Investigation Into Effects Of PC load On DAC Analogue Output

[March Audio]

4 minutes ago, fas42 said:

 

First of all, the background noise can be made to be relatively consistent - to test this, merely record the same playback, with no changes, several times to establish the consistency of the recording space.

 

Secondly, what you are looking are patterns in the waveform which consistently register as being different at certain points in the music - say, a treble crescendo, or transient. These are the "tells" that one's ears are sensitive to, and which are meaningful.

No it can't Frank.  Also before you argue, you have no basis to judge.  You have never analysed any acoustic noise so have no idea about it.

 

Background noise in your listening room will probably be around 30dB on a quiet day and quite variable.  This will mask subtle differences.

 

The tests I have performed are looking far, far below the threshold of audibility.

[March Audio]

So this is a 32 point multitone 1/10 decade.

 

RME ADI2.  PC unloaded.

 

 

PC loaded

 

 

No significant difference.

[opus101]

3 hours ago, idiot_savant said:

Now, strictly speaking, the complaints about PC activity have always been about “noise”, which IMD is clearly not ( clues in the name ). 

 

In the case of an IMD test, then yes its distortion because the number of discrete tones is relatively low. But in the case of music as a stimulus (not all kinds of music, girl-with-a-guitar won't count) then the 'distortion' is actually noise-like due to the 'tones' running into the hundreds if not thousands.

You can read some technical background to this here : https://audiophilestyle.com/forums/topic/58733-which-is-the-threshold-for-audible-thd-in-for-untrained-audiophiles/?do=findComment&comment=1037344

[fas42]

1 hour ago, pkane2001 said:

 

So the real world is about using an obscure setting in XX High End software? How curious!

 

 

The real world is that the electronics which retrieves the source music file may impact the analogue part of the chain, by their operation - vast tracts of conversation have been laid down, in people's pursuit of finding answers to this. That particular  player just happens to make it easy to play with settings which the author has found to be effective in altering the electrical patterns which can disrupt, in subtle ways, the following components - for fussy listeners.

 

So, either all these people are delusional about hearing differences - or it may be that not all electronics are designed and implemented to behave perfectly, when faced with various forms of electrical noise ... now, which do you think is more likely?

[pkane2001]

23 minutes ago, fas42 said:

 

The real world is that the electronics which retrieves the source music file may impact the analogue part of the chain, by their operation - vast tracts of conversation have been laid down, in people's pursuit of finding answers to this. That particular  player just happens to make it easy to play with settings which the author has found to be effective in altering the electrical patterns which can disrupt, in subtle ways, the following components - for fussy listeners.

 

So, either all these people are delusional about hearing differences - or it may be that not all electronics are designed and implemented to behave perfectly, when faced with various forms of electrical noise ... now, which do you think is more likely?

I think it’s more likely that you’ll never answer a question directly or provide a shred of objective evidence to support any of your conjectures….since you asked what I think is more likely ;)

[March Audio]

29 minutes ago, fas42 said:

 

The real world is that the electronics which retrieves the source music file may impact the analogue part of the chain, by their operation - vast tracts of conversation have been laid down, in people's pursuit of finding answers to this. That particular  player just happens to make it easy to play with settings which the author has found to be effective in altering the electrical patterns which can disrupt, in subtle ways, the following components - for fussy listeners.

 

So, either all these people are delusional about hearing differences - or it may be that not all electronics are designed and implemented to behave perfectly, when faced with various forms of electrical noise ... now, which do you think is more likely?

Frank.  This is an objective thread where you need to provide more than your usual nebulous conjecture spam.

 

You have your own thread where you can think out loud and speculate as much as you like, but its off topic here.

[PeterSt]

5 hours ago, March Audio said:

So this is a 32 point multitone 1/10 decade.

 

Maybe you or others have better ideas, but I don't think that watching the multitones themselves would bring anything (well, as we saw). So the - or my idea would be that the multitones would be the stimulus and that with other means other data is observed. Thus for example, give it those tones (the more the better) and observe possible jitter influence. I did such things myself with normal music

 

 

vs

 

 

... when jitter was high enough so I could still do these things (today it is way under the measurable level for me).

This is only about the volume of music and how a higher level (2nd shot) implies more random jitter than low level or even idle (1st).

 

But see ? while this is uncontrollable music, multitones would be controllable (repeated tests with various environmental parameters like you attempt here).

 

There is no way this is really simple, because it will require measuring clock data so (analog) system noise is avoided. And, people may see me write for the xth time that by now 3 years or so ago, I had applied measuring wires to certain in-DAC chips so I could measure USB influence (this originated in the original Lush thread), but the analyser I bought for the purpose is still unpacked (yes, I am serious).  Those wires still stick out in there. Read: so much prep time this takes, including the learning what actually to look at - how to ground the probes and so much more.

And so I will repeat:  the effort you put into this, is much appreciated and I would hope something comes from it. But it won't go easy IMHO.

 

[PeterSt]

You won't be able to do much with noise, as the noise is too low to begin with. So, we must think about how even the lowest noise or noise patterns - all invisible to us - may influence other system elements.

If we take the simple approach, then all what can be influenced and which will theoretically change the sound, is jitter. At least that is what I am saying since I work explicitly on this stuff, so whatever a PC may be doing, it will influence jitter (signature) if we perceive audible changes.

 

Before I forget: it is not to underestimate how relative matters may influence more or just less. For example, you, Alan, will be using a normal PC and if we try to exclude the video card, during idle operation it may draw 130-140 Watts. Now what would change when you put the PC under some load as you did ? ... you may be able to tell (just measure), but on my estimate: hardly anything. 5, maybe 10 Watts. Btw, it (for SQ analysis) would be about the spikes of it, not the consistent draw. However, the spikes will be relative to the consistent draw. Thus, 5-10W against 130W.

Something to hopefully learn from: in the more optimized situation your very same PC will consume 50W (no vid card) and the draw you imply by the very same load will still be 5-10W. Thus, something drastically changes with that relation. The spike occurring will suddenly be quite high in relation to the base load. This thus also influences SQ more *if* we deem PC load influencing SQ to begin with, OK ? (so this is an assumption)

 

Then over to these (idle vs load):

 

 

A random reader in here will not know really that this is all about "dancing spikes" all over (you could attempt a small video to showcase that). Now, a more experienced (say) EE will not see much difference in the above two, but in this more special situation I certainly see "significant" change. I am sure I don't need to point that out either. Just look. 🙂

 

Recalling my said influence which should be onto jitter, there is something not quite normal about what we see here, and this is the side lobes of jitter (in my previous post these are the outside boundaries of the beam).

 

Here too you can see that the left-hand outer band (lobe) is thicker than the right-hand one. The same we see in your two screenshots.

But something is not right with the 2nd screenshot, because the right-hand lobe is way lower. And yes, I say "way" because with jitter everything is "way" because remember, it will influence sound (to what degree and when audible is another matter so for now let's let that be please).

 

I talked about the "dancing spikes" for a reason, because noise would dance quite a lot (it is supposed to be random). But jitter regarding these side lobes should not be dancing much at all unless we are dealing with an influence that influences jitter variably (music does that too to some extent). OK, let's see:

1. you just took a screenshot from a randomly occurring "spiked" situation, are possibly not ware that this should all be about jitter, and posted the screenshots; or

2. you saw it alright as a consistent change and denoted it insignificant.

 

In either case I think something is the matter, with a dose of precaution because it could be your RME. And Yes, I have one too, but as usual with me, that too is still in unopened packing. 😞

So *or* the change is persistent and the right-hand lobe is lower under load than without load, *or* the right hand lobe is suddenly fluctuating with load while the idle situation is stable. Maybe even a bit of both is in order.

 

Alan, I hope you can shed a light on this, with thus the idea that it can also be the RME and which might not be good for the purpose of what we're doing here.

 

 

[March Audio]

11 minutes ago, PeterSt said:

 

Maybe you or others have better ideas, but I don't think that watching the multitones themselves would bring anything (well, as we saw). So the - or my idea would be that the multitones would be the stimulus and that with other means other data is observed. Thus for example, give it those tones (the more the better) and observe possible jitter influence. I did such things myself with normal music

 

 

vs

 

 

... when jitter was high enough so I could still do these things (today it is way under the measurable level for me).

This is only about the volume of music and how a higher level (2nd shot) implies more random jitter than low level or even idle (1st).

 

But see ? while this is uncontrollable music, multitones would be controllable (repeated tests with various environmental parameters like you attempt here).

 

There is no way this is really simple, because it will require measuring clock data so (analog) system noise is avoided. And, people may see me write for the xth time that by now 3 years or so ago, I had applied measuring wires to certain in-DAC chips so I could measure USB influence (this originated in the original Lush thread), but the analyser I bought for the purpose is still unpacked (yes, I am serious).  Those wires still stick out in there. Read: so much prep time this takes, including the learning what actually to look at - how to ground the probes and so much more.

And so I will repeat:  the effort you put into this, is much appreciated and I would hope something comes from it. But it won't go easy IMHO.

 

 

 

Can you explain what "other data"?  Happy to look into things

 

Measuring jitter does not require measuring clock data.  In fact by trying to you will probably introduce additional jitter. You just need to look at the dac output signal.  Thats the only thing we are interested in and if there is jitter in the clock it will be quite apparent there.  The clock timing variations directly translate into sidebands on the test tone.  Close in phase noise appears more like a widening of the tone base.

 

[March Audio]

Oh just to add to the above, more multitones wont affect the jitter levels.  just because your audio signal is more complex it doesnt mean that the dac word clock is affected.

[March Audio]

33 minutes ago, PeterSt said:

You won't be able to do much with noise, as the noise is too low to begin with. So, we must think about how even the lowest noise or noise patterns - all invisible to us - may influence other system elements.

If we take the simple approach, then all what can be influenced and which will theoretically change the sound, is jitter. At least that is what I am saying since I work explicitly on this stuff, so whatever a PC may be doing, it will influence jitter (signature) if we perceive audible changes.

 

Before I forget: it is not to underestimate how relative matters may influence more or just less. For example, you, Alan, will be using a normal PC and if we try to exclude the video card, during idle operation it may draw 130-140 Watts. Now what would change when you put the PC under some load as you did ? ... you may be able to tell (just measure), but on my estimate: hardly anything. 5, maybe 10 Watts. Btw, it (for SQ analysis) would be about the spikes of it, not the consistent draw. However, the spikes will be relative to the consistent draw. Thus, 5-10W against 130W.

Something to hopefully learn from: in the more optimized situation your very same PC will consume 50W (no vid card) and the draw you imply by the very same load will still be 5-10W. Thus, something drastically changes with that relation. The spike occurring will suddenly be quite high in relation to the base load. This thus also influences SQ more *if* we deem PC load influencing SQ to begin with, OK ? (so this is an assumption)

 

Then over to these (idle vs load):

 

 

A random reader in here will not know really that this is all about "dancing spikes" all over (you could attempt a small video to showcase that). Now, a more experienced (say) EE will not see much difference in the above two, but in this more special situation I certainly see "significant" change. I am sure I don't need to point that out either. Just look. 🙂

 

Recalling my said influence which should be onto jitter, there is something not quite normal about what we see here, and this is the side lobes of jitter (in my previous post these are the outside boundaries of the beam).

 

Here too you can see that the left-hand outer band (lobe) is thicker than the right-hand one. The same we see in your two screenshots.

But something is not right with the 2nd screenshot, because the right-hand lobe is way lower. And yes, I say "way" because with jitter everything is "way" because remember, it will influence sound (to what degree and when audible is another matter so for now let's let that be please).

 

I talked about the "dancing spikes" for a reason, because noise would dance quite a lot (it is supposed to be random). But jitter regarding these side lobes should not be dancing much at all unless we are dealing with an influence that influences jitter variably (music does that too to some extent). OK, let's see:

1. you just took a screenshot from a randomly occurring "spiked" situation, are possibly not ware that this should all be about jitter, and posted the screenshots; or

2. you saw it alright as a consistent change and denoted it insignificant.

 

In either case I think something is the matter, with a dose of precaution because it could be your RME. And Yes, I have one too, but as usual with me, that too is still in unopened packing. 😞

So *or* the change is persistent and the right-hand lobe is lower under load than without load, *or* the right hand lobe is suddenly fluctuating with load while the idle situation is stable. Maybe even a bit of both is in order.

 

Alan, I hope you can shed a light on this, with thus the idea that it can also be the RME and which might not be good for the purpose of what we're doing here.

 

 

 

If this noise is so low its invisible to us then it is of no consequence.  Are you seriously saying that things going on below -180dBFS are audible?

 

The lower lobe was lower due to the averaging not catching up.  I had actually moved the DAC on the bench during the measurement and it affected the levels slightly.  

 

The RMEW is just fine for what we are doing here, its just so far there is nothing to see.

[March Audio]

 

[manisandher]

8 hours ago, March Audio said:

With all respect to Mani, unfortuntely Its a hopelessly flawed method.

 

In my defence, I've already undertaken many of the tests you're now trying. They've all come back blank. So, I thought I'd see if capturing the actual sound waves with a mic might prove insightful. This might actually be the case, but not in the noisey enviroment in which I conducted the most recent tests. I've just been too busy to repeat them in my much quieter listening room, but hope to do so at some point.

 

What isn't in question AFAIC is that bit identical playback can sound different. For example, bit identical settings in XXHighEnd change the sound (even with a modern DAC like the RME, that both of us have).

 

I had experienced this for years before inviting Mans up to conduct an essentially double blind ABX test - Mans was controlling the test in a room separated by two doors and a corridor from the listening room where I was, and using a random generator on his phone to select A or B. I scored 9/10 (1% probability of guessing). I really should have scored 10/10, as the differenc between A and B was clearly audible, but it was 15 minutes into the test, I was tired and I got #9 wrong. We captured the digital input to the DAC in real-time througout the ABX. A and B remained bit-identical throughout.

 

Just consider the following sequence of events here:

 

- I was convinced I could hear differences between bit-identical playback

- I was confident I could demonstrate this in a (essentially double) blind ABX

- I invited Mans up to my place (paid for his train ticket, no less)

- I scored 9/10

 

Coincidence? Chance? Luck? I don't think so.

 

Mani.

[March Audio]

2 minutes ago, manisandher said:

 

In my defence, I've already undertaken many of the tests you're now trying. They've all come back blank. So, I thought I'd see if capturing the actual sound waves with a mic might prove insightful. This might actually be the case, but not in the noisey enviroment in which I conducted the most recent tests. I've just been too busy to repeat them in my much quieter listening room, but hope to do so at some point.

 

What isn't in question AFAIC is that bit identical playback can sound different. For example, bit identical settings in XXHighEnd change the sound (even with a modern DAC like the RME, that both of us have).

 

I had experienced this for years before inviting Mans up to conduct an essentially double blind ABX test - Mans was controlling the test in a room separated by two doors and a corridor from the listening room where I was, and using a random generator on his phone to select A or B. I scored 9/10 (1% probability of guessing). I really should have scored 10/10, as the differenc between A and B was clearly audible, but it was 15 minutes into the test, I was tired and I got #9 wrong. We captured the digital input to the DAC in real-time througout the ABX. A and B remained bit-identical throughout.

 

Just consider the following sequence of events here:

 

- I was convinced I could hear differences between bit-identical playback

- I was confident I could demonstrate this in a (essentially double) blind ABX

- I invited Mans up to my place (paid for his train ticket, no less)

- I scored 9/10

 

Coincidence? Chance? Luck? I don't think so.

 

Mani.

 

Even a quiet listening room wont work Im afraid.

 

With respect the devil is in the detail of the ABX test and a sample of one doesnt really tell us much.

 

[manisandher]

1 minute ago, March Audio said:

 

With respect the devil is in the detail of the ABX test and a sample of one doesnt really tell us much.

 

 

It's your prerogative to take it however you want.

 

The most telling part of the whole day was after the ABX when I sat Mans down in the listening room and told him what to listen out for between A and B. I heard the differences easily, he said he couldn't.

 

Couldn't, or couldn't bring himself to???

 

Mani.

[PeterSt]

1 hour ago, March Audio said:

You just need to look at the dac output signal.

 

Please stop telling me how things ought to be. You are the one unable to hear or show differences. Not me.

And FYI: I again don't like your tone.

[manisandher]

8 minutes ago, March Audio said:

Even a quiet listening room wont work Im afraid.

 

And yet, I can hear the differences even in my very far from quiet office. My ears are obviously totally ignoring whatever ambient noise there is.

 

Mani.

[March Audio]

I cant edit my posts now I have admin control haha.  I meant to add to the above that, with respect, I dont accept that its beyond question that bit identical sources can sound different.  I will caveat that statement because it requires expanding.

 

Can DACs be affected by whats happening up stream?  Yes.  Already discussed ground loops, noise currents etc.  However good dacs are not sensitive to this. So its a secondary effect, not that of identical data sounding different.

[March Audio]

1 minute ago, manisandher said:

 

And yet, I can hear the differences even in my very far from quiet office. My ears are obviously totally ignoring whatever ambient noise there is.

 

Mani.

However you are trying to measure.

 

With respect you are entering the territory of "I hear it therefore it is", which is not what an objective thread is about.

[PeterSt]

1 minute ago, March Audio said:

However good dacs are not sensitive to this. So its a secondary effect, not that of identical data sounding different.

 

OK, accepted. But what is the reason for the existence of this thread then ?

[PeterSt]

1 minute ago, March Audio said:

With respect you are entering the territory of "I hear it therefore it is", which is not what an objective thread is about.

 

Again accepted. But how do you know beforehand that you can measure audible differences ?

[March Audio]

5 minutes ago, PeterSt said:

 

Please stop telling me how things ought to be. You are the one unable to hear or show differences. Not me.

And FYI: I again don't like your tone.

Excuse me?

 

My tone has been entirely civil.

 

I just showed you some information about jitter.  Are you aware of where that info came from?  You might want to do a search on Julian Dunn.

[March Audio]

3 minutes ago, PeterSt said:

 

Again accepted. But how do you know beforehand that you can measure audible differences ?

 

You havent demonstrated that these things are audible.

[March Audio]

6 minutes ago, PeterSt said:

 

OK, accepted. But what is the reason for the existence of this thread then ?

Well for one thing it might help people implement proper fixes instead of blindly flailing around in the dark.

[PeterSt]

4 minutes ago, March Audio said:

You havent demonstrated that these things are audible.

 

They are - trust me (no you won't).

So what is the reason for this thread again ?

 

Edit: this crossed with your post above.