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213.7.121.14
can someone please explain what this means in reality?
''Zero Jitter Mode* The Zero Jitter Mode utilises AMR's ingenious Global Master Timing (GMT)* and Intelligent Memory System (IMS) to totally eliminate jitter coming from the source. The Global Master Timing clock system intelligently actualises over 28 million different real-time clock frequencies to exactly match the dynamic input clock down to 0.001Hz (i.e. ~0.04ppm accuracy) of the source. With this new and completely jitterless clock coupled to the Intelligent Memory System (IMS), the GMT/IMS system lock out source jitter once and for all.''
Follow Ups:
Fred,Thank you for continuing to help advertising our products. Do send the bill to the usual address, will you?
For the rest, to quote Charles Lutwidge Dodgson:
"The method employed I would gladly explain,
While I have it so clear in my head,
If I had but the time and you had but the brain-
But much yet remains to be said."I will however try it like this, which you should be able to get.
If you have 20 pence left in your pocket your purchasing power in Pounds for any practical purpose is zero, though in a technical sense you have 0.20 Pound remaining in your pocket. Well, OK, you can probably get some chewing gum for that.
The use of Zero in that case is the first, not the latter. Otherwise it would have read 0.000 Jitter Technology.
And yes, there is some very small amount of jitter remaining, it is just ruddy hard to measure in the audio output. I have been just last week testing the jitter performance of an upcoming (more budget oriented) product that incorporates the same technology.
I tested jitter using the AP2 and sending 48K/24Bit SPDIF signal with the AP2's jitter generation set to a 200Hz squarewave with around 50nS (yes, that is 50nS of 200Hz jitter added to the SPDIF signal). What I get is the noise-floor of DAC and Analogue stage, given the levels of these, we may conclude that the remaining is below around 316 femto-seconds rms, how much below, I cannot measure, the DAC is too noisy.
You should try this kind of measurements one day on your gear. How good does it manage to suppress massive amounts of jitter from a jittery source? Can be very illuminating.
So, what we have implemented with Zero Jitter is like Ronseal (for any non UK residents check the video link) .
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 03/16/14 03/17/14 03/17/14 03/17/14
to the nonsense from your hand?Go to the Anedio website and you will find an honest attempt to explain what they do in their range of hardware, with jitter measurements and an attempt to interpret correctly AP readings.
Edits: 03/17/14
The Abbingdon Music Research marketing people's pants are on fire, not yours. I found your Technical Papers 1 - 5 entirely acceptable. I presume production units reflect the excellence of your design.
If you like this free advertising, you can send a bitcoin donation to the address: 1KnWraym5tHCPHRAPh9uhKZpXpDTbved7t :-)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Tony,
I think for marketing their use of Zero is entirely appropriate and consistent with current practice.
The use of "Zero" for something meaning "very low" is common (e.g. Coke Zero Soda, ArticZero Icecream, "Zero Emission" anything etc.).
So the only pants on fire belong to someone who goes out of his way to stir up trouble and negativity over what amounts to common practice.
BTW, if you read the paper closely, it only claims "zero source jitter", not "absolute zero".
Alas, I am not "into" bitcoin yet, but let me see what can be done.
"They sought it with thimbles, they sought it with care;
They pursued it with forks and hope;
They threatened its life with a railway-share;
They charmed it with smiles and soap"
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
For me, zero means zero. My training is in mathematics and that starts out with the integers. :-) I would take a capitalized phrase as a trademark, as in "Coke Zero Soda." For this reason, I did not take exception to the phrase "Zero Jitter Mode". Here the term can easily be taken to be a name that reflects a design goal and it would be foolish for a purchaser to take this as a assertion that this goal was met. (But IANAL and nor familiar with the draconian U.K. advertising rules.)
The phrase that I take exception to is in fmak's original quote: "With this new and completely jitterless clock" Specifically, I take exception with the use of the word "completely" as this is physically not possible. "Totally eliminating jitter from the source" may be a bit of an exaggeration, but there is enough ambiguity in the phrase "from the source" to pass on this. Your white paper used the phrase, "zero source jitter" and this is also okay for the same reason.
I did a four year stint in the 1970's as the product manager for a line of computer data communications devices and got to write product requirements, user manuals, marketing brochures and white papers. I took great care in my selection of wording, so that my pants would never get more than slightly warm. :-)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Integers only exist in your imagination. There always are measurement errors...+ something else (?).
Observe, before you think. Think before you open your yap. Act on the basis of experience.
"God made the integers; all else is the work of man."
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Coca-Cola Zero's nutritional information reads: 0 Calories, 0g Fat, 0g Total Carbs, 0g Protein , 70mg Sodium.
And a good helping of brain rotting chemicals.
I'd like to see a diseased brain on the side of the can - like the folks on cigarette cartons.
And a big ole hippo on regular soda cans and candy bars. "This is you if you eat/drink this stuff"
McDonald's big M should stand for MOOOOOOOOOO!
And a good helping of brain rotting chemicals.
And exactly which would those be? The list of ingredients is not hidden.
Aspartame gets a lot of bad press - possibly deserved possibly unfairly vilified. The trouble is separating fact from fiction - not automatically trusting whatever the government (and especially any company) tells you but also not landing in the world of conspiracy theory.
Real Science says it's safe http://www.realclearscience.com/articles/2013/04/12/artificial_sweetener_aspartame_isnt_bad_for_you_106508.html
Although it is important to note that a given substance may be safe in itself may not be when mixed with something else - Gun is safe - gun in crazy person's hand is not.
I think it's fair to say that if company A puts out a product like cigarettes - the goal of this product is to get people addicted to the product and keep buying it. If people get sick and get cancer then that's the taxpayer or government or individual who have to pick up the medical costs. Ciggy companies bury lawsuits in the legal system.
The company makes money. I think whether conservative or Liberal people can generally agree that big business is about making themselves bigger (financially) and we see history littered with companies who choose profits over people. Car companies for example that knew they could spend $2 a car to fix a fatal flaw but chose instead to pay out lawsuits because it was cheaper to the bottom line. Profit over people every time - and those cars passed whatever crummy government inspections that existed or still exist.
With lobbying and the financial clout of business they can direct all sorts of policy and bypass safety standards - and in countries that hate paying tax they usually skimp on government checks and rely on companies to self regulate - which is laughable because they will choose profits over safety.
This doesn't necessarily mean ingredients are toxic but putting profit above personal safety is not exactly something new. And swamping the safety concerns in a sea of vague attacks on science is nothing new.
Pay off a few scientists to come out against an issue can cloud the issue for most people enough for them to "doubt" the established scientific community. In other words if you buy off 2% of scientists to say the rest of the science community is wrong and you find a couple of grains of truth then it's enough to question the "Theory" and create doubt. Similar to the Theory of Evolution which is proven to the same degree that gravity is proven but not absolute. It opens the door to have completely baseless views like I.D. be viewed as a 50-50 proposition.
Take these examples on Diet Soda:
"11-year-long Harvard Medical School study of more than 3,000 women, researchers found that diet cola is associated with a two-fold increased risk for kidney decline. Kidney function started declining when women drank more than two sodas a day. Even more interesting: Since kidney decline was not associated with sugar-sweetened sodas, researchers suspect that the diet sweeteners are responsible."
"2008 University of Minnesota study of almost 10,000 adults, even just one diet soda a day is linked to a 34% higher risk of metabolic syndrome, the group of symptoms including belly fat and high cholesterol that puts you at risk for heart disease."
"A University of Texas Health Science Center study found that the more diet sodas a person drank, the greater their risk of becoming overweight. Downing just two or more cans a day increased waistlines by 500%. Why? Artificial sweeteners can disrupt the body's natural ability to regulate calorie intake based on the sweetness of foods, suggested an animal study from Purdue University. That means people who consume diet foods might be more likely to overeat, because your body is being tricked into thinking it's eating sugar, and you crave more."
"In a study of 59,334 pregnant women in Denmark, 1 serving per day of diet drinks was associated with a 38% increased risk of preterm delivery. 4 servings per day increased the risk by 78%"
"Cocktails made with diet soda get you drunker, faster, according to a study out of the Royal Adelaide Hospital in Australia. That's because sugar-free mixers allow liquor to enter your bloodstream much quicker than those with sugar, leaving you with a bigger buzz."
"Diet sodas contain something many regular sodas don't: mold inhibitors. They go by the names sodium benzoate or potassium benzoate, and they're in nearly all diet sodas. But many regular sodas, such as Coke and Pepsi, don't contain this preservative.
That's bad news for diet drinkers. "These chemicals have the ability to cause severe damage to DNA in the mitochondria to the point that they totally inactivate it--they knock it out altogether," Peter Piper, a professor of molecular biology and biotechnology at the University of Sheffield in the U.K., told a British newspaper in 1999. The preservative has also been linked to hives, asthma, and other allergic conditions, according to the Center for Science in the Public Interest.
Since then, some companies have phased out sodium benzoate. Diet Coke and Diet Pepsi have replaced it with another preservative, potassium benzoate. Both sodium and potassium benzoate were classified by the Food Commission in the UK as mild irritants to the skin, eyes, and mucous membranes."
"With a pH of 3.2, diet soda is very acidic. (As a point of reference, the pH of battery acid is 1. Water is 7.) The acid is what readily dissolves enamel, and just because a soda is diet doesn't make it acid-light. Adults who drink three or more sodas a day have worse dental health, says a University of Michigan analysis of dental checkup data. Soda drinkers had far greater decay, more missing teeth, and more fillings."
"Drinking diet soda can also lead to bone loss. This is because the phosphoric acid in the soda causes calcium in your bloodstream to be excreted more quickly than normal through urine. Your bones then give up some of their calcium in order to keep the bloodstream calcium level constant."
So are the above proven? No because in each case there could be other factors influencing the findings. Is there enough here to say "gee maybe I should consider drinking water or lemon tea or something just in case the above are actually true.
Similar is global warming. There is some disagreement - and there are profit motives on both sides - oil wants to protect selling oil and digging for it. They want to say Global warming is BS - the other side has all these profit ventures selling alternative energy so they could, I suppose, be inventing a fictitious problem to sell their goods.
So like an audio reviewer - I'd like to find individual trustworthy scientists and in numbers and then I can be better able to support one side or the other.
If I arrive at an "I don't know" or the "Science may be right or wrong" then I look at the logical outcomes of supporting either stance. Something like this science teacher did with Climate Change"
I lived in China - it is advisable to use alternate energy just for living in a clean air environment even if the anti-science crowd thinks pollution doesn't kill people or affect climate change - it should be changed just for how it looks.
"Considering results from the large number of studies on aspartame's safety, including five previously conducted negative chronic carcinogenicity studies, a recently reported large epidemiology study with negative associations between the use of aspartame and the occurrence of tumors, and negative findings from a series of three transgenic mouse assays, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food. "
The FDA on aspartame
The link is a 2007 FDA knock down of a poorly done study relating aspartame to cancer in rats.
2011-2013 (There are other ingredients in there not just aspartame) - This is about diet pop not aspartame itself.
Two-fold increased risk for kidney decline (Harvard) - I mean if Harvard med is wrong then the best University in your country may as well just close for being incompetent boobs.
Then again Harvard is overrated as I studied under a Harvard professor and I asked him "I guess this A- would be a C at Harvard" and he replied "No at Harvard it would be an A+" I had that confirmed years later with a Harvard Grad who got a B on an assignment and she said "so in other words I failed." The reasons are interesting but off topic.
University of Minnesota study -- just one diet soda a day is linked to a 34% higher risk of metabolic syndrome.
"Artificial sweeteners can disrupt the body's natural ability to regulate calorie intake based on the sweetness of foods, suggested an animal study from (Purdue University)"
It's great if Diet Soda doesn't cause cancer - but cancer isn't the only thing that can kill you.
I'm not taken to worrying about having "all my precious bodily fluids sapped and impurified". :)
There are other ingredients in there not just aspartame
I'll ask the question again:
And exactly which would those {*brain rotting chemicals*} be?
Edits: 03/20/14
Is there a reason you rely 100% on what the FDA says in 2007 but not what Harvard says in 2011?
Do you think the US Food and Drug Administration chartered to "Protecting and Promoting Your Health" doesn't continually review credible claims as they come along?
Sorry, I just don't share your paranoia. :)
Start with this article.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Some of the claims in that link seem very far fetched, however. I won't touch the stuff. I decided on the available evidence that Aspartame is something that is very likely unhealthy and that I should not consume it.
Dave
I don't hear the Black Helicopters circling.
That is because they are the secret invisible silent helicopters.
Just kidding! I couldn't help myself!
Dave
The black helicopters are attacking!!! My security software lists the linked page as an "attack page". :-(
Stay healthy. You are on the right track. :-)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"Considering results from the large number of studies on aspartame's safety, including five previously conducted negative chronic carcinogenicity studies, a recently reported large epidemiology study with negative associations between the use of aspartame and the occurrence of tumors, and negative findings from a series of three transgenic mouse assays, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food."
This is all BS. The use of statistics where results are done at the typical 5% level is subject to all kinds of selection problems. There is an obvious economic motive to do this selection. Real science, e.g. physics, uses statistics properly (e.g. 5 and 6 sigma) and even then runs into the occasional problem of screw ups (e.g. CERN "faster than light" neutrinos, but these results didn't survive peer review).
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Sorry, but I'm not finding the source of your assumptions.
If you followed the link, it relates to their review of the European study. FDA's own studies date back twenty years and are quite numerous.
I haven't read, nor am I going to read, government statistical studies. The phrase "government statistics" is itself an oxymoron where regulatory agencies are involved. Any intelligent person understands that regulatory agencies are captured by the industries they are regulating.
As I said, I tried aspartame. It didn't work and it made me ill. That's good enough for me.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I haven't read, nor am I going to read, government statistical studies.
I guess there's nothing to discuss. :)
"Coca-Cola Zero's nutritional information reads: 0 Calories, 0g Fat, 0g Total Carbs, 0g Protein, 70mg Sodium."
This is compelled speech. One has to read the FDA regulations to interpret these numbers. No doubt there will be a standard somewhere for measurement accuracy.
In the food business, companies take these regulations quite seriously. A friend used to be the plant manager of a potato chip company before he retired. They had a machine that measured the quantity of potato chips going into each package. This machine was cleverly designed to ensure that package contents were never below the labeled amount. By using highly accurate scales they were able to set a low threshold of extra weight. The machine used a clever mechanism that allowed for the excess weight to be far less than the weight of a single chip. My friend said that the machine had cost $250K and paid for itself in material savings in months.
Not so much in high end audio...
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Tony,
Reading it now, I need to have a word with our marketing people, I think someone got carried away a trifle. Anyway, revising this gives us a chance to claim"Femto-Clock" status instead, which is ever somuch more fashionable these days.
I do proof read things, but some stuff gets through. Remember, the marketing people are paid to hype things...
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
first you try to gloss over things; then you eat humble pie.
fmak,I believe that the marketing copy refers to a clock recovery technique based around an NCO (numerically controlled oscillator), rather than around the usual analog VCXO. An NCO can track a wider input range than can an VCXO, yet still generate a frequency locked, low jitter local clock. The NCO frequency can be adjusted in very fine steps so to closely match the remote source's clock frequency, enabling a quasi-free running of the NCO.
Because the source clock's long term frequency average must be followed to account for drift, there still can be some jitter transfer if the NCO frequency requires subsequent adjusting, but such jitter would be at very low frequency. So, yes, there still will be some intrinsic jitter stemming from the NCO circuitry itself, and also possibly some very low frequency jitter transferred from the remote source's clock, depending on that remote clock's long term frequency stability. Not exactly zero jitter, but if properly implemented, can perform very well on reducing both intrinsic and transferred jitter.
_
Ken Newton
Edits: 03/16/14
As Thorsten has explained, once the computer and DAC have warmed up it is unlikely that any adjustments to the DAC frequency will be necessary during a listening session. Apparently the DAC will flash an indicator whenever this happens. The steps are small enough that they won't result in much of an audible glitch. (If they happen to fall in a silent portion of the music or near a zero crossing in the waveform they will almost certainly be completely inaudible.)
The technical challenges here are primarily:
1. the cost and jitter capability of the frequency synthesizer
2. the algorithm to figure out when/what steps to take, which is not something that can be done a priori as it requires some experience with the drift properties of crystal oscillators. There is also a tradeoff between buffer size (cost and latency) vs. number of transitions and this constrains the problem somewhat. There is also a question of possible phase glitches in the synthesizer at the time it's output frequency is changed. The details would depend on the internal design of the synthesizer.
In the past these synthesis devices haven't been good enough for high quality audio, but perhaps this has changed.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
but of course things'numerical' on a chip perhaps carries its own problems?
Do you have links to actual hardware?
Not sure what you mean by, "links to actual hardware".
_
Ken Newton
description of how and where this has been used. DDS, of course, has been round for a while and hasn't been the great white hope in digital audio.
Google is your friend :)
_
Ken Newton
leaves me no wiser on the posted text on the player, nor presumably anyone else.
Well, that would figure, since I don't know what's inside AMR's player. I only wrote what it sounded like AMR may have inside based on their marketing copy.No, I'm not going to take the time and effort necessary to teach you about NCOs, nor lead you to proof that they actually exist, can perform well, and are widely utilized. If, for some reason, you doubt those facts, then you can easily research them for yourself via Google.
_
Ken Newton
Edits: 03/18/14 03/18/14 03/18/14
actually it sounded like nothing. I am familiar with numerical methods, having used them extensively in computer modelling.
I feel that our exchange is on the verge of degenerating, so, you can have the last word.
_
Ken Newton
Edits: 03/18/14 03/18/14
Maybe you or someone else can point us to some specific technical papers on NCOs that describe various methods of implementation and include models and formulas describing and quantifying the jitter these generate. Without this basic knowledge one is in no position to evaluate manufacturer's specifications except by purchasing products and testing them, something that I'm in no position to do. Worse, without this knowledge one may not even be able to think of appropriate tests. (I do know some ways of implementing NCOs, but all the one's I've looked at wouldn't meet my standards of what is needed for high quality audio or are absurdly expensive, as with zillions of crystals.)
Note: I am not interested in manufacturer's spec sheets or technical white papers. I've looked at some of these and, like most spec sheets show specific information calculated to make the devices look good, e.g. numbers of "typical" devices (no guarantee as to the one you have) or RMS averages (no good description of how averaging was done or what the actual worst case behavior might be).
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
http://analogictips.com/using-ad9850-direct-digital-synthesis-dds-ic/
not very impressive since the assumptions in programming the chip are all important
These chips output both analog (sine and cosine) waveforms and digital clock pulses. The analog waveforms are used for software controlled radios, while the digital output is the one that we are concerned with for digital audio applications.Looking at the spikes, I would think the true harmonics wouldn't matter after conversion to digital since they will be synchronized with the fundamental frequency and hence would affect the transition times of all transitions equally. This statement does not apply to the bogus 4th harmonic in the plot. It looks like some kind of aliasing. This could be bad because this can cause periodic jitter and the pattern of this could vary as a function of the synthesized jitter. This could cause people to hear different sound as a function of transport clock frequency.
It seems like digital synthesizers can be made to work very well if the synthesizer DAC uses analog circuitry (including its own DAC) that works sufficiently better than the audio DAC that is actually clocking the audio. This seems like a serious fail to me, not only in cost, but if one can build a better DAC one should just use it for audio in the first place. If the two DACs are equal in performance then it appears like there will be more jitter noise in the audio output compared to just using a fixed reference clock and ditching all the DDS machinery. Here the problem is the noise floor in the analog signal that results in the digital clock. Any noise here appears as jitter in the output audio when the audio DAC uses the jittery clock.
Having built some software generated audio clocks (square waves) I am aware of the various artifacts these devices can produce. The ones that I built suffered from different tone quality due to varying aliases with different synthesized frequencies. This was a hard fail for me, as I was interested in human musical pitch perception at the time, i.e. how different tuning systems for keyboard instruments sound. I was generating square waves, as this was all I could do at the time (early 80's) using software in an Apple II. Eventually, I coded up a generator that produced synthesized square waves at a sampling rate of 1 MHz. At this point the aliases were sufficiently low level that performance was adequate for my purposes. (If you are wondering how one can generate samples and play them at the computer's clock rate when a single instruction uses several clock cycles, that's a different story.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Edits: 03/19/14
a look at the waveform in the link that I provided.
Edits: 03/19/14
I missed the link in your earlier post because it wasn't hot.Thanks for pointing out my omission.
From looking at the waveform (not very accurate) one can see that a clock edge triggered on the rising edge might be reasonably consistent, but one triggered on the falling edge would vary from cycle to cycle, probably producing significant deterministic jitter. It is likely that this jitter pattern will be very different when synthesizing different frequencies. Hence the sound of a DAC clocked by this DDS will be dependent on the average frequency of the input clock. This means that the same DAC might sound significantly different, even when being driven by two essentially perfect transports that differed only in their average clock frequency. From a sonic perspective a straight reclocker would be preferable with a big buffer so that one could play for a long time without overflowing the buffer, thereby avoiding all this dodgy unanalyzable mixed signal circuitry.
Having any of this non-linear interaction between the transport and the DAC creates a situation where audio performance is unlikely to be adequately predictable, as it will vary from unit to unit. None of this nonsense is necessary since there is no need for any kind of adaptive master clock in the DAC in the first place.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Howdy
Chase down the patents... I used to work with John Melanson before he went to Cirrus Logic. I think some of his patents might have the kind of detail you are interested in. I noticed that he has more than 100 of them, but looking for DDS and/or sigma delta might narrow them down.
When I tested them next to a high quality crystal they fared fairly well. I suspect that since their jitter error is fairly white that their errors aren't as audible as they might appear from the numbers. I'd use them in a lower cost DAC.
-Ted
I'll have to look some more details on DDS circuitry. The patent that I read was mostly about the complete system and didn't contain much information on the specific DDS circuit. What it said pretty much matched my model of how such a device might work, except for some additional detail of the DS DAC used to generate the quadrature synthesized waveforms. (Which I didn't understand, in that no one really understands DS modulators, or at least if they do they aren't talking... )
Thanks for your help. Incidentally, I would be curious to see how your DAC sounds when playing PCM files converted in the computer to DSD128 by various programs such as HQPlayer, vs. how the same files sound when the native PCM is converted by your FPGA. Perhaps some of the reviewers can conduct these listening tests.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Thanks. It looks like US 7,557,661 is probably the one. Printing it out now.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
that DDS hardware I have come across and used (2 clocks) are not any better than others.
Having said that, there is also a claim that relatively high phase noise fundamental SAW chips make better clocks!
I think these claims are misguided at best, and that the "improvement" is likely to be a preference for masking noise that hides some more objectionable distortion. However, there are systems where the addition of noise actually improves operation according to theory, measurement and listening. Details matter. Issues involving clocking can be quite difficult.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Were I a commercial DAC vendor, I would implement an NCO if my main jitter related concern were the rejection of transferred jitter, over having the absolutly lowest intrinsic phase noise local oscillator. This is simply because an NCO can be very closely 'tuned' to track the remote clock source's frequency over a very wide range. Sort of like an VCXO, but with an impossibly wide pulling range.Interestingly, Naim appears to have been seeking both the lowest intrinsic and the lowest transferred jitter when they designed their DAC. So, instead of a pullable VCXO, or a programmable NCO, Naim utilizes a series of individual XOs that are tuned to slightly different frequencies. One of these XOs will likely be close enough to the source clock's frequency, and so can be dynamically selected to serve as the local oscillator. Of course, there are practical limits to how many individual XOs are available. At some point, there won't be an close enough frequency match available, whereas an single NCO can be tuned to closely match a great range of remote source clock frequencies.
_
Ken Newton
Edits: 03/19/14 03/19/14 03/19/14 03/19/14 03/19/14 03/19/14 03/19/14
Yes, it was the Naim approach that I had in mind when I mentioned "an absurd number of crystals". With only a few crystals then one will have to have a huge buffer, with resulting limits on responsiveness to user play controls (and suitability for live recording applications) and length glitch free playback.
None of this complexity is necessary if the DAC just outputs a clock that the transport can accept. The problem is that none of the consumer standards except async USB address this issue, making the proper solution impossible to obtain in a standardized plug and play fashion except via USB. IMO USB is not a very good system to have anywhere close to the mixed signal circuitry in a DAC and so this adds substantial costs to a high quality DAC to achieve the needed isolation.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
It's not a question of noise but a question of the harmonics generated. Some chips are fundamental whilst others are 3rd harmonic. Rig up a FFT (I did this sometime ago with the Tent Clock) and one sees that odd order harmonics are quite strong and there does not seem to be a suppression scheme. It has been claimed that the Crystek low phase noise chip is not as good sounding as a SAW chip (hifiduino and Epson or Citizen).
frankly who cares. Listen and decide.Plenty of people really like Audio Note CD players and find them to be "musically correct" and their jitter - well they don't even attempt to reduce jitter. UHF magazine a long while back measured it and noted that the jitter was very high but the distortion was so high it swamped the jitter figures anyway - they also liked it better than their reference CD player - and that was Audio Note's entry level no longer in production model (chortle).
So if a device with massive jitter and distortion can sound THAT good (Art Dudley called the 4.1 one of the two best CD players he's heard (and the other was nearly double the price) and Engineer (founder of Monitor Audio and brought into court cases to resolve audio disputes) Martin Colloms said their DAC is the best sounding digital converter (from either computer or CD) available ranking it at least twice as good as the next closest sounding digital device and again very high THD and no jitter correction then I question the entire validity of "reducing jitter" as being better.
If the best sounding device does the jitterbug then perhaps the rest of the industry is focusing on this aspect is heading down the wrong path. Probably because it's CHEAP. Like adding mega pixels instead of using a quality lens/sensor.
I wish to keep an open mind - if I had a list of say 5 ultra low jitter - considered "elite" CD player/DACs to try I would try to bring one or more of them in. Until then, I'll probably buy an Audio Note DAC 3.1 and be done with computer audio/CD replay for a long time.
Buy the thing that resembles music whether it has .0000005%THD and .00000001% jitter or 5% THD and is a coffee addicted jitter case.
Edits: 03/16/14
I think jitter reduction in playback products would be a big deal only if the jitter during A/D were also infinitesimally low....
I also think preserving the jitter signature of the recording yields better sonic results than trying to eliminate it.
"Plenty of people really like Audio Note CD players and find them to be "musically correct" and their jitter - well they don't even attempt to reduce jitter."
Some people like their music colored in certain ways, whether by the recording process (e.g. softening by passing through magnetic tape) or in the playback chain (e.g. euphonic second harmonic distortion by SET amplifiers). Others prefer a cleaner signal path. Horses for Courses.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I suppose it's comforting to fall back into believing that people are deluded by distortion artifacts when they see the measurements. Too many good ears unfortunately to pass it off as just euphonic distortion.
Then again euphonic means pleasing - and we can;t possibly have any of that in our stereo systems now can we. We must have brutally accurate, not the least bit pleasing and completely banal - let me get my credit card.
One can demonstrate the euphonic effects of second harmonic distortion by deliberately adding it. This can isolate the effect of this distortion from artifacts of amplifier design. A similar test can be done by inducing jitter, but this is much harder to do since jitter is a complicated phenomenon. Other possible "improvements" include deliberately adding noise to the signal for its masking effects. (This is not to be confused with proper use of noise as part of dithering, which is a recording process.) Experiments can be done to sort out these individual psychoacoustic effects.
I might consider an SET system if someone can show that it is possible to produce undistorted peak SPL of 115 dB without using colored transducers such as horns. I listen to Mahler symphonies. SETs would probably be fine if I confined my listening to solo guitar and harpsichord. By the way, I find the vast amount of my music collection to be pleasing and many recordings sound quite realistic. Only a minority of recordings are brutally ugly or banal, and reflect mistakes in my purchase decisions. It is usually possible to weed out poor music or performances on download purchases from sites that allow listening to a good selection of sound clips.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
RE DACs
Art Dudley has a preference for tubes (Shindo Labs - which you've probably never bothered to try for yourself) so I can somewhat understand a preference for a valve CD player.I brought up Martin Colloms because he designs or attempts to design Accurate speakers and is published on them. Looking at his system of top of the line Krell and top of the line Wilson Martin is not a "tube guy" or a "I love distortion guy". He ran the AN CD player with his SS and "accurate attempts" loudspeakers. Art's view is somewhat expected, Martin would be in the objective "if it measures better it should be better" camp. But unlike some he actually bothers to test the stuff before opining on it.
The second and curiously irrelevant attack on SET amps seems strange. SET amplifiers, unlike most SS amplifiers, have a direct correlation of distortion (any distortion) with level.At low level SET amplifiers (and class T for that matter) have very low distortion - when pushed to their limit (beyond their limit) is where they distort - and the distortion is second harmonic. So umm if you don't push them to their limit there is no 2nd harmonic distortion. Therefore, any claims for a preference of SET amplifiers is NOT due to any distortion artifacts because the vast majority of SET owners use speakers that never need to use more than about 10-15% of the amplifier's power. Sure when driven to the max a SET will exhibit soft mushy nice sounding distortion but it is only nice sounding in comparison to SS which goes poppity pop pop and hopefully not taking the tweeter out.
Most SS amplifiers work exactly the opposite way - at 80-100% of their maximum level they have their lowest distortion characteristics - when reduced down to where most people listen is where they exhibit their highest distortion (which of course is never measured cause it doesn't look pretty and won't help them sell).
Amplifiers that are class A/B and operate up to say 5 watts in A and switch to B which is where most even good ones operate will be shifting between A and B constantly. Class A the music plays at 3 watts and everything is fine but the bass at 40hz and treble at 3khz hits a peak due to an impedance drop - the amp has to come up with 10-15 watts and yup there is the switch to class B and then the transient drop and the amp shifts to class A - oops then a drum - amp has to switch back to B - Switch switch switch switch - fluorescent light bulb syndrome. There are good and bad variations of them but none of them are natural light.
Notch distortion occurring continuously with virtually every album all the time. Notch distortion (crossover distortion) is audible and fatiguing and constantly on display with all A/B amplifiers.
Getting a true sense of distortion measurements of any amplifier using feedback is pointless as distortion is not measured "before" the feedback loop is engaged.
SET is a side issue. Why is it that people think they can trot out the old Horns Suck, I listen to Mahler at 115dB as if that's SS for the win?
I have heard tons of systems than can do massive scale at massive levels that truly suck donkey balls on female vocals at low levels. Yes system A may do massive scale and symphony better but they often get simple girl/piano wrong and most people most of the time listen to smaller scale stuff and "occasionally" listen at 115dB to big music. Indeed, I auditioned Avantegarde speaker in Hong Kong and it does massive quite well but was unlistenable with Eva Cassidy.
And there are a lot of other speakers besides horns that can easily be driven with SET amplifiers - and there are, like anything else, good and bad examples of SET amplifiers and a variety of power levels that will drive most speakers quite well including suicide inducing stuff like Mahler.
Lastly, people tend to move FROM solid state amplifiers to tubes to SET. People don't start with the likes of Audio Note CD players - they typically end up there or with something like it AFTER they owned Bryston/Krell.
And while I agree that most of the horns I have heard are tough to take - you need to get out more and listen to some of the good ones properly set-up with appropriate gear. There is more to the world than Klipsch and Altec and Avantgarde. But there are speakers like the Teresonic Ingenium with over 100dB sensitivity if one just can't do a typical horn. There are also speakers like the AN E and DeVore Orangutan - add a sub if you must.
Edits: 03/17/14 03/17/14
When it comes to most of these sonic arguments I often wonder why people gravitate to one thing or the other.
The prices of good audio equipment has dropped. Yes the best costs money but today's affordable stuff is quite doable for audiophiles. So why not have our cake and eat it?
One is not limited to one CD player or one DAC or one kind of amplifier. As a reviewer I am trying to buy a SS based stereo systems as well as a valve based one. I would also like a variety of speakers on hand to compare. But anyone can do that.
Fred Crowder on our staff owns some big Acapella Triolon speakers and directly compared $60,000 SS power amps (arguably some of the best SS in the business from Pass Labs) VS 300B SET power amps. One does some things better the other does some things better.
But heading on down to those of us on meager finances you can get a pretty good 300B SET amplifier from the likes of Audio Note for about $2200. Kit One.
You can then go out and buy a second hand Rotel RB 1090 (1KW into 1ohm) ($2000 new in 2006) weighing in at 100lbs or perhaps a Parasound A21 power amp.
Or newer and cheaper Emotiva XPR-2 which pumps out 1000 watts at 4ohms
And hey to many if its distortion is below the threshold of human hearing JND then they all sound the same so for $1799 it will drive anything and the measurements indicate no one can tell it apart from any more expensive exotic name brands. (measurements is all that matters in the world of SS since no one can hear the difference in controlled level matched tests).
Assuming Emotiva is reliable then here you go - Mahler is covered with pretty much any speaker
Now you have your "precious pretty" SET amplifier as well as your slam your "slam bang" amplifier and you're under $5k for both and at nearly the flip of a switch. Best of all you have a back-up amp should one of the two ever fail.
Check out this power amp!
I have no interest in filling up my limited living space with redudent components. I can deal with an old system and its replacement, but not various mix and match components. Also, having many choices means that I can't just listen to music without first finding some components that make a recording sound good. IMO the result of this approach is constant fiddling and worrying about the technology, rather than just enjoying the music. I also use my system for remastering old analog recordings and without a constant reference of how these recordings sound vs. the range of recordings on the marketplace I have no good way of positioning the sound of these recordings in such a way that they stand a chance of sounding good on a variety of systems. Here the problem is the same as just listening: one's mental confusion about the system leaves little space "in one's head" to think about important things. Similar arguments pretty much cover tube equipment that drifts, has to be rebiased periodically, tube rolling, or many other things associated with retro audio technology. Just IMO, as I realize that some people like to fiddle with equipment. I don't. I like to listen to music or make (i.e. fiddle) with recordings.
Measurements can work when a complete set has been developed that adequately covers the known and unknown aspects of a given technology's limitations and the known and unknown aspects of psycho-acoustics. They are a useful tool for dealing with known factors, but usually useless for dealing with unknown factors. After some of these unknowns become known then it is possible to come up with new measurements that can capture this new knowledge, but this may take years or even decades. The general rule is that new technology creates new unknowns with new distortions that can be heard but not captured by existing measurements. Later, one understands these new distortions and how to measure them as well as how to relate these measurements to what some people can hear. Still later one may get products that sound better than the old technology. Still later, if we're lucky, manufacturers' spec sheets and reviewer's product reviews include these new measurements. In this paragraph the key words are "unknown" and "lucky".
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I dunno but it seems to me a lot of computer audio guys keep fiddling with bitrates - checking which level is right and spending copious amounts of time agonizing over whether it should be DSD/DXD/PCM whether to get the SACD or 24/96 or 24/192 or 32/384.
Not sure why two amps would cause much fiddling and SET amplifiers from Audio Note are all self biasing. The tube in the AN CD player has a 100,000 hour life expectancy or 11 years 24/7. Their amps will get you 8000 hours before you replace a tube - no biasing plug and play.
I was not born in the tube era or the vinyl era - and I concur - I find biasing and dealing with turntables to be a pain. Perfectly fine reasons not to bother with them.
The bias in my Citation II had to be set by hand. I also had a MAC-275 which was very stable and reliable but it never sounded good because of the class B crossover distortion.
I don't recall having to replace the 12AU7s in my Dynaco PAS-2, but some 12AX7's definitely got noisy. Unfortunately, I had to replace all these Mullards after the FBI confiscated them because I had borrowed them for a suspect purpose. :-)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
No question tube amps are a pain - I can't believe the FBI took your tubes LOL.
I think like SS - tube amps have come a long way over the years. After hearing some of the vintage models - ST70, a few McIntosh amps, ARC, and for that matter several new tube amps I'd probably buy a class A SS amp instead.
It was the same with turntables - everyone saying that $200 second hand duals were better than elite CD players. Nope. They can sound excellent but it seems to cost a significant sum to really impress me and most new LPS are just direct transfers from CD and don't sound any better. Still I have some LPS with CD versions that just suck.
Hence why no own both and play the one where it sounds better - if album A sounds better on vinyl - use turntable - if album B sounds better on CD play the CD.
Fortunately the FBI took only the small tubes that were used in my Blue Box, probably Mullard ECC82's (12AU7). They didn't take any of the tubes in the Citation II, including the 4 Gold Lion KT88's, despite the fact that the amp was being used to drive the phone line. More details in the book that I linked in the earlier post. Also, they didn't take the audio oscillator that was used to generate the 2600 Hz tone, which belonged to the college radio station. We had borrowed it to use it to run my turntable at a variable speed, as needed to dub a recording of Wagner's Siegfried at the correct pitch, as the bootleg recording had been made at the wrong speed. (At the time there was no recording of this opera in the Schwann catelog.) The radio station later broadcast a complete Ring cycle.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"2600"One of my favorite publications! :)
Fond memories of says gone by... Did you actually use your Blue Box?
Edits: 03/20/14
Our group were the first people east of the Mississippi to build a blue box. We thought we were the first in the world, but it turns out that one lone wolf in the Pacific NW had figured out how to build one a year or two before us. The term "blue box" came from the color of the chassis that we built our hardware on, which came from an electronics surplus supply house called Eli's, later acquired by Fry's.
We used our blue box to demonstrate that it worked. We called the weather in Nome, Alaska, etc... We did not use it to cheat ATT out of phone calls that we would conceivably have paid for, nor did we sell any products or services. As it turned out, this was fortunate, because had we done so, then the Deputy Federal District Attorney for Boston would not have told the Boston ATT security head that we had not committed any crime and hence could not be prosecuted. (This letter in files obtained by FOIA by the book's author, with our release.) ATT dropped all civil charges against us as part of a deal we negotiated in return for writing up a detailed report on what we had done, how we had done it, how they should design future networks to be less hackable, and how they could detect fellow blue boxers. When we handed in our report we had to sign a contract and were paid $1.00 for the report and given promises of jobs at Bell Labs after college graduation.
N.B. Were someone to do the same thing today (or otherwise hack any computer) they would be sent up for hard time. A lot of fascist laws have been passed since 1963. No thinking person can continue to claim that the USA is still a free country.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Very cool story. :)
" one lone wolf in the Pacific NW"
John Draper "Captain Crunch"
Yes fun times. Build Blue, Red, and Back boxes also. Lots of fun. Never did anything crazy with them, but they were fun. Old pre digital Telco was interesting with loops, busy signals etc... The good old days.
No, Captain Crunch came later. You have to read the book to learn about the first guy.
Captain Crunch came to visit me at one time during the 1970's. Ron Kessler from the Washington Post who wrote the first articles on us for the Boston Herald, The Wall Street Journal and later Fortune Magazine, had contacted me regarding a story that it was possible to bug any phone in the US by keying in various tones on a random pay phone. I had a brief meeting with John Draper at my home in this regard. Later, I did some digging and asking various people who know (ex Bell Labs people, spooks, etc.) and found out that this could have been done for most phones if someone could have done the appropriate computer hacking. I conducted this research in such a way that the people involved thought it was casual questions and no one of them saw more than a piece of the puzzle so they had no idea what I was up to. I declined to come out of the shadows at that time and told Ron Kessler that I did not want to talk to a Congressional Committee.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"They are a useful tool for dealing with known factors, but usually useless for dealing with unknown factors." (re. measurements)
Tony... In my experience the only way to chase down unknown factors in a system is to first "get a handle on the problem". That means first finding things such as actions, environment or measurements that affect or correlate with it. Ultimately both. That's the view from the trenches anyhow.
So rather than measurements being "useless", they are far more commonly "essential".
Regards, Rick
I didn't say that measurements weren't necessary. I said that they aren't sufficient. Actually, there are some genius tinkerers who can produce working systems without understanding any knowledge of electronics, just cut and try, but these talents are rare.
There are some serious puzzles where measurements don't explain what people hear. One of them is 24 bit PCM files sounding different (to some people on some systems) where the only difference is the addition of 1 lsb to every sample, creating a minute DC offset that is lost in the analog circuitry. Another, which I've experienced, is where a 24 bit sound file was converted to 32 bit floating point and then converted back by adding dither noise at 24 bits, so that many samples got a random addition of +1 or -1 and some rare ones +2 or -2. When I sent back this file a notoriously vocal well heeled audiophile who has his own web forum told me that this file was "completely trashed". Both of these examples can not be explained by known models of human hearing, but they can possibly be explained by artifacts in the playback chain.
A classical example concerns the SABRE chips sigma-delta modulator that was described in a (video) talk at RMAF. Here the measurements looked fabulous, but a few audiophiles heard artifacts. Later these were measured and reduced and the resulting design sounded better.
Most practical engineers work with averages and safety margins. They do not do worst case design. Therefore most all product claims must be taken with a grain of salt, and it's not just a case of dishonesty. As an example, the lead designer of DECs first Ethernet controller came to me with a question of a possible failure mode where random numbers in the backup algorithm would match 16 times in a row and cause a failure. A brief analysis showed that the "chance" of this happening was such that if one million devices were used this would happen less than once in 1000 years. After the engineer left, my fellow employee and I laughed that we didn't trust our probability calculation, but we didn't really worry because the engineer was extremely careful. In three days he came back to us and told us that our calculations had been wrong, because the failure happened in his lab on one network with three devices every few minutes. As it turns out we had a bad model of the frequency distribution of clock oscillators and didn't understand how the Ethernet backup algorithm actually worked, the latter involving an error of at least 21 to the power 12. Later there were some proprietary hardware designs to address correlated clocks and some compatible algorithms to the Ethernet backup algorithms that were the subject of several patents as a result of this amusing escapade.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"Most practical engineers work with averages and safety margins. They do not do worst case design."
Well, often they do, hopefully always. But that just means that unless a part or process is out of tolerance that the product should meet it's specifications. And to improve the odds, especially those of catching process failure, there is usually a final test of key parameters.
Doesn't mean it WORKS for Pete's sake, let's not get carried away! But the odds become acceptable that it will...
Measurements are GOOD! It's reason that has failed audiophiles and manufacturers alike. How many factors are there that can be a little out of kilter and be audible under certain conditions? Humans are really really good at sensing small differences.
Especially now, in the digital era, I think we could come up with an adequately reliable electric listener that could do as well as humans at noticing little factors. But what are the odds that there would be one judgement setting for it that everyone would agree with?
Regards, Rick
This reads as a very accurate clock, not a low-jitter clock. Zero jitter is of course impossible. Really a good one for telling time anyway....
about an atomic clock synchronised to the satellite for audio?
"to totally eliminate jitter coming from the source."
Jitter from the source is (largely) replaced with jitter from our digital synthesizer.
"to exactly match the dynamic input clock down to 0.001Hz (i.e. ~0.04ppm accuracy) of the source."
Which are impressive numbers but irrelevant. The main benefit of a small step size is a cost savings for the manufacturer in terms of the buffer memory needed. There will be no benefit in sound quality so long as there is no need to make corrections during playback, which relates to the buffer size and the clock stepping.
"With this new and completely jitterless clock"
Liar, liar, pants on fire! No clock can be completely jitterless. The synthesizer mechanism can not reduce jitter below the jitter of the XO used as its reference.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
when I complained about jibberish not so long ago, you said I was ignorant and the guy knew what he was on about.
"when I complained about jibberish not so long ago, you said I was ignorant and the guy knew what he was on about."
I have no idea which post of mine you are referring to and no idea which guy you are talking about. Perhaps you could provide a citation.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Best not to; you'll have to work it out.
Here's the problem, Fred. I did a pretty complete search of my posts and your posts and I couldn't come up with anything. I think you're blowing smoke, but I'll be glad to eat these words if you come up with a link.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
HowdyA buffer and a digital clock synthesizer? e.g. SiLabs Si570?
-Ted
Edits: 03/15/14
they say these generate more jitter
HowdyWell more than what? I just used the Si570 as a handy example, I don't claim that it is the best one out there, but current clock synthesizers (which use sigma delta "dither" to interpolate between integers when dividing the clock back down) aren't nearly as bad as the older ones that simply used a (big) integer clock multiplier followed by an integer clock divider. Some might claim that specifically whitening the jitter might be a good idea.
Digital isolators have more bandwidth than standard optical isolators and that isolation might be more beneficial than no isolation if the down stream jitter attenuation is high enough. It's all tradeoffs.
I still really don't have any idea what was being described in your original post :)
-Ted
Edits: 03/16/14
They add jitter although they do isolate. I don't know what is better.
Howdy
On my prototype the jitter from the isolators wasn't a problem, but I think some systems wouldn't like having a few gigahertz pulsing radio transmitter on board :)
-Ted
which prototype is it. My W4S DSDSE has isolation on the usb input and sounds very good.
Howdy
The one I posted about in the PC Audio forum a while back.
http://www.audioasylum.com/forums/pcaudio/messages/8/80732.html
-Ted
And what exactly do you do for them and which product(s) has your expertise on it?
Howdy Jerome
I posted about my DSD DAC over on the PS Audio asylum a while back.
When I started working with PS Audio, both for their sake and mine I kept things quiet until it was clear that the DAC would get to market.
In the intervening years I designed and laid it out on a set of boards to work in their chassis so they could manufacture, market and sell it. I also consulted on the PerfectWave DAC MkII, or at least I offered up a menu of things that could lower jitter and they selected what seemed the most practical (or believable :) ) and implemented them.
http://www.psaudio.com/ has the picture of my DAC and if you look at their products it's the DirectStream, near the bottom of the DirectStream brief description is a link to more info with a more long winded version of it and some links to some videos... (Link below for easier navigation.)
-Ted
All the best and hope to listen to the DirectStream Dac soon.
Howdy
I hope you enjoy it.
-Ted
You were one of my favourite posters on the HiRez Forum when it started so many years ago.
I've been reading about your new DAC and have watched all the videos. I don't know enough to comment on the technical aspects (I'm more of a software and VoIP guy) but there is an elegance to your design that is very appealing. I wish you the best with the PS Audio DirectStream DAC and look forward to hearing it when I can.
Regards,
Geoff
Howdy
I've missed you and the others here. I decided to quit work when I found I was spending more time on line at the Asylum and listening to music than I could bring myself to spend at work.
Then I started this project and have had my head down for years :)
At least now I get to listen to music all of the time I want...
-Ted
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