Dr. Howard Johnson Discusses Skin Effect

J

jneutron

Senior Audioholic
<font color='#000000'>Making a flat speaker cable out of ribbon cable to be 4 Ohms does not make sense. Sure, the cable and the load (speaker)will be matched, but the source (amp) impedance is a fraction of an Ohm. You still have an unmatched system. Furthermore, this impedance matching technique that is used at RF frequencies is done because interconnects are several wavelegths long. In low frequency Audio applications, the length from amp to speaker is a tiny fraction of wavelength. So you can assume that the cable is a lumped RLC element!
Or am I wrong?</font>
For transmission line runs, where the impedance of the line is matched, you are entirely correct. Proper temination impedances allow for most power transfer. It is a technique that needs to be done even if the cables are shorter than a wavelength though, as the high speed slews still need the match.

For speaker wires, an impedance match to the speaker will minimize the total energy stored within the wires..both elements of the line impedance, the inductance and capacitance, will show as lag elements in that storage...a matched load impedance will minimize that lag.

It does need to be shown that that storage, which is 90 degrees behind the signal, is significant enough to warrant concern. Of importance is the issue of how we lateralize soundstage...by slew, peak, zero crossing, or some other, yet undiscovered mechanism. Till that is understood, I see no valid reason to specify Mhz bw speaker cables....:)

The audiophile community has yet to even understand the issue of low microsecond timebase lags and the impact on soundstage...nevermind think about testing it. I do am somewhat heartened by the current round of papers and research being done w/r to surround sound and dipole wavefront technology...but I fear the equational relationships will remain IP for way too long..

The same, I have found, to be true with skin effect..the "Ap" community for the most part, does not even understand skin effect...I blame Hawksford's essex paper for a large part of that..that paper did a disservice to the Audiophile community by promoting erroneous methods, calculations, conclusions...and I see very little out there happening to dispel the garbage..I do see lots of web pages that promote the errors of the past, however..

Cheers, John
 
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mtrycrafts

mtrycrafts

Seriously, I have no life.
It is a technique that needs to be done even if the cables are shorter than a wavelength though, as the high speed slews still need the match.

How much shorter? Any amount or is there a fraction beyond which it is not an issue in audio?
I believe the transmission line theory applies down to 1/30 of a wavelength, or that is what I have been told a number of times:)




I blame Hawksford's essex paper for a large part of that..that paper did a disservice to the Audiophile community by promoting erroneous methods, calculations, conclusions...and I see very little out there happening to dispel the garbage..I do see lots of web pages that promote the errors of the past, however..

Cheers, John


Someone needs to make that 'first step' ;)
Hawksford would have a difficulty countering a peer paper especially since his was in a rag to beging with.
 
J

jneutron

Senior Audioholic
mtrycrafts said:
<font color="green"> It is a technique that needs to be done even if the cables are shorter than a wavelength though, as the high speed slews still need the match. </font>

How much shorter? Any amount or is there a fraction beyond which it is not an issue in audio?
I believe the transmission line theory applies down to 1/30 of a wavelength, or that is what I have been told a number of times:)
I wouldn't apply wavelength issues to audio..it's not an issue. The 1/30 sounds like a reasonable guideline...I have forgotten what the generic rules were for t-lines..buuuut, I did find my microwave t line book last night..alas, they don't give any, but they do run standing wave stuff..no use for the discussion at hand..


mtrycrafts said:
<font color="green"> I blame Hawksford's essex paper for a large part of that..that paper did a disservice to the Audiophile community by promoting erroneous methods, calculations, conclusions...and I see very little out there happening to dispel the garbage..I do see lots of web pages that promote the errors of the past, however..

Cheers, John
</font>

Someone needs to make that 'first step' ;)
Hawksford would have a difficulty countering a peer paper especially since his was in a rag to beging with.
Ya ain't gonna be happy till I publish, are ya's...;)
Honestly, I don't see the value in puttin a paper out showing that what all the physics guys know to be inaccurate is indeed just that..inaccurate

Perhaps that could be a subset of something much larger :cool: , but as a standalone? Nah..

Got the workbench up, with bookshelves..and the record rack..that's how I found my micro book...

Gonna do more till fri..then, I'm off to sanfran for a week...lordy, lordy..we got's a hot air balloon ride awaitin in Napa Valley.. :eek: I'm not sure if I'm happy about that...It's not the fear of falling that's the issue...it's the abrupt stop at the end of it...

Cheers, John
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
I wouldn't apply wavelength issues to audio..it's not an issue. The 1/30 sounds like a reasonable guideline...I have forgotten what the generic rules were for t-lines..buuuut, I did find my microwave t line book last night..alas, they don't give any, but they do run standing wave stuff..no use for the discussion at hand..

At micro, just about any cable is longer than 1/30 wavelength, no? So, T line applies. :D


Ya ain't gonna be happy till I publish, are ya's...;)

That would be one that would make me happy, for a day or so. LOL :D


Honestly, I don't see the value in puttin a paper out showing that what all the physics guys know to be inaccurate is indeed just that..inaccurate

But, you'd be publishing in an audio Journal ;) Those guys need to know too :)




Got the workbench up, with bookshelves..and the record rack..that's how I found my micro book...

Hope the shelves and rack leaves room on the bench to work :D
 
J

jneutron

Senior Audioholic
mtrycrafts said:
<font color="green">Got the workbench up, with bookshelves..and the record rack..that's how I found my micro book...</font>

Hope the shelves and rack leaves room on the bench to work :D


No problem...

Cheers, John
 
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mtrycrafts

mtrycrafts

Seriously, I have no life.
jneutron said:
No problem...

Cheers, John

Neat picture and transfer to the message. I was thinking of a real work bench though; that looks like a study table :D Enjoy the vacation ;)
 
U

Unregistered

Guest
LOL. Too funny. The cable debate has been going on for 30 or 35 years now and it has been beaten to death and the answer is obvious. How interesting it is that generation after generation of audio enthusiasts struggles with this.

As far as head-fi goes, my advice is -- apart from spending at most few hours there to research subjective impressions of headphones, and maybe to check out a couple of really nice threads on the Behringer DEQ2496 digital equalizer -- run, do not walk, to the nearest exit. It's a haven for people who are legends in their own minds but have *no clue*.

It'd be nice if a place like this, with an administrator grounded in the technical realities of audio to guide the way, would have a sub-forum for headphones or if that's too narrow a subject matter maybe portables/compression/headphones/computers etc. It's certainly a rapidly expanding area of the audio market. It'd get this place more hits and it'd sure kick head-fi's butt. Plus it'd be a noble undertaking to reverse the considerable damage done by places like head-fi and headroom (though headroom is a mixed bag, with lots of useful information but also an unconscionable dose of snake-oil).

BluesDaddy said:
Absolutely. I was recently involved in a discussion over on Head-fi about aftermarket cables for headphones. A guy declared he quit "believing in" the validity of DBT listening precisely because he couldn't tell a difference.
 
M

MAD 1

Guest
Does cable sound different

Hi all
I have read many articles on cables and yes there are many people and manufacturers that claim that skin effect does affect speaker wire and interconnects at audio frequencies. However this does is not correspond with what what i learnt at university.
However I there is definately audible differences between cables. I can definately hear the difference betwee two different types of wire on a blind listening test. So I can conclude there is somthing in the make up of the cable that is making them sound different.
I think the problem is we have not yet measured the correct parameter that makes these differences in the audio band.
This why you get the marketing bull, because we dont yet know what it is in a cable that makes the difference it cant be marketed so some of the characteristics that are know about cables are falsy used.
It wasnt too long ago that the only real measurement done on turntables was how accurate the speed was, for amplifiers power measurements now there are so many more measurements that we can do we can actually get a a rough idea if it will sound ok, I wouldnt stake any money on the results but there are some meaningful measurements. Probably speaker measurements are the most changes recently with off axis measurements and water fall responses etc. What I am trying to say hear is that eventually we probably will find another characteristic about wires that we can measure that may go some way to explaining why they sound different.

Ultimately i dont care to much about the marketing claims I just know there is a difference. It really comes down to this:-
If you cant hear that it sounds better then why are you buying it save your money and buy something useful. However if you can hear the difference then does this difference give you good value for money could you gain more by buying better speaker or CD player etc.

From my own experience I upgraded from a good £30 interconnect cable to chord chorus which is about £100 and this was massively better. This improvement was much more than changing Naim CD player for one that cost £500 more. This is also true for speaker cable my current favorite is Kimber cable 8TC this is quite expensive but again the benifit over my existing cable (QED 200 strand) was greater than buying a more expensive amplifier so interms of actual sound quality per pound it was good value for money. If some one had paid the same money on an amplifier upgrade and heard the same difference they wouldnt bat an eylid and say they got a really good deal, but since it was "only the wire" they seem to doubt that it can make the difference.

I will only buy things that i can hear are definately better than what I have, I do NOT have the money to waste on marketing claims.

Ultimately isnt that what audio is all about? hearing.

Later
MAD1
 
gene

gene

Audioholics Master Chief
Administrator
I think the problem is we have not yet measured the correct parameter that makes these differences in the audio band.
I respectfully disagree with you on this point. Cables can and do sound differently (at least poorly designed ones). The sonic differences in cables are attributed to differences in RLC metrics and shielding techniques. Many exotic cables have either high inductance or capacitance which can lead to perceived sonic differences, and definately measurable differences. Poorly designed interconnects (Ie. silver wire with teflon insulation) can suffer ill effects of triboelectrics which again can show up sonically and definately measurably.

I can definately hear the difference betwee two different types of wire on a blind listening test.
Just how controlled was your blind listening test? Actually you really need to conduct a Double Blind Listening test to produce consistent and accurate results.

Only good cables are sonically indistinguishable, and good cables need NOT be expensive!
 
mtrycrafts

mtrycrafts

Seriously, I have no life.

I have read many articles on cables and yes there are many people and manufacturers that claim that skin effect does affect speaker wire and interconnects at audio frequencies. However this does is not correspond with what what i learnt at university.



http://bruce.coppola.name/audio/cableInteractions.pdf


Please read JAES document page 464 under para 3, this is also page 4 of 8 when downloaded, left column. Discusses skin effect at audio frequency and the amount of this effect.


However I there is definately audible differences between cables. I can definately hear the difference betwee two different types of wire on a blind listening test.

This is yet to be demonstrated in a credible manner. Stewart Pinkerton is in Englan as are you I believe.

http://groups.google.com/groups?hl=en&lr=&threadm=cjvc2o02buh@news2.newsguy.com&prev=/groups?hl=en&group=rec.audio.high-end


Contact him to help you with the demonstration and collect the $1000 prize he has. You will be the first to do so. Easy money.



So I can conclude there is somthing in the make up of the cable that is making them sound different.

Or, your protocol is not reliable?


I think the problem is we have not yet measured the correct parameter that makes these differences in the audio band.

Wire has been studied to death for 100 years, or longer. With all the brilliant minds out there, you think they don't know what makes it tick? :confused:



What I am trying to say hear is that eventually we probably will find another characteristic about wires that we can measure that may go some way to explaining why they sound different.


Or, there really is nothing left to measure and you are just speculating?



Ultimately i dont care to much about the marketing claims I just know there is a difference.

Is that like saying that I just know that homeopathic medicines work?


Ultimately isnt that what audio is all about? hearing.

Later
MAD1


How about just enjoyment?
 
Mudcat

Mudcat

Senior Audioholic
JoeE SP9 said:
As far as conductivity is concerned Rhodium or Silver are better. Silver does tarnish though. The oxidant of silver is not a good conductor. Platinum is very good but rather expensive. :cool:
Platinum is actually 6 times more resistant than copper and rhodium ain't great either.

Metal
microOhm/cm​
Platimum
10.5​
Iron
9.7​
Cadmium
7.4​
Nickel
7​
Zinc
5.9​
Molybdenum
5.6​
Tungsten
5.6​
Iridium
5.3​
Rhodium
4.7​
Beryllium
4.5​
Magnesium
4.5​
Sodium
4.5​
Aluminum
2.7​
Gold
2.4​
Copper
1.7​
Silver
1.6​


This site was posted in this forum in 2002.

http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/audio/skineffect/page1.html
 
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U

Unregistered

Guest
cables sound different

HI all
I found your replies interesting.
unfortunately at the moment the HIFI has taken a bit of a back stage while I try and do the house up to sell it :eek:(

I havent had a chance to try loads of different cables so but if we already measure all of the parameters that make the wire sound different then we could specify the "perfect" wire in which case a lot of the wires would be very similar in construction. This maybe a simplified way to look at it but the point being is that there are many variations of all the cables so what is everyone specifing.
The differences in RCL and shielding probably do make a difference, I just dont think its the whole story.
I really wish I had more time and resources to listen and study this more I find it quite interesting why the wire should make such a difference. To such an extent that I have heard two CD players made by different companies sound more alike, or less of a difference between them, than an interconnect wire.

For jo public it can be difficult to select a cable as the miriad of cables and marketing hype just serve to make the non technical person more confused.

As for the skin effect question I read the quoted article and it confirms what I already thought.
From a technical point of view the artical was very interesting however i was a little dissapointed that no listening tests were done to put more meaning to the artical. (although I have only read that portion of the document I am not sure if there is any more detail on another part of the document).

Yes wire has been measured for a long time but how long since we looked at wire from an audio point of view. Since the audio quality tends to be subjective it is a little difficult to correlate with objective scientific measurement although not impossible.

Just out of interest what system do you have and what wire do you use also what wires have you tried and found bad and what wire have you found to be good or the best.

The homeopathic medicin question is a little more difficult as you cant repeat the conditions exactly with an illnes and the million variations the people have, but when changing just the wire you can always go back to the previous condition so you can rule out most of the random influences.

Another thought is can we measure an amplifier and say it will sound better than another amplifier and be correct 100% of the time???

Sorry I didnt elaborate more about the final point.... yes the listening experience, enjoyment. I like it when you start listening and cant stop listening to the music because it portrays the emotion, when you can almost touch the instuments and singers, close your eyes and you have the band infront of you with real depth. When you put on some music with a bit of go in it you really feel rythm and drive etc. I try not to let the technical aspect over rule the music itself forget what you are playing it through and enjoy and if you can get it for nothing then good on you.

Enjoy some music tonight people :eek:)

Cheers
Later
MAD 1
 
Mudcat

Mudcat

Senior Audioholic
There will not be an audible difference between quality cables. Quality comes in several forms all joined into a single cable. IMO, the three primary colors are (1) RLC characteristics, then comes (2) construction, last comes (3) finish (it has to look good doesn't it?). To illustrate Gene's point, replace one set of speaker cables with two strands of 24 AWG wire (ripped from some CAT 5 is easiest). Play a very dynamic DVD with the volumn cranked way up into ear bleed territory and have a CO<sub>2</sub> fire extinguisher handy. Those wires will get warm, maybe even hot. That heat is lost energy that would ordinarily go into the speaker. That is what bad RLC does for you (even though CAT 5 usually has very good inductance{L}).

Oh yeah, the speaker will sound terrible too.
 
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mtrycrafts

mtrycrafts

Seriously, I have no life.
I havent had a chance to try loads of different cables so but if we already measure all of the parameters that make the wire sound different then we could specify the "perfect" wire in which case a lot of the wires would be very similar in construction.

There are many perfect wires since only the grossly different ones sound different as was pointed out about the 24 ga wire.
If there is no audible differences between 12 ga and 16 ga wire, then both must be perfect, no?



The differences in RCL and shielding probably do make a difference, I just dont think its the whole story.


You need to read the link further as it has measurements of 12 differeent cables with 12 different RLC. They are all ploted for respons, and in two amp/speaker setups. You will see that all are very close in response even though their RLC numbers are not. We also know from other research what we can detect, what the threshold of detect is. That is not a mystery after 100 years or acoustic research.


I find it quite interesting why the wire should make such a difference.

I would put the horse before the cart, not after it. In another word, we need to establish that wires do sound different. You have not, no one has unless it is grossly different such as 24 ga and 16 or 12ga.

To such an extent that I have heard two CD players made by different companies sound more alike, or less of a difference between them, than an interconnect wire.

So you think a CD player is easier to make to sound the same than wire? I would suggest using a better listeing protocol before you look for causes for differences between wires. No one has demonstrated differences unless broken.

For jo public it can be difficult to select a cable as the miriad of cables and marketing hype just serve to make the non technical person more confused.

One reason this place thrives, to help the less knowledgeable person :D

As for the skin effect question I read the quoted article and it confirms what I already thought.

I thought you stated it is not present at audio frequencies? The article indicates otherwise.


From a technical point of view the artical was very interesting however i was a little dissapointed that no listening tests were done to put more meaning to the artical.

It wasn't about audible differences in wire. It is about measured differences abnd responses. ;)



Yes wire has been measured for a long time but how long since we looked at wire from an audio point of view.

What is so special about audio frequencies?


Since the audio quality tends to be subjective it is a little difficult to correlate with objective scientific measurement although not impossible.

Actually it is not difficult at all. Harman does it all the time. The NRC in canada does it all the time as does a number of speaker companies do this all the time.
http://www.crc.ca/en/html/aas/home/evaluation/evaluation#recent_tests

http://miragespeakers.com/nrc_story.shtml

Just out of interest what system do you have and what wire do you use also what wires have you tried and found bad and what wire have you found to be good or the best.

How is this relevant to the discussions here? I may not even have an audio system, or, I may be deaf. Neither is a requirement to post and discuss issues ;)
We are discussing what you claimed, if I remember correctly.

The homeopathic medicin question is a little more difficult as you cant repeat the conditions exactly with an illnes and the million variations the people have, but when changing just the wire you can always go back to the previous condition so you can rule out most of the random influences.

Actually, it is as testable as any medicine tested today, under DBT, placebo controls, on the population. Right? It is done every day. Homeopathic medicines are not exempt from testing, reproduced by others.

Another thought is can we measure an amplifier and say it will sound better than another amplifier and be correct 100% of the time???

Well, that assumes that amps sound audibly different, right? You would need evidence to support that claim too. Good luck. Much testing will disappoint your beliefs about amps too, not just wires.

I like it when you start listening and cant stop listening to the music because it portrays the emotion, when you can almost touch the instuments and singers, close your eyes and you have the band infront of you with real depth.

I can have that experience in a car just as well. Or, listening to my boombox.



Enjoy some music tonight people :eek:)

Cheers
Later
MAD 1



Thanks. We'll do that :D
 
Mudcat

Mudcat

Senior Audioholic
mtrycrafts said:
I can have that experience in a car just as well. Or, listening to my boombox.
You own a boombox??? Snicker snicker giggle giggle :eek: :D :p
 
J

jneutron

Senior Audioholic
Rip Van Woofer said:
You got a problem with boomboxes, punk?? :D
I tried...I wanted to see the person taking the picture, but...this is the best I could do...

How come CSI can get the pictures so enhanced, but I can't. Darn it... :mad:


Cheers, John
 
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JoeE SP9

JoeE SP9

Senior Audioholic
Mudcat said:
Platinum is actually 6 times more resistant than copper and rhodium ain't great either.

I stand corrected Mudcat. :cool:
 
JoeE SP9

JoeE SP9

Senior Audioholic
jneutron said:
How come CSI can get the pictures so enhanced, but I can't.
If you were on TV you could do it because you would have a large supply of unobtanium. :cool:
 

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