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  1. #1
    Forum Regular Tony_Montana's Avatar
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    Post Effects of Inductance and Skin-effect in a speaker wire.

    As far as sonic effects of inductance and Skin effect is concern, there are alot of debate about this issue that will make your head to spin. But how about effect of above issues theoretically-such as phase shift and Group (frequency) Delay distortion?

    Here is sample picture of an audio wave:



    As one can see, these type of signals have alot of [upper frequency] harmonics, accompanied with lower frequency. The question is since higher frequency(s) will be more subject to cable's Inductance* and Skin effects*, then wouldn't that cause the higher frequency to shift/attenuate more from its original place on the signal (as compared with lower frequency) causing distortion or signal deformation?

    Shouldn't we look for cables [beyond zip cord] that will address these issues also such as twisted cables (inductance), and make cable insulated strands less than 20 gauge size (skin effect)?
    Or should we say that since these effects are not audible, then it should be ignored?

    *Inductance:cable inductance is frequency dependable. Its effect will be higher as frequency increases causing higher frequency to attenuate and shift more than lower frequency(s).
    *Skin Effect:This is also frequency dependable. As frequency increases, it will occupy less [area] space in a conductor causing higher frequency to be more subject to cable's resistance than lower frequency are.
    "Say Hello To My Little Friend."

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    Quote Originally Posted by Tony_Montana
    As far as sonic effects of inductance and Skin effect is concern, there are alot of debate about this issue that will make your head to spin. But how about effect of above issues theoretically-such as phase shift and Group (frequency) Delay distortion?

    Here is sample picture of an audio wave:



    As one can see, these type of signals have alot of [upper frequency] harmonics, accompanied with lower frequency. The question is since higher frequency(s) will be more subject to cable's Inductance* and Skin effects*, then wouldn't that cause the higher frequency to shift/attenuate more from its original place on the signal (as compared with lower frequency) causing distortion or signal deformation?

    Shouldn't we look for cables [beyond zip cord] that will address these issues also such as twisted cables (inductance), and make cable insulated strands less than 20 gauge size (skin effect)?
    Or should we say that since these effects are not audible, then it should be ignored?

    *Inductance:cable inductance is frequency dependable. Its effect will be higher as frequency increases causing higher frequency to attenuate and shift more than lower frequency(s).
    *Skin Effect:This is also frequency dependable. As frequency increases, it will occupy less [area] space in a conductor causing higher frequency to be more subject to cable's resistance than lower frequency are.

    "Amplifier-Loudspeaker Interfacing", Greiner, R.A., JAES vol. 28, no. 5 May 80, page 310-315.


    RA Greiner discusses the issue of group delay due to skin effects between 100Hz and 10kHz. I would not worry about a 1x 10 to -8 power sec.

    Phase angle of 3 degrees at 20kHz if you can hear 20kHz is nothing.

    "Effects of cable, Loudspeaker and Amplifier Interactions", Davis, Fred E., JAES, vol. 39, no. 6 Jun 91,

    Davis calculated a .04dB loss due to skin effect at 20kHz.

    Again, one must be able to detect 20kHz and second, one must have a Just noticable threshold this low on top of it.
    But, JND has been measured at 16kHz to be about 3dB on average. This is of course much more than one would detect closer to the midbands where out acuity is much better.

    Again, th egolden ears make much about nothing as they have too much time on hand to worry about nothing. That is not their fault mostly as the high end audio industry marketing has done a good job of voodoo magic and human gullibility has jumped on it. No different that anything else in consumer land.

    Just reading an article on immunization for whooping cough over the past number of decades. Some raised alarms over the negative effects of immunization. Gullible people followed and the rate of whooping cough skyrocketed again.
    mtrycrafts

  3. #3
    Forum Regular FLZapped's Avatar
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    Quote Originally Posted by mtrycraft
    "Amplifier-Loudspeaker Interfacing", Greiner, R.A., JAES vol. 28, no. 5 May 80, page 310-315.

    RA Greiner discusses the issue of group delay due to skin effects between 100Hz and 10kHz. I would not worry about a 1x 10 to -8 power sec.

    Phase angle of 3 degrees at 20kHz if you can hear 20kHz is nothing.

    "Effects of cable, Loudspeaker and Amplifier Interactions", Davis, Fred E., JAES, vol. 39, no. 6 Jun 91,

    Davis calculated a .04dB loss due to skin effect at 20kHz.
    I calculated 0.03dB additional loss due to skin effect for a 10 foot run of 12 AWG cable at 20kHz.

    As for phase shift, power amplifiers have more than the 3 degrees and no one ever says boo about that! (Although outside of pro amps, this is usually not a published spec)

    Here is a refrence that talks about group delay in loudspeakers. Keep in mind that your speaker cable has a group delay in the hundreds of nano-seconds (10E-09)

    http://www.trueaudio.com/post_010.htm

    Here is a reference where the phase shift and group delay are talked about in wire and where the number I used above came from:

    http://www.st-andrews.ac.uk/~www_pa/...eshift/cp.html

    -Bruce

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    Quote Originally Posted by FLZapped
    I calculated 0.03dB additional loss due to skin effect for a 10 foot run of 12 AWG cable at 20kHz.

    As for phase shift, power amplifiers have more than the 3 degrees and no one ever says boo about that! (Although outside of pro amps, this is usually not a published spec)

    Here is a refrence that talks about group delay in loudspeakers. Keep in mind that your speaker cable has a group delay in the hundreds of nano-seconds (10E-09)

    http://www.trueaudio.com/post_010.htm

    Here is a reference where the phase shift and group delay are talked about in wire and where the number I used above came from:

    http://www.st-andrews.ac.uk/~www_pa/...eshift/cp.html

    -Bruce
    Oh, sucks. I don't know if we can accept that .01dB difference
    Maybe a different cable gauge?
    mtrycrafts

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    Suspended markw's Avatar
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    With all this talk about what wires and cables does to an electrical signal, hoccum nobody ever brings up what a transducer (such as a speaker) does to it?

    That's kinda like refusing to go to a hospital 'cause you're wearing yesterday's underpants when you've just suffered several gunshots to the torso.

  6. #6
    Forum Regular FLZapped's Avatar
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    Quote Originally Posted by mtrycraft
    Oh, sucks. I don't know if we can accept that .01dB difference
    Maybe a different cable gauge?

    Oh, I forgot, JR can hear the difference....-b

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    skin effect...I've heard of that before....

    A #12 zip, at .2 microhenries per foot, will store 2.5 uJoules per foot under a 100 wrms signal into 8 ohms. The same zip, with total and complete skinning, will store 2.0 uJoules per foot.

    A 10 foot cable, will be capable of shedding 5 ujoules (absolute maximum) if the audio changes from lf to hf content during a waveform peak.

    At 10Khz, that is .4% of the load energy of one cycle lobe. That is also a .2 uSec, or 200 nanosecond, leading edge delay and trailing edge advance. (simplistic calculation of integral of energy from one half cycle)

    What does an amplifier do if wire stored energy tries to dump in during high slew rate signals?

    Transducers will have an effect on what we hear (duh), but if the wires can cause different delays because they see different signals, the soundstage will shift, or blur, or whatever..

    Question is...are the energy numbers large enough to be significant? Can the amp have a problem with 5 uJoules being dumped into a 2 millihenry line in series with the x-ducer?

    Beats me..I'm not at the level to measure that.

    But, you shoulda seen my condo upgrades...sweet.. Now, restoring an 1873 built house. Test setup is backburner.

    Cheers, John

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    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by FLZapped
    Here is a reference where the phase shift and group delay are talked about in wire and where the number I used above came from:
    The conclusions of that study using dummy speaker loads are worth considering:

    "The fact that the reported observations can be modelled so easily does not, of course, constitute ‘proof’ that no new and unknown cable properties can possibly exist. Nor does it ‘prove’ that cables cannot affect the perceived quality of audio signals."

    Indeed.

    rw

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    Quote Originally Posted by E-Stat
    The conclusions of that study using dummy speaker loads are worth considering:

    "The fact that the reported observations can be modelled so easily does not, of course, constitute ‘proof’ that no new and unknown cable properties can possibly exist. Nor does it ‘prove’ that cables cannot affect the perceived quality of audio signals."

    Indeed.

    rw
    Jim does show he is open with those comments..I'd have been all over him if he said otherwise..course, the word "perceived" within that context is rather interesting..it leaves open the possible explanation of visual cueing as a possible reason.

    The fact that the observations can be explained using standard theory just tosses the incorrect explanations out. That was the reason for the analysis.

    John

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    Quote Originally Posted by markw
    With all this talk about what wires and cables does to an electrical signal, hoccum nobody ever brings up what a transducer (such as a speaker) does to it?
    .

    Because then they would have nothing to talk about or worry about
    Then, all their pet voodoo nonsense would go uo in smoke and they would have to eat crow, lots of it.
    mtrycrafts

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    Quote Originally Posted by FLZapped
    Oh, I forgot, JR can hear the difference....-b

    Hell, he can hear the differences insulation causes, at the .00001dB level.
    mtrycrafts

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    Quote Originally Posted by jneutron



    Question is...are the energy numbers large enough to be significant? Can the amp have a problem with 5 uJoules being dumped into a 2 millihenry line in series with the x-ducer?

    Beats me..I'm not at the level to measure that.

    But, you shoulda seen my condo upgrades...sweet.. Now, restoring an 1873 built house. Test setup is backburner.

    Cheers, John
    Good to see you posting again

    That much energy? Should I worry? ")

    1873 house restore? WOW. I guess too late to back out? Is this the first restoration job it sees?
    mtrycrafts

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    Quote Originally Posted by jneutron
    Jim does show he is open with those comments..I'd have been all over him if he said otherwise..course, the word "perceived" within that context is rather interesting..it leaves open the possible explanation of visual cueing as a possible reason.

    The fact that the observations can be explained using standard theory just tosses the incorrect explanations out. That was the reason for the analysis.

    John

    Perceived observations? That is what all the glowing reports of cable differences are based on, perceptions only. And, we know perceptions can be unreliable and fooled so easy.
    mtrycrafts

  14. #14
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by markw
    With all this talk about what wires and cables does to an electrical signal, hoccum nobody ever brings up what a transducer (such as a speaker) does to it?
    Look near the top of your computer screen. This is the Cables Forum. You will also find a Speaker Forum.

    rw

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    Quote Originally Posted by mtrycraft
    Good to see you posting again

    That much energy? Should I worry? ")

    1873 house restore? WOW. I guess too late to back out? Is this the first restoration job it sees?
    When I did the calcs, it did seem to be really low energy numbers. But, in reality, it does represent a good fraction of the total, good fraction being .1% to .5%. How that energy bandies about, I don't know yet..could just be innocuous, or it could be some kind of nefarious off harmonic garbage..my guess is just slight temporal shifts, but I've been wrong before..

    Back out? you gotta be kiddin me...using my hands with the tools is the second best therapy I can think of..

    It's been worked and modified through the years. Plaster yes, but romex throughout, some sheetrock, plumbing meets present code. It's not on the historic register, so I can use current materials.

    Tin roof..12/12 pitch..just starting to make an AV room up there, back half HT, front computer room, 3 systems networked. Got a pair of 18 inchers I think I'll be building in along the sides where the low kick wall is gonna be, so that wall will be 2 by 6 construction.

    Then, the basement ele workshop. Looks like my home testing desires will be delayed about 4 months...oh well, priorities prevail..

    Cheers, John

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    The question is not merely one of magnitude of frequency response change but of whether this is the ONLY difference in wires. Linear distortion (frequency response deviation) is easily correctable through pre-equalization to compensate for it. Non linear distortion (harmonic and intermodulation distortion) isn't. If the best the high end cable advocates can come up with is lower linear distortion, they have a very poor case. And so far they haven't even been able to do that. Both forms are easily measurable electrically and their auditory significance can be determined by DBTs. Where are their results? After 25 years I'm still waiting.

  17. #17
    Forum Regular FLZapped's Avatar
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    Talking Happy New year to you, too....

    Quote Originally Posted by jneutron
    A #12 zip, at .2 microhenries per foot, will store 2.5 uJoules per foot under a 100 wrms signal into 8 ohms. The same zip, with total and complete skinning, will store 2.0 uJoules per foot.

    A 10 foot cable, will be capable of shedding 5 ujoules (absolute maximum) if the audio changes from lf to hf content during a waveform peak.

    At 10Khz, that is .4% of the load energy of one cycle lobe. That is also a .2 uSec, or 200 nanosecond, leading edge delay and trailing edge advance. (simplistic calculation of integral of energy from one half cycle)

    What does an amplifier do if wire stored energy tries to dump in during high slew rate signals?

    Transducers will have an effect on what we hear (duh), but if the wires can cause different delays because they see different signals, the soundstage will shift, or blur, or whatever..

    Question is...are the energy numbers large enough to be significant? Can the amp have a problem with 5 uJoules being dumped into a 2 millihenry line in series with the x-ducer?

    Beats me..I'm not at the level to measure that.

    But, you shoulda seen my condo upgrades...sweet.. Now, restoring an 1873 built house. Test setup is backburner.

    Cheers, John

    'Bout bloody time you got yer behind back here

    Now then, what about the other end of the termination, the amp....how will the damping factor(output impedance) affect where this energy goes considering an SS amp is several orders of magnitude lower in impedance than the speaker they are driving......

    -Bruce

  18. #18
    Forum Regular FLZapped's Avatar
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    Quote Originally Posted by jneutron
    A #12 zip, at .2 microhenries per foot, will store 2.5 uJoules per foot under a 100 wrms signal into 8 ohms. The same zip, with total and complete skinning, will store 2.0 uJoules per foot.

    A 10 foot cable, will be capable of shedding 5 ujoules (absolute maximum) if the audio changes from lf to hf content during a waveform peak.

    At 10Khz, that is .4% of the load energy of one cycle lobe. That is also a .2 uSec, or 200 nanosecond, leading edge delay and trailing edge advance. (simplistic calculation of integral of energy from one half cycle)
    Considering the group delay of the typical loudspeaker is in the millisecond range, I'd say you're safe in assuming this won't be audible.

    Another way of looking at it is suddenly displacing your hearing point by 2 microinches(0.05 micrometers).....your heartbeat probably does that...or blinking...or clenching your teeth....or the remodelling dust settling on the furniture.....or.....


    -Bruce

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    Quote Originally Posted by FLZapped
    'Bout bloody time you got yer behind back here

    Now then, what about the other end of the termination, the amp....how will the damping factor(output impedance) affect where this energy goes considering an SS amp is several orders of magnitude lower in impedance than the speaker they are driving......

    -Bruce
    First order...The amp (most, anyway) is not a current device, but a voltage one. If skinning of the current and shedding scenario is actually happening (don't forget, I'm still talking about hypothetical stuff), if the wire response to storage or shedding is to change the current of the loop, the amp will see nothing to correct..the error would simply be dissipated at the load. The amp will only guarantee that it's terminal voltage is what it expects it to be, we rely on the speaker to draw the appropriate current from that correct voltage to accelerate the voice coil.

    That is why I'm so anal about the b dot error of my load resistors...I really, really, need to have the current read of the resistor reflect the actual current..not current plus a factor times the rate of change of current..as well as the voltage read at the load not including b dot errors. Because the rate of change stuff(hate typing that, so I'll use b dot) is orthogonal to the current, it will defy FFT analysis, and any skinning effect that is simply orthogonal to slew will be lost in the load inaccuracies.

    I also worry that the damping factor of an amp, at higher frequencies, will vary based on the quadrant of operation involved..it the output transistors are heavily into absorbing reactive speaker energy return, then, is the loop they are in still capable of the same damping factor across the spectrum..I can't answer that particular question.

    Skep...

    B dot error and b dot shedding will be very difficult to measure correctly..as to whether it has anything to do with audible? Darned if I know...I'll walk first, then see if I'm walking long on a short bridge..

    I don't know if what I look for is harmonically related to the drive signal, or if it's just time shifting..I do know that the FFT stuff I have used in the past was unable to discern relative time shifting of the various components of a complex waveform..It's along the line of using an FFT to display a square wave...then, anytime you see that spectra, voila..it's a square wave...course, there are many different waveforms that can produce the same spectra as a square wave..
    Leaving me with the ol' dual IA setup/difference hardware method.

    Cheers, John

  20. #20
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    Quote Originally Posted by FLZapped
    Considering the group delay of the typical loudspeaker is in the millisecond range, I'd say you're safe in assuming this won't be audible.

    Another way of looking at it is suddenly displacing your hearing point by 2 microinches(0.05 micrometers).....your heartbeat probably does that...or blinking...or clenching your teeth....or the remodelling dust settling on the furniture.....or.....


    -Bruce
    Group delay of a speaker will only be important for single source fidelity..and I'm not considering that at all.

    I am considering only the possibility that the left-right signals will temporally shift independently of each other, causing temporal relative shifts in the 10 to 20 microsecond range, as that is the shift magnitudes needed for a one foot shift of apparent source at ten feet distance directly in front...ears 6 inches apart (as if it's adjustable). If I find 1 usec shifts from skin effect....that ain't audible.

    Dust? get this...

    My ex father-in-law is a real prominent bridge/tunnel engineer in manhattan. When the first plane hit...MTA called him to get there fast and eval the structural integrity including the subway system. He got within four blocks when they collapsed (there are times when traffic delays are a blessing). He got home covered head to toe..left dust everywhere.

    When I was spackling my condo kitchen, I made huge amounts of dust...My six year old daughter saw the dust on my coffee table, and asked me if I had been in the city..

    Cheers, John

  21. #21
    Forum Regular Tony_Montana's Avatar
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    Smile

    Quote Originally Posted by mtrycraft
    "Amplifier-Loudspeaker Interfacing", Greiner, R.A., JAES vol. 28, no. 5 May 80, page 310-315.


    RA Greiner discusses the issue of group delay due to skin effects between 100Hz and 10kHz. I would not worry about a 1x 10 to -8 power sec.

    Phase angle of 3 degrees at 20kHz if you can hear 20kHz is nothing.

    "Effects of cable, Loudspeaker and Amplifier Interactions", Davis, Fred E., JAES, vol. 39, no. 6 Jun 91,

    Davis calculated a .04dB loss due to skin effect at 20kHz.
    Thank Mtry.

    The references you provide seem to be alot of good reading. Do you know how can I get a copy of those reports....free be best ?

    You know, I got so bugged down on details about inductance and skin effects of the cable that I forgot to take into consideration the effects of speaker and amplifier on the signal (as others have mentioned). That does bring this issue to whole new light as far as cable's effect on the system [as a whole] is concern.

    S I guess the question now becomes...will be worth to fix few nanosecond/dB of signal shift/attenuation caused by cables, as compared to greater magnitude of phase-shift/attenuation caused by speaker/amplifier?

    Back to the drawing board again
    "Say Hello To My Little Friend."

  22. #22
    Suspended markw's Avatar
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    Quote Originally Posted by E-Stat
    Look near the top of your computer screen. This is the Cables Forum. You will also find a Speaker Forum.
    Since this entire discussion is about the audiability of differences in cables, by ignoring the speakers contribution to this, you render any further discussion on your part null, void and silly unless you can tell me how you can hear your widely touted differences without a speaker, or transducer?

    Measurments alone? Be serious.

    If such is the case, the next step would be to ascertain at which point the results of those measurements are audiable. Nobody on "that side" seems interested in that. They "just know".

    What you are trying to do is arrest a hunter for urinating in a river and causing the death of said river's ecosystem when a chemical plant 100 feet downstream is dumping thousands of gallons of toxic waste daily.

    Again, be serious. nice trolling
    Last edited by markw; 01-08-2004 at 06:45 AM.

  23. #23
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by markw
    Without a speaker, how can you tell if cables make a difference?
    I'm pretty new to this site, but it would seem to me that the purpose of having specialized forums is to focus attention on that individual aspect of the playback chain.

    rw

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    Suspended markw's Avatar
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    <click> <click>

    Quote Originally Posted by E-Stat
    I'm pretty new to this site, but it would seem to me that the purpose of having specialized forums is to focus attention on that individual aspect of the playback chain.
    What's that clicking sound? Out of ammo, eh?

    heh heh heh... since when can one listen to only one part of that chain without taking into account any others, up to and including the ear? heh heh heh...

    Perhaps a recap of the first sentence in this thread is called for...
    "As far as sonic effects of inductance and Skin effect is concern..."

    Key word here is "sonic", which refers to sound, which is generally sense by using ones ears to listen.

    .... or have we removed listening itself from the table?
    Last edited by markw; 01-08-2004 at 07:07 AM.

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    JBL Whore Bobby Blacklight's Avatar
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    Just reading through the thread but wouldn't any stored energy in the cables be insignificant or secondary to the back EMF from the drivers?? Or is this only an issue with the woofer as the midrange/tweeter would be an easier load?? I would think the drivers would be the real issue the amp has to deal with.

    Hey John good luck on the house!!

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