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BLIND TEST INVITE: Do digital audio players sound different?


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18 hours ago, pkane2001 said:

I would have absolutely no problem with that. Maybe 24/48, just to leave a margin for ADC filter outside the audible range. 24/96 if you want to be absolutely, positively, 110% safe.

 

Then you both test your ADC anti-alias filter heavily (they are not actually designed to clean up DAC outputs, but instead real analog sources). And if your ADC anti-alias filter manages well, it massively cleans up output of typical DAC. But of course if that' what you specifically want...

 

In any case, just take that into account, it is a fact that you are altering the DAC output signal by doing that.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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1 hour ago, Miska said:

 

Yes, take almost any NOS R2R ladder DAC and listen how it sounds! :D

 

 

That is precisely why I'm against them and use digital filters that have >192 dB stop-band attenuation and Nyquist at 6 or 12 MHz! So first image would be there instead of 352.8 kHz... Quite a bit easier for low-order analog filters in the DAC output.

 

 

Now you are throwing in quite a bit of assumptions. I don't like "almost surely" and such. I just go and look at everything. If you are fine to go with mediocre "good enough", it is all fine for me. But I personally  want things perfect and then improved all over to be even more perfect. Things cannot be "too perfect", ever.

Here are some tests I did of aliasing with a some recording interface ADCS I had on hand. None are NOS R2R, and there is a good reason I don't own such DACs. 

 

https://www.audiosciencereview.com/forum/index.php?threads/comparing-aliasing-in-three-adcs.3272/

 

Now all of these were with max signals.  So an ADC will cut off almost completely any ultrasonic garbage a DAC is putting out.  Of course the recordings under discussion were done to 96 khz.  Is there anything put out by such players above what 96 khz rates sample that will heavily react to create signals down into the audible band?  Seems unlikely.  

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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On 2/4/2019 at 1:38 AM, Miska said:

 

I think this test captures relevant phase errors, because largely their practical impact reaches only up to about 30 kHz.

 

I'm not sure which ADC anti-alias filter setting @Archimago used in this test... They also have some impact on the result, depending on the setting.

 

Hi @Miska, I'm using the RME's linear phase sharp filter at 24/96 on the ADC side.

 

Prior to putting up this test, I ran the devices through some testing of the filters and evaluated the performance with the music I chose. Yes, with test tones, I can see the filter imperfections quite well on a wideband capture to check for extreme amounts of high frequency material up to 384kHz.

 

This was not a problem with the music used.

 

Perhaps in the next couple weeks I'll put something up on the blog to show what I mean using what I would consider is the "worst" device in the blind test...

 

 

Archimago's Musings: A "more objective" take for the Rational Audiophile.

Beyond mere fidelity, into immersion and realism.

:nomqa: R.I.P. MQA 2014-2023: Hyped product thanks to uneducated, uncritical advocates & captured press.

 

 

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On 2/6/2019 at 7:03 AM, Arpiben said:

@Archimago

On due time will you provide the four 16/44.1kHz original samples played in DAPs A,B,C&D?

 

Yes Arpiben,

Will put a package together with the original 16/44 music used when the test concludes...

 

 

Archimago's Musings: A "more objective" take for the Rational Audiophile.

Beyond mere fidelity, into immersion and realism.

:nomqa: R.I.P. MQA 2014-2023: Hyped product thanks to uneducated, uncritical advocates & captured press.

 

 

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5 hours ago, Archimago said:

This was not a problem with the music used.

 

All the music repeats at those higher frequencies as well with forward and inverse spectrum. So it doesn't matter whether it is music or test tone.

 

To properly capture the behavior, I use sweep tone and "peak hold" spectrum. This works for music as well, leave the spectrum at peak hold and play entire song.

 

My point was mostly that the ADC's anti-alias filter removes those images when you run it at 96k. If you've made the recording at DSD256, a little bit more would have been preserved.

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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3 hours ago, Miska said:

 

All the music repeats at those higher frequencies as well with forward and inverse spectrum. So it doesn't matter whether it is music or test tone.

 

To properly capture the behavior, I use sweep tone and "peak hold" spectrum. This works for music as well, leave the spectrum at peak hold and play entire song.

 

My point was mostly that the ADC's anti-alias filter removes those images when you run it at 96k. If you've made the recording at DSD256, a little bit more would have been preserved.

 

And what's the audible significance  of these images above 40 khz? 

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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3 hours ago, esldude said:

And what's the audible significance  of these images above 40 khz? 

 

I answered that already earlier. Amount of intermodulation products (and in this case aliasing) you get from those fully correlated inverse and forward frequency spectrum components is system dependent.

 

Essentially it just demonstrates incomplete and non-precise reconstruction of the original waveform. If you don't capture this for the tests, you don't capture whole picture.

 

Good quality D/A conversion process doesn't produce any images at all.

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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16 hours ago, Miska said:

 

I answered that already earlier. Amount of intermodulation products (and in this case aliasing) you get from those fully correlated inverse and forward frequency spectrum components is system dependent.

 

Essentially it just demonstrates incomplete and non-precise reconstruction of the original waveform. If you don't capture this for the tests, you don't capture whole picture.

 

Good quality D/A conversion process doesn't produce any images at all.

 

I agree, and don't promote the idea of poor DA or AD conversion.  But what I've seen is aliasing and imaging in the -90 dbFS and lower range.  This with a full max signal.  Reduce the level of the aliased signals or the signals that image and you reduce what leaks thru.  So just how much can make for any difference that corrupts a test like Archimago's?  Looks to me like pretty much a non-problem on playback and equally so for Archimago recording these devices at 96 khz while they playback at lower rates. 

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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1 hour ago, esldude said:

I agree, and don't promote the idea of poor DA or AD conversion.  But what I've seen is aliasing and imaging in the -90 dbFS and lower range.  This with a full max signal.  Reduce the level of the aliased signals or the signals that image and you reduce what leaks thru.  So just how much can make for any difference that corrupts a test like Archimago's?  Looks to me like pretty much a non-problem on playback and equally so for Archimago recording these devices at 96 khz while they playback at lower rates. 

 

Images are quite a bit higher typically, depending on the reconstruction analog filter. If it is more aggressive with lower cut-off point, then it spoils phase response at top of audio range.

 

RME ADI-2's image levels at 44.1k input for the record:

ADI2-sweep-44k1-sharp-wide.thumb.png.d50cc1c49745e7961b849e44803e03fd.png

 

Run the DAC with upsampling to 705.6/768 and it gets much lower, run it with properly upsampled DSD256 in DSD Direct mode and you have no images at all and any noise left overs are lower level than images at 705.6/768k - and totally uncorrelated!

 

1 hour ago, esldude said:

This with a full max signal.

 

Given current loudness wars, RedBook content is typically full max signal at all times with clipping.

 

1 hour ago, esldude said:

Reduce the level of the aliased signals or the signals that image and you reduce what leaks thru.

 

So now you need to select test music so that it works well for a DAC? :D

 

1 hour ago, esldude said:

So just how much can make for any difference that corrupts a test like Archimago's?

 

You don't know, so you cannot disregard it as an important factor. Let's not make assumptions here.

 

1 hour ago, esldude said:

Looks to me like pretty much a non-problem on playback and equally so for Archimago recording these devices at 96 khz while they playback at lower rates.

 

The recordings reveal some of the badness of the devices, but not all. That's the point.

 

Sounds like you want to conveniently ignore aspects that don't fit in your PCM ideology... ;)

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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As with any recording, you first need to analyze bandwidth needed to accurately reproduce the source you want to record. So you need to check what is the highest frequency it puts out. And then you select sampling rate that is sufficient for the required bandwidth. This is the fundamental requirement for accurate reproduction.

 

I'm not at all saying this is wouldn't already show differences, it does. But it doesn't tell the whole picture, only part of it.

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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1 hour ago, Miska said:

 

Images are quite a bit higher typically, depending on the reconstruction analog filter. If it is more aggressive with lower cut-off point, then it spoils phase response at top of audio range.

 

RME ADI-2's image levels at 44.1k input for the record:

ADI2-sweep-44k1-sharp-wide.thumb.png.d50cc1c49745e7961b849e44803e03fd.png

 

So what are the effects of an image at 300 khz?  The amp likely won't respond much usually, the speakers won't for sure.   Our ears don't care much about phase at higher frequencies. 

1 hour ago, Miska said:

Run the DAC with upsampling to 705.6/768 and it gets much lower, run it with properly upsampled DSD256 in DSD Direct mode and you have no images at all and any noise left overs are lower level than images at 705.6/768k - and totally uncorrelated!

 

 

Given current loudness wars, RedBook content is typically full max signal at all times with clipping.

Well not the way it works.  The 90 db or so I've seen from 192 khz, is with a single tone max frequency.  Get multiple tones or noise and max total signal is still much lower at a given frequency and much lower in what images across it.  Way below the noise floor of any gear for the most part. 

1 hour ago, Miska said:

 

 

So now you need to select test music so that it works well for a DAC? :D

 

 

You don't know, so you cannot disregard it as an important factor. Let's not make assumptions here.

 

 

The recordings reveal some of the badness of the devices, but not all. That's the point.

 

Sounds like you want to conveniently ignore aspects that don't fit in your PCM ideology... ;)

 

No I simply don't wish to chase more ghosts that are smaller than the angels dancing on the head of a pin at great complication, expense and no benefit to human ears.  

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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1 hour ago, Miska said:

As with any recording, you first need to analyze bandwidth needed to accurately reproduce the source you want to record. So you need to check what is the highest frequency it puts out. And then you select sampling rate that is sufficient for the required bandwidth. This is the fundamental requirement for accurate reproduction.

 

I'm not at all saying this is wouldn't already show differences, it does. But it doesn't tell the whole picture, only part of it.

 

I don't agree with you here.  If the hearing is the bottleneck of bandwidth, and it is, then you don't need all the frequencies that are above a noise floor out to some megahertz range.  You end up with differences that make no difference.  Analyzing the bandwidth needed in such a case would indicate 96 khz sampling is enough with quite a margin for safety. 

 

Do we need to sample up to optical frequencies because the glare of a spotlight on the horn of a trumpet will shine across our ears and make a difference?

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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9 hours ago, Miska said:

 

Again, intermodulation and other effects they cause... To make such choice you would first need to prove that it certainly doesn't cause any detectable differences in anybody's system.

 

You cannot claim to accurately represent a DAC if you don't capture all of it's output. In addition now you have effect of ADC and another DAC baked in.

 

For me, margin of safety would be to use rate 2x higher than highest detected output frequency from a DAC.

 

Again, why not make the recording for example using DSD256 where you don't have for example effects of the digital anti-alias filtering baked into the result?

 

IMD would show up even if the ADC is running at 44.1 khz.  You don't need wideband measures for that.  So whatever the ultrasonic sources of IMD into the audible band you'd already be seeing them.  They aren't much apparently. 

 

The reason I don't record such things with DSD256 is I don't have an ADC for that.  So I'm limited to 192 khz.  That doesn't mean nothing above that can't matter, but I'm incredulous it matters much if at all.  I'm not worried if something shows up at -120 db, because you'll not hear it.  It is not perfect, but it also isn't an audible problem. 

 

The things I showed earlier may have been aliasing only.  I've done the reverse test for imaging as well.  Similar levels were seen.  My test signals were all at max level.  And I believe I described the limits of the spectrograms. So they aren't meaningless. 

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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23 minutes ago, esldude said:

IMD would show up even if the ADC is running at 44.1 khz.  You don't need wideband measures for that.  So whatever the ultrasonic sources of IMD into the audible band you'd already be seeing them.  They aren't much apparently. 

 

Only if it originates from the DAC itself, and not for example from power amplifier.

 

23 minutes ago, esldude said:

The reason I don't record such things with DSD256 is I don't have an ADC for that.

 

That's not a technical reason justifying why it wouldn't be helpful. This test was recorded with ADI-2 Pro which can record DSD256.

 

23 minutes ago, esldude said:

I'm not worried if something shows up at -120 db, because you'll not hear it.

 

You cannot make statements about what I will or won't hear. You can only make statements about your own hearing. You would be surprised what people are capable of hearing.

 

23 minutes ago, esldude said:

I've done the reverse test for imaging as well.  Similar levels were seen.

 

Can you explain your testing methodology and DACs in question? At 192k ADC rate you cannot test imaging except for first step of on-chip digital filter. And what I'm talking about here is output rate of the on-chip digital filter at 352.8k (for 44.1k input). You need at least 768k sampling rate to see even lower half of that image.

 

In this another DAC example I posted, that image is down about -45 dB.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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5 hours ago, Miska said:

I had some fun and recorded 0 - 22.05 kHz 0 dBFS sweep from Meridian Explorer2 DAC. So you can see some fun with the MQA's upsampling filters it has too. Recording was done using ADI-2 Pro AE in both in DSD256 and 768/32 PCM, usable audio bandwidth in both is about the same. File size difference is quite notable though, DSF file is 186 MB (7z compressed 114 MB) and WAV 399 MB (7z compressed 242 MB), when WAV is 705.6/24 the size is 274 MB. So some about of space saving for DSD's benefit, these WAVs cannot be compressed into FLAC because FLAC maxes out at 384/24.

 

Wide band spectrum:

tmp.thumb.png.5faf3cbae8910ca287bb7c8a6e57f546.png

 

Zoom into 250 kHz banwidth:

tmp2-2.thumb.png.32418e4e11f43d542b7efa4eaa4351b1.png

 

And into 100 kHz bandwidth:

tmp3-2.thumb.png.95361f43e9454c79456ea41530907bc5.png

 

 

And for comparison recording done using 96 kHz sampling rate:

tmp-t.thumb.png.c4b444fa42cda0083d14d85018764346.png

Does this tell the whole story?

 

You used something with MQA filters?  I mean we know those are leaky.  Not typical.  And for that reason not a good example.  Can you have leaky filters than muck up the results?  Sure, I never implied you couldn't.  

Here are some for the Forte, which I think you also have.  

 

This spectrogram goes to gray at -144 db.  You see an idle tone which is in the Forte DAC at about 31 khz, -95 db in level which isn't great.  You see double that frequency at -125 db.  Otherwise no imaging above -144 db for 2hz-20khz.   On the 2hz-40 khz sweep, you get a little imaging just above 20 khz at about -132 db.  It gets a little higher in level as the frequency increases, but never exceeds -115 db.  This is not a perfect result, but there is not a whole lot up there to 96 khz at least. 

 

Imaging of Forte DAC.png

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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Just now, esldude said:

This spectrogram goes to gray at -144 db.  You see an idle tone which is in the Forte DAC at about 31 khz, -95 db in level which isn't great.  You see double that frequency at -125 db.  Otherwise no imaging above -144 db for 2hz-20khz.   On the 2hz-40 khz sweep, you get a little imaging just above 20 khz at about -132 db.  It gets a little higher in level as the frequency increases, but never exceeds -115 db.  This is not a perfect result, but there is not a whole lot up there to 96 khz at least. 

 

Imaging of Forte DAC.png

 

Because you don't reach output rate of the digital filter at all! :)

 

You are looking at very narrow frequency band and believe that that's all? That's what I'm trying to say, you are not seeing the whole picture.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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15 minutes ago, Miska said:

 

Only if it originates from the DAC itself, and not for example from power amplifier.

 

 

That's not a technical reason justifying why it wouldn't be helpful. This test was recorded with ADI-2 Pro which can record DSD256.

 

 

You cannot make statements about what I will or won't hear. You can only make statements about your own hearing. You would be surprised what people are capable of hearing.

 

 

Can you explain your testing methodology and DACs in question? At 192k ADC rate you cannot test imaging except for first step of on-chip digital filter. And what I'm talking about here is output rate of the on-chip digital filter at 352.8k (for 44.1k input). You need at least 768k sampling rate to see even lower half of that image.

 

In this another DAC example I posted, that image is down about -45 dB.

No, I've said I don't have an ADC that does above 192 sample rates.  So I used one at 192 khz for a DAC playing I think 48 khz.  So yes, I can't see imaging like the RME you show.  Now okay the RME has some imaging at -46 db.  Where do the results of that show up in the audible band.  We can all suppose it might show up somewhere.  And we can't definitely say it doesn't until you check it.  But at that level if IMD from the amp it would have to have a very poor 1 % imd for it to show up back at 2 khz at -86 db.  Is it possible with some amp?  Sure.  It is a problem for most good amps?  I don't think so.  Most amps that have that kind of bandwidth will have low IMD and especially for a -46 db pair of signals.  It is going to be lost in the noise and then some. 

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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11 minutes ago, Miska said:

 

Because you don't reach output rate of the digital filter at all! :)

 

You are looking at very narrow frequency band and believe that that's all? That's what I'm trying to say, you are not seeing the whole picture.

Okay so how does the imaging of the RME show up where we can hear it?  And I will say if someone is saying they can hear such things at -120 db they'll have to prove it. I'll say I don't believe it for all 7 billion people on the planet.  Just like if someone says no one can say how fast they can run and they claim to run the 100 meters in 7 seconds.  

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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