Capacitance and Inductance

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Carlman

Capacitance and Inductance
« on: 12 Oct 2004, 07:29 pm »
I was considering a pair of speaker cables and started thinking I'd experiment with high and low capacitance speaker cable and amplifiers.

I know that some amps like low capacitance and others are OK with high... and didn't really know much about inductance.

Can someone provide a simple explanation of how capacitance and inductance 'should' fit into the amp and speaker connection?

Also, when does a cable become high or low in one of those areas?

Here's some specs from Kimber's site on the 4vs cable:

4VS
Basic Electrical Specifications
DUT: 4VS 2.5m bare wire ends.
 
• (Cp) parallel capacitance: 340.0 pF @ 20 kHz
• (Ls) series inductance: 0.596 H @ 20 kHz
• (Rdc) dc loop resistance: 0.041  
• (Xt) total reactance: 0.075  @ 20 kHz
• Frequency response ± 0.5 dB dc - 250 kHz


Would this be considered 'average' cap and ind?

Thanks,
Carl

audioengr

Capacitance and Inductance
« Reply #1 on: 12 Oct 2004, 08:14 pm »
Carl - capacitance should be low for interconnects.  Inductance and resistance should be low for speaker cables.  The lower you can make the other parameters and still satisfy the above requirements, the better.  Here is a recent measurement shootout:

http://www.audioholics.com/techtips/audioprinciples/interconnects/speakercable2p1.php

It is really the R*L*C product that must be minimized as well as the above specific parameters. In other words, which speaker cable has the lowest of both L and R*L*C.

dado5

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Capacitance and Inductance
« Reply #2 on: 13 Oct 2004, 02:17 pm »
Steve,

Mighty big of you to reference a source that is less than kind about your product.

I really do not understand their quest. Who are they trying to save? If someone prefers the sound of one cable over another and agrees with the price offered, how is he being ripped off, misled, fed snake oil, etc.? Seems like Gene and company are really spilling ink ( er, spending bandwidth?) for no good reason.

Anywho, I always did enjoy your posts over at the cable asylum when I used to spend time there. Keep up the good work.

Rob

nathanm

Capacitance and Inductance
« Reply #3 on: 13 Oct 2004, 06:53 pm »
It's not about "saving" anybody.  You can buy whatever you want, but at the same time it's essential to have people who are after the facts, who want to disseminate the claims of marketing departments and find out what's real and what's a load of crap.  If that constitutes a waste of bandwidth to anyone then fine, don't read the site.  Simple.  But if there's no logical engineering types out there reining in the flim flam men and their overblown claims we're then supposed to take whatever advertisers say as hard fact.  No thank you.

If there weren't people like around who actually have studied and know a thing or two about electricity then nobody would be able to answer Carl's question, all they could offer is a sales pitch about how cable XYZ will fill your life with Palpable Tonal Smoothness and Euphonic Sonorousity without a hint of Grain. :roll:

dado5

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Capacitance and Inductance
« Reply #4 on: 14 Oct 2004, 03:51 am »
Fundamentally, the main problem here is the attempt to use materailism to validate perception.  

The folks at audioholics rely on materialism to show that various products cannot perform as stated by those who market them.  This only works as far as materialism is used in the marketing.  Lets say Gene looks at current bunching (skin effect)  in the Nodust ValKilmer. He can factually say that significant current bunching was observed in the at frequencies above 50KHz.  If Nodust claimed that the ValKilmer shows no current bunching until 100KHz, then Gene showed that the cables did not work as advertised. However, Gene cannot factually say that Nodust's claims about minimal skin effect being the main reason for the great sound of ValKilmer are bunk. All he can do here is opine. The coin is two sided of course, as Nodust cannot prove (in the proper sense) that skin effect is the cause of good sound. At best they can show correlation and no more.  Materialism can only prove so much, it cannot account for a subjective internal experience. It cannot prove or disprove a perception.

As music lovers/audiophiles/stereo geeks, our perception is the main factor in our selection of home sound reproduction equipment.  This is a simple economic fact. We derive pleasure from how music sounds in our home first and foremost, and we make our consumer calculations accordingly. This is why I say Gene and company are jousting with windmills. As we ultimately favor what we find audibly pleasing, pronouncements of discrepancies between physical measurements and marketing claims mean nothing. Our ears tell us what we like, not someone else’s opinions.

In reality, audioholics calls of snake oil sales and carnival barking are as much opinion and marketing as any line coming from Noel Lee or George Cardas. Both are attempting to influence consumers in a particular direction. Cardas is trying to get you to buy his cable and Gene is trying to get you to spend your money on something he thinks is more valuable (that is to say not spend it on something he thinks is not valuable.).  One uses marketing to convince you to buy his product, the other uses it to to get you to agree with his personal value scale.

And that brings us to the 'saving' comment. The motivation of audioholics comes from moral outrage at what they perceive is deceptive marketing and/or price gouging on one level or another.  They step beyond what most of us do when we have similar feelings - stew, complain, or just ignore. They are compelled to do something about it.  They strive to show how cable manufacturers make exaggerated or false claims about their products and charge more than similar longstanding, industry-standard units.  They seek to convert others to their own value scale which, by definition, is absolute.  In short, they preach. Like all preachers, they seek to save the lost.  The question is, who is lost? When someone buys a cable he likes for a price he likes, how is he ripped off? How has he been taken in by pseudoscience? How has he been wronged in any way?

Thanks,
Rob

nathanm

Capacitance and Inductance
« Reply #5 on: 14 Oct 2004, 03:52 pm »
I assume it is this definition of "materialism" you are talking about and not the kind Madonna sang about in the 1980s? (although I guess they ARE the same thing actually...)

Code: [Select]
Main Entry: ma·te·ri·al·ism Pronunciation: m&-'tir-E-&-"li-z&m Function: noun 1 a : a theory that physical matter is the only or fundamental reality and that all being and processes and phenomena can be explained as manifestations or results of matter b : a doctrine that the only or the highest values or objectives lie in material well-being and in the furtherance of material progress c : a doctrine that economic or social change is materially caused -- compare HISTORICAL MATERIALISM 2 : a preoccupation with or stress upon material rather than intellectual or spiritual things

If so I would say yes, that is exactly what Audioholics is on about.  And I would say that is an absolute GOOD thing that they do!  Cables are supposed to perform a specific function, it's not supposed to be there to make you feel good.  Therefore materialism is only the right thing to judge them on, and not people's feelings about using them.  Although that in itself would be a very telling study to do; meaning the effect that mental constructs have on listeners.  Another topic I suppose...

Quote
Materialism can only prove so much, it cannot account for a subjective internal experience. It cannot prove or disprove a perception.


Of course it can't, and isn't that the point? The cable companies are claiming that their particular materials are going to give you superior sound quality.  Both AH and the vendors are on the same playing field.  The marketing line is NOT telling you, "this cable is great because you THINK it is" they give you all sorts of technical, material reasons why that is so.  So it would be fair of AH to point out any shortcomings in the measurements which show that the marketing claim ain't all it's cracked up to be.

What I don't understand is why anyone is rushing to defend their right to purchase overpriced wire when the objective sciences tell us that there should only be insignificant differences and even more insignificant within the audio band.  Wouldn't you like to have a GOOD reason to spend all that money above and beyond your own perception?  Something based on science and not faith?  I don't understand why anyone is prideful about their sonic perceptions.  I am always grateful if someone can point out how what I think or hear may perhaps be based upon factors other than the one I think it is.  I don't WANT to think that a $500 piece of wire is the reason why I am enjoying the sound.

Does anyone claim they can hear "current bunching" at 100KHz, much less 50 or even 20?  It's ridiculous.  Even moreso when you take into account the limitations of microphones, preamps, recording mediums and so forth.

Quote
In reality, audioholics calls of snake oil sales and carnival barking are as much opinion and marketing as any line coming from Noel Lee or George Cardas. Both are attempting to influence consumers in a particular direction. Cardas is trying to get you to buy his cable and Gene is trying to get you to spend your money on something he thinks is more valuable (that is to say not spend it on something he thinks is not valuable.). One uses marketing to convince you to buy his product, the other uses it to to get you to agree with his personal value scale.


Gene is using marketing!?  I thought he was using science and engineering?  I strongly disagree with this, the two parties are NOT using the same methods to argue their point.  It WOULD be true if the cable makers were marketing based on purely subjective matters, (Our Swankylinks XTs are better because they have cool wooden plug barrels and you'll perceive better sound because of them!) but they aren't.  But even so, if they both were using the same methods which side would you rather be on?  Perception or reality?  Although you might find it silly for them to be "morally outraged" I am damn glad there's someone out there standing up for what's right.  It is a good thing that there is a dissenting view out there arguing against wasting your money on minutia.

Why is anyone defending this price gouging?  Even AH says they have no objections to buying "audio jewelry" or buying a well-constructed, durable cable.  How does this fall into preaching?  Preachers want you to believe because they SAY SO.  AH and others want you to believe based on demonstrable, repeatable, measureable, material objective evidence.  Those two approaches are NOT at all alike.

But enough on that, onto another tangent.  Now let's say that you want to spend $500 to improve your sound.  Doesn't matter what gadget it is, maybe your granny snuffed it and left you $500 and you'd like to rock out in a better way.  Wouldn't it be hugely more logical, more measurable, and more audible to put that money towards a circuit whose effect is perceptible to everyone from your once-living granny to a cable salesman to the staunchest, pocket-protectored EE in his lab?  A TONE CONTROL!!!  Ahhh!  Does it make more sense to sink $500 (or whatever amount you wish) into a supposedly passive material such as a length of wire than it does into a tone control which will unquestionably affect the sound no matter what your opinion of hifi is?

For me personally, I DON'T understand the desire to own extremely expensive wire.  I DO understand the desire to own cool LOOKING stuff.  I DON'T understand why anyone would argue that cool looks or high price alone equals better sonic performance.  As far as looks go, anyone with opposable thumbs can make a cheap cable look cool with a little arts 'n crafts action.  

Quote
The question is, who is lost? When someone buys a cable he likes for a price he likes, how is he ripped off? How has he been taken in by pseudoscience? How has he been wronged in any way?


I can go along with that, but I wonder how many people actually buy cable based on actually hearing it in their own system as opposed to those who read reviews or other people's opinions, or look at advertising before they decide to buy it?  I'd like to include the views and demonstrable evidence of those who are debunking all of that as well.  That I think is a good thing and why I think AH's "moral crusade" if you wish to call it that, is a helpful tool and not simply a shallow thumbing of their noses at the cable guys.

Cripes, this post is almost as long as one by azryan, only it has paragraphs! :lol:

Carlman: I apologize for wrecking your topic, but I was in the mood for a cable fight. :P

warnerwh

Capacitance and Inductance
« Reply #6 on: 15 Oct 2004, 12:21 am »
Nathan's right!  That's not an opinion btw.

Carlman

Capacitance and Inductance
« Reply #7 on: 15 Oct 2004, 01:03 am »
I enjoy a good ol' cable discussion as much as anyone... the only reason I asked is that I got this kick ass new speaker cable that sounds better than what I had.  I've compared other speaker cables without much change but these were actually quite a nice change.

So, I got to thinking, there must me some reason for the change.  'Occam' had mentioned good luck with my particular combo and I thought he'd mentioned some technical reasoning... like capacitance/inductance... so, I was hoping to get some more info to quantify what I heard.

As it turns out, I'm one of those guys that actually compares wire to find a sound that suits me... however, I generally like to know why I heard the improvement.  I don't care why a cable sounds worse, only better, though. ;)

I would like a more elaborate explanation than was given but I'll take what I can get for free. :)  -even if it means wading through the Material Girl discussion. ;)

-C

dado5

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Capacitance and Inductance
« Reply #8 on: 15 Oct 2004, 03:02 pm »
C-

My overarching point is that you can't know what causes the difference in sound.  No methodology exists to test whether or not a given physical parameter difference the cables is the CAUSE of the perceived difference in sound.  The perception and the metric can be correlated, but that is as far as we can go objectively.  Causation is another matter. To prove causation would require independent, isolated testing of both correlates.  As one of the correlates is an internal subjective experience related only through language, it is not independently verifiable.  

Knowing the difference in metrics between the cables you like and the one you do not gets you no assurance that these parameters are the ones responsible for the differences you hear.  All anyone can do is speculate. The aural differences may well be due to these physical differences in the cables. They may be due to unobserved physical differences. They may be due to purely internal factors (physical or psychic) of the listener.  We just can't tell.  As such, cable makers and cable naysayers alike can only offer opinions on this issue, not facts.

As we cannot state that a given metric is the cause of improved sound, we have no need to rely on the metric to assess the cable's performance- that is if we judge performance by our aural perception. Given this, the most that this metric can do is give us measure of comfort or pleasure in a purely psychic/intellectual way.  

Now I am as curious as the next guy. Every time I make a new cable (I have not bought a commercial cable in 3 years) that sounds better than the one before, I wonder why.  And like everyone else, I am loath to think my mind is generating the difference, so I speculate on the obvious parameters that might be responsible. This is fun and food for conversation, but that is about it.  It does not provide me with any more facts about the cable's performance than I had at the start. And that's the long and the short of it.

Just listen and go with what pleases you.

Thanks,
Rob

audioengr

Capacitance and Inductance
« Reply #9 on: 15 Oct 2004, 05:32 pm »
Quote from: nathanm
It's not about "saving" anybody.  You can buy whatever you want, but at the same time it's essential to have people who are after the facts, who want to disseminate the claims of marketing departments and find out what's real and what's a load of crap.  If that constitutes a waste of bandwidth to anyone then fine, don't read the site.  Simple.  But if there's no logical engineering types out there reining in the flim flam men and their overblown claims we're then supposed to take whatever advertisers say as ...


Gene is definitely trying hard to be the cable consumer reports.  However, one thing that is clear is that: like many that have tried this before, he is relying on a limited set of tools to do his analysis.  IMO, these tools are inadequate to properly characterize cables.

audioengr

Capacitance and Inductance
« Reply #10 on: 15 Oct 2004, 05:36 pm »
Quote from: dado5
Steve,

Mighty big of you to reference a source that is less than kind about your product.

I really do not understand their quest. Who are they trying to save? If someone prefers the sound of one cable over another and agrees with the price offered, how is he being ripped off, misled, fed snake oil, etc.? Seems like Gene and company are really spilling ink ( er, spending bandwidth?) for no good reason.

Anywho, I always did enjoy your posts over at the cable asylum when I used to spend time there. Keep up the good work.

Rob


Rob - thanks for the vote of confidence.  I didn't really look at it that way.  If you study the numbers carefully (and there were errors in his measurements of my cables because the ferrites were not removed before measuring), of the 4 or 5 lowest inductance speaker cables, my Clarity7 had the lowest R*L*C product.  this means that you can get low inductance without being penalized with high capacitance.  Not so bad, really.

nathanm

Capacitance and Inductance
« Reply #11 on: 15 Oct 2004, 06:46 pm »
Quote from: audioengr
IMO, these tools are inadequate to properly characterize cables.


According to experts it has something to do with the amount up to or exceeding $500 exchanging hands.  I can't remember where I read that, but in any case I'm sure it's true.

Quote from: dado5
...like everyone else, I am loath to think my mind is generating the difference, so I speculate on the obvious parameters that might be responsible.


Okay, but why are you loath to think so? Is the electrical activity in your brain more stable and consistent than current flowing through a wire? Do you feel the exact same way every day? Is your mood always the same?  Your taste in music never altering?

If you ask me I think it's the human brain that we don't have enough tools to fully understand. In comparison to that I thought electricity was something we had pretty well licked, but apparently not?

warnerwh

Capacitance and Inductance
« Reply #12 on: 15 Oct 2004, 11:15 pm »
Being loath to accept that you may be tricking yourself is certainly understandable. I was that way too and felt so many times I could hear a difference then switched back some time later to see what I thought and guess what? I had the placebo affect working just fine.  I now have inexpensive cabling (not that I had very expensive cables before) in my system. It sounds as good as it did with better or should I say more expensive wire.  The holy grail for me has been room acoustics and correcting them.  Let me assure you though that for the same money someone spends on cable I've treated my room, built bass traps and have a good equalizer.  The improvement is nothing short of major.   Far too much time is spent talking about wire when the major contributing factor in each of our systems is our room which gets little bandwidth.  Until your room is done and you understand where you are at with your acoustics is the only time wire should be considered.  And then only as a conversation piece.

audioengr

Capacitance and Inductance
« Reply #13 on: 16 Oct 2004, 01:02 am »
Quote from: nathanm
Okay, but why are you loath to think so? Is the electrical activity in your brain more stable and consistent than current flowing through a wire? Do you feel the exact same way every day? Is your mood always the same?  Your taste in music never altering?

If you ask me I think it's the human brain that we don't have enough tools to fully understand. In comparison to that I thought electricity was something we had pretty well licked, but apparently not?


Apparently not.  It turns-out that most physical relationships that are described by equations are only simplifying approximations where a number of assumptions are made.  This makes the math easier to do, but at the same time, ignores some of the physical phenomenon.  It's not so much that we dont have a handle on the math to describe electricity and fields. It's more that we are not looking in the right places for phenomena that is audible, or can become audible, IMO.

dado5

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Capacitance and Inductance
« Reply #14 on: 16 Oct 2004, 03:06 pm »
warnerwh,

You hit the nail that most people miss on the head.  The room-speaker interaction has the single biggest impact on the sound of a system, period.  It affects loudness, frequency and stereo performance all that the same time. Ideally, this needs to be ironed out before any component/cable upgrade is sought.  Of course if you upgrade the speakers then it all starts over.  

Considering that a purchase of a suite of some high end cables would exceed the cost of building a dedicated listening room, much less treating an existing one, if I were well heeled I know where I would put my money.

Thanks,
Rob

dado5

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Capacitance and Inductance
« Reply #15 on: 16 Oct 2004, 03:22 pm »
Quote
Okay, but why are you loath to think so?........
Being loath to accept that you may be tricking yourself is certainly understandable......


That's it really.  We all like to think we are sane and not prone to regular halucination.  Of course I have no way of telling for sure. Could the differences I perceive be purely internal? Sure, they may well be. Does it matter?  Considering the only factor involved is personal enjoyment of music in my home, not really.  

Thanks,
Rob

warnerwh

Capacitance and Inductance
« Reply #16 on: 16 Oct 2004, 05:21 pm »
Rob: Maybe it does matter.  If you have any low end cables laying around why not swap them into your system for a week or two.  See how things work out for you.  Don't even worry about trying to hear a difference, just see how your system sounds and how enjoyable it is.  That may give you a better perspective as long as you keep an open mind. In all parts of our lives it's best to be honest with ourselves or who do we end up screwing?

PEB

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Capacitance and Inductance
« Reply #17 on: 18 Oct 2004, 02:19 pm »
Carl,
A speaker wire can be modeled as a transmission line, which can be considered a sequence of many small inductors and capacitors connected together.  All the inductors are in series, connected end-to-end from the amp's red post to the speaker's red post.  There are an equal number of caps, and each cap connects to the node between any two pairs of inductors.  The other end of each cap connects to ground.

It looks like this:
AMP -L-L-L-L-....L-SPKR red post
...........|  |  |  |    |
..........C-C-C-C...C
...........|  |  |   |    |
GND ------------------SPKR black post

(Ignore the dots; they were needed for spacing. Also, for simplicity, I have left out distributed resistance in the model.)

Each L-C combo is a low pass filter.  Which is why reducing L and C in magnitude pushes the low pass filter up higher in frequency.  The speaker is the load, and is not a simple resistor.  However, drivers with voice coils tend to model as a simple inductive load above 20kHz.  This means that the load presented to the amp is overall inductive at high frequencies.

One reason that I publish my speakers' impedance curves to 100kHz, is to prove that the load truly tends toward the inductive, so as to assure the owner that any amp oscillation problem will not be caused by the speaker itself.

This may be of importance to some tube amps, or SS amps with very high bandwidth (such as those in my reference system).  IOW, if the amp can reproduce >200kHz, then the possibility for it oscillating as a reaction to the load is greater, too.  Note that oscillation can be severe to the point where the amp is trying to reproduce its full rated output at a very high frequency.  While the duty cycle is low at this high frequency, over time it can overheat the amp.  The listener won't hear this (nor will his dog) because it can be as high as more than 500kHz.

The distibuted L-C model is a simple one, which applies to say zip cord style speaker cable.  

There are certainly more complex models which are even more accurate.  A more complex model might be appropriate for some of the speaker cable recipes that reduce parasitic inductance/capacitance by extensive use of strand geometry.  (I like the sound of such cables myself, and yet I have amps that could oscillate if the cable is taken to extreme.)  Some of these cables can exhibit RLC tank circuit behavior above 150kHz.  

Considering the distributed resistance in the model, we know that this helps to damp the tank circuit, which helps fight oscillation tendencies.  However, it is also desirable to get the total resistance low, as resistance tends to "decouple" the speaker from the amp, reducing damping in the bass, and dynamics overall.

Normally, it is not possible for one to measure cable parameters with a standard RLC meter, since the meter really only tests the device with a 1kHz signal.  And since the model is not a simple, single R or L or C, the meter cannot detect the complexity.

I am working on an affordable speaker cable for my customers now.  It offers low R-L-C, but is stable for all amps. It will be available in single- or bi-wire versions, and is a 5/8" diameter round cable.

audioengr

Capacitance and Inductance
« Reply #18 on: 18 Oct 2004, 04:50 pm »
Philip - the transmission-line circuit model is a good first-order approximation for a speaker cable and adequate for interconnects.  However, in order to model speaker cable accurately, you really need a model that takes into account the field coupling between conductors and the dielectric absorption of the insulators.  This is why I use Ansoft Maxwell to build models that I can run in SPICE.

audiojerry

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Capacitance and Inductance
« Reply #19 on: 18 Oct 2004, 07:18 pm »
gosh, this can get heavy. I feel like I'm kibitzing on a philisophical discussion of the origins of life, but it's fun. It's amazing how much intellectual discourse the subject of audio cable inspires.

Quote
Knowing the difference in metrics between the cables you like and the one you do not gets you no assurance that these parameters are the ones responsible for the differences you hear. All anyone can do is speculate. The aural differences may well be due to these physical differences in the cables. They may be due to unobserved physical differences.


Excellent point! (because I agree  :lol:)
It seems like Nathan gets irritated at folks who espouse hearing significant differences in wire when measurements just don't support their claims. Unfortunately, there are no measurements that correlate closely enough to what we hear. And sorry, Nathan, but the process of hearing does generate emotional responses, like just about anything else, and one should be motivated by emotion when deciding which wire one prefers. Not to say we can't all be fooled by hype and deception, but in the end, many of us are willing spend the extra $$$ because the differences we hear are worth it regardless of what the actual cost of manufature might be.  

Maybe it's not a valid point, but is there any way to measure empirically how much better a Gibson guitar sounds than a Fender or vise versa?