>This is much safer. However, in C++, this >problem simply wouldn't exist because structs >are typically never used and classes have >constructors that always initialize them >properly and user doesn't have to care so much >about possible changes in the classes.
Sure, always, if you've bothered to take the time to write your constructor, copy constructor, and destructor to properly initialize, manage, and delete your data structures.
There's nothing inherently secure about default constructors, and it's just as easy to create a bug in your own constructors than it is in the rest of your code.
It's the natural scanline frequency of the horizontal refresh rate of the monitor. For television, it's a constant frequency, so the pitch really only changes volume based on the brightness of the screen.
For multisync non-interlaced monitors, the refresh rates change based on your resolution, hence the change in pitch. Of course, whenever there are sharp lines on the screen (especialy TV screens), you'll really start to hear harmonics of the vertical refresh rate as well!
The cause is the high voltages that are used in order to bend the electron beam toward the aperture grill on the screen. The constant changing of voltages causes minute vibrations throughout the entire system that can be heard as an audible whine.
I wish that they would come out with a TV with active noise reduction for those predominant frequencies. Doesn't seem like it would be too difficult a task, heck you might even be able to do it with the speaker on the TV! I'd be willing to pay the extra $50-$100 mark-up for a feature like that... (even though the circuitry probably won't cost more than $0.99)...
No one validates them. Never believe what's printed on the box. That's one of the big differences between 'proferssional' equipment and 'consumer' equipment. Professionals need to know this information, and so that line of products usually includes very details specifications, including the methods used to make those measurements.
For example, speakers are usually given a frequency range in their specifications. Consumer speakers often tout 20Hz-20kHz covering the full range of human hearing. But they don't tell you that the output of the speaker can fluctuate wildly across that range. A professional speaker will give detailed plots and graphs covering the frequency output that can be expected, as well as how that output changes depending on what angle to the speaker you're listening from. Also, you will be able to expect what kind of equipment and measuring scheme was used to gather that data.
Remember all those lab reports you skimped on in college? you can bet there's one about 50 pages thick for just about every piece of professional equipment you can find. Consumer equipment is cheap because the manufacturers don't necessarily research the development, materials, and the manufacturing techniques of their products nearly as much. Either that, or they take an existing product and replace all the components with drastically cheaper counterparts -- same technology, different quality.
Basically, don't believe anything you read. Decibel readings for sound pressure level (SPL) don't mean anything unless they tell you exactly what frequency range and weighting procedure they used, as well as the relative positions and orientations of the source and receiver.
As far as the decibel argument is concerned, only one link above has given some detail into the situation. Decibel ratings are defined as 10*log(I/I0), where I0 is the sound pressure intensity at the threshold of human hearing. If you double intensity, your equation becomes 10*log(2)= 3.0102999dB... But the volume we hear is proportional to the square of the intensity, therefore volume (derivation omitted) = 20*log(v/v0), so a doubling of volume = 6.0205999dB...
We usually just approximate to 3dB and 6dB when discussing the matter.
Amazing... The week after I finish my undergraduate research project on this, there's a slashdot article covering the technoogy. If anyone wants to check out the kind of code needed to compute stereographic holograms in realtime, check it out. It's not very pretty at the moment (I may clean it up after I get the degree...), but it works! Paper and documentation forthcoming...
One of the postulates of General Relativity concludes rather elegantly that light is affected by gravity in exactly the same manner that any other mass is. Since mass is energy, and light is energy, gravity has the same effect. The explanation is actually quite a bit more complicated than that, but that is the conclusion you can derive.
So basically, if you drop a cannonball in a vacuum and fire a photon off at the same time, the light will fall at the same rate as the cannonball. Unfortunately, light travels so FREAKIN' fast, that you'd never be able to observe this phenomonon. One of the cooler 'thought proofs' I've ever heard in college, though...
Actually, all the case, gender, and plural aspects of our languages are direct stems from Latin. So why isn't Latin a required language anymore? People usually study a European language as a second language because many of its forms are still fairly close to their Latin forms. Latin is a 'dead' language, but it should still be studied because it's practically impossible to know anything about Latin without a very strong understanding of grammar. English is the laziest of all European languages, as a result of its speakers dropping and shortening any difficult to pronounce words or phrases. We also at some point decided that gender was too complicated in our language, so we just threw it all out. At one point, all the germanic languages were much more similar than they are now. English has always been 'adjusted' over the years because of its extended dialects and overuse of slang.
This is simply not true... Or at least, not *as* true as the posters comments would lead you to believe.
Lossy formats do have their drawbacks, but the reason we use them is because we can forgive a small loss in quality that for most is completely inaudible. If you want to know exactly what information is lost between compression and decompression, go ahead and encode a wav file, and decode back to a wav. Invert one of the waveforms in any decent audio editing app, and add the two wavs together. The result would be the information you've lost. I'm willing to bet that for most peoples' stereo systems, this audio information lies well beneath the noise floor of their audio chain. In other words, this is distortion you'd probably never hear, and chances are, you don't care either way. If you did, you wouldn't be listening to mp3 files.
Now whether or not a re-encoding to ogg is going to distort sound even more is another matter. The answer is yes, of course it will. But saying that mp3 and ogg throw away 'different' pieces of information is moot, because both encoding processes have to be decompressed back to the original wav stream in order to be furter processed. Even though you've lost some fairly inaudible information, you're going to be re-encoding a fresh wav stream. The point of the decompression is to put all that 'missing' audio data back in to the stream. The only thing you'll be re-encoding is the very slight distortion caused by the initial encoding/decoding process.
So convert away. I'm not sure exactly how mp32ogg works, but I'm assuming it's basically just a script-like process that includes an mp3 decoder and an ogg encoder.
If you are an audiophile, you're listening to the noise, not the music... If you're a musician, you're listening to the performance, not the noise, and if you're the other 90% of the world, you're going to be just happy with either format.
~Loren
Re:Completely Explainable...
on
Time Travel
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· Score: 1
That's all we do for any other dimension in space-time - Measure change. Time is just a difference. Unfortunately, things don't seem to work out quite right in the universe if time doesn't get some special attention. It's definitely not the same thing as space. It's too closely related to the nature of light.
Seriously, that depends on your budget and the kind of equipment you're using. Mic cables out on the studio floor should be as robust as possible, whereas multicable that stays behind your equipment, or is permanently run through walls and such can be a little more relaxed on the reinforcement. If you pick a distributor and order enough cable through them for your entire studio, you may be able to bargain a discount. The last venue I worked in used Belden multicable for all permanent runs, and Whirlwind snakes and cables on the floor. Speaker runs, if you're curious, were 12 gauge stranded copper pair made by West Penn Wire.
I made all the fiber interconnects myself, even though I doubt they'll be used in the near future. Past that, we just made whatever cables we needed. I trust my cables more anyways. That way I know they were stripped and soldered with love and care;-).
I didn't mention the actual reason for the 'directional cable' in my previous post. It seems that the 'direction' is there to indicate which side of the cable the shielding is connected to. It's common practice to disconnect the shielding at once end of a cable in certain instances to alleviate ground loop hum. The shielding still shields RF, but noise-carrying current won't flow between equipment. This is only a solution for a balanced signal. Usually it just indicates that your setup has poor grounding to start with, or that you've got a poorly designed piece of equipment somewhere. Sometimes it is very necessary, like in some temporary live sound reinforcement installations, where you can't go through and optimize ground paths.
"From my experience much of the snippy reaction from engineers when it comes to audiophiles stems from the fact that audiophiles have a tendency of describing experiences with certain setups in emotional terms rather than analytical ones. You will hear things like "warm", "bright", "harsh", "muddy" and "crisp" because these feelings are often more effective at communicating what is a fairly complicated mixture of technical issues succinctly. Additionally audiophiles have different tastes."
I think you'll find that audio engineers use these terms more than anyone else. Words like 'bright', and 'muddy, etc., refer to a specific problem with the equalization of a recorded sound. As far as audiophiles having different taste, I'd say that that's best summed up by a quote I heard somewhere "Audiophiles don't listen to the sound, they listen to the noise."
Just to keep people from making overgeneralized statements about engineers, I'll offer this other observation: Engineers will always think that the audiophile market is a joke -- probably even many of those that make and design such equipment. The reason is fairly personal to many engineers. People spend a large portion of their life studying the construction and use of professional audio gear. Some people even take the time to learn about the physics that governs the nature of the sounds we are trying to reproduce. Professional audio engineers work everyday with the best of the best equipment, or at least the equipment that's best suited for a particular task. We know all about the engineering that goes in to componenents, especially cables and interconnects. We also, god forbid, every once in a while have to go out and make a purchase to install new equipment in a studio or concert venue. We will buy the best cable that is optimized for the task we will use it for. The animosity comes from the fact that the audiophile community makes these outlandishly overpriced purchases, and then proceeds to advertise that their equipment is somehow better than any professional equipment you can buy? Well, I'm sorry, but if audiophile equipment actually reasonably increased the quality of sound, you can be assured that the professional market would have been involved, and you'd find that kind of gear in studios and venues all over the world.
For the price that some audiophiles spend on their home stereo equipment, they could own their own professional recording studio. Or better yet, plane and front row concert tickets to every show they could possibly ever want to see.
As far as groups that aren't around to hear anykmore? Well, you're not gonna find any recordings with enough fidelity to make use of any 'audiophile' gear anyways.
With that, I would hope that people would go to an audio engineer for a question about a certain piece of equipment, including cable, not an audiophile.
People seem to forget that a digital signal still has to be carried over, and stored on, analog media. Those pits that store your 'digital' audio have distinct edges and variations in depth. The laser diodes that record and read the data also has a 'shape' to the digital signal it produces. The power output of the laser determines how fast the pit is 'burned' into the disk, which coupled with the rotational speed of the moter produces a varying pit shape. The frequency and linewidth of the light from the laser diode varies from player to player, and from recorder to recorder. The detector that reads off the reflected data from the disk also has its own response curve, probably nonlinear, as well as its own transient response.
The main benefit of digitally encoded information is that there is a wide range of input variables for which the output signal will be exactly the same. There are many factors that will affect the encoding and decoding of a digital signal, especially when it has to be processed through something like a CD - an optical medium.
So let's think: Sound pressure -> microphone transducer -> A/D converter -> optical transducer -> CD storage medium -> optical transducer -> D/A converter -> amplification -> speaker (still a transducer) -> Sound Pressure...
That's a lot of energy transformation. We can fairly safely believe that any changes to the digital signal will occur at the point of the transducers. Now all you have to do is believe that the optics and laser circuitry are the first place that the cost engineers are going to start trimming from when the plans leave the design engineers' desks, and you'll be well on your way to understanding why getting a true digital copy from CDs is so difficult.
If that doesn't convince you, ask yourself why they wasted so much space on error correction data in the format to start with. I think it's safe to assume that the very presence of those error correction codes tells us that the people that designed the standard were some VERY smart cookies, and they know a helluva lot about digital optical systems, and just how fragile they can be. I for one am amazed of how much we've actually been able to accomplish with light, and I spent a large portion of my life studying electro-optics.
Of course, the irony of the whole development is that 99% of audio piracy going on today I can barely accept as being 'music' in the first place...
Then again, I just heard that Johannes Brahms is now asking Napster to filter all of his works from their servers, as it's costing him millions in loss of... oh, never mind...
Basically, all a cable does is carry a signal from one point to another. All wire introduces resistive and capacitive effects on an electrical signal due to the physics of how electrons bounce around in there. A cable's use is specified by:
1) Impedence/Resistance.
2) Power rating.
3) Electro-magnetic shielding.
4) Resiliance to abuse.
5) Quality of connectors.
There are relations between these specifications. A cable with more shielding will tend to take more abuse before breaking. A cable with a lower resistance will usually have a larger cross-sectional area, and will also have a higher power rating. In coaxial cable, the application of the cable normally determines its impedence, and the amount of shielding you need will change the overall design of the cable.
Speaker cables have an almost unnnoticeable impedence unless you're making runs of thousands of feet. They have no shielding because normal outside electrical interference will never produce a large enough current to move a speaker magnet. Run any tests you want: I promise you that a run of 10 or 12-gauge extension cord electrical cable from your local hardware store will perform just as well on ANY amp/speaker setup as equivalent Monster cable will. The 'skin effect' is laughably negligable at the voltages we're dealing with, especially in the 20Hz-20kHz frequency range. (Don't believe me? I've done the math... You do it, and we'll compare results).
Unfortunately, aside from power loss through length or impedence mismatch, the quality of a cable is almost always dominated by the quality of the connector. In pro audio, you pay for the amount of abuse the cable will take, and for the quality of the connectors. Almost all signal loss in an audio chain takes place at the point of connection between a cable and a device. Be wary of salespeople trying to sell you on the 'gold plated' connectors. Gold is a very inert metal, and is resistant to corrosive effects, but you will not 'hear' a better signal unless the device you're plugging it in to has gold connectors as well.
If you're dealing with analog video, your eyes are much more sensitive to interference due to inadequate shielding than your ears are. Video cables tend to be much beefier than their audio counterparts in order to minimize RF interference. Just about all the interference that most people will 'hear' in an audio system is hum and buzz due to noise caused by AC power. And even then, this is usually caused by ground loops and poorly grounded equipment rather than interference.
So don't believe the hype. But also don't believe that there's not a lot of very complicated electrical engineering going on in cable design. Rest assured, the engineering was not intended for your stereo. Monster Cable uses a genius marketing scheme to exploit the paranoia of consumers that they're buying 'inferior' equipment.
I will give them this - they make some damn strong cables and connectors. But honestly, how often have you stepped on a cable going from the back of your CD player to your amplifier?
Just another audio engineer who's always willing to burst the bubble of a potential 'Audiophool',
"It will reduce the 'skin effect' for better sound, and the arrows on the side indicate that it should be plugged in in that direction, because the electrons flow better that way." -- pimply 18 year old at The Good Guys
Very good observation!! I'd mod you up if I could...
This, for those curious, would be an analysis of the amplitudes of the common modes of vibration of the system. In our case, we have a synchronous mode and an antisynchronous mode. The state of the system in any point (moving back to linear systems for simplicity) is a linear superposition of these two modes. The synchronous mode causes the coupling mass to move, thus causing loss of energy in this mode due to heat. The amplitude of this frequency (yes, these two modes WILL have slightly different frequencies) of vibration will diminish exponentially due to these losses. The antisynchronous mode, however, creates no net force on the supporting mass, therefore the only losses are due to friction at the pivot, and in the air.
The interesting thing to note is that if you place many many clocks on a wall, over time they will all become synchronized. some may be 180 degrees out of phase, but they all seem to lock in to the slight vibrations transferred through the wall.
And for everyone's food for thought, the above post is correct about ALL systems tending toward greater disorder in an effort to reduce energy. pendulums, planets, electronics, biology, chemistry... You can't escape that fact, which is why it is one of the *laws* of thermodynamics.
With only two bodies, the only nonlinearities is in the motion of the pendulum itself (usually there is a small angle approximation applied to the formula in order to solve the system linearly). With two linear bodies, there is always a simple solution. You can predict the behavior of the system for all time.
However, a nonlinear dynamics sneaks in whenever you have three or more interacting bodies. A planet orbiting a sun is a very simple linear system. The planet has an elliptical orbit, and will continue to stay in that orbit as long as the parameters of the system do not change. As soon as you throw a third body into the mix, the system will show some very chaotic properties, with the different gravitational fields (all 'linear', as far as we're concerned) interacting in very unpredictable ways. Throw more interactions into the equation - linear or not - and you only increase the degrees of freedom.
I really hate to cause anything remotely flame-related, but this is one of the poorest examples of good physics and reasoning I've come across...
I'm not gonna say that it's wrong (ahem...), but without examining resonance and vibrational coupling, you have no way to explain your 'noise'. Energy will be transferred whether something is at rest or not... You can't stop it.
We really have no clue how any action at a distance works. There's plenty of hypotheses out there, but nothing with a shred of proof.
Doesn't mean they're wrong though... Who knows, the explanation with the most truth could involve tiny little quantum midgets on horseback sending messages between particles...
It's a very difficult problem to model. It involves two pendulums (both of which, despite what many of your freshmen physics professors told you, are nonlinear oscillators), and a coupling mass.
The coupled oscillators are difficult enough to model by themselves. I wrote a paper once on coupled physical pendulums. After quite a bit of very complicated physics involving Hamiltonians and Lagrangians and other silly names, I managed to derive an equation that describes the motion of the two pendulums in terms of the 'normal modes' of oscillation (these are closely related to the 'in phase' and 'out of phase' vibrations). Needless to say, the equation took up a good 3 lines in the report. I should have just put it in an appendix.
Now if you add a coupling mass between them, you're talking about an even MORE complicated problem, because the inertia of the coupling platform affects the resonance of the pendulums. It's very much like an inductor in electronics. It doesn't allow energy transfer to happen directly through the two pendulums, because a pendulum has to push the whole mass in order to get energy over to the other pendulum. I would imagine, just through experience in nonlinear systems, that increasing and decreasing this mass will have yet more nonlinear effects on the system (such as the complete stopping of one pendulum, although the article was unclear as to whether this was a complete halt, or just momentary).
You'll find very little chaos in this system, unless the pendulums are started at a very large height. Also, like most undergraduate physics, this analysis completely ignores the effects of friction, which is where the only true energy 'loss' would happen.
Slashdot Mirror
>This is much safer. However, in C++, this
>problem simply wouldn't exist because structs
>are typically never used and classes have
>constructors that always initialize them
>properly and user doesn't have to care so much
>about possible changes in the classes.
Sure, always, if you've bothered to take the time to write your constructor, copy constructor, and destructor to properly initialize, manage, and delete your data structures.
There's nothing inherently secure about default constructors, and it's just as easy to create a bug in your own constructors than it is in the rest of your code.
~Loren
I wonder if those radio waves can somehow manage to spontaneously create some gaseous fluid capable of carrying these sound waves in space...
Food for thought...
If someone farts in space, does it make a noise???
~Loren
It's the natural scanline frequency of the horizontal refresh rate of the monitor. For television, it's a constant frequency, so the pitch really only changes volume based on the brightness of the screen.
For multisync non-interlaced monitors, the refresh rates change based on your resolution, hence the change in pitch. Of course, whenever there are sharp lines on the screen (especialy TV screens), you'll really start to hear harmonics of the vertical refresh rate as well!
The cause is the high voltages that are used in order to bend the electron beam toward the aperture grill on the screen. The constant changing of voltages causes minute vibrations throughout the entire system that can be heard as an audible whine.
I wish that they would come out with a TV with active noise reduction for those predominant frequencies. Doesn't seem like it would be too difficult a task, heck you might even be able to do it with the speaker on the TV! I'd be willing to pay the extra $50-$100 mark-up for a feature like that... (even though the circuitry probably won't cost more than $0.99)...
~Loren
15625 Hz... It's a slightly flat B-natural... I used to tune to it as a last resort when I played a lot more music than I do now ;-)
~Loren
That's great... now will someone PLEASE make a CRT without that damned high frequency whine? ;-)
My TV can be more annoying than my computer with all the fans at full blast!
~Loren
No one validates them. Never believe what's printed on the box. That's one of the big differences between 'proferssional' equipment and 'consumer' equipment. Professionals need to know this information, and so that line of products usually includes very details specifications, including the methods used to make those measurements.
For example, speakers are usually given a frequency range in their specifications. Consumer speakers often tout 20Hz-20kHz covering the full range of human hearing. But they don't tell you that the output of the speaker can fluctuate wildly across that range. A professional speaker will give detailed plots and graphs covering the frequency output that can be expected, as well as how that output changes depending on what angle to the speaker you're listening from. Also, you will be able to expect what kind of equipment and measuring scheme was used to gather that data.
Remember all those lab reports you skimped on in college? you can bet there's one about 50 pages thick for just about every piece of professional equipment you can find. Consumer equipment is cheap because the manufacturers don't necessarily research the development, materials, and the manufacturing techniques of their products nearly as much. Either that, or they take an existing product and replace all the components with drastically cheaper counterparts -- same technology, different quality.
Basically, don't believe anything you read. Decibel readings for sound pressure level (SPL) don't mean anything unless they tell you exactly what frequency range and weighting procedure they used, as well as the relative positions and orientations of the source and receiver.
As far as the decibel argument is concerned, only one link above has given some detail into the situation. Decibel ratings are defined as 10*log(I/I0), where I0 is the sound pressure intensity at the threshold of human hearing. If you double intensity, your equation becomes 10*log(2)= 3.0102999dB... But the volume we hear is proportional to the square of the intensity, therefore volume (derivation omitted) = 20*log(v/v0), so a doubling of volume = 6.0205999dB...
We usually just approximate to 3dB and 6dB when discussing the matter.
~Loren
Amazing... The week after I finish my undergraduate research project on this, there's a slashdot article covering the technoogy. If anyone wants to check out the kind of code needed to compute stereographic holograms in realtime, check it out. It's not very pretty at the moment (I may clean it up after I get the degree...), but it works! Paper and documentation forthcoming...
http://www.band.calpoly.edu/~lkeagle/holo/
~Loren Keagle
One of the postulates of General Relativity concludes rather elegantly that light is affected by gravity in exactly the same manner that any other mass is. Since mass is energy, and light is energy, gravity has the same effect. The explanation is actually quite a bit more complicated than that, but that is the conclusion you can derive.
So basically, if you drop a cannonball in a vacuum and fire a photon off at the same time, the light will fall at the same rate as the cannonball. Unfortunately, light travels so FREAKIN' fast, that you'd never be able to observe this phenomonon. One of the cooler 'thought proofs' I've ever heard in college, though...
~Loren
Actually, all the case, gender, and plural aspects of our languages are direct stems from Latin. So why isn't Latin a required language anymore? People usually study a European language as a second language because many of its forms are still fairly close to their Latin forms. Latin is a 'dead' language, but it should still be studied because it's practically impossible to know anything about Latin without a very strong understanding of grammar. English is the laziest of all European languages, as a result of its speakers dropping and shortening any difficult to pronounce words or phrases. We also at some point decided that gender was too complicated in our language, so we just threw it all out. At one point, all the germanic languages were much more similar than they are now. English has always been 'adjusted' over the years because of its extended dialects and overuse of slang.
Internet slang is no exception.
~Loren
This is simply not true... Or at least, not *as* true as the posters comments would lead you to believe.
Lossy formats do have their drawbacks, but the reason we use them is because we can forgive a small loss in quality that for most is completely inaudible. If you want to know exactly what information is lost between compression and decompression, go ahead and encode a wav file, and decode back to a wav. Invert one of the waveforms in any decent audio editing app, and add the two wavs together. The result would be the information you've lost. I'm willing to bet that for most peoples' stereo systems, this audio information lies well beneath the noise floor of their audio chain. In other words, this is distortion you'd probably never hear, and chances are, you don't care either way. If you did, you wouldn't be listening to mp3 files.
Now whether or not a re-encoding to ogg is going to distort sound even more is another matter. The answer is yes, of course it will. But saying that mp3 and ogg throw away 'different' pieces of information is moot, because both encoding processes have to be decompressed back to the original wav stream in order to be furter processed. Even though you've lost some fairly inaudible information, you're going to be re-encoding a fresh wav stream. The point of the decompression is to put all that 'missing' audio data back in to the stream. The only thing you'll be re-encoding is the very slight distortion caused by the initial encoding/decoding process.
So convert away. I'm not sure exactly how mp32ogg works, but I'm assuming it's basically just a script-like process that includes an mp3 decoder and an ogg encoder.
If you are an audiophile, you're listening to the noise, not the music... If you're a musician, you're listening to the performance, not the noise, and if you're the other 90% of the world, you're going to be just happy with either format.
~Loren
That's all we do for any other dimension in space-time - Measure change. Time is just a difference. Unfortunately, things don't seem to work out quite right in the universe if time doesn't get some special attention. It's definitely not the same thing as space. It's too closely related to the nature of light.
~Loren
Not Monster ;-)
;-).
Seriously, that depends on your budget and the kind of equipment you're using. Mic cables out on the studio floor should be as robust as possible, whereas multicable that stays behind your equipment, or is permanently run through walls and such can be a little more relaxed on the reinforcement. If you pick a distributor and order enough cable through them for your entire studio, you may be able to bargain a discount. The last venue I worked in used Belden multicable for all permanent runs, and Whirlwind snakes and cables on the floor. Speaker runs, if you're curious, were 12 gauge stranded copper pair made by West Penn Wire.
I made all the fiber interconnects myself, even though I doubt they'll be used in the near future. Past that, we just made whatever cables we needed. I trust my cables more anyways. That way I know they were stripped and soldered with love and care
~Loren
I didn't mention the actual reason for the 'directional cable' in my previous post. It seems that the 'direction' is there to indicate which side of the cable the shielding is connected to. It's common practice to disconnect the shielding at once end of a cable in certain instances to alleviate ground loop hum. The shielding still shields RF, but noise-carrying current won't flow between equipment. This is only a solution for a balanced signal. Usually it just indicates that your setup has poor grounding to start with, or that you've got a poorly designed piece of equipment somewhere. Sometimes it is very necessary, like in some temporary live sound reinforcement installations, where you can't go through and optimize ground paths.
Still pretty rediculous, though.
~Loren
"From my experience much of the snippy reaction from engineers when it comes to audiophiles stems from the fact that audiophiles have a tendency of describing experiences with certain setups in emotional terms rather than analytical ones. You will hear things like "warm", "bright", "harsh", "muddy" and "crisp" because these feelings are often more effective at communicating what is a fairly complicated mixture of technical issues succinctly. Additionally audiophiles have different tastes."
I think you'll find that audio engineers use these terms more than anyone else. Words like 'bright', and 'muddy, etc., refer to a specific problem with the equalization of a recorded sound. As far as audiophiles having different taste, I'd say that that's best summed up by a quote I heard somewhere "Audiophiles don't listen to the sound, they listen to the noise."
Just to keep people from making overgeneralized statements about engineers, I'll offer this other observation: Engineers will always think that the audiophile market is a joke -- probably even many of those that make and design such equipment. The reason is fairly personal to many engineers. People spend a large portion of their life studying the construction and use of professional audio gear. Some people even take the time to learn about the physics that governs the nature of the sounds we are trying to reproduce. Professional audio engineers work everyday with the best of the best equipment, or at least the equipment that's best suited for a particular task. We know all about the engineering that goes in to componenents, especially cables and interconnects. We also, god forbid, every once in a while have to go out and make a purchase to install new equipment in a studio or concert venue. We will buy the best cable that is optimized for the task we will use it for. The animosity comes from the fact that the audiophile community makes these outlandishly overpriced purchases, and then proceeds to advertise that their equipment is somehow better than any professional equipment you can buy? Well, I'm sorry, but if audiophile equipment actually reasonably increased the quality of sound, you can be assured that the professional market would have been involved, and you'd find that kind of gear in studios and venues all over the world.
For the price that some audiophiles spend on their home stereo equipment, they could own their own professional recording studio. Or better yet, plane and front row concert tickets to every show they could possibly ever want to see.
As far as groups that aren't around to hear anykmore? Well, you're not gonna find any recordings with enough fidelity to make use of any 'audiophile' gear anyways.
With that, I would hope that people would go to an audio engineer for a question about a certain piece of equipment, including cable, not an audiophile.
~Loren
People seem to forget that a digital signal still has to be carried over, and stored on, analog media. Those pits that store your 'digital' audio have distinct edges and variations in depth. The laser diodes that record and read the data also has a 'shape' to the digital signal it produces. The power output of the laser determines how fast the pit is 'burned' into the disk, which coupled with the rotational speed of the moter produces a varying pit shape. The frequency and linewidth of the light from the laser diode varies from player to player, and from recorder to recorder. The detector that reads off the reflected data from the disk also has its own response curve, probably nonlinear, as well as its own transient response.
The main benefit of digitally encoded information is that there is a wide range of input variables for which the output signal will be exactly the same. There are many factors that will affect the encoding and decoding of a digital signal, especially when it has to be processed through something like a CD - an optical medium.
So let's think: Sound pressure -> microphone transducer -> A/D converter -> optical transducer -> CD storage medium -> optical transducer -> D/A converter -> amplification -> speaker (still a transducer) -> Sound Pressure...
That's a lot of energy transformation. We can fairly safely believe that any changes to the digital signal will occur at the point of the transducers. Now all you have to do is believe that the optics and laser circuitry are the first place that the cost engineers are going to start trimming from when the plans leave the design engineers' desks, and you'll be well on your way to understanding why getting a true digital copy from CDs is so difficult.
If that doesn't convince you, ask yourself why they wasted so much space on error correction data in the format to start with. I think it's safe to assume that the very presence of those error correction codes tells us that the people that designed the standard were some VERY smart cookies, and they know a helluva lot about digital optical systems, and just how fragile they can be. I for one am amazed of how much we've actually been able to accomplish with light, and I spent a large portion of my life studying electro-optics.
Of course, the irony of the whole development is that 99% of audio piracy going on today I can barely accept as being 'music' in the first place...
Then again, I just heard that Johannes Brahms is now asking Napster to filter all of his works from their servers, as it's costing him millions in loss of... oh, never mind...
~Loren
Basically, all a cable does is carry a signal from one point to another. All wire introduces resistive and capacitive effects on an electrical signal due to the physics of how electrons bounce around in there. A cable's use is specified by:
1) Impedence/Resistance.
2) Power rating.
3) Electro-magnetic shielding.
4) Resiliance to abuse.
5) Quality of connectors.
There are relations between these specifications. A cable with more shielding will tend to take more abuse before breaking. A cable with a lower resistance will usually have a larger cross-sectional area, and will also have a higher power rating. In coaxial cable, the application of the cable normally determines its impedence, and the amount of shielding you need will change the overall design of the cable.
Speaker cables have an almost unnnoticeable impedence unless you're making runs of thousands of feet. They have no shielding because normal outside electrical interference will never produce a large enough current to move a speaker magnet. Run any tests you want: I promise you that a run of 10 or 12-gauge extension cord electrical cable from your local hardware store will perform just as well on ANY amp/speaker setup as equivalent Monster cable will. The 'skin effect' is laughably negligable at the voltages we're dealing with, especially in the 20Hz-20kHz frequency range. (Don't believe me? I've done the math... You do it, and we'll compare results).
Unfortunately, aside from power loss through length or impedence mismatch, the quality of a cable is almost always dominated by the quality of the connector. In pro audio, you pay for the amount of abuse the cable will take, and for the quality of the connectors. Almost all signal loss in an audio chain takes place at the point of connection between a cable and a device. Be wary of salespeople trying to sell you on the 'gold plated' connectors. Gold is a very inert metal, and is resistant to corrosive effects, but you will not 'hear' a better signal unless the device you're plugging it in to has gold connectors as well.
If you're dealing with analog video, your eyes are much more sensitive to interference due to inadequate shielding than your ears are. Video cables tend to be much beefier than their audio counterparts in order to minimize RF interference. Just about all the interference that most people will 'hear' in an audio system is hum and buzz due to noise caused by AC power. And even then, this is usually caused by ground loops and poorly grounded equipment rather than interference.
So don't believe the hype. But also don't believe that there's not a lot of very complicated electrical engineering going on in cable design. Rest assured, the engineering was not intended for your stereo. Monster Cable uses a genius marketing scheme to exploit the paranoia of consumers that they're buying 'inferior' equipment.
I will give them this - they make some damn strong cables and connectors. But honestly, how often have you stepped on a cable going from the back of your CD player to your amplifier?
Just another audio engineer who's always willing to burst the bubble of a potential 'Audiophool',
~Loren
"It will reduce the 'skin effect' for better sound, and the arrows on the side indicate that it should be plugged in in that direction, because the electrons flow better that way." -- pimply 18 year old at The Good Guys
~Loren
Move really fast...
Very good observation!! I'd mod you up if I could...
This, for those curious, would be an analysis of the amplitudes of the common modes of vibration of the system. In our case, we have a synchronous mode and an antisynchronous mode. The state of the system in any point (moving back to linear systems for simplicity) is a linear superposition of these two modes. The synchronous mode causes the coupling mass to move, thus causing loss of energy in this mode due to heat. The amplitude of this frequency (yes, these two modes WILL have slightly different frequencies) of vibration will diminish exponentially due to these losses. The antisynchronous mode, however, creates no net force on the supporting mass, therefore the only losses are due to friction at the pivot, and in the air.
The interesting thing to note is that if you place many many clocks on a wall, over time they will all become synchronized. some may be 180 degrees out of phase, but they all seem to lock in to the slight vibrations transferred through the wall.
And for everyone's food for thought, the above post is correct about ALL systems tending toward greater disorder in an effort to reduce energy. pendulums, planets, electronics, biology, chemistry... You can't escape that fact, which is why it is one of the *laws* of thermodynamics.
~Loren
With only two bodies, the only nonlinearities is in the motion of the pendulum itself (usually there is a small angle approximation applied to the formula in order to solve the system linearly). With two linear bodies, there is always a simple solution. You can predict the behavior of the system for all time.
However, a nonlinear dynamics sneaks in whenever you have three or more interacting bodies. A planet orbiting a sun is a very simple linear system. The planet has an elliptical orbit, and will continue to stay in that orbit as long as the parameters of the system do not change. As soon as you throw a third body into the mix, the system will show some very chaotic properties, with the different gravitational fields (all 'linear', as far as we're concerned) interacting in very unpredictable ways. Throw more interactions into the equation - linear or not - and you only increase the degrees of freedom.
~Loren
I really hate to cause anything remotely flame-related, but this is one of the poorest examples of good physics and reasoning I've come across...
I'm not gonna say that it's wrong (ahem...), but without examining resonance and vibrational coupling, you have no way to explain your 'noise'. Energy will be transferred whether something is at rest or not... You can't stop it.
~Loren
Black magic... nothing more...
We really have no clue how any action at a distance works. There's plenty of hypotheses out there, but nothing with a shred of proof.
Doesn't mean they're wrong though... Who knows, the explanation with the most truth could involve tiny little quantum midgets on horseback sending messages between particles...
But what are the quantum midgets made out of?!?!?
Oh dear, the search never ends,
~Loren
It's a very difficult problem to model. It involves two pendulums (both of which, despite what many of your freshmen physics professors told you, are nonlinear oscillators), and a coupling mass.
The coupled oscillators are difficult enough to model by themselves. I wrote a paper once on coupled physical pendulums. After quite a bit of very complicated physics involving Hamiltonians and Lagrangians and other silly names, I managed to derive an equation that describes the motion of the two pendulums in terms of the 'normal modes' of oscillation (these are closely related to the 'in phase' and 'out of phase' vibrations). Needless to say, the equation took up a good 3 lines in the report. I should have just put it in an appendix.
Now if you add a coupling mass between them, you're talking about an even MORE complicated problem, because the inertia of the coupling platform affects the resonance of the pendulums. It's very much like an inductor in electronics. It doesn't allow energy transfer to happen directly through the two pendulums, because a pendulum has to push the whole mass in order to get energy over to the other pendulum. I would imagine, just through experience in nonlinear systems, that increasing and decreasing this mass will have yet more nonlinear effects on the system (such as the complete stopping of one pendulum, although the article was unclear as to whether this was a complete halt, or just momentary).
You'll find very little chaos in this system, unless the pendulums are started at a very large height. Also, like most undergraduate physics, this analysis completely ignores the effects of friction, which is where the only true energy 'loss' would happen.
Mod this down for overkill,
~Loren
oops, that's exactly correct... Thank you.
~Loren
FYI, the highest contrasting color scheme for text has been found to be yellow text on a black background... Yuck...
~Loren