| AcidOrangeJuice |
Hi guys.. I am new here. This site I like a lot. I have around six months visiting it. But, finally I decided to register.
I am electronics engineer, specialized in solid state audio amplifiers, and by this cause I obtained of status of banned in SteveHoffman forums... Incredible not? :xeye:
do you wanted to listen my history?
I still am impressed with the bad experience... :xeye: |
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| janneman |
| quote: | Originally posted by AcidOrangeJuice
Hi guys.. I am new here. This site I like a lot. I have around six months visiting it. But, finally I decided to register.
I am electronics engineer, specialized in solid state audio amplifiers, and by this cause I obtained of status of banned in SteveHoffman forums... Incredible not? :xeye:
do you wanted to listen my history?
I still am impressed with the bad experience... :xeye: |
Are you banned for being an engineer or for what you said
;) ?
Welcome, anyway.
Jan Didden |
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| Cal Weldon |
AOJ,
Welcome to this forum. Hope we don't have to ban you here.;) |
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| AcidOrangeJuice |
| quote: | Originally posted by karma
welcome;) |
Thanks :)
| quote: | Originally posted by janneman
Are you banned for being an engineer or for what you said
;) ?
Welcome, anyway.
Jan Didden |
Both things :) .
Exactly by the title of electronics engineer not, but by the knowledge that an engineer has, yes; because this seems "to affect" some myths about audio what that people maintains by some reason :xeye: .
Anyway, I expressed my opinions as engineer, the forum administrator and some moderators obtained :hot: and after I obtained :dead: and :smash: .
Let me explain better.
A guy in that forum is promoting the misinformation that NEGATIVE FEEDBACK is not a good thing. This guy does "supposed Hi-Fi" single-ended class A tube amplifiers. The publicity of this guy is this: Zero negative feedback is used!!.
In other words, he promotes the idea that Zero negative feedback at all is a good thing, and that this is a lot better that to use negative feedback. We know that this statement is false.
Apparently, this guy is not using AC negative feedback at all; but I discovered that the power triode output is self-biasing, that this is essentially DC negative feedback. When I tried to express this, I obtained complete ban.:xeye:
Another thing: the designs of this guy are simple and basic class A topologies without any negative feedback (the typical introductory basic electronics course:xeye: ), and these amps. have 10%:dodgy: of distortion. These designs are equivalent in performance to a very poor and cheap design.
This guy, with the publicity of: "Zero negative feedback" as promotion:dead: sell these poor designs around 9.500 dollars.
It is really pathetic.
Guys, opinions?:xeye: |
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| jacco vermeulen |
OK, that's it, you're out of here !
On the other hand, welcome.
(but don't pee on my territory. btw, your coat looks a mess) |
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| SY |
You'll find that even among trained engineers, the blithe assertion, "We know that this statement is false" will raise a few eyebrows.
In any event we have NEVER banned anyone for expressing technical opinions, no matter how crazy, wrong, obtuse, whatever- only unreasonably dangerous stuff and personal attacks will cause moderator action. |
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| Netlist |
IOW: Telling someone is wrong isn’t wrong. He’ll probably ask to backup your statement but as long as that discussion is polite and with respect of each other’s opinion it’s fine.
/Hugo - will keep an eye on you... ;) |
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| sagarverma |
| u got blessings of the moderator.;) |
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| analog_sa |
Welcome Acid
You seem to be interested in measurements and advanced topologies and completely uninterested in nonsense like subjective perception. This will guarantee you the blessings of the moderators and you'll hopefully provide endless entertainment for the rest of us. Rest assured you won't be banned - you'll just fit in here naturally.
Just out of curiosity - can you provide links to the booting episode? |
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| steenoe |
Well, welcome to DIYaudio Acidorangejuice! Sounds like you are one of those colourfull additions that I like:D
Steen:cool: |
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| Tweeker |
| Negative feedback is not always a good thing, though it is not always a bad thing either, especially in moderation. Negative feedback is not always good when its through a transformer of poor bandwidth or otherwise poorly implemented. Its also not that great when your clipping alot. I suspect that both might apply to that design were it used. |
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| anatech |
Hi AcidOrangeJuice,
Welcome!| quote: | | Negative feedback is not always a good thing, though it is not always a bad thing either, especially in moderation. Negative feedback is not always good when its through a transformer of poor bandwidth or otherwise poorly implemented. Its also not that great when your clipping alot. I suspect that both might apply to that design were it used. |
Look what you've started already!:eek:
I think you will feel at home here.
-Chris |
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| dhaen |
I'll defend to the end, your right to be wrong...:cannotbe:
There is always more that one side to an argument, usually more than three.:D |
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| Tweeker |
| Oh and hi and welcome! Whats the point of a discussion board where you cant discuss things? |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by AcidOrangeJuice
I am electronics engineer, specialized in solid state audio amplifiers, and by this cause I obtained of status of banned in SteveHoffman forums... Incredible not? |
Not incredible at all. I am on the other side of the fence (EE yes but prefering valves and for sound reasons [pun intentional]) and have been banned from Robert E Greene's (of TAS) Yahoo group for persuing a line of argument that was actually fully and comprehensively backed in which I argued that from a system wide view in the correct context a SE Valve Amplifier without feedback resulting in dramatically lower distortion than using a "virtually no distortion" SE Amplifier (BTW, that bit is also completely true).
It seems that people who have attained certain levels of prominece find very poor moral affordibility (moral affordability is a term which I define as the cost to a persons worldview in accepting a given contention as true) in tolerating views that contradict their own, no matter how well founded such views may be. They seem less interested in the actual truth than in merely preaching the same party line (whichever it happens to be).
Now don't get me wrong, I like a good party as much as the guy next door or more (more actually, a lot more, ask him, he nearly called da police on one of my ones), but when they become a dogma to the exclusion of having fun it gets tedious.
Sayonara |
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| demogorgon |
Good to have more people with knowledge rather that belife on the board.
I look forward to draw on your knowledge :)
welcome!
marius |
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| mastertech |
Hi all, how sad a story this must be, i for one feel for this guy
cause i have experienced ban only too well in philosophical
forums, anyway from what ive seen so far, youre a hardcore
objectivist i have high respect for objectivists becuase they
try to catch up in high tech areas of art, as a scientist who
creates art with science i welcome you, i have a lot to learn
from you my friend, cheer up ;) |
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| Enzo |
Usually it is not what you say, but rather the way that you say it.
If you disagree with someone, it is OK to express disagreement and present a case as to why you disagree and even find the flaws in someone else's presentation. But it is rude to enter an argument telling someone that they are liars and what they say is false. No one wants to hear that. Even if you are right and he is wrong. |
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| sagarverma |
| quote: | Originally posted by Enzo
Usually it is not what you say, but rather the way that you say it.
If you disagree with someone, it is OK to express disagreement and present a case as to why you disagree and even find the flaws in someone else's presentation. But it is rude to enter an argument telling someone that they are liars and what they say is false. No one wants to hear that. Even if you are right and he is wrong. |
it as happened on this forum.but thanks to the moderators who have interviened(check spelling:)) at right time.
most ugly form is racial or ethnic refrences. they must be avoided at all cost 4 they try to hurt the very roots of this great forum.what has race etc to with the intellect? |
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| jacco vermeulen |
| quote: | Originally posted by Kuei Yang Wang
It seems that people who have attained certain levels of prominece find very poor moral affordibility |
Mr Löesch, your presence here is affordable, and a luxury. |
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| dhaen |
| quote: | Originally posted by Enzo
Usually it is not what you say, but rather the way that you say it.
...snip.. |
Indeed, that is the key. Forgetting that other members are human beings and have feelings.
Some of our most memorable food-fights have arisen from knowlegeable members who battle like stags, becoming more and more entrenched in their positions. They are so used to having "the last word" in normal dicussions, that they just can't put it down. This can then degenerate to a personal level argument - which we do not allow:whazzat: |
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| mastertech |
I would think the moderators have the toughest job to play with
here's a scenario
two knowledgeable members are fighting out one gets banned the
other leaves the forum because he thinks the forums is going
down hill
we lost two good members
i think the moderators should think twice before they take action
because a heated discussion has a begining and ending by its
own accord not to mention how entertaining it would be to others
How do you moderate? you do by moderation for example
you show an example of politeness by saying a joke this will
divert the spirits and bring peace
i am not a moderator or even an expert on moderation but it
would be good when things go bad moderators would come in
with jokes to cool things off
cheers |
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| Tweeker |
| Some forums seem to use heavy water for thier moderation. |
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| SY |
| I tend to use a high pressure fire hose and tactical nukes. |
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| mastertech |
Sy not bad at all, if you would like to upgrade your skill, there are
many good joke books around, and you know what the joker
is a joke -joking! |
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| anatech |
Hi mastertech,
I would hazard a guess that most moderation is simply enforcing the rules as evenly as one can.
Personal attacks are one of them. There is a grey area and it is up to the member is define where he is.
Bad language is pretty clear. Since most of us are adults, involking moderation is the members fault. Moderators are the last resort so to speak.
One also has to expect some comments from other members from time to time. An overreaction to this is not helpful to anyone.
So the board is like life. Be an adult and don't break the rules. Otherwise you can expect to talk to a "cop".
-Chris |
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| Cal Weldon |
| Well said Chris |
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| AcidOrangeJuice |
| quote: | Originally posted by anatech
Hi mastertech,
I would hazard a guess that most moderation is simply enforcing the rules as evenly as one can.
....
So the board is like life. Be an adult and don't break the rules. Otherwise you can expect to talk to a "cop".
-Chris |
The rules are done by common humans, as you or as I; and these, are not necessarily perfect. The rules always are subject to change, mainly in science. If Thomas Alva Edison had not questioned "the rules" of their time, very probably, our houses and cities still would be illuminated with gas lamps.
All the corrupt systems of government in the history; as Hitler, or the Inquisition for example, were protagonists of many innocent deaths and injustices. The doctrine of these systems of government was: Hey man!!!, don't think, don't question, and don't break the rules!!
In this point I believe that Galileo Galilei had been in agreement with me. |
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| poobah |
| Has there been any conclusive research on the comparitive merits of polypropylene versus teflon moderators? |
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| anatech |
| Well ..... nothing sticks to teflon so ..... Teflon also withstands higher temperatures and so is preferred over polypropylene moderators. :D |
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| poobah |
| Ahhhh.... but, don't forget that poplypropylene is "self-healing". |
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| Variac |
When mods make decisions about behavior, we take into account the past actions of the member. A new member might get one stern warning , when an established member might get some bin time.
On the other hand, a member that has for years never offended anyone and then makes one intemperate statement probably just gets a stern warning.
It is clear to me that new members often need a bit of time to understand the tone of this forum. Once they do, they either adapt to our "culture", or get punished and/or leave.
We firmly believe the really quite amazing success of the forum is due to the civil tone and respect required of members, and really this is the predominant rule. |
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| anatech |
Mark,
Yes, absolutely. This board is far more professional and helpful than any other I have seen yet. The amount of knowledge available is astounding. This is due in large part because of the rules and rather high standard of moderation I see here.
This was my original viewpoint and has not changed over the time I have been a member here. I understand there have been trying times, but like a film (poobah) cap, it is self healing. Although we want to make sure the capacity isn't reduced too much.:clown:
In the end it is up to the members as a group to behave themselves.
-Chris |
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| poobah |
Acid Orange Juice,
Welcome, I share your frustration regarding feedback and how it is routinely dismissed. I have learned much though here as to why this came about. Furthermore, I don't think that discussing it will get you kicked out. The feelings against it here are not so prevalent either.
I believe where feedback has been hurt is in its misapplication. You need a lot of bandwidth to use feedback properly. Sandmen embrace feedback for its virtues and the fact that bandwidth comes easily. Tube guys, steer away from it because coupling caps and trannies work to eat bandwidth up.
You will find the masses to be more pragmatic here... some very hardheaded scientists, engineeers, technicians as well that won't listen to "facts" without proof.
I also think alot of the tube guys are very motivated to avoid feedback because when all is said and done... it IS a pretty d_mn fine accomplishment to get 2-3% (or less) distortion without NFB.
I have yet to build a tube amp as an adult... did so when I was a kid... with a recipe. I am waiting to learn what the real difference is between PP and SE is. I have to wait until the speaker cable gods have been appeased though.
Cheers, |
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| poobah |
Anatech,
To your credit, teflon moderators would have less dieclectic absorption.
;) |
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| anatech |
Hi poobah,
Mods need to absorb like the rest of us. ;)
Acid Orange Juice,
We tend to go off topic sometimes too. Mostly in fun without chest beating. Many points of view make life interesting for the most part.
-Chris |
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| sagarverma |
| quote: | Originally posted by Variac
We firmly believe the really quite amazing success of the forum is due to the civil tone and respect required of members, and really this is the predominant rule. |
good.
:judge:
| quote: | Originally posted by anatech
Mark,
Yes, absolutely. This board is far more professional and helpful than any other I have seen yet. The amount of knowledge available is astounding. This is due in large part because of the rules and rather high standard of moderation I see here.
In the end it is up to the members as a group to behave themselves.
-Chris |
RIGHTly said |
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| Variac |
If we are giving out accolades, I tend to agree with Enzo:
| quote: | | Usually it is not what you say, but rather the way that you say it. |
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| janneman |
| quote: | Originally posted by AcidOrangeJuice
The rules are done by common humans, as you or as I; and these, are not necessarily perfect. The rules always are subject to change, mainly in science. If Thomas Alva Edison had not questioned "the rules" of their time, very probably, our houses and cities still would be illuminated with gas lamps.
All the corrupt systems of government in the history; as Hitler, or the Inquisition for example, were protagonists of many innocent deaths and injustices. The doctrine of these systems of government was: Hey man!!!, don't think, don't question, and don't break the rules!!
In this point I believe that Galileo Galilei had been in agreement with me. |
So far everybody is agreeing with everybody else. What a boring thread this has become! Waste of time, really.:o
Jan Didden |
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| anatech |
Heck, it's long and interesting for a "Hi, my name is .... " thread. It should have died in 3 or 4 posts really.:D
Just got through the door and we're discussing moderation already!
-Chris |
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| JimRodgers |
Like I was saying: of course, there are always special cases...
For example, when too much negative feedback is used and wrapped back into a diff amp at an early stage, there is the potential that the feedback signal will suck all the juice out of the ["constant"] current source biasing that diff amp. In some cases, this can cause something nasty to happen in the signal path. As I recall, this is considered an advanced form of slewing, and it is revealed by measuring transient intermodulation distorion using a sine wave riding synchronized on top of a square wave.
This is one of the many little design details that may have caused some early solid state amps not so sound as good as they could have with less feedback. As engineers, we learn diff amp as small signal problems and as biasing problems -- but often with little care about how the two problems can interact. On the other hand, what do you say to a smartypants know-it-all expert who refuses to believe that electrons can get back there fast enough to have a beneficial effect on the signal?
I'm a million years old, and I've heard a lot of arguments in the audio world. Such passions! At the end of the day (or at the end of one of the days, eventually), we realize a number of important things:
(1) Some people hear what they want to hear, :rolleyes: and they may delve into buffoonery when they take an aggressive technical position based on their imaginary evidence.
(2) Some people can hear real differences, but for whatever reasons, attribute these differences to ridiculous theories (often overlooking the fact their test system is a piece of, or broken, etc.); we need to remember there are points taken off for wrong answers.
(3) Certain technical people dive into buffoonery when they assert the impossibility of sound qualities :whazzat: reported by truly excellent and perhaps even gifted listeners.
(4) Many audio nuts (like I am) sometimes enjoy taking sides in a way that polarizes forums :bigeyes: including the once popular neighborhood stereo equipment store. Thank God for the Internet!
(5) There are seven more items on this list -- unless I am entirely mistaken in that belief. :clown: Do you know what I'm saying?
Cheers, Dude. Welcome to the Free World. And be gentle. :yinyang: |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by JimRodgers
On the other hand, what do you say to a smartypants know-it-all expert who refuses to believe that electrons can get back there fast enough to have a beneficial effect on the signal? |
I would not know about that, considering that "Electrons" are imaginary and have no proven reality doews it matter what these inaginary particles do? BTW, I agree that there is something, but the "Electron Particle" model is by far to poorely correlated with reality to be taken as the gospel (eg. IF the electron where a traditional newtonian particle as the model aledges Heisen would have never become famous).
| quote: | Originally posted by JimRodgers
(1) Some people hear what they want to hear, :rolleyes: and they may delve into buffoonery when they take an aggressive technical position based on their imaginary evidence. |
Note, that includes those who want to hear "NO DIFFERENCE" and who then fo on to endlessly wave "no result" DB Tests around which are easily dismissed purely on statistical grounds, never mind the validity of the actual test-setup.
The problem is that people want certainties. They (the pee-pull) rather live with false certainties (as in 'we know what is going on') than to face the real uncertainty (as in 'we have no footbaling clue why it does that') and are always ready to laugh at and ridicule the fool who sits on his hill with his cap and his bells, completely failing to note that the real fools is they....
Sayonara |
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| SY |
| Thorsten, where does that "Newtonian particle" stuff come from? I'm no expert in QM, but I have managed to eke out a few papers on the subject in refereed journals, and AFAIK, there's no such thing as the "Electron Particle Model" in any post-1921 conception of QM. |
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| Kuei Yang Wang |
Konnichwa,
| quote: | Originally posted by SY
there's no such thing as the "Electron Particle Model" in any post-1921 conception of QM. |
Yet it persists among EE's.... Who arguably did not take Quantum Physics (I myself was thought it more or less like that at University in the 80's).
I guess the debate would be if the particle model suffices in Electronics, or not.
Satonara |
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| janneman |
| quote: | Originally posted by JimRodgers
[snip] On the other hand, what do you say to a smartypants know-it-all expert who refuses to believe that electrons can get back there fast enough to have a beneficial effect on the signal?[snip] |
Hi Jim,
I gather you refer to the fact that feedback can't work because the electrons come back too late to prevent the damage?
I must say you make a convincing case, and I really would like to believe you, but there I have a problem. You see, all those millions of years I have been building equipment with feedback, it worked everytime. All the time. Exactly as predicted. Exactly as calculated. So why does reality refuse to follow your theory, or am I missing something?
Edit: Jim, if I misread you, that is, if you DO believe that electrons CAN get there fast enough, scratch my above post, in that case you, I and reality DO agree. Semantics...
Jan Didden |
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| JimRodgers |
What debate? Did I start a thread? This is cool. :cool:
Thanks, SY, for running to my side. I'm new here, so I appreciate the third dimension of your remarks.
Satonara, I welcome your remarks on my other points as well. like numbers 4, 8, and 11.
And keep in mind that while electrons are a theoretical abstraction, so also is electricity: the theoretical flow of theoretical charge in a over a supposed period of so-called time and in an approximate place. I remember those days -- in the dorm at Emory: what if the whole universe is just a spec under the thumbnail of some giant... :clown: Wait a minute! Electricity is the flow of positive charges!!! I KNOW there is no such thing as THAT in a wire? OR what do I REALLY know?
Seriously, I did not mean to trip over any previous positions you may have expressed about electrons or positive feedback, etc. I was just trying to make the point feedback theory very often gets repeatable results we can hear in the sound machines we build using that theory. Good results and bad results. Actually, I thought I was posting a response to welcome a new guy who was as odds with another forum for expressing himself about the theory feedback in amplifer circuit design. So I was just trying to be nice ot him.
By the way, I just saw a certain lodspeaker website was selling audiophile duplex power receptacles for $150! For electrons! :eek: Any takers? :devilr:
Just kidding. It nice to have such a rich place to bring up Audio topics. I have many questions to ask, and I hope I can offer some information back from time to time. |
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| JimRodgers |
| quote: | Originally posted by janneman
Edit: Jim, if I misread you, that is, if you DO believe that electrons CAN get there fast enough, scratch my above post, in that case you, I and reality DO agree. Semantics...
Jan Didden |
That's right, Jan, I DO believe feedback works.
It's really a matter of bandwidth, I believe. Maybe it's really true that some "damage" must occur if the feedback is created that that can be helpful in preventing further "damage." But this delay is irrelevant in our frame of reference. If I'm not mistaken, a detailed treatment of this issue involves the Theory of Relativity.
Perhaps it is even more useful to make the approximation that charge carriers move close enough to the speed of light most of the time that this is VIRTUALLY instantaneous as far as most human audio engineers and listeners are concerned. Given, then, that the technical problem involves no delays due to charge carrier transit times, we are dealing with a set of simultaneous equations in the context of control theory. The solution does not imply anything about whether the damage ever really occurred.
However, there also is the concept of position error (and/or velocity error and/or acceleration error, etc.). This may seem to address the idea that some damage is necessary in order to correct it. Personally, I’m not convinced that this is what it means. Then you have the issue of zero order, first order, second order control systems where integrators may/may not be present in the feedback loop.
One must be careful not to forget that there are BIG delays, however, associated with reactive elements in the system. Thus, negative feedback can become positive feedback at certain frequencies, etc. Also, it is interesting to solve these equations when discrete delays are present in the system. Formulated with Laplace variables, as I recall, a discrete delay of time=T is described by
f(s) = exp(-sT)
Perhaps this is useful for modeling processing delay in computer controlled systems. Anybody done this? I wonder: what are the stability criteria of a control system (feedback network) where such a delay is in the feedback path? Any takers? (How about you carputer guys?)
Bringing this full circle (in infinite-dimensional Hilbert Space, perhaps!), couldn't charge carrier transit delays be treated mathematically as discrete delays? I assume the extra terms drop out as too tiny to calculate.
Signal and System Theory stands on the shoulders of wonderful mathematicians like Laplace and Fourier who lived long before Einstein, Bohr, or Heisenberg got us wondering about everything.
But if it were not for the occasional reminder that electrons are somewhat nebulous in many ways, ;) we might not want to stay sharp enough to remember where our canned engineering formulas came from. |
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| poobah |
Jim,
Never had to incorporate any fixed time delays into control loop design... LaPlace style at least. They can be simply modeled in BODE analysis (NOT perfectly by any means). Flat gain and a curious phase function.
I generally try to keep control loops smaller than a state or country.
Got me thinking though... now I want to dig out some books. I remember vaguely that time delay is on some level related to backlash and freeplay (equivalent or reciprocal in s domain?)
As far as numerical loops though, and again these are systems running much slower than the computer; I have found that the math gets you close, but compensation coefficients still had to be tweaked in by hand. Done by careful measurement and trial and error over all extremes of operation. Before I get the "ear" people all riled up; let me say that our inability to achieve perfect results through math was a function of our inability to precisely model the system (usually electro-mech or electro therm) under control... or that we had deliberately simplified the model to ease the math knowing that we would tweak it in anyway.
In the case of purely electronic systems, I have had the same luck as Jan... math works.
Hmmmm....... your turn,
Oh, BTW, the site is really about violent writers & authors that are interested in audio & electronics. Read your posts at least 400 times before pushing button... the vultures are always nearby. :D |
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| janneman |
| quote: | Originally posted by JimRodgers
That's right, Jan, I DO believe feedback works.
[snip] |
Jim,
Thank ohm! Another guy who has his facts straight! I fully agree with you.
I think part of the feedback-comes-too-late confusion comes from failing to understand two separate things:
- the fact that the electrons or charge or whatever needs a finite time to travel trough the wires to get back to the input. That is as you say for practical purposed neglectable (although it is not zero of course);
- the phase shift within the (forward and) feedback loop due to reactive elements, which eventually turns neg feedback into pos feedback with all the known problems. That is sometimes also seen as delay but it isn't.
A good example is the phaseshift between current into a cap and the voltage across it. It seems superficially that the voltage is delayed w.r.t. the current, but it isn't! At the very instance that the current starts to flow, the voltage starts to rise. There is NO 'dead-time' between start of the current and start of the voltage (other then the propagation effects mentioned above). So, in this sense, there is NO delay in feedback, only phase shift. Not always easy to keep apart.
Neg feedback works by subtracting the input from the feedback signal so that the (inverted) error remains that is then amplified to correct the output. Because of the phase shift, the subtraction gets less and less complete with rising freq so the feedback gets less and less effective. If the phase shift is large enough, the subtraction changes into addition and the output signal is sustained without an input: we've got ourselves an oscillator.
Jan Didden |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by janneman
Neg feedback works by subtracting the input from the feedback signal so that the (inverted) error remains that is then amplified to correct the output. Because of the phase shift, the subtraction gets less and less complete with rising freq so the feedback gets less and less effective. |
And circuits with negative feedback invariably display an "error band" (which is in other words the resut of the neccesity for an error to be present first before feedback operates), meaning a previously straight line signal becomes rather fuzzy. The error band becomes the wider the slower the circuit is.
As large open loop gains and wide open loop bandwidth are generally mutually exclusive you allways have your rocks between a hard place and a hard wall.
What has also been only very incompletely researched is the subjective effect of this "fuzziness" with music.
Another way of viewing this is to say that a Feedback amplifier circuit is allways a little wrong by about the same absolute amount in an entierly unpredictable fashion while a non-feedback Amplifier is progressively less wrong with falling signal and is wrong in an entierly predictable fashion.
Yet another view of feedback is as distortion multiplier, in other words distortion energy as such is not actually reduced, merely high levels of low order distrotion are converted into low levels of high order distortion which is hoped will be below the error band and other noise.
On another note, electrons do not travel through wire or semiconductors at lightspeed (or even at an appreciable fraction of it), what travels are EM Waves, electrons as such travel through solids at speeds in the region of a few meters per second....
Sayonara
PS, I am not saying "feedback does not work", on the contrary, merely that it's proponents rarely explain the sideeffects and drawbacks in detail. |
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| AcidOrangeJuice |
| quote: | Originally posted by janneman
...all those millions of years I have been building equipment with feedback, it worked everytime. All the time. Exactly as predicted. Exactly as calculated... |
What this is exactly my point and my experience too. I have at least 10 years designing and building audio amplifiers; and all the time this has worked perfectly. With negative feedback is possible with relative cheap components and basic topologies working altogether to build an accurate and stable Hi-Fi audio amplifier; with flat frequency response, ultra low distortion (<0.1%), high damping factor and excelent signal to noise ratio (90db to 120db typical).
Negative feedback has been proven and verified even the death to be very successful; and has been used as a essential tool of design by engineers by decades.
The vendors of snake oil (as the guy in SteveHoffman for example) that promotes the lie that negative feedback is not good cause a big damage; and, in the end, the honest engineer is who is harmed by this. |
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| janneman |
| quote: | Originally posted by Kuei Yang Wang
Konnichiwa,
And circuits with negative feedback invariably display an "error band" (which is in other words the resut of the neccesity for an error to be present first before feedback operates), meaning a previously straight line signal becomes rather fuzzy. The error band becomes the wider the slower the circuit is. [snip] |
Thorsten,
Yes indeed there is always a cause before the effect! But I don't see the fuzziness? There is an error band, increasing with freq, or as you say, increasing the slower the circuit is (because of the increased phase shift, NOT because of some mythical 'delay').
But that error band is fully defined, theoretically, and can be measured in practise. It is not fuzzy, it is a continuous, smooth function showing the delta between what we would like and what we have.
The only case I can understand some 'raggedness' is when the system is on the verge of instability and the delta function becomes oscillatory, swinging around the 'average' value so to say.
Jan Didden |
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| phase_accurate |
IMO NFB is a powerful tool but by no means a cure-all.
Regards
Charles |
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| janneman |
| quote: | Originally posted by phase_accurate
IMO NFB is a powerful tool but by no means a cure-all.
Regards
Charles |
NOTHING ever is a cure-all...
Jan Didden |
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| SY |
| quote: | | Wait a minute! Electricity is the flow of positive charges!!! |
You understand, of course, that light is NOT the presence of photons, but rather, the absence of darkons. I'm awaiting the call from Sweden.
Actually, if you stick two electrodes in an acidic solution, the net current actually is due to the motion of positive charges.
| quote: | | On another note, electrons do not travel through wire or semiconductors at lightspeed (or even at an appreciable fraction of it), what travels are EM Waves, electrons as such travel through solids at speeds in the region of a few meters per second.... |
How about DC?
In reality, it's useless to talk about electron speed, just as it's useless for me to worry about how long it takes water to get to me from the reservoir/treatment plant when I open the tap in my kitchen. |
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| janneman |
| quote: | Originally posted by SY
You understand, of course, that light is NOT the presence of photons, but rather, the absence of darkons. I'm awaiting the call from Sweden.
Actually, if you stick two electrodes in an acidic solution, the net current actually is due to the motion of positive charges.
How about DC?
In reality, it's useless to talk about electron speed, just as it's useless for me to worry about how long it takes water to get to me from the reservoir/treatment plant when I open the tap in my kitchen. |
How about this Stuart, can a shadow move faster than light?
Jan Didden |
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| classd4sure |
Hi Acid et al,
Acid, welcome fellow troublemaker. I've been banned from everywhere, expect here. Just one example would be an ATI support forum. I was having stability issues with a new game and suspected the recommended drivers were at fault. Fanboys attacked. Some self professed guru who worked in his brothers PC shop and who fixed all his conflicts by freely swapping hardware off the shelf, got under my skin, insisting my PC that met or exceeded min requirements all had to be replaced.
The mods gave me fair warning I was headed for a ban, my reply was that if that's the extent of their help, _please_ ban me. They banned us both. I had a total of less then ten posts and he had over a thousand. I was only there to get a problem solved though. The updated patch was released that same week and solved all my issues :)
I've walked the line a few times here, but never crossed it with both feet... you just get passionate about certain things.
I think there's a few other things that make this place work.
The common goal in our quest for the ultimate audio experience.
Our disgust for snake oil, those who thrive on it, and those who are unwilling to see beyond it.
Tolerance for all who are making an effort to better their knowledge, project, whatever, basically the lesser skilled such as myself.
Marketing is frowned upon, which I think keeps snake oil at bay, along with the diligence of the people when it does rear its head.
I don't blame the guy for banning you, I'm surprised that you seem surprised by it, maybe you don't have the experience getting banned I do I don't know. Maybe you'd hoped he could defend his stance a little better?
You went to his turf and muddied the waters. Your intentions were good from our point of view, but from his, you may as well have been stealing food off his table. I applaude your efforts.
On a different note, all the above posts about feedback and control theory brightened my morning. Good stuff! Too good for a thread of this nature, I fear it will get burried, as most out of the box thinking typicall does.
Cheers,
Chris |
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| SY |
| quote: | Originally posted by janneman
How about this Stuart, can a shadow move faster than light?
Jan Didden |
Yes, it can. It doesn't transmit information. |
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| janneman |
| quote: | Originally posted by SY
Yes, it can. It doesn't transmit information. |
Hmmm.... |
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| SY |
| Should I draw a picture of an example? Or just propose a gedankenexperiment? |
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| janneman |
| quote: | Originally posted by SY
Should I draw a picture of an example? Or just propose a gedankenexperiment? |
Oh, I can do both, it's just I am not sure that it would conform to reality (whatever that is). An obvious case would be a beam of light and an object moving through it at close to the speed of light. If the shadow of that object is shown on a surface very far away, you can calculate that with finite speed and distances, the shadow would move faster than light speed. But would it?
Jan Didden |
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| SY |
Here's an easier one. Consider two objects, each a light year from Earth and a light year from one another, froming an equilateral triangle. Now turn on a laser pointed at object 1. Swing it in an arc 60 degrees to hit object 2. Though delayed by a year, the "spot" of light would be seen to move from object 1 to object 2 at many times the speed of light. It transmits no information from 1 to 2, so there's no relativity violation.
With a source that subtends 60 degrees, you can see a similar example but with a shadow by moving your hand across the source at very much less than light speed. |
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| janneman |
SY in your eample it would take an observer on earth a year to realise the spot has moved from #1 to #2, no? That is just lightspeed, not more (1 lightyear in 1 year, by definition).
In my example, the moving shadow, the question arises, which observer sees it move faster than light: the observer at the lighthouse, the one at the place where the shadow strikes, another one or none? We are talking relativistic speeds & distances so somewherew a time-dilution would occur, no?
Jan Didden |
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| SY |
Yes, there's a year delay, but once that year is over, the observer sees the spot move from 1 to 2 in seconds.
(edit: actually, a two year delay...) |
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| classd4sure |
| Seems as if A had a link to B and you swing the beam along that link it would also transmit information and be faster than light.. an illusion. It's not really travelling from A to B though, is it? |
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| janneman |
| quote: | Originally posted by classd4sure
Seems as if A had a link to B and you swing the beam along that link it would also transmit information and be faster than light.. an illusion. It's not really travelling from A to B though, is it? |
That was my problem. It would take one year for the observer to see the dot move from A to B: He would see it at A, and then after the spot goes to B it takes a year until the image of the spot on B gets to him. So, it takes a year to see a change in position of one lightyear -> lightspeed, not more. Right?
Jan Didden |
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| classd4sure |
Hmmm, I think what's being neglected is the point of origin. The point of origin is never A. There's one point of origin, and two travellers each having their own destinations.
So say you the observer on earth aims the light at point A for 5 seconds, then take two seconds to swing it to B and aim it there for 5 seconds more.
What you'll see in a year (wouldn't it really be two years though, it has to go there and back) is a dot on A for five seconds, and after it vanishes, two seconds later it appears on B. It's not because it went from A to B faster than light, it's because they both left from the same point of origin, two seconds apart, and hit different destinations but at equal distance.
Yeah?
Best,
Chris |
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| SY |
Chris, that's right. But, form the POV of the observer, the spot of light (something totally analogous to a shadow) moved from 1 to 2, a distance of a light year, in seconds.
If there weren't the two year delay, relativity WOULD be violated because information would be transmitted at greater-than-c. |
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| janneman |
As I said, hmmmm... My head aches, but I *think* I get it. Thanks guys. Next one's on me.
Jan Didden |
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