Jitter Audibility

[WmAx]

This one is in English!

http://www.stereophile.com/digitalsourcereviews/886/

Mtrycrafts referred to a double-blinded listening test. The link you have provided is a worthless sighted listening impression/review. However, the measurement section on the product that is accessible from the link you provided is useful. The subjective review part should basicly be ignored.

-Chris

 

[tbewick]

Hi Westcott,

I think the two links you gave, particularly the first one, can give a rather misleading impression of typical digital audio performance. Stereophile has a tendency to overstate the shortcomings of modern equipment. This may be why they are so liked by hi-fi manufacturers, as they get you to spend more money than you need to. I am also immediately skeptical of any source that only gives facts or bold claims about 'myths and misconceptions' but offers no hard explanations. The Dolby paper which mtrycrafts originally provided does provide evidence showing that jitter audibility is low. In an average hi-fi set up you would probably not hear it. There are far more important factors which limit system performance, like the loudspeakers and room acoustics. These would be readily verifiable in a double-blind test.

I would also contest that any differences between CD player performance through the analogue outputs would more likely be the result of the analogue circuitry used by the player. A digital connection like S/P-DIF allows the digital receiver to reject noise and distortion and bypasses the analogue circuitry of the CD/DVD player. The S/P-DIF channel coding is of the bi-phase modulation type which ensures proper clocking [1]. Unless the CD player and receiver are of poor design, then any jitter should be rejected to the point of inaudibility. I have included some pages from the book I referred to earlier which should hopefully clear this up for you. If I haven't already made the point clearly enough -

'A remote convertor which sounds different when reproducing, for example, the same Compact Disc via the digital outputs of a variety of CD players is simply not well engineered and should be rejected. Similarly if the effect of changing the type of digital cable feeding the convertor can be heard, the unit is a dud.'[2]

As Chris pointed out, this book is over ten years old, and digital equipment has improved in this time. It is therefore unlikely that such poorly designed equipment would be available now.

'In the real world everything has a cost, and one of the greatest strengths of digital technology is low cost... the cost of ownership of digital equipment is less than that of analog. Debates about quality are academic except where compression is concerned; analog equipment can no longer compete economically, and it will dwindle away as surely as the transistor once replaced the vacuum-tube in electronics and the turbine replaced the piston engine in aviation.'[2]

The authors of this book are Francis Rumsey and John Watkinson. At the time of publication, Francis Rumsey was a lecturer at Surrey University and a Governor of the AES, while John Watkinson was a fellow of the AES. I don't think that any of the writers of Stereophile magazine have such good credentials.


[1] Digital Audio Technology, 4th edition, J. Maes & M. Vercammen, Focal Press 2001. p 337.

[2] The Digital Interface Handbook, 2nd edition, by Francis Rumsey and John Watkinson, Focal Press 1995. p 26-27 (attachments 2 and 3 respectively), p 37-38 (attachment 1).

 

[WmAx]

As wmax said, you'd be wasting good $$$. Spend it on your room acoustics or speakers.

That depends. I specified at least 2 cases where it is not a waste of money.

-Chris

 

[Rock&Roll Ninja]

And thats why my next system's will do-away with the pre-amp alltogether. I'll run CD transport -> DAC (with level adjust like Benchmark) -> Power Amps. or CD->Benchmark DAC1 in the case of my headphone system.

If you are buying that stuff for decorative or pride of ownership purposes, cool. If you are buying it for some supposed performance advantage; it's nothing more than a big jar of snake oil.

-Chris

Now you've confused me.....

1st listed setup: Transport CD -> DAC1 (with it's Volume adjust) -> power amp ->loudspeakers.

2nd listed (headphone rig): Transport CD ->DAC1 (with it's built-in headphone amp) ->Headphones.

I understand your point if you think Benchmark is a snakeoil company (or its DAC1 a snakeoil product), but those are all required links in a music reproduction chain. In setup1 it removes the Pre-Amp link; a Volume adjusting CD player would remove the need for the seperate DAC1 also, but I don't know of any such CD player for under $2000, making the $800 DAC1 the cheaper choice. setup 2 needs all of those things to make music, again unless you can tell me about a CD player with decent headphone output*.

*decent headphone output = something to drive 300+Ohm headphones, such as Senn 650's. with 1/4" plugs. $100 PCDPs really can't do this. My NAD c370 Integrated has a very nice headphone amp, but its connected to my system in the other room, and I can't use it for a bedroom system.

 

[WmAx]

Now you've confused me.....

1st listed setup: Transport CD -> DAC+Volume adjust -> power amp ->loudspeaker.

2nd listed (headphone rig): Transport CD ->DAC+amp ->Headphone.

I understand your point if you think Benchmark is a snakeoil company (or its DAC1 a snakeoil product), but those are all required links in a music reproduction chain. (In setup1 it removes the Pre-Amp link, a Volume adjusting CD player would remove the seperate DAC, but I don't know of any for under $2000. setup 2 needs all of those things to make music, again unless you can tell me about a CD player with decent headphone output*).

*decent headphone output = something to drive 300+Ohm headphones, such as Senn 650's. with 1/4" plugs. $100 PCDPs really can't do this.

I don't understand the need for occluding a pre-amp from the loudspeaker chain. Perhaps you can explain this. As for the headphone situation, you can acquire perfectly capable headphone amplifiers from $80 on up. May even be cheaper units that perform flawlessly. If you want a low price device that can basically power anything(even the super low sensitivity AKG K 340), the compact Behringer UB1202 mixer has a headphone amp on it that transparently amplifiers virtually any headphone, and without any audible noise(assuming you set the gain controls correctly), even on a super sensitive headphone such as the Sony MDR-CD3000. Or you can spend more money to get a purpose specific headphone amplifier of equal capability. I can't see a reason to use an external DAC from a performance perspective, unless you require some specific external control of parameters only possible on an external DAC. Please let me know if that is the case. Even then, I can refer to much lower priced device than the Benchmark product, and the cheaper product will have greater functionality/flexibility.

-Chris

 

[Rock&Roll Ninja]

I don't understand the need for occluding a pre-amp from the loudspeaker chain. Perhaps you can explain this.

With a 1 source system (in my case, CD), the need for a seperate pre-amp (and the potential degradation of another 2 pairs of analog connections in the system that isn't neccessary)is no longer there if I can find a CD player with an adjustable volume output. The Benchmark unit functions as a studio-quality DAC and a volume regulator for less than half of the price of the only CD player I have personally seen that can controll the level of its RCA outputs (The McIntosh MCD201).

If theres a sub $500 player that can do this, please please please tell me what it is so I can buy one.

As for the headphone situation, you can acquire perfectly capable headphone amplifiers from $80 on up. May even be cheaper units that perform flawlessly.

6 months ago I didn't even know a headphone amp existed. The only pace I had ever heard of such a product was Head-Fi, and since everyone, or seemingly everyone on that forum, purchases at least a half dozen of the things to match their wide collection of silver headphone cables and $2000 iPod "modifications" (that make it sound better while removing the headphone output, ensuring the need for an external DAC + Batterypack). So naturally I assumed these esoteric amps (most of which are tube powered) were of the same class of product as $400 power cords and Mpombi-wood tuner dials.

Meanwhile stereo receiver headphone amps work very well (at least my NAD does), and the Benchmark was the first solid-state product with a headphone amp, was also a DAC used my several recording studios (according to their website) so I assumed it was a decent product, and it was small enough to use in a bedroom system + cheaper than the 'toob' amps the golden-cabled crowd like to buy. ("the enemy of my enemy is my friend", or something to the effect).

The only headphone amp equiped CD player I know of is a Marantz unit that many people say is underpowered for my 650 headphones (which I already own). Sony & Grado 'cans may be more efficient, but I like my Senn's and don't want to buy more headphones than I already have.

 

[mtrycrafts]

.

I understand your point if you think Benchmark is a snakeoil company (or its DAC1 a snakeoil product), but those are all required links in a music reproduction chain. In setup1 it removes the Pre-Amp link; a Volume adjusting CD player would remove the need for the seperate DAC1 also, but I don't know of any such CD player for under $2000, making the $800 DAC1 the cheaper choice. setup 2 needs all of those things to make music, again unless you can tell me about a CD player with decent headphone output*.

.

No, Benchmark is not a snake oil company. And I don't see them making any snake oil claims either. Their dac is excellent in fact from the spec sheet and testing at TAC. But does one really need such a product, is the question. I see your point to a point. But, can't you get a preamp for less than $800 with a DAC in it and a volume control?

 

[mtrycrafts]

That depends. I specified at least 2 cases where it is not a waste of money.

-Chris

Short reading memory, just like that acoustic memory
Does his condition fits?

 

[mtrycrafts]

I would also contest that any differences between CD player performance through the analogue outputs would more likely be the result of the analogue circuitry used by the player. A digital connection like S/P-DIF allows the digital receiver to reject noise and distortion and bypasses the analogue circuitry of the CD/DVD player. The S/P-DIF channel coding is of the bi-phase modulation type which ensures proper clocking [1]. Unless the CD player and receiver are of poor design, then any jitter should be rejected to the point of inaudibility.

As Chris pointed out, this book is over ten years old, and digital equipment has improved in this time. It is therefore unlikely that such poorly designed equipment would be available now.

One day you may wan to chase these down for your collection that seems to be mounting:

Masters, Ian G 'Do All CD Players Sound the Same?' Stereo review, Jan 1986, pg 50-57.

Pholmann, Ken C. '6 Top CD Players: Can You Hear the Difference?' Stereo Review, Dec 1988, pg 76-84.

Phollmann, Ken C. 'The New CD Players: Can You Hear the Difference?' Stereo Review, Oct 1990, pg 60-67.

CD Player Comparison, The Sensible Sound, # 75, Jun/Jul 1999.

CD Player Comparison, The Sensible Sound, # 74, Apr/May 1999.

20 years ago


Yes, Ken C is still around at Miami U, professor of music and such. Wrote the Digital audio Handbook

 

[WmAx]

Note: This is my last reply in this thread concerning your DAC/headphone situation, because I believe this is now flooding tbewick's thread with off topic discussion. If you wish to continue this discussion, please start a thread dedicated to this issue or PM me.

With a 1 source system (in my case, CD), the need for a seperate pre-amp (and the potential degradation of another 2 pairs of analog connections in the system that isn't neccessary)is no longer there if I can find a CD player with an adjustable volume output.

A modern, well-designed pre-amp will not create any audible degradation(s).

The Benchmark unit functions as a studio-quality DAC and a volume regulator for less than half of the price of the only CD player I have personally seen that can controll the level of its RCA outputs (The McIntosh MCD201).

The Benchmark does not have a remote control so far as I can tell. Since this is the case, you can purchase a used, excellent quality pre-amp such as those by Adcom off of ebay for $100-$200, at least the ones without remote control volume.

If theres a sub $500 player that can do this, please please please tell me what it is so I can buy one.

Oddly, this used to be a typical feature in the 90's. Why it's rare today, I don't know. Pioneer, especially, had many units with volume control capability. If you do not mind purchasing a used device, you could aquire one of these units from Ebay for probably $100-$200.

-Chris

 

[westcott]

Mtrycrafts referred to a double-blinded listening test. The link you have provided is a worthless sighted listening impression/review. However, the measurement section on the product that is accessible from the link you provided is useful. The subjective review part should basicly be ignored.

-Chris

Since I did not translate the article, I had no idea what was in the mtry link.

 

[westcott]

Hi Westcott,

I think the two links you gave, particularly the first one, can give a rather misleading impression of typical digital audio performance. Stereophile has a tendency to overstate the shortcomings of modern equipment. This may be why they are so liked by hi-fi manufacturers, as they get you to spend more money than you need to. I am also immediately skeptical of any source that only gives facts or bold claims about 'myths and misconceptions' but offers no hard explanations. The Dolby paper which mtrycrafts originally provided does provide evidence showing that jitter audibility is low. In an average hi-fi set up you would probably not hear it. There are far more important factors which limit system performance, like the loudspeakers and room acoustics. These would be readily verifiable in a double-blind test.

I would also contest that any differences between CD player performance through the analogue outputs would more likely be the result of the analogue circuitry used by the player. A digital connection like S/P-DIF allows the digital receiver to reject noise and distortion and bypasses the analogue circuitry of the CD/DVD player. The S/P-DIF channel coding is of the bi-phase modulation type which ensures proper clocking [1]. Unless the CD player and receiver are of poor design, then any jitter should be rejected to the point of inaudibility. I have included some pages from the book I referred to earlier which should hopefully clear this up for you. If I haven't already made the point clearly enough -

'A remote convertor which sounds different when reproducing, for example, the same Compact Disc via the digital outputs of a variety of CD players is simply not well engineered and should be rejected. Similarly if the effect of changing the type of digital cable feeding the convertor can be heard, the unit is a dud.'[2]

As Chris pointed out, this book is over ten years old, and digital equipment has improved in this time. It is therefore unlikely that such poorly designed equipment would be available now.

'In the real world everything has a cost, and one of the greatest strengths of digital technology is low cost... the cost of ownership of digital equipment is less than that of analog. Debates about quality are academic except where compression is concerned; analog equipment can no longer compete economically, and it will dwindle away as surely as the transistor once replaced the vacuum-tube in electronics and the turbine replaced the piston engine in aviation.'[2]

The authors of this book are Francis Rumsey and John Watkinson. At the time of publication, Francis Rumsey was a lecturer at Surrey University and a Governor of the AES, while John Watkinson was a fellow of the AES. I don't think that any of the writers of Stereophile magazine have such good credentials.


[1] Digital Audio Technology, 4th edition, J. Maes & M. Vercammen, Focal Press 2001. p 337.

[2] The Digital Interface Handbook, 2nd edition, by Francis Rumsey and John Watkinson, Focal Press 1995. p 26-27 (attachments 2 and 3 respectively), p 37-38 (attachment 1).

I think his solution comes right out of the professional sound studio market. I see no exageration, just a straight forward solution that seems common place in the pro audio world. A simple timing issue with a simple solution.

 

[tbewick]

One day you may wan to chase these down for your collection that seems to be mounting:

Masters, Ian G 'Do All CD Players Sound the Same?' Stereo review, Jan 1986, pg 50-57.

Pholmann, Ken C. '6 Top CD Players: Can You Hear the Difference?' Stereo Review, Dec 1988, pg 76-84.

Phollmann, Ken C. 'The New CD Players: Can You Hear the Difference?' Stereo Review, Oct 1990, pg 60-67.

CD Player Comparison, The Sensible Sound, # 75, Jun/Jul 1999.

CD Player Comparison, The Sensible Sound, # 74, Apr/May 1999.

20 years ago


Yes, Ken C is still around at Miami U, professor of music and such. Wrote the Digital audio Handbook

Cheers for that. I have tried geting hold of The Digital Audio Handbook but it appears to either have been lost or miscatalogued at my library.

I did finish the AES Convention paper you linked to - thanks very much. It's a shame that further study wasn't done on those who could distinguish the formats.

"Because of its principle of operation, when a “stop” or “play” command was issued directly or indirectly, the DSD encoding in conjunction with the “non-audio format” which was used for file storage on the multichannel audio workstation caused a very brief, low-level crackling sound. A similar sound also occurred in PCM mode at similar moments, but was subtly different sounding.
...If one considers the test results with Treisman’s “Suppression Theory of Selective Auditory Attention,” which is based on perceptual psychology and is recognized today as the most far-reaching approach, sonic elements such as crackling sounds might be regarded by a Tonmeister as valid semantic content, and thus might influence a decision-making process either consciously or unconsciously. This level of importance could have been in effect particularly in this case: All four of the test subjects whose scores were in the range of critical probability were students in the Tonmeister course; all were aged 25 – 28; and tellingly, all auditioned their music examples over headphones."

- DVD-Audio versus SACD Perceptual Discrimination of Digital Audio Coding Formats Listening Comparison Test between DSD and High Resolution PCM (24-bit/176.4 kHz) by Dominik Blech and Min-Chi Yang

The statistical result does appear quite conclusive -

"Of a total 2,900 choices (145 test sequences × 20 choices per test sequence) there were 1,454 correct choices and 1,446 incorrect ones (see Figure 10). This result comes remarkably close to that which would be expected (arithmetic mean value of 1,450 correct and 1,450 incorrect responses) in a statistically “pure chance” experiment. The four extra correct choices (not to be confused with the four test subjects who attained critical probability with their test scores) represents a deviation of only 0.28%."

and matches up with the subjective comments made by the listeners -

"Though less readily formulated with mathematical equations, the high level of frustration felt by many subjects during their tests left quite a strong impression. These people, for the most part, were well accustomed to critical listening on a professional level, but they found that they could not even begin to recognize any sonic differences."

The only thing is that this isn't a peer-reviewed paper, but the results are still interesting to look at.

I think his solution comes right out of the professional sound studio market. I see no exageration, just a straight forward solution that seems common place in the pro audio world. A simple timing issue with a simple solution.

You must be much cleverer than me. I really struggle with the conceptual explanations given in those books a referred to. It's just merciful that the authors put in their own comments from time to time to space out and contextualise the theory.

 

[WmAx]

Thanks for the SACD/DVD Audio paper link you gave earlier (http://www.hfm-detmold.de/eti/projek...paper_6086.pdf). I haven't read through it fully yet but it should be interesting.

Could you repost this link? The link does not work for me.

-Chris

 

[tbewick]

http://www.hfm-detmold.de/eti/projekte/diplomarbeiten/dsdvspcm/aes_paper_6086.pdf

If that doesn't work, mtrycrafts posted the link on the first page of MDS's 'Quest for Perfection' thread.

 

[mtrycrafts]

http://www.hfm-detmold.de/eti/projekte/diplomarbeiten/dsdvspcm/aes_paper_6086.pdf

If that doesn't work, mtrycrafts posted the link on the first page of MDS's 'Quest for Perfection' thread.

It seems to be off line right now. Maybe they saw it used too much?

Maybe it will be up next week, hopefully.