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YOU MUST KNOW THIS MAN
MUHAMMAD
(May peace and blessings of God Almighty be upon him) You may be an atheist or an agnostic; or you may belong to anyone of the religious denominations that exist in the world today. You may be a Communist or a believer in democracy and freedom. No matter what you are, and no matter what your religious and political beliefs, personal and social habits happen to be - YOU MUST STILL KNOW THIS MAN! He was by far the most remarkable man that ever set foot on this earth. He preached a religion, founded a state, built a nation, laid down a moral code, initiated numberless social and political reforms, established a dynamic and powerful society to practice and represent his teachings, and completely revolutionized the worlds of human thought and action for all times to come. HIS NAME IS MUHAMMAD, peace and blessings of Almighty God be upon him and he accomplished all these wonders in the unbelievably short span of twenty-three years. Muhammad, peace and blessings of God Almighty be upon him was born in Arabia on the 20th of August, in the year 570 of the Christian era, and when he died after 63 years, the whole of the Arabian Peninsula had changed from paganism and idol-worship to the worship of One God; from tribal quarrels and wars to national solidarity and cohesion; from drunkenness and debauchery to sobriety and piety; from lawlessness and anarchy to disciplined living; from utter moral bankruptcy to the highest standards of moral excellence. Human history has never known such a complete transformation of a people or a place before or since! The Encyclopedia Britannica calls him "the most successful of all religious personalities of the world". Bernard Shaw said about him that if Muhammad were alive today he would succeed in solving all those problems which threaten to destroy human civilization in our times. Thomas Carlysle was simply amazed as to how one man, single-handedly, could weld warring tribes and wandering Bedouins into a most powerful and civilized nation in less than two decades. Napoleon and Gandhi never tired of dreaming of a society along the lines established by this man in Arabia fourteen centuries ago. Indeed no other human being ever accomplished so much, in such diverse fields of human thought and behavior, in so limited a space of time, as did Muhammad, peace and blessings of God Almighty be upon him. He was a religious teacher, a social reformer, a moral guide, a political thinker, a military genius, an administrative colossus, a faithful friend, a wonderful companion, a devoted husband, a loving father - all in one. No other man in history ever excelled or equaled him in any of these difficult departments of life. The world has had its share of great personalities. But these were one sided figures who distinguished themselves in but one or two fields such as religious thought or military leadership. None of the other great leaders of the world ever combined in himself so many different qualities to such an amazing level of perfection as did Muhammad, peace and blessings of God Almighty be upon him. The lives and teachings of other great personalities of the world are shrouded in the mist of time. There is so much speculation about the time and the place of their birth, the mode and style of their life, the nature and detail of their teachings and the degree and measure of their success or failure that it is impossible for humanity today to reconstruct accurately and precisely the lives and teachings of those men. Not so this man Muhammad, peace and blessings of God Almighty be upon him. Not only was he born in the fullest blaze of recorded history, but every detail of his private and public life, of his actions and utterances, has been accurately documented and faithfully preserved to our day. The authenticity of the information so preserved is vouched for not only by faithful followers but also by unbiased critics and open-minded scholars. At the level of ideas there is no system of thought and belief-secular or religious, social or political-which could surpass or equal ISLAAM- the system which Muhammad peace and blessings of God Almighty be upon him propounded. In a fast changing world, while other systems have undergone profound transformations, Islaam alone has remained above all change and mutation, and retained its original form for the past 1400 years. What is more, the positive changes that are taking place in the world of human thought and behavior, truly and consistently reflect the healthy influence of Islam in these areas. Further, it is not given to the best of thinkers to put their ideas completely into practice, and to see the seeds of their labors grow and bear fruit, in their own lifetime. Except of course, Muhammad, peace and blessings of God Almighty be upon him, who not only preached the most wonderful ideas but also successfully translated each one of them into practice in his own lifetime. At the time of his death his teachings were not mere precepts and ideas straining for fulfillment, but had become the very core of the life of tens of thousands of perfectly trained individuals, each one of whom was a marvelous personification of everything that Muhammad peace and blessings of God Almighty be upon him taught and stood for. At what other time or place and in relation to what other political, social, religious system, philosophy or ideology-did the world ever witness such a perfectly amazing phenomenon? Indeed no other system or ideology secular or religious, social or political, ancient or modern - could ever claim the distinction of having been put into practice in its fullness and entirety EVEN ONCE in this world, either before or after the death of its founder. Except of course ISLAAM, the ideology preached by Muhammad, peace and blessings of God Almighty be upon him which was established as a complete way of life by the teacher himself, before he departed from this world. History bears testimony to this fact and the greatest skeptics have no option but to concede this point. In spite of these amazing achievements and in spite of the countless absolutely convincing and authentic miracles performed by him and the phenomenal success which crowned his efforts, he did not for a moment claim to be God or God's incarnation or Son - but only a human being who was chosen and ordained by God to be a teacher of truth to man kind and a complete model and pattern for their actions. He was nothing more or less than a human being. But he was a man with a noble and exalted mission-and his unique mission was to unite humanity on the worship of ONE AND ONLY GOD and to teach them the way to honest and upright living in accordance with the laws and commands of God. He always described himself as A MESSENGER AND SERVANT OF GOD, and so indeed every single action and movement of his proclaimed him to be. A world which has not hesitated to raise to Divinity individuals whose very lives and missions have been lost in legend and who historically speaking did not accomplish half as much-or even one tenth-as was accomplished by Muhammad, peace and blessings of God Almighty be upon him should stop to take serious note of this remarkable man's claim to be God's messenger to mankind. Today after the lapse of some 1400 years the life and teachings of Prophet Muhammad, peace and blessings of God Almighty be upon him, have survived without the slightest loss, alteration or interpolation. Today they offer the same undying hope for treating mankind's many ills which they did when Prophet Muhammad, peace and blessings of God Almighty be upon him, was alive. This is our honest claim and this is the inescapable conclusion forced upon us by a critical and unbiased study of history. The least YOU should do as a thinking, sensitive, concerned human being is to stop for one brief moment and ask yourself: Could it be that these statements, extraordinary and revolutionary as they sound, are really true? Supposing they really are true, and you did not know this man Muhammad, peace and blessings of God Almighty be upon him or hear about his teachings? Or did not know him well and intimately enough to be able to benefit from his guidance and example? Isn't it time you responded to this tremendous challenge and made some effort to know him? It will not cost you anything but it may well prove to be the beginning of a completely new era in your life. Come, let us make a new discovery of the life of this wonderful man Muhammad, peace and blessings of God Almighty be upon him the like of whom never walked on this earth, and whose example and teachings can change YOUR LIFE and OUR WORLD for the better. May God shower His choicest blessings upon him! Written by S.H. Pasha we love uoy |
YOU MUST KNOW THIS MAN
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YOU MUST KNOW THIS MAN
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YOU MUST KNOW THIS MAN
MUHAMMAD (May peace and blessings of God Almighty be upon him) You may be an atheist or an agnostic; or you may belong to anyone of the religious denominations that exist in the world today. You may be if you believe in him you will be telling us you can hear speaker cables differences lol |
YOU MUST KNOW THIS MAN
So, are you planning to blow anyone up anytime soon?
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YOU MUST KNOW THIS MAN
wrote in message oups.com... MUHAMMAD (May peace and blessings of God Almighty be upon him) You may be an atheist or an agnostic; or you may belong to anyone of the religious denominations that exist in the world today. You may be a Communist or a believer in democracy and freedom. No matter what you are, and no matter what your religious and political beliefs, personal and social habits happen to be - YOU MUST STILL KNOW THIS MAN! He was by far the most remarkable man that ever set foot on this earth. He preached a religion, founded a state, built a nation, laid down a moral code, initiated numberless social and political reforms, established a dynamic and powerful society to practice and represent his teachings, and completely revolutionized the worlds of human thought and action for all times to come. HIS NAME IS MUHAMMAD snip Yeah i know him!! he served me in the shop last week! nice chap, but he short changed me the *******!! |
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Yeah.
He floats like a butterfly & stings like a bee. That's him, ain't it? |
YOU MUST KNOW THIS MAN
Christopher A. Lee wrote:
IF NOT, WHY ARE YOU RUBBING THIS STUPIDITY IN OUR FACES? Because for some reason the phrase "live and let live" does not exist in the minds of most religious zealots. Incidentally, I had to appear in court today as a witness. I was asked if I would rather swear on the book of lies or just swear a non-denominational affirmation. I said that as a committed atheist I'd better take the latter, as the former would be meaningless. -- Glenn Richards Tel: (01453) 845735 Squirrel Solutions http://www.squirrelsolutions.co.uk/ IT consultancy, hardware and software support, broadband installation |
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Dave xxxx wrote:
if you believe in him you will be telling us you can hear speaker cables differences lol Actually, a lot of agnostics and atheists can hear speaker cable differences. There's no hocus-pocus involved, just some science that the sceptics disregard. So, you can send a sine wave down a bit of cable and it'll come out the other end as exactly the same sine wave. Guess what? Music isn't a sine wave. As for blind or double-blind testing, well, the sceptics will already have made up their mind that there's no difference, so their minds will tell them there is none. It's like the Creationist fundies who would refuse to believe in evolution even if God himself appeared before them and told them it was true. And just trying to get this vaguely back on-topic (I'm reading in uk.rec.audio atm) I seem to have acquired a pair of Chord Rumour 4 speaker cables today, at no cost to myself. Been trying them out with some interesting results. -- Glenn Richards Tel: (01453) 845735 Squirrel Solutions http://www.squirrelsolutions.co.uk/ IT consultancy, hardware and software support, broadband installation |
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On Thu, 30 Mar 2006 23:48:38 +0100, Glenn Richards
wrote: Christopher A. Lee wrote: IF NOT, WHY ARE YOU RUBBING THIS STUPIDITY IN OUR FACES? Because for some reason the phrase "live and let live" does not exist in the minds of most religious zealots. Incidentally, I had to appear in court today as a witness. I was asked if I would rather swear on the book of lies or just swear a non-denominational affirmation. I said that as a committed atheist I'd better take the latter, as the former would be meaningless. Academic really! They will believe what they wish to. Your faith or lack of it is immaterial. Make the most of an oath in court. Draw blood. Drag a few Krishna,s and Mormons into the proceedings and when you have everything settled explain that you have seen the light and converted to Jedi. HN |
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In article , Glenn Richards wrote:
if you believe in him you will be telling us you can hear speaker cables differences lol Actually, a lot of agnostics and atheists can hear speaker cable differences. There's no hocus-pocus involved, just some science that the sceptics disregard. It *would* be science if it was the result of experiments or observations conducted and documented according to the scientific method. Simple declarations of somebody's opinions, or of what they claim to be able to hear, don't count, unless there is some unbiassed and verifiable evidence in support of them. So, you can send a sine wave down a bit of cable and it'll come out the other end as exactly the same sine wave. Guess what? Music isn't a sine wave. Quite so, but it can be analysed as lots of sine waves superimposed, and they will have various amplitudes and phase angles relative to each other. And it is possible to devise test signals and measurement methods that will show when any of these properties would be significantly altered within any range of frequencies and amplitudes in which we may be interested. And that *is* science. Rod. |
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On Thu, 30 Mar 2006 23:54:06 +0100, Glenn Richards
wrote: Dave xxxx wrote: if you believe in him you will be telling us you can hear speaker cables differences lol Actually, a lot of agnostics and atheists can hear speaker cable differences. Actually no they can't, they just *believe* that they can - hence the comment. There's no hocus-pocus involved, just some science that the sceptics disregard. No, skeptics do *not* disregard science, but chicken**** clowns like you carefully avoid scientifically *proving* your wildass claims about cable sound. So, you can send a sine wave down a bit of cable and it'll come out the other end as exactly the same sine wave. Guess what? Music isn't a sine wave. It can however be represented as a superposition of many sine waves. BTW, flute and organ music pretty much *is* sine waves. As for blind or double-blind testing, well, the sceptics will already have made up their mind that there's no difference, so their minds will tell them there is none. It's like the Creationist fundies who would refuse to believe in evolution even if God himself appeared before them and told them it was true. Not the point. The point is that in a blind test, *you* can't tell the difference, and that's why you're avoiding it like the plague. And just trying to get this vaguely back on-topic (I'm reading in uk.rec.audio atm) I seem to have acquired a pair of Chord Rumour 4 speaker cables today, at no cost to myself. Been trying them out with some interesting results. Bull****. -- Stewart Pinkerton | Music is Art - Audio is Engineering Posted Via Usenet.com Premium Usenet Newsgroup Services ---------------------------------------------------------- ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY ** ---------------------------------------------------------- http://www.usenet.com |
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Glenn Richards wrote: Dave xxxx wrote: if you believe in him you will be telling us you can hear speaker cables differences lol Actually, a lot of agnostics and atheists can hear speaker cable differences. There's no hocus-pocus involved, just some science that the sceptics disregard. So, you can send a sine wave down a bit of cable and it'll come out the other end as exactly the same sine wave. Guess what? Music isn't a sine wave. All sound can be treated as though it is composed of sine waves. As for blind or double-blind testing, well, the sceptics will already have made up their mind that there's no difference, so their minds will And the non-sceptics refuse to submit themselves to it because they know what the result will be. tell them there is none. It's like the Creationist fundies who would refuse to believe in evolution even if God himself appeared before them and told them it was true. And just trying to get this vaguely back on-topic (I'm reading in uk.rec.audio atm) I seem to have acquired a pair of Chord Rumour 4 speaker cables today, at no cost to myself. Been trying them out with some interesting results. Good for you. MBQ |
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In article ,
Dave xxxx wrote: MUHAMMAD (May peace and blessings of God Almighty be upon him) You may be an atheist or an agnostic; or you may belong to anyone of the religious denominations that exist in the world today. You may be if you believe in him you will be telling us you can hear speaker cables differences lol Stereo for you. -- Member - Liberal International This is Ici God Queen and country! Beware Anti-Christ rising! Canada's New CONservatives - Same old Tory. |
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In article ,
Glenn Richards wrote: Dave xxxx wrote: if you believe in him you will be telling us you can hear speaker cables differences lol Actually, a lot of agnostics and atheists can hear speaker cable differences. There's no hocus-pocus involved, just some science that the sceptics disregard. So, you can send a sine wave down a bit of cable and it'll come out the other end as exactly the same sine wave. Guess what? Music isn't a sine wave. As for blind or double-blind testing, well, the sceptics will already have made up their mind that there's no difference, so their minds will tell them there is none. It's like the Creationist fundies who would refuse to believe in evolution even if God himself appeared before them and told them it was true. And just trying to get this vaguely back on-topic (I'm reading in uk.rec.audio atm) I seem to have acquired a pair of Chord Rumour 4 speaker cables today, at no cost to myself. Been trying them out with some interesting results. Anyone has a copy of Planet of the Spiders? -- Member - Liberal International This is Ici God Queen and country! Beware Anti-Christ rising! Canada's New CONservatives - Same old Tory. |
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In article ,
Stewart Pinkerton wrote: On Thu, 30 Mar 2006 23:13:02 GMT, (H. Neary) wrote: On Thu, 30 Mar 2006 23:48:38 +0100, Glenn Richards wrote: Christopher A. Lee wrote: IF NOT, WHY ARE YOU RUBBING THIS STUPIDITY IN OUR FACES? Because for some reason the phrase "live and let live" does not exist in the minds of most religious zealots. Incidentally, I had to appear in court today as a witness. I was asked if I would rather swear on the book of lies or just swear a non-denominational affirmation. I said that as a committed atheist I'd better take the latter, as the former would be meaningless. Academic really! They will believe what they wish to. Your faith or lack of it is immaterial. Make the most of an oath in court. Draw blood. Drag a few Krishna,s and Mormons into the proceedings and when you have everything settled explain that you have seen the light and converted to Jedi. But not until May the Fourth be with you......... -- Sounds like deadly force. -- Member - Liberal International This is Ici God Queen and country! Beware Anti-Christ rising! Canada's New CONservatives - Same old Tory. |
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YOU MUST KNOW THIS MAN
On Fri, 31 Mar 2006 14:55:34 +0100, Nick Gorham
wrote: wrote: Glenn Richards wrote: Dave xxxx wrote: if you believe in him you will be telling us you can hear speaker cables differences lol Actually, a lot of agnostics and atheists can hear speaker cable differences. There's no hocus-pocus involved, just some science that the sceptics disregard. So, you can send a sine wave down a bit of cable and it'll come out the other end as exactly the same sine wave. Guess what? Music isn't a sine wave. All sound can be treated as though it is composed of sine waves. All sound can be treated as if its composed of putty, but that still doesn't mean that it is. Dealing with waves only in the frequency domain does mean you have lost temperal (phase) information. And how exactly do you think that a cable might screw this up? And do bear in mind that the speaker itself subsequently does a heroic job of doing exactly that. d Pearce Consulting http://www.pearce.uk.com |
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Don Pearce wrote:
All sound can be treated as though it is composed of sine waves. All sound can be treated as if its composed of putty, but that still doesn't mean that it is. Dealing with waves only in the frequency domain does mean you have lost temperal (phase) information. And how exactly do you think that a cable might screw this up? And do bear in mind that the speaker itself subsequently does a heroic job of doing exactly that. d Pearce Consulting http://www.pearce.uk.com And what exactly makes you think I was suggesting it would, Don't assume what side of the fence I am on this one. I was just replying to the assumption that a FFT gives you ALL the information about a signal, and the deeper assumption that just because a model is useful, then the model is equivalent to the reality. -- Nick |
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On Fri, 31 Mar 2006 15:25:24 +0100, Nick Gorham
wrote: Don Pearce wrote: All sound can be treated as though it is composed of sine waves. All sound can be treated as if its composed of putty, but that still doesn't mean that it is. Dealing with waves only in the frequency domain does mean you have lost temperal (phase) information. And how exactly do you think that a cable might screw this up? And do bear in mind that the speaker itself subsequently does a heroic job of doing exactly that. d Pearce Consulting http://www.pearce.uk.com And what exactly makes you think I was suggesting it would, Don't assume what side of the fence I am on this one. I was just replying to the assumption that a FFT gives you ALL the information about a signal, and the deeper assumption that just because a model is useful, then the model is equivalent to the reality. But an FFT DOES give you all the information - phase as well as frequency. THe fact that the normal presentation of the data is simply a magnitude plot is neither here nor there. THe FFT is not, though, as you say, a model of reality. It is a model of what reality would look like if it were repeated for ever - it should have the word Groundhog in there somewhere. Provided you understand the depths of it, though, it is a very useful tool that can do virtually anything an audio engineer would want of it. d Pearce Consulting http://www.pearce.uk.com |
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In article , Nick Gorham
wrote: wrote: Glenn Richards wrote: Dave xxxx wrote: All sound can be treated as though it is composed of sine waves. All sound can be treated as if its composed of putty, but that still doesn't mean that it is. Indeed. Hard to see that such a 'treatment' would make much sense... Although it may have its uses for Handel's "Water Music". :-) Dealing with waves only in the frequency domain does mean you have lost temperal (phase) information. Not so. :-) You simply define the phase of each frequency component as well as its amplitude. It then follows from the standard maths methods of 'Orthogonality' that any real signal pattern (i.e. finite amplitude, duration, and bandwidth) can be fully represented as a series of sinusoidal components. Indeed, Information Theory relies on this. :-) There may be some similar maths behind 'putty theory', but if I was taught about it, it didn't stick... ;- Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
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In article , Nick Gorham
wrote: Don Pearce wrote: Dealing with waves only in the frequency domain does mean you have lost temperal (phase) information. And how exactly do you think that a cable might screw this up? And do bear in mind that the speaker itself subsequently does a heroic job of doing exactly that. d Pearce Consulting http://www.pearce.uk.com And what exactly makes you think I was suggesting it would, Don't assume what side of the fence I am on this one. I was just replying to the assumption that a FFT gives you ALL the information about a signal, and the deeper assumption that just because a model is useful, then the model is equivalent to the reality. Alas, what you said is incorrect. Please see earlier posting. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
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In article , Don Pearce
wrote: But an FFT DOES give you all the information - phase as well as frequency. THe fact that the normal presentation of the data is simply a magnitude plot is neither here nor there. It seems common to plot 'power' versus 'frequency', but in theory all an FT or FFT does is gives you a method to transform information from one form into another, nominally with no loss at all. People then may choose to discard the phase info if they so wish, but the transform can provide it. THe FFT is not, though, as you say, a model of reality. It is a model of what reality would look like if it were repeated for ever - it should have the word Groundhog in there somewhere. Actually *an* FFT (since there are various processes which can be called such) is a computational method that returns the same transformation as an FT. The advantage is computational speed. The snag is source code that may cause some head-scratching, and makes finding some typos a nightmare. :-) Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
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On Fri, 31 Mar 2006 16:23:33 +0100, Jim Lesurf
wrote: In article , Don Pearce wrote: But an FFT DOES give you all the information - phase as well as frequency. THe fact that the normal presentation of the data is simply a magnitude plot is neither here nor there. It seems common to plot 'power' versus 'frequency', but in theory all an FT or FFT does is gives you a method to transform information from one form into another, nominally with no loss at all. People then may choose to discard the phase info if they so wish, but the transform can provide it. It is just as well that phase information is preserved; if it weren't, then reversing the procedure back into the frequency domain would result in an unrecognizable signal. THe FFT is not, though, as you say, a model of reality. It is a model of what reality would look like if it were repeated for ever - it should have the word Groundhog in there somewhere. Actually *an* FFT (since there are various processes which can be called such) is a computational method that returns the same transformation as an FT. The advantage is computational speed. The snag is source code that may cause some head-scratching, and makes finding some typos a nightmare. :-) FFT, DFT - whatever. As long as the number of calculations doesn't increase exponentially with the number of points, It'll do for me. The central looped core of an FFT is fairly small, though - not too much trouble to debug. Just don't use an in-place algorithm. d Pearce Consulting http://www.pearce.uk.com |
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Don Pearce wrote:
On Fri, 31 Mar 2006 16:23:33 +0100, Jim Lesurf wrote: In article , Don Pearce wrote: But an FFT DOES give you all the information - phase as well as frequency. THe fact that the normal presentation of the data is simply a magnitude plot is neither here nor there. It seems common to plot 'power' versus 'frequency', but in theory all an FT or FFT does is gives you a method to transform information from one form into another, nominally with no loss at all. People then may choose to discard the phase info if they so wish, but the transform can provide it. It is just as well that phase information is preserved; if it weren't, then reversing the procedure back into the frequency domain would result in an unrecognizable signal. THe FFT is not, though, as you say, a model of reality. It is a model of what reality would look like if it were repeated for ever - it should have the word Groundhog in there somewhere. Actually *an* FFT (since there are various processes which can be called such) is a computational method that returns the same transformation as an FT. The advantage is computational speed. The snag is source code that may cause some head-scratching, and makes finding some typos a nightmare. :-) FFT, DFT - whatever. As long as the number of calculations doesn't increase exponentially with the number of points, It'll do for me. The central looped core of an FFT is fairly small, though - not too much trouble to debug. Just don't use an in-place algorithm. Ok, I stand corrected :-) Actually I have spent much more time dealing with DCT than anyhing else. What I notice a lot and Jim may be able to explain this, is the HiFi mags seem to often do FR plots using what they describe as a convolved inpulse analysis, I have a theory what this means, but it would be nice to have some references (ok, so I guess I could just look it up). Its mainly through playing with RIAA stages that I have become aware of the importance of maintaining phase as well as frequency response, but maybe this is old hat for you pro's. -- Nick |
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On Fri, 31 Mar 2006 17:07:23 +0100, Nick Gorham
wrote: Don Pearce wrote: On Fri, 31 Mar 2006 16:23:33 +0100, Jim Lesurf wrote: In article , Don Pearce wrote: But an FFT DOES give you all the information - phase as well as frequency. THe fact that the normal presentation of the data is simply a magnitude plot is neither here nor there. It seems common to plot 'power' versus 'frequency', but in theory all an FT or FFT does is gives you a method to transform information from one form into another, nominally with no loss at all. People then may choose to discard the phase info if they so wish, but the transform can provide it. It is just as well that phase information is preserved; if it weren't, then reversing the procedure back into the frequency domain would result in an unrecognizable signal. THe FFT is not, though, as you say, a model of reality. It is a model of what reality would look like if it were repeated for ever - it should have the word Groundhog in there somewhere. Actually *an* FFT (since there are various processes which can be called such) is a computational method that returns the same transformation as an FT. The advantage is computational speed. The snag is source code that may cause some head-scratching, and makes finding some typos a nightmare. :-) FFT, DFT - whatever. As long as the number of calculations doesn't increase exponentially with the number of points, It'll do for me. The central looped core of an FFT is fairly small, though - not too much trouble to debug. Just don't use an in-place algorithm. Ok, I stand corrected :-) Actually I have spent much more time dealing with DCT than anyhing else. What I notice a lot and Jim may be able to explain this, is the HiFi mags seem to often do FR plots using what they describe as a convolved inpulse analysis, I have a theory what this means, but it would be nice to have some references (ok, so I guess I could just look it up). Its mainly through playing with RIAA stages that I have become aware of the importance of maintaining phase as well as frequency response, but maybe this is old hat for you pro's. The thing about impulse analysis is that it results in something that is visually very easy to understand. Convolution is just a mathematical trick for subjecting a signal to some sort of fequency-dependent transformation. Roughly speaking, convolution of a signal and a response in the time domain is equivalent to FFTing them both into the frequency domain, multiplying them together point-by-point and then re-FFTing them back to the time domain. As for things like RIAA correction, it uses what is called a minimum phase response. What this means is that each amplitude value has a unique and unambiguous phase associated with it. In practice, what this means is that you don't have to worry about it. Get the amplitude right, and the phase will follow. d Pearce Consulting http://www.pearce.uk.com |
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In article ,
Glenn Richards wrote: Dave xxxx wrote: if you believe in him you will be telling us you can hear speaker cables differences lol Actually, a lot of agnostics and atheists can hear speaker cable differences. There's no hocus-pocus involved, just some science that the sceptics disregard. The science is called psychology and it's called "The emperor's new clothes syndrome" -- Stuart Winsor From is valid but subject to change without notice if it gets spammed. For Barn dances and folk evenings in the Coventry and Warwickshire area See: http://www.barndance.org.uk |
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On Fri, 31 Mar 2006 14:55:34 +0100, Nick Gorham
wrote: wrote: Glenn Richards wrote: Dave xxxx wrote: if you believe in him you will be telling us you can hear speaker cables differences lol Actually, a lot of agnostics and atheists can hear speaker cable differences. There's no hocus-pocus involved, just some science that the sceptics disregard. So, you can send a sine wave down a bit of cable and it'll come out the other end as exactly the same sine wave. Guess what? Music isn't a sine wave. All sound can be treated as though it is composed of sine waves. All sound can be treated as if its composed of putty, but that still doesn't mean that it is. Dealing with waves only in the frequency domain does mean you have lost temperal (phase) information. Sampling techniques such as PCM digital audio accurately maintain all phase relationships within the frequency band of interest, they do not operate only in the frequency domain. -- Stewart Pinkerton | Music is Art - Audio is Engineering Posted Via Usenet.com Premium Usenet Newsgroup Services ---------------------------------------------------------- ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY ** ---------------------------------------------------------- http://www.usenet.com |
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On Fri, 31 Mar 2006 17:07:23 +0100, Nick Gorham
wrote: Its mainly through playing with RIAA stages that I have become aware of the importance of maintaining phase as well as frequency response, but maybe this is old hat for you pro's. The *vast* majority of RIAA stages are of minimum phase design, so that if you have the amplitude response correct, then the phase response *must* be correct. -- Stewart Pinkerton | Music is Art - Audio is Engineering Posted Via Usenet.com Premium Usenet Newsgroup Services ---------------------------------------------------------- ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY ** ---------------------------------------------------------- http://www.usenet.com |
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Stewart Pinkerton wrote:
Sampling techniques such as PCM digital audio accurately maintain all phase relationships within the frequency band of interest, they do not operate only in the frequency domain. Yes, I know that, its was the additional transform that I was refering too. -- Nick |
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"Nick Gorham" wrote in message ... Its mainly through playing with RIAA stages that I have become aware of the importance of maintaining phase as well as frequency response, but maybe this is old hat for you pro's. -- Nick Hi Nick. The replay phase is specified for RIAA but you will seldom see it quoted in hi-fi literature. It is of course the inverse of the cutter head. phase response. It is quoted in data from Neumann, Lyrec, Decca, Westrex etc, and you can also find it, together with tabulated gain vs frequency in Morgan Jones pp355. Iain |
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In article , Don Pearce
wrote: On Fri, 31 Mar 2006 17:07:23 +0100, Nick Gorham wrote: What I notice a lot and Jim may be able to explain this, is the HiFi mags seem to often do FR plots using what they describe as a convolved inpulse analysis, I have a theory what this means, but it would be nice to have some references (ok, so I guess I could just look it up). TBH I am often not quite sure *what* magazine reviewers mean when they make statements like the above. All to often their results, and their interpretation of them, seem rather odd... :-) e,.g in this context I am weary of 'spectra' of broadband noise that have the vertical axis labled as a 'voltage' or a 'power' when it should be in units like 'power/Hz', and they give no info on how many samples, etc, were used to work out the spectrum. Thus making the plotted values meaningless... Its mainly through playing with RIAA stages that I have become aware of the importance of maintaining phase as well as frequency response, but maybe this is old hat for you pro's. The thing about impulse analysis is that it results in something that is visually very easy to understand. The use of 'impulses' to excite systems is, conceptually, a neat one. The snag is that it may require either very high peak powers, or 'infinite' peak powers! As such, it can lead to problems with nonlinear systems since the output then may not be what you'd have found using signals with a much lower peak level. Hence you may find that a frequency response obtained this way isn't the same as you'd got from a swept sinewave, or quasi-random 'wideband noise'. IIRC for this reason, although adopted enthusiastically at first for loudspeaker analysis, it is now used with care. Ditto for MLSSA which can give similar problems if not used with due care. The key point is that the 'impulse' has a predefined spectrum. i.e. it can be used to inject, 'symultaneously' a range of frequencies with a defined set of amplitudes and phases. You can then use the result to determine the entire spectral response. Convolution is just a mathematical trick for subjecting a signal to some sort of fequency-dependent transformation. Roughly speaking, convolution of a signal and a response in the time domain is equivalent to FFTing them both into the frequency domain, multiplying them together point-by-point and then re-FFTing them back to the time domain. More generally, convolution means 'scanning' one pattern across another and working out the result as a function of the 'offet' between them. The resulting pattern is the 'convolution' of the two which have been 'convolved'. The snag here is that people often want to do the 'inverse convolution' and try to work out what one of the 'original patterns' was from knowing the convolution and one of the inputs patterns. This is sometimes formally impossible. An area where astronomers and others sometimes rely on 'inspired guesswork'... :-) It is useful in this context for working out power spectra or correlations. The basaic details of all this and FT's, etc are IIRC all in the original Blackman & Tukey (spelling?) papers that were published in the Bell System Tech J. ages ago, then published as a book (Dover?). Used by many IT and analysis engineers as the foundation of work in this general area of analysis. Alas, the emphasis of the above book is pretty mathematical, and doesn't really explain examples that would be relevant here. I'm not sure what source I'd recommend for this. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
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On Fri, 31 Mar 2006 21:04:03 +0300, "Iain Churches"
wrote: "Nick Gorham" wrote in message .. . Its mainly through playing with RIAA stages that I have become aware of the importance of maintaining phase as well as frequency response, but maybe this is old hat for you pro's. -- Nick Hi Nick. The replay phase is specified for RIAA but you will seldom see it quoted in hi-fi literature. It is of course the inverse of the cutter head. phase response. It is quoted in data from Neumann, Lyrec, Decca, Westrex etc, and you can also find it, together with tabulated gain vs frequency in Morgan Jones pp355. Unnecessary, as RIAA preamps are minimum-phase designs. If you get the amplitude response right, then the phase *must* be correct. You'd think a 'recording engineer' and 'amplifier designer' would know this. -- Stewart Pinkerton | Music is Art - Audio is Engineering Posted Via Usenet.com Premium Usenet Newsgroup Services ---------------------------------------------------------- ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY ** ---------------------------------------------------------- http://www.usenet.com |
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