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Are there differences in sound quality when using a player only as digital source?

AleXsr700

Active Member
Hi,
I am discussing this on two forums and now I would like to also talk about it here.

The questions is:

When using different CDPlayers and DVDPlayers to source a CD digitally via SPDIF to an amp, will there be differences in sound quality?

The DA-conversion is being done in the same AVR. Only the sources change. The CD is always the same one, the cables are always the same and in the end, the players only supply the digital PCM feed.

Will there be differences in sound and if yes or no, have you tried it in a blindtest?

And does your answer only apply to music-CDs (PCM streams) or also or maybe only to DD and DTS streams?

Thanks!

Alex
 

Steve.EX

Novice Member
Yes there will be differences.
Jitter is a good place to start for reasons as to why they will sound different.
 

AleXsr700

Active Member
But jitter could easily be eliminated at any time. Plus, where should the jitter come from? Jitter is only present when converting analog to digital or vice versa. If the stream was digital to start with and stays digital within the source, there will be no jitter. And even if there was, jitter could easily be removed as modern DACs already do.
 

Steve.EX

Novice Member
I believe jitter (to put it crudely) can be quantified not only in an AD/DA process but in the timing between what what is actually on the disc and what comes off the disc, all in the digital domain.
 

PJTX100

Well-known Member
With DVD players I'm sure there is a difference but probably not one worth paying £100's of pounds more for. I suspect the better option for music is to spend the money on a dedicated CD player and let that do the D->A conversion...PJ
 

Steve.EX

Novice Member
Another option is by way of syncing or slaving all clocks to a master. Tag do this via a TL2 link, which is a simple rca - rca interconnect (i use a av32r DP, dvd32r and also a cdt20r). Both transports (dvd and cd) are slaved to the processor and as such (IIRC) have some of the lowest jitter figures recorded (single figure numbers IIRC).
Low jitter does not in any way equate to guaranteed sound quality however. It is more a measure of accuracy or faithfulness to the original source. In its own right it does not dictate tonality.
 

Steve.EX

Novice Member
In hindsight i will redress that last sentence and say of course it can affect tonality, but perhaps should be considered as a form of distortion.
 

Steve.EX

Novice Member
Damenace.

In answer to your question however if the two bitstreams (measured) are identical and all other things are equal then "in theory" it should sound identical.
However, i notice you are a Naim lover and wonder if you would settle (i.e) for a £100 Toshiba dvd player that had identical jitter and amplitude figures to a £2000 Naim cd transport?
 

Timbo21

Well-known Member
It's funny some steady digital clocks improve things, & others don't. Where I work they bought in a master digital clock (can't remember the make). It did reduce jitter, but I really didn't like how it made things sound. The only way I can describe it was that it seemed to take the colours away from the sound ( :rolleyes: a bit hippyish), and gave everything a sort of bland same sound.

Jitter, AFAIK, is the slight time variation of the clock rate. If you pass audio digitally through different pieces of digital audio outboard equipment (in bypass) before the D/A you will notice the change in sound from adding or taking away different equipment. I would think this proves that jitter is not only incurred at the conversion process. Also, the change in sound using different digital cables & interfaces I would think would prove this also.

Another possible way a digital clock can change the sound, apart from jitter, is because not all clocks are, for example, exactly 44.1khz. Some might be 44.0995, others might be 44.1005. Perhaps the one slightly under 44.1 might give a chunkier sound, and the one slightly over perhaps more airy. This is just a theory, I haven't tested it. However, it is true digital audio clocks may not be exacly 44.1 khz. The equipment needs it to be within a certain range for it to lock, and I guess spdif & AES/EBU standards will dictate how much it can vary.
 

Steve.EX

Novice Member
This is very true.
I have, in my passing, often read of those who dislike the effect removing jitter can have on some kit. Many many times it would seem the expressions used are words like "sterility and souless". I prefer unerring accuarcy myself. Is this the "unnatural digital" sound that analogue lovers refer too.
It does seem (on the face of this subject) that many people prefer their sound with a bit of "distortion" thrown in.
 

Timbo21

Well-known Member
Steve.EX said:
It does seem (on the face of this subject) that many people prefer their sound with a bit of "distortion" thrown in.
I know Jimmy Hendrix did :)
 

AleXsr700

Active Member
Do you guys know, whether the digital signal actually passes through any circuit before being sent to the amp? Or will the signal be read from the disc and directly be past to the coax output?
 

stebbo

Standard Member
Jitter is only important at the point if Digital to Analogue conversion. As long as the DAC in the AV amp is slaved to the incoming data stream and is designed to cope many variations of timing, then there will be no diiference.
More specifically, the only place where the jitter is relevant is in the DAC's sample and hold clock. Nowhere else does jitter have any relevance.

BUT! how can you tell if the DAC is designed correctly or if the AV amp is designed correctly?

Jitter was fully understood and many techniques to solve it have been around since the 1960's. Here are a couple of papers that cover the concepts very well.
Blesser, B. A., "Digitization of Audio: A Comprehensive
Examination of Theory, Implementation and Current
Practice," J. Audio Eng. Soc., vol 26, no 10,
and just to make it easy for you I will point out the pages 739-771, 1978 Oct.
Much discussion on jitter and its relevancy

and of course not forgetting

Manson, W., "Digital Sound Signals: Subjective Effect
of Timing Jitter," BBC Research Eng. Div, Great Britain,
Monograph 1974/11, 1974.


Unfortunately we cannot assume good design with any player, but in general the big brands like Sony/Denon/pioneer & meridian do it as well as is possible
 

Xyberbat

Standard Member
Yes, there is a difference.

I have tested this with my Pioneer DV535 and DVL919e, both running copies of the same CD, using identical digital co-ax cables, into a Pioneer VSA-AX10 amplifier.

A friend and I both noticed the difference 5 out of 5 times, with my son doing the random switching using the remote.

This resulted in me now using the DVL919 as my primary CD player, as I prefer that soundstage more.

Why the difference? I don't know, but it is there.
 

alefsin

Standard Member
In short my answer is: No. In practice you should not be able to differentiate between different players under these assumptions.
I don't say Xyberbat's experience was not real. What I say is that he has just compared one DV535 and one DVL919e. What if we could compare a batch of 100 DVL919e and 100 DV535 and run a blind test and see if a group of audience can separate the two models? I believe the variation between different players of different models is as big as the variations between different players of the same model.
 

Nic Rhodes

Well-known Member
alefsin said:
I believe the variation between different players of different models is as big as the variations between different players of the same model.
I am not sure about this, perhaps we should do a test rather than speculate on one outcome before the test has been done.

Search engine has loads on this.....

Back in the distant past I wrote a long essay about this and hit all the Chord 64 DAC owners who claimed their buffer removed all jitter. I argued it helped but was only one partial solution and perhaps a better one (the best one) was as described by Steve on the Tag with a timing signal. Role on a few years and the Chord 64 has now been adapted to have a timing signal (just like the Tag and what I suggested would help). Chord then produced a separate transport which used the timing signal and they now do not use the buffer I was told was the solution to all jitter woes. People have been silent on this one…..The Chord is much better for it.

Jitter affect all areas, and there are many things that can help from disc to cable and all the electronics in between. But at least people now have a much better understanding of the issues involved and the chips available are now MUCH better than they were a few years ago.

PCM is more susceptible to jitter than bitstream signals.
 

stebbo

Standard Member
Nic Rhodes said:
I

Snip!

Jitter affect all areas, and there are many things that can help from disc to cable and all the electronics in between. But at least people now have a much better understanding of the issues involved and the chips available are now MUCH better than they were a few years ago.

PCM is more susceptible to jitter than bitstream signals.
What do you mean "at least people now have a better understanding of the issues???"

Blesser, B. A., "Digitization of Audio: A Comprehensive
Examination of Theory, Implementation and Current
Practice," J. Audio Eng. Soc., vol 26, no 10,
and just to make it easy for you I will point out the pages 739-771, 1978 Oct.
Much discussion on jitter and its relevancy


1978!!!
That is a good 5 to 6 years before the commercial release of the CD product!
 

Nic Rhodes

Well-known Member
Err?

Care to explain the theory of relativity to me please, been around the best part of 100 years now, everyone of course knows about it. or perhaps they don't.....surely they must, it has been written about for years.... :D

Perhaps it is down to people having the right skills now designing the products and chips.

It is quite simple. Ask people about jitter now and quite few will give you a half decent answer. This includes designers. Care asking the same question in 1978?
 

Nic Rhodes

Well-known Member
oh I am familiar with the jitter references as I am one of the researchers who is still working in this field :hiya:

Jitter reference go back MUCH further than that, even in the BBC. Audio jitter papers that were here really taken seriously however by other researchers started appearing in the late 80s. Their effect on products started to come into the market during the 90s but in small numbers. Chips which stated to deal with jitter properly started appearing 2000+ era and it was the late 90s that good quality commercial analysis equipment was started to being used by manufacturers to optimise audio design. Now in 2005 we start to see players like Arcam DV29 that are really well sorted out re jitter, quality engineering. However we did have well sorted out jitter players 10 years earlier from specialists who really understood the subject well but they were the preserve of the few not the many.

Just out of interest, much of the jitter analysis equipment ain't cheep. I had to rent an oscillascope recently for a single measurement of Jitter as the cost was well excess of £30k for the oscillascope alone.....
 
M

monotone

Guest
Done 2 separate tests before, and the difference wasn't subtle...

Denon DVD1910 VS DVD2910

Marantz CD17mkII VS DV8400

The better built models tend to give a wider stage & depth in details. Comparisons were made on same amp. Just a guide, best to trust your ears.
 

Knyght_byte

Novice Member
the sound does change, definitely a difference between my cheapo Thompson DVD player i won at work to the 3910 i own now, exactly the same amp and cables, yet the Denon is definitely a better sound......

i would imagine, especially in home cinema or when listening to loud music, the build quality of the player helps reduce possibly loss of data through vibration.........i know that older less stable CD-ROM drives in computers used to suffer data problems on occasion...now of course they spin much faster and read the data more times to ensure they lift all the data so very little chance of drop-out.....but DVD's in a hifi unit dont do that.....

this could be a factor.....i guess...lol...
 

stebbo

Standard Member
Nic Rhodes said:
Err?

Care to explain the theory of relativity to me please, been around the best part of 100 years now, everyone of course knows about it. or perhaps they don't.....surely they must, it has been written about for years.... :D

Perhaps it is down to people having the right skills now designing the products and chips.

It is quite simple. Ask people about jitter now and quite few will give you a half decent answer. This includes designers. Care asking the same question in 1978?
I will expalin it to you if you like, but its relevance to this topic is ZERO.

Designers from the beginning have know about jitter as it was solved in the 1960´s.
People like Bob Stuart from Meridian. John Dawson of Arcam and the people at Sony to name but a few have been producing players of the utmost quality for many many years. These people know there stuff they have forgotten more about the CD systen than most "high end" companies know
The problems are the "******s" of the high end industry who produce such rubbish that people think that the crap they produce are good because of the price tag I can think of a couple off hand like Wadia, with a spline filter than leaves artifacts above 15kHz, of Levinson who produce so much over priced rubbish that I dont even know wher to start.
 

AleXsr700

Active Member
So stebbo,
You are saying that there is no Jitter in any Meridian players and hence all Meridian DVDPlayer they ever made have the same digital sound? Hence movies and CDs sourced digitally to the amp all sound the same, no matter which Meridian player I use?
 

Nic Rhodes

Well-known Member
Stuart

what you say does have relevance and is what I have argued for years here, many years. It is easy to balls it all up up, but it ain't difficult to get right and at decent money if you deal with people who know what they are doing.

My comment of the 'high end' are more related to guys like Audio Synthesis rather than the Wadia / Levinsons of this world, both of whom I have had mixed experriences but the former REALLY knows their stuff re jitter.

For the record I think Arcam got smart re jitter when they got their test equipment that could do jitter, in the late 90s as hinted at earlier. Before that it was more hit and miss but some lovely players never the less.

Even though Sony, Meridian, Arcam etc all know about jitter, the interfaces and chips they had to use (SPDIF / receiver chips) were somewhat flawed re jitter and they often struggled to get the best out of them. Luckily chips have now changed for the better (see earlier comments) and many have ditched SPDIF in favour of well sorted out single boxes (far better). But in the dark ages Sony had SDIF (2?), Meridian had it's 'recoding of the digital signal' and Arcam had a sync link. Audio synthesis had Arcam compatible sync link and the N and C code 'recoding'. All were designed to combat the J word. They understood the problems and found solutions, allbeit not main stream.
 

stebbo

Standard Member
damenace said:
So stebbo,
You are saying that there is no Jitter in any Meridian players and hence all Meridian DVDPlayer they ever made have the same digital sound? Hence movies and CDs sourced digitally to the amp all sound the same, no matter which Meridian player I use?
Damence My Good man
Have I said this?? In fact how can you tell if something sounds the same unless you do a blind trial.
Have you ever read this paper
Eric Benjamin and Benjamin Gannon - "Theoretical and Audible Effects of Jitter on Digital Audio Quality", AES preprint 4826 105th convention, 1998. ?

I will summarise it for you.

Audible jitter is in the nanoseconds. will virtually ever commercial cd-dvd mech which as I am sure you are aware is a prebuilt pre ordered unit is in the picoseconds region.

In fact if the designer knows he is having a nanosecond jitter or even a milisecond one he can design the player or dac to cope with it. Meridian use a fairly large memory buffer to read the data into then it is reclocked out at a very very accurate stable rate.
 

stebbo

Standard Member
Nic Rhodes said:
Stuart

what you say does have relevance and is what I have argued for years here, many years. It is easy to balls it all up up, but it ain't difficult to get right and at decent money if you deal with people who know what they are doing.

My comment of the 'high end' are more related to guys like Audio Synthesis rather than the Wadia / Levinsons of this world, both of whom I have had mixed experriences but the former REALLY knows their stuff re jitter.

For the record I think Arcam got smart re jitter when they got their test equipment that could do jitter, in the late 90s as hinted at earlier. Before that it was more hit and miss but some lovely players never the less.

Even though Sony, Meridian, Arcam etc all know about jitter, the interfaces and chips they had to use (SPDIF / receiver chips) were somewhat flawed re jitter and they often struggled to get the best out of them. Luckily chips have now changed for the better (see earlier comments) and many have ditched SPDIF in favour of well sorted out single boxes (far better). But in the dark ages Sony had SDIF (2?), Meridian had it's 'recoding of the digital signal' and Arcam had a sync link. Audio synthesis had Arcam compatible sync link and the N and C code 'recoding'. All were designed to combat the J word. They understood the problems and found solutions, allbeit not main stream.
I knew we were in the same camp on this subject sorry if I went off a bit, I am not at home and only have a few mins to look at the web every other night or.
 

AleXsr700

Active Member
Stebbo, so do you think that Jitter is a known problem which could be resolved to an inaudible degree or not?

If so, then are you saying that there are no differences in sound quality from a digital source or are there?

If there are, are you saying that all manufacturers simply don't want to correct or remove jitter and intentionally produce a certain amount of disturbances in order to make their products sound different? Or do they even cheat by using DSPs?

If the masterclock idea, meaning the signal will be reclocked in the DAC-Unit is the way to go, then would you say that Meridian, who actually use this method, sounds best or are they not able to get it right and hence even though using this method the sound still isn't without errors? And if they do manage to sort this out with the reclocking, then would you say that you could use ANY source on a MEridian amp as the signal will be reclocked anyway and hence every source will sound the same?
 

Steve.EX

Novice Member
I have a question also re: the Meridian solution.

When reclocking is implemented is this a best guess scenario? Or to put it another way if the data is dumped to memory how or what/where is the "correct" timing established/derived from?
 

stebbo

Standard Member
Steve.EX said:
I have a question also re: the Meridian solution.

When reclocking is implemented is this a best guess scenario? Or to put it another way if the data is dumped to memory how or what/where is the "correct" timing established/derived from?
Sorry for the delay. I am in Spain so it isnt that easy to keep up to date
When the analogue signal is converted to digital at the recording stage the data is mulitplexed. This is where the timing comes from. So when it is copied into buffer memory it has time to be reconstructed properly.
It is obviously a lot more complex than that, but that is a simplified version.
 

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