (2006 or so).

 

Also see next post.

Well,  I invite people to take part in the experiment (I won't be able to sort it out for a few days) and you can discover the point of the exercise.

[March Audio]

14 hours ago, PeterSt said:

.

Still the differences *are* there.

 

Amplify all through the power amp, put t through some speakers and all, say, "resonances" of the differences because audible, thinking that the room too is a huge amplifier. Thus we can easily hear what's hard to record at the output of the DAC (output of the power amp probably still the same issue).

But as said, what we can hear in the room obviously can be recorded. By noisy microphone environment or not.

 

The gist of the thread is also about being under 70dB loud kitchen hoovers, and still being able to pick 10 out of 10 the differences.

That easy it is.

Can I just clarify something?  I don't know you but from your comments "my software" would I be correct in saying that you sell audio playback software?

 

So if I understand you correctly what you are saying here is that rooms distort the sound so much that unmeasureable deviations in the input signal become so amplified that they become audible?

 

By definition this effect would vary from room to room and so would the outcome.  So is there any reason to assume that the differences any one audio player makes to the sound would result in a consistently "better" sound?  That one particular player always sounds superior regardless of the room?

 

Oh BTW my experiment can be conducted over speakers so the room effects will be taken into account.

 

[PeterSt]

1 minute ago, March Audio said:

So if I understand you correctly what you are saying here is that rooms distort the sound so much

 

No, not distorts (although that too will happen obviously). Amplifies.

Compare with the anechoic room.

[March Audio]

2 minutes ago, PeterSt said:

 

No, not distorts (although that too will happen obviously). Amplifies.

Compare with the anechoic room.

That is a form of distortion.