CD quality surprise

[andyjm]

I can't believe what I've just read. Let me just run through this...

24/96 sounds identical to 16/44 when you downsampled it to 16/44 (of course, in the process removing any possibility of it sounding different). It's apparently the standard thing to do, and there's never any difference...

But no one has ever tried (and it is being recommended against doing here) upsampling a 16/44 file to 24/96 because it would be pointless because it would be the same?!

Someone suggests a good idea and it is instantly rubbished without any further discussion. Pointless? Priceless more like.

David,

This sort of problem has faced scientists over the years. How best to reach a logical conclusion. Along with his many other contributions to the human race, Sir Isaac Newton was one of the first to define a process for tackling these sorts of problems - which became known as 'the scientific method'. It goes like this:

1. Postulate a theory,

2. Devise an experiment to test the theory,

3. If the theory doesn't work, change it and go back to step 2.

In our case, the theory is that '24/96 files contain more music than 16/44.1 files' Now we could argue about 'music' - I would have thought that something along the lines of 'sound perceivable by humans' would be a good start, but you might want to have a different definition.

Good practice in an experiment is to only change one variable at a time, otherwise you can never figure out what caused the change (if any). So, for our experiment, we need two files of the same 'music', one 24/96 and one 16/44.1. As has been discussed at length in this thread, it is difficult to establish the provenance of the files, so the only way to be sure that you are comparing like with like is to start off with a 24/96 file and then make your own 16/44.1 file from it. Now if the theory is correct, downsampling the 24/96 file to 16/44.1 will strip out all the extra 'music' contained in the 24/96 file and the 16/44.1 file will sound different.

All the tests I have been able to find on the web, and tests I have performed myself indicate that there is no difference to the sound between the files, therefore the theory would appear to be wrong. There is no extra 'music' in 24/96 files that can't be contained in 16/44.1 files.

As for upsampling 16/44.1 files - I don't see the point. As explained above, the only way to get a 16/44.1 file known to have come from exactly the same source as the 24/96 file is to make it yourself. The process would then be - start with a 24/96 file, downsample to 16/44.1 then upsample to 24/96 again and then compare with the original 24/96 file. I guess if there was no audible difference, then this would also prove that the original theory (24/96 holds more music) is incorrect, but why introduce the extra step? If the 24/96 and 16/44.1 files were indistinguisable, then then theory has been shown to be incorrect, why upsample and do the test again?

 

[davedotco]

Does upsampling in the replay chain perform a similar function to oversampling?

If I understand correctly, oversampling helps with the design of filters in such a way that any artefacts produced by such filters are further away from the audible range.

Is this even relevant with modern 'bitstream' dacs?

Any help much appreciated.

 

[andyjm]

Does upsampling in the replay chain perform a similar function to oversampling?

If I understand correctly, oversampling helps with the design of filters in such a way that any artefacts produced by such filters are further away from the audible range.

Is this even relevant with modern 'bitstream' dacs?

Any help much appreciated.

Upsampling / oversampling get used interchangably. As far as I can see, oversampling tends to get used more to describe a specific process within a DAC where the sample rate gets multiplied by 2 or 4 or 8..... to make the life of the downstream reconstitution filter easier. Upsampling seems to be used more to describe the conversion between specific sample rates - 44.1 to 48 or 96 and so on.

Underneath, it amounts the same thing, making up samples that don't exist to increase the apparent sample rate. There are various level of complexity about how these extra samples get made up.

It all depends how the DAC is designed, but oversampling within the DAC or upsampling prior to the DAC will both have the same effect of moving the ailiases further up the spectrum away from the wanted audio signal and will mean that the slope of output filter can be gentler, making design easier.

 

[davedotco]

Kind of what I thought, nice summary though thanks...*good*

Back in the late 90's I did quite a lot of research, with the help of a US hi-end digital munufacturer, into this sort of hi-fi and how it works. I really should know this sort of stuff, but it is a long time ago now.

The aim was to represent them in the uk and europe, marketing mainly, but with enough background to hold my own with the likes of Steve Harris, Martin Colloms and Paul Millar.

One of the things that we did at that time was measure the signal to noise of real (often quite hi-end) systems in peoples homes. Perhaps surprisingly around half were unable to fully resolve the equivilent of a 16bit signal, ie a s/noise of less than 96dB. The results were much the same on both sides of the atlantic.

 

[TomSawyer]

I've downloaded a hi-res sample from the Sony website into Audacity and created an exact replica using copy/paste:

I then downsampled/reduced bit-depth to 16/44:

I then inverted the lower sound file to create a mirror image (I also zoomed in to make it easier to see):

I then added the two tracks together and this was the result:

I can also confirm the file is silent to the naked ear when played.

What I'd like to do is the same thing creating matching hi-res and 16/44 files and then run them through a DAC and re-record them at a full 24/192, and then compare them. The reason being, no-one in contending that a 24/96 file looks the same as a 16/44 file - that's not the debate, the debate is whether the recreated waveform after the DAC is identical and so feeding the resultant output straight back into an ADC sampled super high would show the resultant waveforms.

 

[andyjm]

I've downloaded a hi-res sample from the Sony website into Audacity and created an exact replica using copy/paste:

I then downsampled/reduced bit-depth to 16/44:

I then inverted the lower sound file to create a mirror image (I also zoomed in to make it easier to see):

I then added the two tracks together and this was the result:

I can also confirm the file is silent to the naked ear when played.

What I'd like to do is the same thing creating matching hi-res and 16/44 files and then run them through a DAC and re-record them at a full 24/192, and then compare them. The reason being, no-one in contending that a 24/96 file looks the same as a 16/44 file - that's not the debate, the debate is whether the recreated waveform after the DAC is identical and so feeding the resultant output straight back into an ADC sampled super high would show the resultant waveforms.

Tom,

You may be familiar with this, but if not, google 'Audio Diffmaker'

 

[TomSawyer]

Thanks Andy, I'm not. I'll check it out.

 

[FunkyMonkey]

I am not familiar with Kraftwerk except via TV so I cannot comment. However, I was astonished enough at the imaging, the detail, and yes, the dynamic range (if that means quietness to loudness ratio?) to post on here.

I bought Bon Iver a few months ago as it was on a list of quality CDs and I was not wowed by the quality difference between its MP3 copy and CD copy. The one in my title is more wow I would say, if not as complex.

I am a big fan of SACD, and people often miss the point of it. To use an analogy, the best DVD player ever made cannot co.e close to even a cheapo Blu Ray player for picture quality. The same goes for a SACD disk. You need relatively cheap equipment to get stunning sound. Even a modest, but well set up 5.1 system will exude musical prowess for a 5.1 sa-cd. A great example of this is Brothers in Arms. Amazing in 5.1. also, Norah Jones come away with me, or Billy Joel Stranger, or Jeff Wayne's War of the World's, or Tommy by the who. This list goes on.

I would stick my neck out and say that SACD is the best disk medium for music, given that Blu Ray audio never really took off as it should have, and that is, scandalously, almost uniquely stereo.

SACD has all the benefits and qualities of vinyl sound and the convenience of CD, except you cannot rip the tracks to MP3.

I am a recent disciple of vinyl although not a convert. You could say I have all bases covered now.

 

[Andrewjvt]

Do the people on here say there is no difference between standard cd and sacd?

 

[Blacksabbath25]

Do the people on here say there is no difference between standard cd and sacd?

well I am not an expert but with my ears tell me and depending on what sacd player you have and how good it is and the dac inside plus the rest of your setup I can tell a differences between cd +sacd but when I had my marantz sacd player I could not tell much of a difference between the cd version of brothers in arms on cd and the sacd but now I have a much more better setup yes I can definitely tell the difference between cd + sacds but also there are some really well recorded CDs out there that come close to sacds

 

[spiny norman]

But no one has ever tried (and it is being recommended against doing here) upsampling a 16/44 file to 24/96 because it would be pointless because it would be the same?!

16/44 to 24/96? Someone here can do much better than that

 

[Frank Harvey]

Do the people on here say there is no difference between standard cd and sacd?

Yup. Apparently you 'downconvert' it to 16/44 and it sounds the same.

 

[Andrewjvt]

Do the people on here say there is no difference between standard cd and sacd?

Yup. Apparently you 'downconvert' it to 16/44 and it sounds the same.

Then why the heavy vinyl love?

 

[Andrewjvt]

Do the people on here say there is no difference between standard cd and sacd?

well I am not an expert but with my ears tell me and depending on what sacd player you have and how good it is and the dac inside plus the rest of your setup I can tell a differences between cd +sacd  but when I had my marantz sacd player I could not tell much of a difference between the cd version of brothers in arms on cd and the sacd but now I have a much more better setup yes I can definitely tell the difference between cd + sacds but also there are some really well recorded CDs out there that come close to sacds 

I believe you black sab..
Ive also heard wonderful results with sacd but as yet have not had the chance to directly compare though i admit.

 

[Blacksabbath25]

Do the people on here say there is no difference between standard cd and sacd?

well I am not an expert but with my ears tell me and depending on what sacd player you have and how good it is and the dac inside plus the rest of your setup I can tell a differences between cd +sacd but when I had my marantz sacd player I could not tell much of a difference between the cd version of brothers in arms on cd and the sacd but now I have a much more better setup yes I can definitely tell the difference between cd + sacds but also there are some really well recorded CDs out there that come close to sacds

I believe you black sab.. Ive also heard wonderful results with sacd but as yet have not had the chance to directly compare though i admit.

you would be welcome to come and hear my setup anytime mate I've got the brothers in arms on cd and sacd to compare

 

[davedotco]

Do the people on here say there is no difference between standard cd and sacd?

well I am not an expert but with my ears tell me and depending on what sacd player you have and how good it is and the dac inside plus the rest of your setup I can tell a differences between cd +sacd but when I had my marantz sacd player I could not tell much of a difference between the cd version of brothers in arms on cd and the sacd but now I have a much more better setup yes I can definitely tell the difference between cd + sacds but also there are some really well recorded CDs out there that come close to sacds

I believe you black sab.. Ive also heard wonderful results with sacd but as yet have not had the chance to directly compare though i admit.

you would be welcome to come and hear my setup anytime mate I've got the brothers in arms on cd and sacd to compare

Is Brothers in arms a DSD recording?

 

[Al ears]

Do the people on here say there is no difference between standard cd and sacd?

well I am not an expert but with my ears tell me and depending on what sacd player you have and how good it is and the dac inside plus the rest of your setup I can tell a differences between cd +sacd but when I had my marantz sacd player I could not tell much of a difference between the cd version of brothers in arms on cd and the sacd but now I have a much more better setup yes I can definitely tell the difference between cd + sacds but also there are some really well recorded CDs out there that come close to sacds

I believe you black sab.. Ive also heard wonderful results with sacd but as yet have not had the chance to directly compare though i admit.

you would be welcome to come and hear my setup anytime mate I've got the brothers in arms on cd and sacd to compare

Is Brothers in arms a DSD recording?

I would imagine, from it's age, it would be a DSD recording from original analogue tape. Could be wrong however.

 

[Blacksabbath25]

Do the people on here say there is no difference between standard cd and sacd?

well I am not an expert but with my ears tell me and depending on what sacd player you have and how good it is and the dac inside plus the rest of your setup I can tell a differences between cd +sacd but when I had my marantz sacd player I could not tell much of a difference between the cd version of brothers in arms on cd and the sacd but now I have a much more better setup yes I can definitely tell the difference between cd + sacds but also there are some really well recorded CDs out there that come close to sacds

I believe you black sab.. Ive also heard wonderful results with sacd but as yet have not had the chance to directly compare though i admit.

you would be welcome to come and hear my setup anytime mate I've got the brothers in arms on cd and sacd to compare

Is Brothers in arms a DSD recording?

I would imagine, from it's age, it would be a DSD recording from original analogue tape. Could be wrong however.

yes it is dsd ( direct stream digital ) going by the back of the sacd copy of brothers in arms

 

[Frank Harvey]

It's far from perfect, but the 5.1 mix of Brothers In Arms sounds amazing on SACD. It was originally a digital recording, although at what bit depth and sampling rate I don't know without some research.

 

[Blacksabbath25]

its 96kHz /24bit taken direct from the master tapes the version i have the 20th anniversary edition but there is a sacd 2005 version too which is meant to be better

 

[davedotco]

its 96kHz /24bit taken direct from the master tapes the version i have the 20th anniversary edition but there is a sacd 2005 version too which is meant to be better

Both multitrack and 2 channel master.

Which removes the only important advantage of the DSD/SACD format.

It's a PCM recording so can not be DSD, so once again we have to ask why the 'best' versions (assuming they are, of course) of this album are only available on a high price 'premium' formats.

 

[Blacksabbath25]

its 96kHz /24bit taken direct from the master tapes the version i have the 20th anniversary edition but there is a sacd 2005 version too which is meant to be better

Both multitrack and 2 channel master.

Which removes the only important advantage of the DSD/SACD format.

It's a PCM recording so can not be DSD, so once again we have to ask why the 'best' versions (assuming they are, of course) of this album are only available on a high price 'premium' formats.

i am not sure if both versions on the disc are DSD i would say the 5.1 side is DSD but anyway the case says DSD on the back for sure but the differences between the two versions cd / sacd version is the sacd sounds sharper a little loader and sounds cleaner recording then the cd version

 

[davedotco]

I am becoming a little lost here.

I was under the impression that anything on a SACD was/is recorded in DSD...*unknw*

Or is the SACD disc simply a container for data in any format, as DVD was?

Help needed...*crazy*

 

[BigH]

its 96kHz /24bit taken direct from the master tapes the version i have the 20th anniversary edition but there is a sacd 2005 version too which is meant to be better

I'm reading a lot of negative reports about the original SACD which is 2005. The MoFi is meant to be better. It seems the original recording was done in 16bit. Certainly the 2005 remaster is the most compressed by some way at around 8 on drdatabase, the 1985 cd is 16.

 

[Blacksabbath25]

here is a link this will explain ......http://www.highfidelityreview.com/brothers-in-arms.html *smile*