Investigation Into Effects Of PC load On DAC Analogue Output

[March Audio]

3 minutes ago, PeterSt said:

 

Wait ... that is a good one. So yes please, demonstrate for example the output of two bit perfect players and how they change the output of the DAC you measure relatively to each other.

That should be doable.

Haha

 

Peter, havent you grasped that it's not the players creating the difference?

 

I have always mentioned the issues of ground loops etc.

[PeterSt]

20 minutes ago, March Audio said:

Peter, havent you grasped that it's not the players creating the difference?

 

That depends who is thinking about it. I only work 15 years on players doing just that.

I work for 13 years on DAC's being able to withstand that. I still fail.

 

You ?

No wait, I already know the answer. Haha.

 

You know, it is such a pity that you keep on thinking I know shit.

And that makes it the other way around. Without words now, but you know ...

[jabbr]

On 6/10/2021 at 1:12 AM, March Audio said:

So to conclude, with this PC, load makes no significant measurable difference to this DACs performance.

 

Please note that these tests do not account for other potential issues that may be encountered such as ground loops in single ended RCA systems.

 

Thanks for this. Lots of arguments that are incomprehensible to me. For a real counterargument perhaps people could reproduce your measurements and show different results, or give us other good measurements that are comprehensible. I agree -- bottom line is 1) output of DAC or perhaps 2) output of speakers assuming volumes can be normalized.

[jabbr]

On 6/10/2021 at 10:14 AM, firedog said:

Maybe you didn't read the whole thing at ASR or the other threads on the topic. The point was the ISO Regen lessened the noise, but only with a DAC that is essentially "broken" b/c of improper design. With other DACs it made no difference. 

Same for other DACs - except for a small minority that are improperly designed, March Audio's results hold. Conclusion: the PC doesn't matter for these measurements, unless you have a DAC that is inherently defective. 

Archimago did similar testing at his site a while back and got the same results. 

 

My own listening tests over months have likewise indicated to me that the ISO Regen helps certain DACs and doesn't help other DACs. The DAC that it helped was otherwise quite good and quite cheap so no problem with isolation devices when needed.

[idiot_savant]

@PeterSt - you say you’ve spent many years trying to optimise DACs and PCs/ software, which I believe. So, I’ve never seen you share these improvements/optimisations, apart from that you sell some kind of bespoke system? 
How annoying would you find it if a competitor came on here and just kept say “haha - I know this” repeatedly? 
I understand if you believe you’ve discovered some secret sauce, but just saying you have a secret sauce doesn’t make it fingerlicking good?

 

your friendly neighbourhood idiot 

[March Audio]

7 hours ago, PeterSt said:

 

That depends who is thinking about it. I only work 15 years on players doing just that.

I work for 13 years on DAC's being able to withstand that. I still fail.

 

You ?

No wait, I already know the answer. Haha.

 

You know, it is such a pity that you keep on thinking I know shit.

And that makes it the other way around. Without words now, but you know ...

Appealing to your own authority is an unconvincing argument.  It's your own statements that keep betraying your lack of knowledge.  Basics that needed to be explained to you by others in this thread.

 

All we have seen is "hand waving",  zero objective evidence that supports your position and an awful lot of noise. 

[March Audio]

5 hours ago, jabbr said:

Thanks for this. Lots of arguments that are incomprehensible to me. For a real counterargument perhaps people could reproduce your measurements and show different results, or give us other good measurements that are comprehensible. I agree -- bottom line is 1) output of DAC or perhaps 2) output of speakers assuming volumes can be normalized.

Please ask questions, it's a complex subject.  I'm sure between myself, @pkane2001 and @idiot_savant we can make it more understandable.

 

Indeed, controlled subjective listening tests are something I intend to move on to.  Will take a bit of time and organising however.

[March Audio]

@pkane2001 would you be able to give a description of your DeltaWave software, what is does, but not too technical?  It would help others to understand the analysis being performed.

 

Thanks 

[manueljenkin]

1 hour ago, March Audio said:

Appealing to your own authority is an unconvincing argument.  It's your own statements that keep betraying your lack of knowledge.  Basics that needed to be explained to you by others in this thread.

 

All we have seen is "hand waving",  zero objective evidence that supports your position and an awful lot of noise. 

Just because it's not measurable with present state of apparatus doesn't mean it doesn't exist. Has happened in science many times, that a top level abstraction is shattered with a new discovery bringing life to older approaches that were earlier ridiculed.

 

I don't think anyone here has demonstrated lack of knowledge. You seem to be adamant that there is a magical fix down the line that can remove "all" aberrations introduced by noise from pc ground planes while the only measurements you have are mostly uncorrelated to real world audio signal performance, and some of the issues beyond that has already been demonstrated by John Swenson and others. 

 

Measurements are great, but conclusion is not. Objectivity is different from science. If required to be objective one can rank cows by their aerodynamic structure, but would it make any sense?

[manueljenkin]

10 hours ago, March Audio said:

Actually you might be interested in the paper below which shows those conclusions about negative feedback were wrong.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf&ved=2ahUKEwjp3IWGvZLxAhW6wjgGHbMSA4gQFjAAegQIBBAC&usg=AOvVaw3TQHX7dKj3pUiCoPCahlPA&cshid=1623514050065

Was this article peer reviewed? Remember, this is an objective forum.

[pkane2001]

1 hour ago, March Audio said:

@pkane2001 would you be able to give a description of your DeltaWave software, what is does, but not too technical?  It would help others to understand the analysis being performed.

 

Thanks 

Sure. At the most basic level it computes the difference between two audio files. Assuming one file is the original and the other is something recorded by passing this original signal through a device, such difference represents all the distortions, noise, jitter, etc. that were caused by the device being tested. 
 

There are all kinds of things that can then be computed from the difference file, from frequency differences to jitter to nonlinearity to phase response. 
 

At the core, DeltaWave computes the difference file and then runs a number of tests and analysis displaying results visually and allowing you to listen to the differences.

[March Audio]

4 hours ago, manueljenkin said:

Just because it's not measurable with present state of apparatus doesn't mean it doesn't exist. Has happened in science many times, that a top level abstraction is shattered with a new discovery bringing life to older approaches that were earlier ridiculed.

 

I don't think anyone here has demonstrated lack of knowledge. You seem to be adamant that there is a magical fix down the line that can remove "all" aberrations introduced by noise from pc ground planes while the only measurements you have are mostly uncorrelated to real world audio signal performance, and some of the issues beyond that has already been demonstrated by John Swenson and others. 

 

Measurements are great, but conclusion is not. Objectivity is different from science. If required to be objective one can rank cows by their aerodynamic structure, but would it make any sense?

Sorry but this is the standard reply trotted out by those that have no ability to justify their beliefs.  It's pretty unimaginative TBH.

 

This is an objective thread.  Your faith has no place here.

 

I have just stumbled across this which makes the point.

 

https://archimago.blogspot.com/2021/01/musings-noise-jitter-faith-autistic.html?m=1

 

[March Audio]

4 hours ago, manueljenkin said:

Was this article peer reviewed? Remember, this is an objective forum.

If you want to question the technical credibility of Bruno Putzeys you go ahead.  Best of luck.

 

Also the fact that his class d designs use massive amounts of negative feedback and don't suffer the alleged "1970s amp bad sound" sort of proves the point that negative feedback is not a problem, quite the opposite.

[March Audio]

Oh just as an aside, if anyone thinks the audibility  jitter is anything that hasn't been very well researched for many years, then take a look at this BBC research paper from 1974.

 

https://www.bbc.co.uk/rd/publications/rdreport_1974_11

 

http://downloads.bbc.co.uk/rd/pubs/reports/1974-11.pdf

[manueljenkin]

2 hours ago, March Audio said:

If you want to question the technical credibility of Bruno Putzeys you go ahead.  Best of luck.

 

Also the fact that his class d designs use massive amounts of negative feedback and don't suffer the alleged "1970s amp bad sound" sort of proves the point that negative feedback is not a problem, quite the opposite.

So you don't have a peer reviewed paper for the same! Just your anectodal experience.

 

2 hours ago, March Audio said:

Sorry but this is the standard reply trotted out by those that have no ability to justify their beliefs.  It's pretty unimaginative TBH.

 

This is an objective thread.  Your faith has no place here.

 

I have just stumbled across this which makes the point.

 

https://archimago.blogspot.com/2021/01/musings-noise-jitter-faith-autistic.html?m=1

 

There's nothing about faith here. I just mentioned that your tests objectively don't provide full coverage to fully conclude on any of the modulations and the audibility (if so, it would require you to first conclude everything about human hearing and weights to different fidelity indexes before you could trickle down to the rest). And a bit of history on why science and objectivity aren't completely the same, just to let you know you can't make "conclusions" at will.

[manueljenkin]

1 hour ago, March Audio said:

Oh just as an aside, if anyone thinks the audibility  jitter is anything that hasn't been very well researched for many years, then take a look at this BBC research paper from 1974.

 

https://www.bbc.co.uk/rd/publications/rdreport_1974_11

 

http://downloads.bbc.co.uk/rd/pubs/reports/1974-11.pdf

Oh yeah, trying to derive conclusions from a paper about jitter effects from 1974 when the whole domain of phase noise analysis methods was described to fair accuracy only after 2000s.

[March Audio]

2 hours ago, manueljenkin said:

So you don't have a peer reviewed paper for the same! Just your anectodal experience.

 

There's nothing about faith here. I just mentioned that your tests objectively don't provide full coverage to fully conclude on any of the modulations and the audibility (if so, it would require you to first conclude everything about human hearing and weights to different fidelity indexes before you could trickle down to the rest). And a bit of history on why science and objectivity aren't completely the same, just to let you know you can't make "conclusions" at will.

OK, please explain the faults in the paper.   Know you can't.  You are trying to spread FUD.

 

I never stated those tests did.  You have misunderstood.  I haven't made any conclusions.  This is just an investigation, one that's not complete.

 

 

[March Audio]

2 hours ago, manueljenkin said:

Oh yeah, trying to derive conclusions from a paper about jitter effects from 1974 when the whole domain of phase noise analysis methods was described to fair accuracy only after 2000s.

You appear to have a lack of understanding.  I was merely pointing out, as clearly stated, that the audibility of jitter has been thoroughly studied over many decades.

 

The levels of jitter that are required to becaudible are actually quite high compared to the levels seen in dacs these days.

 

Yet there are assertions in this thread that imply the tiniest, immeasurable of levels are audible.  That is not consistent with the decades of research into the phenomenon.

[March Audio]

2 hours ago, manueljenkin said:

 the whole domain of phase noise analysis methods was described to fair accuracy only after 2000s.

You didn't read the paper did you?  You didn't notice the parts about sinusoidal and random jitter stimuli.

[March Audio]

2 hours ago, manueljenkin said:

 the whole domain of phase noise analysis methods was described to fair accuracy only after 2000s.

This is not correct.  Phase noise was known about and measured long before then.  I suggest you do some research.

 

One example from 1987, but hardly the first.

 

https://www.hpmemoryproject.org/news/3048/hp3048_01.htm

 

 

 

 

 

[March Audio]

The HP 3048A System appeared for the first time in the HP general catalog in 1987, it was the successor of the 3047A which was born in 1983.

[semente]

19 hours ago, March Audio said:

Actually you might be interested in the paper below which shows those conclusions about negative feedback were wrong.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf&ved=2ahUKEwjp3IWGvZLxAhW6wjgGHbMSA4gQFjAAegQIBBAC&usg=AOvVaw3TQHX7dKj3pUiCoPCahlPA&cshid=1623514050065

 

Controlled subjective listening tests are the next step and I am planning to do that.

 

I had read that paper before. It says that:

 

"If there is a relationship, it has to be through the behaviour of the specific circuit implementation. For a given GBW, slew rate is a fixed quantity and slew induced distortion can be predicted exactly from the ratio of actual to maximum slew rate. Nothing will reduce SID other than improving slew rate unless we modify the circuit."

 

I don't see any discrepancy between perceived audible distortion and engineers not wishing to believe it.

[March Audio]

1 minute ago, semente said:

 

I had read that paper before. It says that:

 

"If there is a relationship, it has to be through the behaviour of the specific circuit implementation. For a given GBW, slew rate is a fixed quantity and slew induced distortion can be predicted exactly from the ratio of actual to maximum slew rate. Nothing will reduce SID other than improving slew rate unless we modify the circuit."

 

I don't see any discrepancy between perceived audible distortion and engineers not wishing to believe it.

The blame was put at the door of negative feedback which is not correct.

[semente]

9 minutes ago, March Audio said:

The blame was put at the door of negative feedback which is not correct.

 

So the Putzeys is correcting Otala. But does he deny TIM audibility and engineers not wishing to believe there was something wrong?

[March Audio]

1 minute ago, semente said:

 

So the Putzeys is correcting Otala. But does he deny TIM audibility and engineers not wishing to believe there was something wrong?

Was it a case of engineers not wanting to believe it?  

 

Storyline 3: Marketing hype, specmanship and “lots of zeros”.
During my tender years, “Japanese Transistor Amps” were held up as prime examples of things that measured well and sounded terrible.  remember the 80’s when we were flooded with amps that had 0.00001% distortion.....

 

.......That doesn’t mitigate that the leaflets were misleading. Sometimes subtly by stating only THD at 1kHz/1W, often more brutally through a technique called lying. These amps didn’t measure at all well and they sounded the part.

 

Bruno is saying it was marketing.  That's quite different to saying there was a refusal to believe there was an issue.

 

Anyway, how does this apply to the situation today?  Do we have components that sound awful despite good measurements?

 

I keep asking people to provide such examples and they never do.

 

In this specific case we are looking at here, the people who are claiming audible differencesccant provide on jot of supporting evidence beyond "I hear it therefore it is".