Why speaker cables do sound different .........
You must have seen the effect that a non zero amplifier output impedance has on the 'electrical' signal across a real loudspeaker.
Most speakers have impedance that is not uniform and often varies a lot across the bandwidth . When the amplifier's output impedance starts to become significant , say upward of 0.2 ohms , the electrical frequency response across the speaker terminals is noticeably no longer flat . With speakers that have very uniform impedance this will be less.
But these variations from 'flat electical response' will be audible on many speakers . Make the source impedance complex and this will be more significant and audible. We are not even considering any possible interaction with the amplifier itself.
Complex cables have their own complex impedance and so the 'electrical response ' at the speaker terminals with different cables should be different . If this is audible on that system , it should sound slightly different with different speaker cables.
However as the cable length get shorter the differences should become too small to be audible. But though there are differences they are all departures from a 'flat ' response at the speaker terminals and hence are all in " ERROR".
The best of course will be a zero ohm ( impedance) speaker cable. Practically it should have the lowest capacitance , inductance and dc resistance that is possible.
So cables can make the sound different because they depart from ideal performance. The sound however can never be "better" than a very short speaker cable. The user might 'prefer' what he hears but that doesn't make it 'better'.
You must have seen the effect that a non zero amplifier output impedance has on the 'electrical' signal across a real loudspeaker.
Most speakers have impedance that is not uniform and often varies a lot across the bandwidth . When the amplifier's output impedance starts to become significant , say upward of 0.2 ohms , the electrical frequency response across the speaker terminals is noticeably no longer flat . With speakers that have very uniform impedance this will be less.
But these variations from 'flat electical response' will be audible on many speakers . Make the source impedance complex and this will be more significant and audible. We are not even considering any possible interaction with the amplifier itself.
Complex cables have their own complex impedance and so the 'electrical response ' at the speaker terminals with different cables should be different . If this is audible on that system , it should sound slightly different with different speaker cables.
However as the cable length get shorter the differences should become too small to be audible. But though there are differences they are all departures from a 'flat ' response at the speaker terminals and hence are all in " ERROR".
The best of course will be a zero ohm ( impedance) speaker cable. Practically it should have the lowest capacitance , inductance and dc resistance that is possible.
So cables can make the sound different because they depart from ideal performance. The sound however can never be "better" than a very short speaker cable. The user might 'prefer' what he hears but that doesn't make it 'better'.
Re: Why speaker cables do sound different .........
Ashok, nice to hear from you in this thread! I missed you!
Two comments:
If indeed what you say is true, why on earth should anybody in his right mind ever buy those 'complex cables' ??
Secondly, it is all fine and dandy to find a possible explanation of why a different cable could lead to a diffrent sound. But that is starting on the wrong side. It would be all much easier if FIRST we establish THAT there is an audible difference. In, as James Moray noted, a scientific way. That does NOT mean to come up with possible explanations. It means to establish, in a repeatable and reliable way, that there IS a difference.
Jan Didden
ashok said:
Ashok, nice to hear from you in this thread! I missed you!
Two comments:
If indeed what you say is true, why on earth should anybody in his right mind ever buy those 'complex cables' ??
Secondly, it is all fine and dandy to find a possible explanation of why a different cable could lead to a diffrent sound. But that is starting on the wrong side. It would be all much easier if FIRST we establish THAT there is an audible difference. In, as James Moray noted, a scientific way. That does NOT mean to come up with possible explanations. It means to establish, in a repeatable and reliable way, that there IS a difference.
Jan Didden
Hi Jan,
I have to say that everything may possibly make a difference in certain situations. On average, I have views on cables that are close to yours.
The other thing that should be pointed out is that some signals are more prone to be degraded than others. A speaker cable argument would have you place the amps by the speakers. The signal driving those amps are now subject to more deterioration than the high level signal would be. It's all a matter of degree. One should never lose sight of the entire system.
-Chris
I have to say that everything may possibly make a difference in certain situations. On average, I have views on cables that are close to yours.
The other thing that should be pointed out is that some signals are more prone to be degraded than others. A speaker cable argument would have you place the amps by the speakers. The signal driving those amps are now subject to more deterioration than the high level signal would be. It's all a matter of degree. One should never lose sight of the entire system.
-Chris
jn[/i] [B] No said:
As I stated, the classical definition of a transmission line has the characteristic impedance as being sqr L/C. As I also stated, that was the context I was speaking of. Invoking lump element reactance is correct within the context of lumped element analysis, this is not what I was speaking of..I made that clear, perhaps you missed that.
sagarverma said:
He is incorrect. As are you. Please allow me to explain.
The characteristic impedance of any media whatsoever, free air, waveguides, transmission lines, for the propogation of electromagnetic energy, be it TE, TM, or TEM waves, in any polarization, is defined by the storage within the media of both magnetic and electric forms of energy. The characteristic impedance is the impedance at which the energy stored is EQUAL..in other words, the equations E = 1/2 L I2 and E = 1/2 C V2 are equal to each other.
I've attached a graph showing how the capacitive and inductive storage of energy pertains to an 8 ohm load, vs the characteristic impedance of the cable. As is clearly evident, the minima occurs when the Z of the cable matches the load Z.
jn[/i] [B] When the Z of the cable matches the load said:
As I stated, when the load Z matches the cable characteristic impedance, which is sqr (L/C), the storage of energy within the cable is a minima.
Your statement that z is freq dependent is correct, but as a rebuttal to mine, it does not have any bearing.
The Z of a line has two components of dependence. First, the dielectric will have a freq dependence, I will not elaborate on the inner workings of that.
The L of a line has two simple
components of frequency dependence. The first of which is skin effect. The more a conductor skins, the lower the internal inductance...in the hf limit, there will be zero internal inductance. External inductance, however, is invariant to the skinning of the conductor of interest. It can, however, be lowered by the proximity of another conductive surface due to eddy currents within the conductor (this of course, is exactly what causes the exclusion of current density we refer to as skin effect).If you wish more in the way of explanation, I will be happy to oblige.
Cheers, John
ps...I lament having posted this graph three times here. Eventually, perhaps I'll have one of the forums host a page for me.
Attachments
Hi jneutron,
It's still a question of degree. How does the magnitude of these effects compare to the speaker? The amplifier? Between components?
There are times the effects may be significant, and times when they aren't. I am not disagreeing. I am saying that before you try to fix something, make sure it's broke first.
-Chris
It's still a question of degree. How does the magnitude of these effects compare to the speaker? The amplifier? Between components?
There are times the effects may be significant, and times when they aren't. I am not disagreeing. I am saying that before you try to fix something, make sure it's broke first.
-Chris
anatech said:
My goodness, you should wait until I finish editing all my mistakes...geeze..
You are correct..it is a matter of degree. I cannot claim audibility, nor can I claim inaudibility. Human localization capabilities are not yet fully defined. I can estimate based on ideal localization equations, leading to about 2 uSec ITD and .06 dB IID, but those are numbers based on ideal receiver capability, which we all know is not what the ears really are. The best one could hope for is the characterization of a system spacial resolution based on an area of uncertainty.
Cheers, John
Hi John,
-Chris
Edit: you know, if you read too quickly you don't get it right. I will read the link to Moer's site.
The only time that power interconnects have been seen to make a difference is when there is either something wrong with the original, or the power supply design in the equipment is poor. This is in my experience anyway, and I'm fairly open minded. I will read your article, thanks for the link.
-Chris
Edit: you know, if you read too quickly you don't get it right. I will read the link to Moer's site.
anatech said:
Wait wait wait wait..that link was not mine, it was included as part of the quote. Sorry bout that.
What I am referring to is a ground loop. When you connect a source and an amp with an IC, and plug both them in...and get a hum, or hear pops out of the system when something else has been turned on in the house.. This is because the signal ground is being referred to the ground of the outlet plate, either hard connnection, or reactive. AC power distribution is such a mess, especially with single ended equipment.
It has nothing to do with the PSRR of the supply, or the miles and miles of wires argument.
Cheers, John
ps...just read your edit..in the immortal words of gilda radner...nevermind..
poobah said:
And that means what
All cables are transmission lines. A discussion of transmission lines allows the use of equations to relate all the physical parameters to allow understanding.
The characteristic impedance is directly related to the inductance (magnetic permeability and geometry) and capacitance (electric permittivity and geometry).
This is an inviolate relationship.
The inductance and capacitance are further related by the equation LC = 1034 times DC, for mu equal 1. This directly sets the relationship between the inductance and the capacitance of the cable. This is also inviolate.
The prop velocity of the cable is directly related to the DC of the insulator, or for the general case, related to epsilon times mu. This is also inviolate. And, strangely enough, it states that the higher the prop velocity of the cable, the lower the total energy storage within the cable. As an aside, it also sets lower bounds on the L times C product, as the speed of light in free space cannot be exceeded.
For the general case of arbitrary geometry, the equation L * C = 1034 times DC must be modified to one of :
L times C = 1034 times EDC, or effective DC.
This equation allows for the generally sloppy way in which both the electric and magnetic field are unhampered by the conductors, and is free to spill out into free space..
All of this is inviolate, meaning that the equations don't give a hoot whether or not somebody believes them..they just are..
Audibility? Who knows..
But the definition of audibility when it comes to human localization capabilities is sadly, in it's infancy.
Cheers, John
Hi John,
I don't think your point can be argued against by itself. It's a question of degree once more. If you are piping RF to a transmitting tower, you are clearly talking transmission line. Speaker cables for the most part have less transmission line behavior at lower audio frequencies. I think a distinction should be made.
The idea has merit, how it affects the system is undefined at best. Mostly because the system is undefined in a general discussion.
-Chris
I don't think your point can be argued against by itself. It's a question of degree once more. If you are piping RF to a transmitting tower, you are clearly talking transmission line. Speaker cables for the most part have less transmission line behavior at lower audio frequencies. I think a distinction should be made.
The idea has merit, how it affects the system is undefined at best. Mostly because the system is undefined in a general discussion.
-Chris
Hi Jan,
I will put up some measured electrical response curves at the speaker terminals using different speaker cables. I don't have any exotic ones at hand ( I could borrow some if really needed ).
This might take a few days as I'm going to be out of town till the 8th of Dec. I'll try to follow that with some pink noise listening tests.
I did do some listening tests with different cables and did hear a difference. However I'll measure the parameters and see if it matches the listening test. I'll repeat the tests to ensure we were not being misled by our own 'expectation' of a different sound.
About people buying the complex cables. They probably 'hear ' a difference and like what they hear. What they prefer can be way off from what it ' really ' should be . In some cases the 'improvement' could be just an illusion !! It's very easy to 'believe' one is hearing subtle differences. That's why magicians are successful.
I'm not suggesting that all people hearing differences are being misled. I'm just saying that it is VERY easy to be misled. Keeping this in mind , do all tests very carefully.
No two people hear exactly the same way and so I think there could always be a difference in opinion about what they hear.
Reminds me of the story of a person who kept adding gadgets and changing fluids in his car several times. Each change was supposed to improve the gas consumption by 5 to 10 % and he kept 'feeling' the improvement everytime . One day he realised that the overall improvement when added up ( or multiplied) should have dropped his gas bill tremendously. It didn't. So he did a check to see what mileage he was getting now. It was exactly the same as what he got before he made any changes to the engine!
So I guess the moral of the story for us is that audible changes should be quantifiable in some repeatable way.
I mentioned earlier about source impedance ( which includes cable impedance ) affecting the electrical response at the speaker terminals. That's measureable but should relate to what we hear if the change is audible .
I'm beginning to ramble. It's 11pm and I'm feeling very sleepy. I'll get back when I return.
I had an old article from the Audio magazine with cable impedance measurements ( R , L and C ) and listening tests. I can't find it. Wish someone here has it. Anyone ?
Cheers,
Ashok.
I will put up some measured electrical response curves at the speaker terminals using different speaker cables. I don't have any exotic ones at hand ( I could borrow some if really needed ).
This might take a few days as I'm going to be out of town till the 8th of Dec. I'll try to follow that with some pink noise listening tests.
I did do some listening tests with different cables and did hear a difference. However I'll measure the parameters and see if it matches the listening test. I'll repeat the tests to ensure we were not being misled by our own 'expectation' of a different sound.
About people buying the complex cables. They probably 'hear ' a difference and like what they hear. What they prefer can be way off from what it ' really ' should be . In some cases the 'improvement' could be just an illusion !! It's very easy to 'believe' one is hearing subtle differences. That's why magicians are successful.
I'm not suggesting that all people hearing differences are being misled. I'm just saying that it is VERY easy to be misled. Keeping this in mind , do all tests very carefully.
No two people hear exactly the same way and so I think there could always be a difference in opinion about what they hear.
Reminds me of the story of a person who kept adding gadgets and changing fluids in his car several times. Each change was supposed to improve the gas consumption by 5 to 10 % and he kept 'feeling' the improvement everytime . One day he realised that the overall improvement when added up ( or multiplied) should have dropped his gas bill tremendously. It didn't. So he did a check to see what mileage he was getting now. It was exactly the same as what he got before he made any changes to the engine!
So I guess the moral of the story for us is that audible changes should be quantifiable in some repeatable way.
I mentioned earlier about source impedance ( which includes cable impedance ) affecting the electrical response at the speaker terminals. That's measureable but should relate to what we hear if the change is audible .
I'm beginning to ramble. It's 11pm and I'm feeling very sleepy. I'll get back when I return.
I had an old article from the Audio magazine with cable impedance measurements ( R , L and C ) and listening tests. I can't find it. Wish someone here has it. Anyone ?
Cheers,
Ashok.
Transmission Lines?
Correct me if I am wrong, but should transmission lines even be considered here? Even a signal as high as 100,00Hz, which is probably the highest you will have going through the cable has a wavelength of 3000 meters! This is FAR larger than the length of the cable! And I always thought you choose to follow transmission line design techniques when the size of the wavelength is the same order of magnitude as the component (in this case the cable). Clearly it is not even close.
I have designed microwave frequency PCBs and with those we had to calculate the exacting dimensions of each trace. If we are going to get into transmission lines in the cables we would have to talk about the traces in the circuits as transmission lines, and believe me that would make this whole DIY exprerience a lot more difficult.
I have no opinion either way on whether cables affect sound, as I have never heard an expensive cable. I will hold judgment for now, but I do think the transmission line discussion should stop (although I realize it was only brought up in reference to the mistakes being pointed out in Rod's article) as it doesn't have a bearing at this frequency (i am pretty sure anyway).
- Ron
Correct me if I am wrong, but should transmission lines even be considered here? Even a signal as high as 100,00Hz, which is probably the highest you will have going through the cable has a wavelength of 3000 meters! This is FAR larger than the length of the cable! And I always thought you choose to follow transmission line design techniques when the size of the wavelength is the same order of magnitude as the component (in this case the cable). Clearly it is not even close.
I have designed microwave frequency PCBs and with those we had to calculate the exacting dimensions of each trace. If we are going to get into transmission lines in the cables we would have to talk about the traces in the circuits as transmission lines, and believe me that would make this whole DIY exprerience a lot more difficult.
I have no opinion either way on whether cables affect sound, as I have never heard an expensive cable. I will hold judgment for now, but I do think the transmission line discussion should stop (although I realize it was only brought up in reference to the mistakes being pointed out in Rod's article) as it doesn't have a bearing at this frequency (i am pretty sure anyway).
- Ron
anatech said:
Speaker wires and ic's are always transmission lines..however, for audio frequencies, one has to remember which parts of transmission line theory one should ignore.
Prop velocity is one..who gives a darn whether the speed of prop is 50% of C or 95%
It doesn't matter a bit..However, it is related directly to the relationship between L and C. So, if the lumped L or C are important, then the prop velocity by default is. I just have to laugh at the vendors who tout prop speed... they don't understand the LC product..
Reflections in transmission lines are another goofball market bloob..c'mon, it's audio for goodness sakes...
But, again, even though the reflection coeff is useless in itself for audio, it clearly defines the relationship between the energy that is stored within the lumped L and the lumped C, and that which is dissipated by the load.
T line theory not only has merit, it completely describes the cable behaviour..but care must be taken not to use the terms incorrectly.anatech said:
Cheers, John
Re: Transmission Lines?
T line theory relates L, C, the insulation dielectric, and the build geometry. In that way, it is relevant. I concur with you, prop vel and wavelength issues are moot, but T line theory gets you the lumped element numbers..
Ewwww, microwave...yuccch.. Gold plating, dabs of conductive epoxy for tuning, smith charts, stubs......ewwww...I try to forget that stuff..it happened so long ago...
Cheers, John
ron.eddy said:
T line theory relates L, C, the insulation dielectric, and the build geometry. In that way, it is relevant. I concur with you, prop vel and wavelength issues are moot, but T line theory gets you the lumped element numbers..
Ewwww, microwave...yuccch.. Gold plating, dabs of conductive epoxy for tuning, smith charts, stubs......ewwww...I try to forget that stuff..it happened so long ago...
Cheers, John
Makes sense. After all, the cables still have L, C, and R paramters, no matter how small compared to wavelength they are.
My next question would be, do different circuit traces (more copper weight, better separation from other signal conducting paths, etc...) have an effect on the audio? As I said, I have no opinion either way on cables and I maintain that, but if one were to look at the traces on the circuit board would we not find the same effects on audio in many areas of the signal? And so what if the traces are only a foot long total (signal path) they should still matter, right?
It is admittedly hard for me to concentrate on cables as a sore spot in the chain when the circuits are sitting there on their FR4 material with no shielding (other than (maybe) a metal case around the whole thing). How short does it have to be of a run for nothing to matter as far as the audible difference? Would a 6" cable made of anything perform just as good as an expensive 6" cable? How about 3" or maybe a circuit board trace of 2"? My point in this is that there is no point - there is no one place where all of this could ever stop. For every one thing you could say for cables and how they may degrade the signals, you could say something about the rest of the circuit based on that.
This is a fun thread to have once in a while, no doubt about it, but it is also frustrating in that there will be no resolve to it. Whether cables make a difference or not makes little difference to the main fact that we are all crazy (in a good DIY audio sort of way )
- I do realize this post does not solve or help to solve any of the questions, but I hope it makes everyone feel a little better about this impossible argument we have gotten ourselves into, hehe.
- Ron
My next question would be, do different circuit traces (more copper weight, better separation from other signal conducting paths, etc...) have an effect on the audio? As I said, I have no opinion either way on cables and I maintain that, but if one were to look at the traces on the circuit board would we not find the same effects on audio in many areas of the signal? And so what if the traces are only a foot long total (signal path) they should still matter, right?
It is admittedly hard for me to concentrate on cables as a sore spot in the chain when the circuits are sitting there on their FR4 material with no shielding (other than (maybe) a metal case around the whole thing). How short does it have to be of a run for nothing to matter as far as the audible difference? Would a 6" cable made of anything perform just as good as an expensive 6" cable? How about 3" or maybe a circuit board trace of 2"? My point in this is that there is no point - there is no one place where all of this could ever stop. For every one thing you could say for cables and how they may degrade the signals, you could say something about the rest of the circuit based on that.
This is a fun thread to have once in a while, no doubt about it, but it is also frustrating in that there will be no resolve to it. Whether cables make a difference or not makes little difference to the main fact that we are all crazy (in a good DIY audio sort of way
)- I do realize this post does not solve or help to solve any of the questions, but I hope it makes everyone feel a little better about this impossible argument we have gotten ourselves into, hehe.
- Ron
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