The information in the compendium consists of only the answers John gave on questions posted in several forums. In many cases it is almost equally important to know what the question was to which the answer is directly related.
However a good compendium to read and re-read to get the hang of some design topics, especially when the answers are somehow cryptic.
However a good compendium to read and re-read to get the hang of some design topics, especially when the answers are somehow cryptic.
hermanv said:
That'll be the day.
More interesting is if Mr Curl thought about making an Emergency Rescue package for the CTC now that the lost one is on the loose.
I'm sure all of them received plenty burn-in time during sofa hours, but one day the first will be getting hickups.
(in any case, in the +2 years of this thread i for one managed to become slightly wiser than the thermostat from Mr Curl's crumbs, incorporating some of it in the pre-amp package i'm currently fumbling)
Charles Hansen said:
Charles my biggest problem is how readable are the subtitles
(if you catch my drift). Samsung is already pushing UHD and has built a few prototypes, have you seen one? Had a meeting a month ago with one of the largest satellite providers, I was surprised that there are no plans to ever provide 1080p content (have to admit I never really thought about it).
x-pro said:
All very true, Alex, but how relevant?
So initial burn-in, soak-test, call it what you will, accelerates parameter values towards the flat part of the bath-tub curve. (I know we are not talking about reliability or "failures" here, but the analogy works.)
This is very well known and not controversial.
What IS contoversial is the almost uniform claim that in doing so, the parameter change sounds BETTER!
Why, in your example, does the decreasing cap leakage current "sound better"? Why does an offset change by a few uV "sound better"?
In any competent design, and I know yours are, such small changes are not important and will not sound different, let alone better.
Cliff
cliff said:
Hi Cliff,
I did quote from LM399 datasheet just to show that even in a semiconductor structure there are some changes in the initial burn-in period. Jan claimed in his post that there is no documented changes except for the speakers which is plainly untrue. How relevant these changes to the changes in the sound of the amplifier is a different question altogether. A change of a few uV in a reference voltage most likely is irrelevant, however the changes in a "standard" grade components are generally larger - just not documented as well as for precision bits. All what I was trying to point out in my post that there are changes and the time scale of these changes is somewhat close to the timescale of the sound change in the amp.
Now to the second part - why there is usually an improvement in the sound. There are two sides to it. One is that the parameters of electrolytic capacitors are really, measurably and by a well understood mechanism are improving over a period of minutes, hours, days and sometimes weeks after the voltage is applied to them.
The leakage current is (IMHO) a very good indicator of the oxide layer condition and the quality of this layer would greatly influence the sound (even measurable distortion). Electrolytics are the main culprits in this situation and many times when the only part I've replaced in the amp were power supply capacitors I had to wait till these will run-in.
Second side is that the final tuning of an amplifier circuit sound usually done on a well run-in prototype. In this respect whatever changes in components during the run-in period is accepted in it's stable state. We need an amplifier that will sound right AFTER this initial run-in period. There is no point in getting the amp with the right sound only in a "fresh" state so the sound would deteriorate shortly
. But that is usually only important in a really top-notch design, when all other bits are well sorted out. Most of the time, I think, the electrolytics are to blame for the changes.Cheers
Alex
I found more sound difference caused by every-day-different content of interference in mains voltage net (depends on how many and which industrial products are connected) than any burning-in of semiconductors.
Only very poor designs, that change bias of some 30% after turn-on or change distortion because of self-heating are prone to "burn-in", which is nothing else than slow approach to stabilized operating conditions. Some gear are never stabilized and drift all the time.
Only very poor designs, that change bias of some 30% after turn-on or change distortion because of self-heating are prone to "burn-in", which is nothing else than slow approach to stabilized operating conditions. Some gear are never stabilized and drift all the time.
PMA said:
These are not mutually exclusive problems
. I usually try to reduce the interference to a reasonable minimum by switching off all unnecessary appliances during critical listening sessions. If there is another influence on the sound you need to find it and treat it accordingly, separating apples from oranges. However - presence of even a large apple does not exclude existance of a small orange behind it.PMA said:
That is a very different effect altogether - a "warm-up", I suppose. It would occure every time you switch on a unit, even after a short "off" period. It is not necessarily a sign of a bad design - sometimes it is just unavoidable, like in a tube amplifier or in many cases in a "zero NFB" designs. It could be a design desision, not more, not less, a matter of taste.
Alex
The CBC studios on Ottawa, Ontario, are supportive of Canadian Businesses..so..they are chock full of Bryston amplifiers.
If the engineers plan to do any real recording or reference work..they turn the amplifiers on, on the Friday..and then record on the Monday. Seriously.
This is due to the way that Brystons are 'tuned' at the factory. When built, they are initially biased..then run in for 100 hrs on a burn in rack..and then they receive the final tweak.
Brystons then have a quite notable, repeatable tendency (this is older information, might be different, now) to not sound 100% as good as they can ..until that final moment passes. And, you can hear it take place all of a sudden, relatively speaking..over a 1 hour period, ~ that 100 hrs later. (plus or minus some time, due to local ambient conditions.) So yes, any factory adjusted Bryston will do this 'trick'. The last vestige of harshness just gets up and 'goes away' over this one hour period and it literally takes place..in a few minutes. The same time frame it took the technician on the set-up bench to do the final tuning of that given Bryston. Like a seeming ghost...it echoes the set up, exactly.
CRT projectors have similar thermal and electrical issues. The tweaking of the focus and alignment, etc..will follow the EXACT timing and order of operations issue, over the SAME time period that the original set-up took place in. What I mean, is that the Projector will not look it's best until it thermally and electrically 'drifts' into the alignment that was done to it, as it was being set up. For example, if it was set up 40 minutes into it's warm up, then it will drift into that set-up..40 minutes after turn on.
Except, a CRT projector requires 1 to 1.5 hours to reach full stability, on average, in a 70 degree (21C) 40% humidity 'standard' environment. So... the PJ's calibration will not be optimal, as it was 'adjusted' too soon. But the viewer WILL be able to view a perfected image SOONER in the given film they are attempting to watch..but..the image fidelity will worsen as one gets near the end of the film..or attempts to watch more video.
The trick, when calibrating CRT projectors, is knowing the meaning, direction, and level (of the relative 'size' of the given issues) that the warm up 'cycle components' involved have, that take place with the given design or model. Then one makes as intelligent a decision or guess as possible, when calibrating, with regards to order of operations and final focus and alignment, with respects to time the act is committed. Also, lid off, lid on, changes in the electrostatic field and charge considerations, besides any temperature related issues..and of course, the mechanics of magnetics. The set up environment must reflect viewing conditions.
This, of course, is not a pile of gross or basic considerations, but really comes into play when perfecting 1080P (and better) images at the highest level of image perfection. A lesson that 'everything counts', one that is transferable to audio, if one is paying attention. For example, that prototypes MUST replicate the exact end user's situation to perfection, otherwise you seriously stand a chance of delivering the customer an item which bears less sonic identity to the prototype than you might want..or specifically..expect.
If the engineers plan to do any real recording or reference work..they turn the amplifiers on, on the Friday..and then record on the Monday. Seriously.
This is due to the way that Brystons are 'tuned' at the factory. When built, they are initially biased..then run in for 100 hrs on a burn in rack..and then they receive the final tweak.
Brystons then have a quite notable, repeatable tendency (this is older information, might be different, now) to not sound 100% as good as they can ..until that final moment passes. And, you can hear it take place all of a sudden, relatively speaking..over a 1 hour period, ~ that 100 hrs later. (plus or minus some time, due to local ambient conditions.) So yes, any factory adjusted Bryston will do this 'trick'. The last vestige of harshness just gets up and 'goes away' over this one hour period and it literally takes place..in a few minutes. The same time frame it took the technician on the set-up bench to do the final tuning of that given Bryston. Like a seeming ghost...it echoes the set up, exactly.
CRT projectors have similar thermal and electrical issues. The tweaking of the focus and alignment, etc..will follow the EXACT timing and order of operations issue, over the SAME time period that the original set-up took place in. What I mean, is that the Projector will not look it's best until it thermally and electrically 'drifts' into the alignment that was done to it, as it was being set up. For example, if it was set up 40 minutes into it's warm up, then it will drift into that set-up..40 minutes after turn on.
Except, a CRT projector requires 1 to 1.5 hours to reach full stability, on average, in a 70 degree (21C) 40% humidity 'standard' environment. So... the PJ's calibration will not be optimal, as it was 'adjusted' too soon. But the viewer WILL be able to view a perfected image SOONER in the given film they are attempting to watch..but..the image fidelity will worsen as one gets near the end of the film..or attempts to watch more video.
The trick, when calibrating CRT projectors, is knowing the meaning, direction, and level (of the relative 'size' of the given issues) that the warm up 'cycle components' involved have, that take place with the given design or model. Then one makes as intelligent a decision or guess as possible, when calibrating, with regards to order of operations and final focus and alignment, with respects to time the act is committed. Also, lid off, lid on, changes in the electrostatic field and charge considerations, besides any temperature related issues..and of course, the mechanics of magnetics. The set up environment must reflect viewing conditions.
This, of course, is not a pile of gross or basic considerations, but really comes into play when perfecting 1080P (and better) images at the highest level of image perfection. A lesson that 'everything counts', one that is transferable to audio, if one is paying attention. For example, that prototypes MUST replicate the exact end user's situation to perfection, otherwise you seriously stand a chance of delivering the customer an item which bears less sonic identity to the prototype than you might want..or specifically..expect.
And the fun part is, that folks who have no familiarity with the situaiton surrounding the idea of these 'tidbits of experience', also are not familiar with the 'pattern of reception' the given person becomes involved in, when they are on the side of having and attempting to share that information.
Think westerns. The new guy gets finally gets to his imagined 'wet dream' and becomes the 'fastest gun in the west'. Suddenly he's confronted with a situation that most folks would not understand, and that is that every single bloke with a gun attempts to 'pull out' on him for a 'quick draw' contest. He ends up living in a surreal world of having to be constantly on his guard. One he would not have expected, before he became the 'fastest gun in the west'. Now he's in a different world, with regards to the reception that he receives from the average dude.
What I'm saying, is that the average guy is not aware of the extensive level of poo that the innovators have to wade through....all because of the lack of awareness of some folks with regards to the situations that one can get into, when attempting to try and bring new and interesting stuff to the table. A combination of multiple ignorance conditionals, and not thinking things through.
The point that science itself suffers from this human evolutional and emotionally based deficiency, is horrifically obvious for anyone who's ever been on the side of the fence of attempting to bring in and ring in the new. Which is why I've always said that anyone attemtping to get a engineering degree or doctorate should be forced to take a minimum of two to three full credits in basic human psychology courses. A bit of self awareness counselling would do wonders for science. It's doing the head-stuffed-butt thing in a very wondrous splendiferous fashion.
If science would unite it's more level headed people to a point where they would continually 'smack down' (and smack down HARD) their more 'bull in a china shop' mentality, the 'low psychological self awareness' compatriots..who..let's face it, are the root of and the entire problem itself..then science would stand a decent chance of moving at twice the rate it does now.
Is this point transferable to the world of audio? You betchya!
Think westerns. The new guy gets finally gets to his imagined 'wet dream' and becomes the 'fastest gun in the west'. Suddenly he's confronted with a situation that most folks would not understand, and that is that every single bloke with a gun attempts to 'pull out' on him for a 'quick draw' contest. He ends up living in a surreal world of having to be constantly on his guard. One he would not have expected, before he became the 'fastest gun in the west'. Now he's in a different world, with regards to the reception that he receives from the average dude.
What I'm saying, is that the average guy is not aware of the extensive level of poo that the innovators have to wade through....all because of the lack of awareness of some folks with regards to the situations that one can get into, when attempting to try and bring new and interesting stuff to the table. A combination of multiple ignorance conditionals, and not thinking things through.
The point that science itself suffers from this human evolutional and emotionally based deficiency, is horrifically obvious for anyone who's ever been on the side of the fence of attempting to bring in and ring in the new. Which is why I've always said that anyone attemtping to get a engineering degree or doctorate should be forced to take a minimum of two to three full credits in basic human psychology courses. A bit of self awareness counselling would do wonders for science. It's doing the head-stuffed-butt thing in a very wondrous splendiferous fashion.
If science would unite it's more level headed people to a point where they would continually 'smack down' (and smack down HARD) their more 'bull in a china shop' mentality, the 'low psychological self awareness' compatriots..who..let's face it, are the root of and the entire problem itself..then science would stand a decent chance of moving at twice the rate it does now.
Is this point transferable to the world of audio? You betchya!
Well said, KBK. I was rereading 'The Structure of Scientific Revolutions' by Thomas S. Kuhn, and I came upon p. 92: "IX. The Nature and Necessity of Scientific Revolutions"
It is about the X-ray 'hoax' why the accidental discovery of the X-ray was fought over and denied by Kelvin, to the best of his ability, etc. It is because it crumbled EVERYTHING that people knew about the world, and reduced it to a useful approximation. Because of the 'ultraviolet catastrophe' which showed that X-rays were impossible, Planck looked for a 'constant' that 'might' be inserted into a formula that would allow the existence of X-rays. The birth of contemporary physics was, in many ways, at this point. Do you know Planck's constant and how it was derived?
It is about the X-ray 'hoax' why the accidental discovery of the X-ray was fought over and denied by Kelvin, to the best of his ability, etc. It is because it crumbled EVERYTHING that people knew about the world, and reduced it to a useful approximation. Because of the 'ultraviolet catastrophe' which showed that X-rays were impossible, Planck looked for a 'constant' that 'might' be inserted into a formula that would allow the existence of X-rays. The birth of contemporary physics was, in many ways, at this point. Do you know Planck's constant and how it was derived?
AndrewT said:
Due to telecine electronic hardware 1080P 'master' ..uh..reduction of that 1080P image to the 720x480 dvd master...and the techniques involved, the scaling to that 1080P of the DVD is the way to go. It looks it's best on a 1080P monitor of course. It's the visual equivalent of using proper reduction and then transmission and reconstruction techniques in digital audio.
It all comes down to the algorithms used to scale it down vs the algorithms used to scale it back up. A good 're scaling' algorithm used to get back to the 1080P level from a 720x480 DVD, will bring about a better image than any other DVD scaling technique, if properly executed. With regards to DVD done on a true baseline scaler, which is a 'pixel by pixel' any ratio device like a HTPC, the best algorithms are still the ones used in the core of the ATI video cards. The core of a ATI video card was specifically designed to do so.
Nowadays, the odd monitor, like the new gateway or 30" 2560x1600 monitors, some use a "teranex' chip core, which is likely more intelligent than the ATI algorithms, when it comes to making decisions which best benefit the eye, when scaling..specifically across motional frames-in time --- The key point to take away that also involves the previous paragraphs and echoes requirements that exist in digital audio. Interesting, both the eye and ear are logarithmic devices. Who'da thunk it!
. For example, the most powerful single box unit, with regards to capacity and price, is a Playstation 3. Some guys are doing 3-d and 4-d fractal rendering and analysis using daisychained Playstation 3's. I'd think that the algorithms could ALSO be utilized to make an obscenely powerful device for manipulating audio signals. Far faster and perfect a rendering device than is otherwise available.
Oops. Now will someone take that, run with it, do a bit of software development and bust up some of the companies at the high end of the audio recording/encoding field? The opportunity is there.
I did such a good job on the HTPC and CRT forums at the AVS forum site, and with the conversations I had with one particular original HTPC 'scaler in a box' manufacturer..that I ended up accidentally being one of the main folks who helped end the run of Faroudja, as a vital company. Whoops. I gained nothing financially out of it, I just published my findings and understandings.
syn08 said:
... AND that are (repeatable and verifiable) audible, AND that always seem to improve the sound.
\Edit: Best regards from the 124th AES; just attended a 2-hr talk by Mr Neville Thiele and Mr Richard Small. Just a random statement of Mr. Small: "Speaker drivers don't have parameters. Models do".
Very interesting!
Jan Didden
john curl said:
My vague understanding of Planck's constant is similar to that of most 'constants' added into physics. They are to fill holes in knowledge, like placing dirt in a hole that trips folks up, due to components that they don't understand, yet nevertheless..must deal with. So they fix their lack of understanding with imagined patches. I'm not 100% correct in that statement, but you might get my feelings on the subject coming through, just a tiny bit.
Planck's constant = Duct Tape for Physics.
janneman said:
It's pretty clear that any such long term behavior is going to be
obscured by the burn-in of the listener. People come to new
audio components carrying the experience of the previous
equipment, and may experience some dissonance with the new
sonic character, even if they like it overall. Over time they often
get used to it and grow to like it.
There are plenty of cases where they initially like it, but the sound
becomes irritating over time. That is called burn-out.
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