Depth, the final frontier.

[jkeny]

What I've said is, if, in the digital domain, I can null two files against each other, 100% to the sample, that *suggests* to me what what I'm feeding my DAC is identical in both instances.

Sorry,again we are talking about nulling in the digital domain i.e the bits match. It says nothing about any other noise or distortion that might be riding on the digital signal. This could be very different between the two files & they would still null in the digital domain.

I would expect them to be treated identically by the DAC chip, audio-wise, jitter-wise and any other way I can imagine.

if the noise is different between both files then I think this expectation is very optimistic.

Ergo, I would expect the output from the DAC chip to the analog stages and ultimately, the output from the box to my power amps, to be identical too.

Not if the above scenario is a possibility

To be clear, I'm not saying this IS the case and I'm not saying it is a Universal Truth (please add reverb to those words ;-}). I'm saying this is my understanding and expectation, flawed though they may be in the face of any new evidence to say otherwise.

Not at all the same (at least to me) as "bits is bits" because the latter doesn't take into account timing between those bits during decoding and perhaps a host of other as yet unquantified factors. I've certainly heard differences, from very subtle to quite pronounced, in comparing CD pressings from different replication facilities against each other and against the master used to create them. The data, once extracted to computer, have consistently (i.e. 100% of the time over several thousand examples in the course of close to three decades now) proven to be 100%, bit-for-bit identical. Of course, except in the case when one is in the presence of a fax machine, we don't listen to data.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

Interestingly, I would love to see how you would expect jitter to show up in a null test of a digital signal? Any ideas?

Edit: I see this thread has progressed a bit. One thing I would like to tentatively add to this is that I'm of the opinion that it's not just noise that will cause audible issues - I'm convinced that the waveform of the digital signal will have an influence on the sound. I have done an experiment with USB cable Vs no USB cable & many people now confirm that no cable is a far better sounding configuration. Yes blind test were conducted. My tentative conclusion based on follow on tests, the digital waveform matters! Why? Maybe, like in the case of the extra processing required for Lossless decoding giving rise to noise, the less ideal waveform causes some extra level of processing effort with the USB receiver chip which causes noise? It's just a possibility, don't take it literally.

 

[bdiament]

Hi jkeny,

...I would love to see how you would expect jitter to show up in a null test of a digital signal? Any ideas?...

I would *not* expect jitter (from D-A conversion) to show up in a null test.

If you're asking, the only instance in which I can think this would be possible would be if the original A-D encoding suffered from sufficient jitter. But if it did, I would also expect a null test would *not* show a null, as I suspect the encoded data would differ.

Not sure what you mean by "digital waveform". I've never seen one; only analog.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

[jkeny]

Hi jkeny,



I would *not* expect jitter (from D-A conversion) to show up in a null test.

This is what I don't understand with your statements. You are saying that jitter can be audible, right? Yet you are saying that it will not show up on your null test of the digital signal, right? Yet, you say that if a null test of two signals taken just before input to the DAC chip are the same then you expect the sound to be the same?? Yet one of these signals could have jitter & we will not see it in a null test but will hear it???

If you're asking, the only instance in which I can think this would be possible would be if the original A-D encoding suffered from sufficient jitter. But if it did, I would also expect a null test would *not* show a null, as I suspect the encoded data would differ.

How would you expect the encoded data would differ at the bit level?i.e would you expect bits would differ?

Not sure what you mean by "digital waveform". I've never seen one; only analog.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

If you put a scope on a digital signal going into a DAC (chip or box) you will see a waveform. It will differ in shape & other respects from an analogue waveform but the main difference will be in the rise & fall times of the waveform slopes - the digital signal will be very much faster!


Edit: This is what I'm getting at - digital is no different from analogue, at the electrical level. It is just that digital is an agreed protocol - signals above a certain threshold are ON bits & below a certain voltage threshold are OFF bits. This gives these signals a certain immunity to interference - interference that would play havoc with pure analogue signals.
http://en.wikipedia.org/wiki/Digital_electronics

Digital electronics represent signals by discrete bands of analog levels, rather than by a continuous range. All levels within a band represent the same signal state. Relatively small changes to the analog signal levels due to manufacturing tolerance, signal attenuation or parasitic noise do not leave the discrete envelope, and as a result are ignored by signal state sensing circuitry.
In most cases the number of these states is two, and they are represented by two voltage bands: one near a reference value (typically termed as "ground" or zero volts) and a value near the supply voltage, corresponding to the "false" ("0") and "true" ("1") values of the Boolean domain respectively.

 

[JackD201]

Moderators, may I please request a thread split? Methinks this good discussion deserves it's own home.

 

[bdiament]

Hi jkeny,

This is what I don't understand with your statements. You are saying that jitter can be audible, right? Yet you are saying that it will not show up on your null test of the digital signal, right? Yet, you say that if a null test of two signals taken just before input to the DAC chip are the same then you expect the sound to be the same?? Yet one of these signals could have jitter & we will not see it in a null test but will hear it???

I'm not sure where jitter entered the picture in terms of this discussion. While it is a real, measurable phenomenon, it is *not* what I'm attributing the audible differences between PCM and decoded-while-listening "lossless" files to. For all I know, it *may* be a factor but I suspect it is not the whole story, if it is a significant part at all.

Jitter in playback won't show up in a null test between digital files because jitter in playback occurs during D-A conversion (after the null test). I would think that jitter in the A-D conversion however, i.e., during *recording*, if sufficient, would result in different data (i.e., not exactly the same "ones and zeros") as it would result in small changes in the audio itself prior to the completion of conversion. (I would emphasize this is all hypothetical and theoretical as I have not conducted any testing along these lines; we're just having a conversation.)

If the jitter at play enters the picture during D-A conversion, I'd be confident it would *not* show in a null test conducted just ahead of the DAC chip.

If you put a scope on a digital signal going into a DAC (chip or box) you will see a waveform. It will differ in shape & other respects from an analogue waveform but the main difference will be in the rise & fall times of the waveform slopes - the digital signal will be very much faster!

Still not sure of what you mean. Are you referring to looking at the retrieved signal from say, a CD read on a 'scope? If so, that would be a series of sine waves representing the different length pits on the disc. That too, is an analog waveform (or a series of analog waveforms).
If you are referring to something else, it may be something I've never seen before and I'd be curious to see a screen capture if you can do one.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

[jkeny]

Hi jkeny,

I'm not sure where jitter entered the picture in terms of this discussion. While it is a real, measurable phenomenon, it is *not* what I'm attributing the audible differences between PCM and decoded-while-listening "lossless" files to. For all I know, it *may* be a factor but I suspect it is not the whole story, if it is a significant part at all.

Jitter in playback won't show up in a null test between digital files because jitter in playback occurs during D-A conversion (after the null test). I would think that jitter in the A-D conversion however, i.e., during *recording*, if sufficient, would result in different data (i.e., not exactly the same "ones and zeros") as it would result in small changes in the audio itself prior to the completion of conversion. (I would emphasize this is all hypothetical and theoretical as I have not conducted any testing along these lines; we're just having a conversation.)

Cable induced jitter is very real & will be in the signal at the input to the DAC chip. This would be before the null test signal is captured! So will this jitter show on the null test & how ?

If the jitter at play enters the picture during D-A conversion, I'd be confident it would *not* show in a null test conducted just ahead of the DAC chip.

Still not sure of what you mean. Are you referring to looking at the retrieved signal from say, a CD read on a 'scope? If so, that would be a series of sine waves representing the different length pits on the disc. That too, is an analog waveform (or a series of analog waveforms).
If you are referring to something else, it may be something I've never seen before and I'd be curious to see a screen capture if you can do one.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

If you do a search for "scope shots of SPDIF signals" or I2S signals you will see many examples

 

[jkeny]

Hi jkeny,

I'm not sure where jitter entered the picture in terms of this discussion. While it is a real, measurable phenomenon, it is *not* what I'm attributing the audible differences between PCM and decoded-while-listening "lossless" files to. For all I know, it *may* be a factor but I suspect it is not the whole story, if it is a significant part at all.

Jitter arises because it is an example of something you agree exists & can be audible. It exists in the incoming digital signal that gets fed to the DAC's input (just look at all the Stereophile tests of CD transports to see examples of measured jitter on their outputs). Now you have a null test taken just before the DAC chip's inputs which you say will sound the same for any two files which null out in this null test. I'm asking how jitter will be seen in this null test. If it can't be seen then nulling of digital files (as you are suggesting) is only a test of bit-perfectdness - it doesn't mean two file will sound the same

Jitter in playback won't show up in a null test between digital files because jitter in playback occurs during D-A conversion (after the null test). I would think that jitter in the A-D conversion however, i.e., during *recording*, if sufficient, would result in different data (i.e., not exactly the same "ones and zeros") as it would result in small changes in the audio itself prior to the completion of conversion. (I would emphasize this is all hypothetical and theoretical as I have not conducted any testing along these lines; we're just having a conversation.)

If the jitter at play enters the picture during D-A conversion, I'd be confident it would *not* show in a null test conducted just ahead of the DAC chip.
............................

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

[bdiament]

Hi jkeny,

Cable induced jitter is very real & will be in the signal at the input to the DAC chip. This would be before the null test signal is captured! So will this jitter show on the null test & how ?

I don't know. Do you? If there is any jitter introduced by the Firewire cable between my laptop and my ULN-8, unless is is being applied in exactly the same way, at the same instances to everything I play, it is not showing up in null tests. But I don't know if the Firewire connection is introducing jitter or not.

If you do a search for "scope shots of SPDIF signals" or I2S signals you will see many examples

I did a search and see all sorts of shots but nothing I would describe as a "digital waveform". Or perhaps I misunderstood what you mean by the term. I was hoping you had a screen capture you could share.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

[jkeny]

Hi jkeny,

I did a search and see all sorts of shots but nothing I would describe as a "digital waveform". Or perhaps I misunderstood what you mean by the term. I was hoping you had a screen capture you could share.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

I'm not sure where your confusion arises - maybe you can elucidate? I have many scope shots but on another computer which is packed away. This is a screen capture of a SPDIF device - you can see the fast risetime of 3.92nS

http://enjoythemusic.com/magazine/equipment/1110/m2tech/scope_jk_hiface_rise_time_no_attenuators.jpg

Another one of the same device but this has a risetime of 6.10nS

http://enjoythemusic.com/magazine/e...scope_usb_hiface_rise_time_no_attenuators.jpg

 

[bdiament]

Hi jkeny,

I see a "." but no screenshot. Am I missing something?
The confusion is with regard to your use of the term "digital waveform". It is new to me, as I've only seen analog waveforms.
Within "analog waveforms", I would include the voltage variations in an electronic circuit used to play digital audio.

Perhaps we're just defining the same thing differently.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

[jkeny]

Hi jkeny,

I see a "." but no screenshot. Am I missing something?
The confusion is with regard to your use of the term "digital waveform". It is new to me, as I've only seen analog waveforms.
Within "analog waveforms", I would include the voltage variations in an electronic circuit used to play digital audio.

Perhaps we're just defining the same thing differently.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

It seems my links didn't work as I expected! Fixed now.

Ok, so you are really talking about semantics now - yes I mean the analogue waveform of a digital signal - sorry for the shorthand but I expected you knew what I was saying - the context & explanations were enough for all to understand, I believe!!

Originally Posted by jkeny
If you put a scope on a digital signal going into a DAC (chip or box) you will see a waveform. It will differ in shape & other respects from an analogue waveform but the main difference will be in the rise & fall times of the waveform slopes - the digital signal will be very much faster!

It seems that you now understand fully what I was saying????

 

[Steve williams]

To jkeny and barry it has been suggested that this thread be split and since it involves the two of you, could one of you please start a separate thread on what you are discussing and let's try to stay OT here

 

[jkeny]

To jkeny and barry it has been suggested that this thread be split and since it involves the two of you, could one of you please start a separate thread on what you are discussing and let's try to stay OT here

I'm pretty much done with Barry here unless he wants to continue on another thread - it's up to him!

 

[Steve williams]

I'm pretty much done with Barry here unless he wants to continue on another thread - it's up to him!

well then in the absence of any reply from Barry, let's drop it and get back OT

 

[bdiament]

Hi Steve and jkeny,

...please start a separate thread on what you are discussing and let's try to stay OT here

No need. I'm done. Sorry for the off topic diversion.

...It seems that you now understand fully what I was saying????

Not really but let's drop it and allow this thread back on track again.
Thanks for the dialogue.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com