Audio Misconceptions?

[MDS]

Thanks for the reference to the Wilkinson book. I will read this. Does your above quote imply that an expensive interconnect will correct the problems with poorly designed DACs?

I would love to see a reference to a 'poorly designed' DAC. Even the cheapest dacs available do a fine job. Jitter is inherent in any digital system and can never be totally removed. Nonetheless, even a 'poor' dac exhibits jitter on the order of nanoseconds, which is for all intents and purposes inaudible. No interconnect can reduce jitter and an expensive interconnect won't do anything to improve a poor dac.

 

[John S]

tbewick---did you mean John Watkinson? I hope this book is for laymen, 'cause I could only get through the second chapter of Stephen Hawking's A Brief History of Time, and I ain't too proud to admit it.

 

[John S]

Good ol' Peter Aczel - one of the original founders of my favorites speakers to this day.

What speakers would those be?

 

[WmAx]

You described the ideal state of a piston in operation, internal combustion engine, pump, etc but is that what he meant by "pistonics"? Like a piston in the real world, a loudspeaker also often functions differently in actual operation, it is subject to many forces and its design attempts to deal with them as best it can.

Yes, I meant exactly what mustang_steve explained.

-Chris

 

[MBauer]

More on Newton

Yes, I meant exactly what mustang_steve explained.

-Chris

Oh, so given the context of the response about delay, mass and so forth we could say something like the "Pistonics is impactful"? But in the context of delay, if "Pistonics is impactful" is inertia not impactful? Recalling Newton's first law and considering inertia, might there not be a delay in movement until the unbalanced force took effect?

 

[cornelius]

What speakers would those be?

Trivia question!

Hint: _'s Law

 

[WmAx]

Oh, so given the context of the response about delay, mass and so forth we could say something like the "Pistonics is impactful"? But in the context of delay, if "Pistonics is impactful" is inertia not impactful? Recalling Newton's first law and considering inertia, might there not be a delay in movement until the unbalanced force took effect?

The delay to which you are now referring is propagation delay, and it decreases as the medium density increases. The physical delay at the pratically applied frequencies, from the center to edge of a midrange, for example, is not of a degree that is perceptually relevant within the context of hearing an actual delay. The resonances in a transducer diaphragm are classified as non-delayed resonances. The important issue[aspect] is the non-linear behaviour of the medium on propogation vs. different freqencies[causing resonances], when it becomes non-pistonic, and the result is frequency response anomolies[resonances]. But even these, due to the small scale of physical delay through the solid medium, can be corrected with corrective filters[for example a notch filter that is the inverse of a modal peak applied to the input signal of the transducer. The limitation of the amount of correction that can be performed is one of practical application: every filter adds cost/bulk to a physical crossover circuit, or alternatively requires additional processing power[in a DSP based system]].

-Chris

 

[Sleestack]

The one misconception that I see thrown around here all the time is that all CD players sound the same. While I haven't been able to detect the differences using digital outs on a cheap v. expensive player, analog ouput stages on various players make a significant difference. I don't think it matters if your interest is primarily HT, but if you are a 2 channel nut like me, a good CD player makes all the difference.

 

[mtrycrafts]

Silver is better than copper

Well, it is more expensive It is used in flatware where as copper is not
Has less resistance

 

[mulester7]

Well, it is more expensive It is used in flatware where as copper is not
Has less resistance

......aaaaaaaaaaaaaaand....no corrosion.....

 

[Buckle-meister]

......aaaaaaaaaaaaaaand....no corrosion.....

Not true. Silver does oxidise if left out in the open. It will do so fairly quickly too; especially so in a moist atmosphere.

Regards

 

[jaxvon]

But, Silver Oxide is still highly conductive, wheras copper oxide is not.

 

[Buckle-meister]

But, Silver Oxide is still highly conductive, wheras copper oxide is not.

I have no problem with this, but how are cables with silver content manufactured? I wouldn't have thought they were plated.

Regards

 

[mtrycrafts]

I have no problem with this, but how are cables with silver content manufactured? I wouldn't have thought they were plated.

Regards

Some are plated, others are pure.

 

[tbewick]

Here is the trace I referred to earlier when talking about differences in the ability of a loudspeaker to preserve timing. It is taken from 'Practical Hi-Fi Sound', page 139, by Rodger Discoll (c) 1980, published by The Hamlyn Publishing Group Limited.

John S,

I apologise, it was John Watkinson, not Wilkinson, who is the author of 'An Introduction to Digital Audio'.

I've also included a grab from this book, to show a digtal audio system that can suffer from jitter. I know this isn't too helpful by itself, and as such I'd recommend that if you're interested, to read the book in full. There are, no doubt, other books on this subject, but John W wrote what is considered a classic on the subject, 'The Art of Digital Audio'. They might be in later editions by now, seeing as the book I'm reading dates back to 1994.

Image of digital audio system is taken from 'An Introduction to Digital Audio', by John Watkinson, Focal Press, (c) John Watkinson 1994.

 

[WmAx]

Here is the trace I referred to earlier when talking about differences in the ability of a loudspeaker to preserve timing. It is taken from 'Practical Hi-Fi Sound', page 139, by Rodger Discoll (c) 1980, published by The Hamlyn Publishing Group Limited.

Thank you for clearing up what you mean when you refer to "timing". I covered this in my prior responses, as what this image is trying to represent is a design that is not a so called transiet-perfect design. The differences shown in such an image as you present are caused by one or more of the following: driver z axis position in relation to voice-coil center in a multi-way system, non-transiet perfect crossover in a multi-way design, and/or frequency response non-linearity.

As far as existance of jitter, I don't think anyone contends that it does not exist. The issue here is that of audibility.

-Chris

 

[tbewick]

Chris,

The author of the book doesn't get very specific on how jitter will sound, but does say that it is audible. It is of course possible to test for jitter by experiment, which involves sending two different tones through the DAC and seeing if the noise floor changes with each tone. If it does, jitter is an issue.

I don't know how audible jitter is in normal listening. The author just says that it is audible. There are, no doubt, published papers on jitter and on how audible it is.

I did find it useful to find out that an external DAC that is well designed with clock loops (or something like that) should be unaffected by the choice of interconnect used (to connect it to the digital out of the CD player). In fact, it says that poorly designed external DAC's, (with jitter) can sound worse than the internal DAC of the CD player.

There are meant to be other failings of DAC/ADC designs, other than jitter, which affect performance.

 

[WmAx]

There are, no doubt, published papers on jitter and on how audible it is.

There is exactly one semi-credible paper on jitter audibility[with actual perception tests to back it up] of which I am aware. I say 'semi-credible' because it was not a full double-blinded test protocol, but it is the only one ever carried out that attempted to actually use some degree of control, versus the myriad of other articles that do nothing more than use either a sighted test or speculate[or both]:

Theoretical and Audible Effects of Jitter on Digital Audio Quality
Benjamin, Eric; Gannon, Benjamin[Dolby Labs]
AES Preprint: 4826

Here are some images of the perceptual data graphs:

http://www.linaeum.com/images/dolby_jitter.jpg

The values found to be audible by the most sensative test subject on the most sensitive music[using sections of music with prolonged tones/sustains, as the normal parts of music masked the distortion significantly] was about 20 nanoseconds. Note 1: these tests were carried out on monitor headphones which further increase sensitivity to distortion. Note 2: The jitter error of typical DACs does not leave the picosecond range.

-Chris

 

[mulester7]

Not true. Silver does oxidise if left out in the open. It will do so fairly quickly too; especially so in a moist atmosphere.

Regards

.....aaaaaaaaaaaaaaaaaaaaaand....LESS corrosion, haha....

.....we'll put on the gloves taking it further by the way, and you think an old fart can't bob-and-weave???.....

.....hey, Buckle-Meister, you've got silver speaker-wire running to your pool speakers???....wow, you've got an income, huh?......

.....(feel free to disregard most of the above)......

 

[Buckle-meister]

Ask Not, Get Not, Apply Honor.

Ask, Get Not, Lost honour (English English spelling ) by asking.

Hey, if we're going to spar, might as well go for the jugular.

Regards