>>According to that data, the zip cord showed a .25 dB drop just above 20
KHz at 8 ohms.<<
As usual, this is vague. "Just above 20Khz?" When you talk about
a .1 dB drop at 20Khz as if it is the Niagra Falls, who knows what "Just
above" means to you. But, even if this were true, .25 dB is still waaaaay
below the 3.05 dB change needed for detection WITHIN the audio band. |
I extrapolated the figures that i posted from the original data that you were referencing. According to that data, the zip cord showed a .25 dB drop just above 20 KHz at 8 ohms. There was no mention of results into a 4 ohm load there, so i have to wonder where you obtained the figure of .1 dB at 4 ohms. Obviously, these figures don't jive mathematically, so there is some disparity in terms of testing methods and / or materials used. Sean
> |
A 10 foot length of 12AWG Zip Cord is 0.1dB down at 20kHz into a 4 ohm
load.
This is waaaaaay below the threshold of audibility -- see reference above.
>>If it was true or factual in the least, i would remember it.<<
Perhaps you should write it down.
>>The fact that i've refuted your past arguments using your own reference
materials<<
Dude -- you've never refuted anything, you simply claimed that people who
disagree with you really agree with you, but don't want to say it. Since I do
not believe you are Kreskin, I hardly find this a credible "refutation."
The evidence shows you are talking about .1db at 20Khz -- waaaaay
below the level of human audibility and yet you continually refer to a "
roll-off" without specifying the amount, which I've posted for you and
given you references to charts. Since you've been given this information, it is
highly irresponsible for you to refer to a "roll-off" without
mentioning that it is .1db at 20Khz into a 4 ohm load. Completely
misleading. It doesn't take a rocket scientist to figure out why you leave out
this information -- because if you include it, most folks would simply chuckle
at the notion and your urban myth would die. You also have information
about the limits of human audibility and it is irresponsible not to mention this
as well. At least the guy from Empirical gives a nod to this. If you were
honest, you'd say it is .1 db down at 20Khz, that available studies show that it
takes a 3.05 dB change to be audible at those frequencies and if you still
want to press the point, you could say it is "debatable" or as the Empirical guy
said, "there is some question" about whether or not anyone could possibly
hear such a thing. If anyone could, he/she would reject all cables because
every cable has .1db variations over the audio spectrum, so there really isn't
any debate or question, but at least it would sound a little more credible. |
Rsbeck: The measurements that you initially referenced showed roll-off starting at appr 22 KHz if i remember correctly. This frequency is based on an 8 ohm load. Using a 4 ohm load, roll-off would occur at half that frequency i.e. 11 khz. At a 2 ohm load, roll-off would occur at appr 5.5 KHz. With a 1 ohm load, roll-off would occur at appr 2.75 KHz.
Given that impedance varies with frequency on most every speaker known to man, the associated roll-off's and phase shifts are quite audible when one has both good listening ability and a reasonably transparent system. It should be noted that there is a BIG difference between having "good hearing" and being a "good listener". For the record, i have several sets of speakers that drop below 2 ohms, hence my concern over such matters.
Obviously, the zip cord only works "acceptably" with a theoretically non-reactive speaker that maintains an impedance of 8 ohms or higher. It should also be noted that not all zip cord is of the same inductance level or nominal impedance, so these figures are based on best case scenarios. As length of the cabling is increased and / or the inductance climbs higher, the effects will become even more pronounced and severe in amplitude. The fact that the nominal impedance of the cable is 100 ohms or more, and will negatively effect power transfer characteristics from the amp to the speaker, is true regardless of the length used.
As to what you've told me, i forgot all of that. If it was true or factual in the least, i would remember it. You keep painting pictures but you leave out the most important details i.e. the ones that discredit your point of view and the message that you are trying to promote. The fact that i've refuted your past arguments using your own reference materials shows that those you rely on to do your homework for you also paint "half pictures".
Like i said, put your money where your mouth is. If zip cord works as well as you've said, you'll hear no difference, can continue to enjoy your system as you know it and can actually put a few dollars in your pocket from the sales of the "snake oil" cables that you're currently using. Until you actually do as you suggest that others do, you will be thought of as the boy who cried wolf. Over and over again. Sean
>
PS... Nelson Pass demonstrated that different cables affect power transfer, transient response and even the ability to make or break a system in terms of operating or shutting down simply by changing speaker cabling. He did so 25+ years ago and that evidence is still posted today. The fact that Nelson does not market ANY type of cabling and only did this because of the differences in how amplifiers were responding to specific loads doesn't seem to phase those that wish to promote a specific agenda i.e. that such things can and do alter what we hear and how the system responds. |
Some reality ---
The psycho-acoustic data shows that for pure tones at 16kHz the smallest average detectable difference in level is 3.05 dB. The findings were based on individuals 20 to 24 years old that had normal hearing to 20 kHz.
"Speaker cables: Measurements Vs Psycho-acoustic data," Audio, July 1994 |
>>The only issue is whether this is audible or not,<<
I appreciate this bit of honesty -- you seldom see this mentioned.
The graph on your web-site confirms that this "roll-off" happens waaaaay
outside the range of audibility.
If you have DBT or ABX listening tests to back up your claim that people can
hear this, I would be most interested in seeing that data because it would
shock the scientific world.
I also appreciate that you've identified yourself as a cable manufacturer.
I suspect there are many people in cable sales who frequent sites such as this
and do not identify themselves as such. |
Rsbeck - you can see plots of measured and computer simulated response of ZIP cord versus my speaker cables at this website:
http://www.empiricalaudio.com/frclarity7_electrical_performance.html
The simulated and measured are both obviously rolling-off with ZIP and have different phase response. The only issue is whether this is audible or not, and based on my listening tests, it is. My cables must be doing something right as they were favorably reviewed in April Sterophile, and I might add that I have never put any ads in Stereophile.
Steve N.
Empirical Audio
Manufacturer |
Sean -- sorry, buddy, but you know I don't care about your "roll-
off" that happens outside the range of audibility so it doesn't matter
how many times you bring it up, it ain't like fine wine and it doesn't get any
better with age.
In fact, it is the exact kind of half-truth I am talking about.
I challenge you to present the facts honestly and do not leave anything out.
Every time you talk about this "roll-off," I challenge you to post
the truth -- that it is outside the range of audibility. I think that is a pretty
important point.
I posted a reference to a whole chart of cables I do not own, but I am not
allowed to mention the Zip Cord listing? Not allowed to say anything good
about Zip Cord? Who made that rule? You?
Finally, next time, don't just reference what YOU wrote last time -- try to
recall what *I* tell you each time you bring up the bogus "roll-off" -- that
way, you can expect me to have the same answer as before.
Save us both time.
|
Rsbeck: We've been through this before. The test results published for frequency response do not take into account impedance variations whatsoever.
As i've posted before based on figures extrapolated from the data that they provided, "zip cord" can introduce very measurable treble roll-off starting within the upper midrange / lower treble region on some speakers. Your refusal to see or acknowledge this potential problem, yet quote the same crap over and over again, makes me question your agenda.
The fact that you keep promoting zip cord yet chose other wires to run in your own system speaks volumes in itself. Make us proud and put your money where your mouth is. Doing so and selling your "fancy cabling" will buy you another couple of discs and tell us that you really do believe what you post. Saying one thing and doing something completely different doesn't set much of an example, nor will it sway anybody to believe what you are promoting. Once you swap those cables out of your system, you can keep telling yourself that it sounds exactly the same and that you are happy with your decision. Sean
> |
Perhaps this one of the reasons the 10 guage Zip Cord exhibits lower Capacitance and Inductance than many of the more expensive speaker cables in the chart referenced above and why none of the more expensive cables produce a more linear frequency response over the audio band. |
From Audioholics Web-site ----
Dielectric Absorption in Cables Debunked
Before we debate the relevancy of Dielectric Absorption relating to speaker cables, and commonly perpetuated by many exotic cable vendors and cable cult hobbyists, let us first define the roll of a dielectric.
According to Wikipedia (http://en.wikipedia.org/wiki/Dielectric) the definition a Dielectric material is an insulator. The ideal dielectric would be a vacuum or infinite impedance. However, real world dielectrics do NOT have infinite impedance and therefore are not perfect. As frequency increases, the Dielectric starts exhibiting shunt resistive losses which can be measured and quantified as signal loss across the termination load. Fortunately for our application (audio) these shunt losses don't begin to surface until frequencies much higher than the audio bandwidth.
At audio frequencies, even the worst dielectrics (IE. Polyvinyl Chloride, aka. PVC / plastic) used in cheap and many exotic speaker cables maintain shunt resistive impedances in the mega ohms or more. When dealing with a low termination impedance of a loudspeakers (usually in the order of several ohms) the dielectric shunt resistance is on the order of 10^6 greater, thus the parallel impedance remains virtually unaffected and we see no losses due to the dielectric at audio frequencies.
Cont'd....
http://www.audioholics.com/techtips/audioprinciples/interconnects/dielectricabsorptioncables.php |
>>most of the time, this is audible and sounds like sibilance on top of the high-frequency information in the music. Metal purity, choice of metals, cryo treatment and other factors affect this.<<
This is what I mean by myths and wive's tales. I predict no hard evidence will be offered to back the idea that any of this is true.
>>the dielectric material absorbs charge and releases it when transients occur.<<
Sounds like advertising from a cable site -- this has been debunked.
>>smearing will occur.<<
No one has ever been able to measure audible distortion caused by a speaker cable. No one. Zip, zilch, null set.
>>The effect of this is usually a loss of HF dynamics, often described as a roll-off, but technically it isn't.<<
This ought to be measurable. I predict we will not get any back-up for this, either. No way to quantify the loss of dynamics, no double blind listening tests to see if anyone can hear any such thing.
Basically, in the audio world, you can say anything you want about cables because standard of proof is completely absent. So people run around saying whatever they want, throw a few big words in there for good effect, people repeat it and pretty soon, you've got another urban audio myth -- and possibly another cable sale. |
Frequencies and speed is not accurate to describe the effect. Geometries aside (spacings and wire gauge etc) , materials in cables have several effects, both insulation and metals. Lets start with metals:
The crystal lattice in the metal can cause reflections in the cable, because they are impedance discontinuities. These occur at very high frequencies, but this does not mean that they will not become audible. Depends on whether the driver reacts to these reflections or not. most of the time, this is audible and sounds like sibilance on top of the high-frequency information in the music. Metal purity, choice of metals, cryo treatment and other factors affect this.
The insulation has several effects as well. Besides the obvious effect on capacitance per unit length, the dielectric material absorbs charge and releases it when transients occur. Depending on the material, it is not completely released either. In general, if the time-constant of the material release is slower than the time-constant of the transient, smearing will occur. Dielectrics with a lot of air will usually have the least dielectric absorption effect. The effect of this is usually a loss of HF dynamics, often described as a roll-off, but technically it isn't. |
My impression is that people like to throw myths and wive's tales together
with things that are half-true and extrapolate from that into the land of the
hypothetical based on hypothetical on top of wishful thinking.
I had a strong feeling that no one was going to be able to tell me anything
solid about this affect on dynamics, how it is measured, or if there is anything
to back any of this.
What isn't in dispute in this discussion is that it is desirable to have low
capacitance and inductance. But, we also know that several very expensive
cables exhibit far higher inductance and capacitance than 10 guage Zip Cord
(See table referenced above). If there *was* any solid proof that higher
capacitance and inductance -- at the levels exhibited by these expensive
cables -- degrade the performance of these cables with regard to dynamics
-- that would be interesting. Especially, perhaps, to the owners of those
cables. But, since there apparently isn't anything solid, "No one
knows for sure -- there are a lot of variables." We don't really have
anything.
Yes, we do know that the configuration matters most if one is attempting to
manipulate inductance and capacitance, but this just supports the counter-
point that materials -- silver versus copper -- matters least. And that's the
answer to the original question. If capacitance, resistance, and inductance
matter most with regard to dynamics, a whole lot of expensive speaker cables
do not measure as well as 10 guage Zip Cord (see table referenced above) nor
do they provide more linear frequency response (see frequency response
charts included in referenced article). |
Thank you Bob. Coming from an EE with an open mind and years of audio experience, your summary was both brief and technically excellent ( as usual ). I couldn't have said it any better and i surely couldn't have done it as briefly as you did. Kudo's to you for an excellent post : ) Sean
> |
My perception of the impedance issues which have been brought up seems at least partially corollary...
Source components have unique reactive impedance characteristics comprised of a resistive component, an inductive component, a capacitive component. Terminating (load) components also have these characteristics although they typically don't match the source component's reactive signature. Then add the connecting cables' complex impedance (which is yet again different from source & load reactive component) into this complex impedance network. The source impedance doesn't match the load impedance, & the transmission line impedance matches neither.
These mismatches are a guaranteed formula for signal-reflections which result in standing waves. Propagation delay of various frequencies within the bandpass differs significantly. The result is a smearing of the signal throughout the transmission process of simply coupling a waveform from one box of components to the next box.
Considering the radically varying complex-impedance network of everyone's own unique combination of audio componentry & interconnecting cables, it's not too hard to understand why (obvious differences aside) no two rigs sound quite alike, and why a cable moved from one system to another system can sound so very different. |
Gregm is right. Dynamics involves several things - not just dynamic range which is noise floor related. I was referring to slew rates but typically, cables have less impact on slew than p-n junctions and circuit bandwidth so the point is academic.
I took "combination" to mean configuration. It is meaningless to talk about just the materials since their configuration plays a significantly larger role than material resistivity alone.
"At what point does an increase in inductance and capacitance cause an audible impact on dynamics?"
No one knows for sure - there are simply too many variables.
Arthur |
Here's a chart comparing resistance, inductance, and capacitance between several popular cables -- you might be surprised to see which cables have the highest capacitance.
http://www.audioholics.com/techtips/audioprinciples/interconnects/speakercablereviewsfaceoff7.php |
>>the broadest spectrum be derived from the use of all three?<<
Are you looking for the broadest spectrum? Or, the flattest response over the audio spectrum?
Are you talking about at audio frequencies?
You can get flat signal response within the range of audibility with the use of copper. Silver has slightly less resistance, but you can overcome that with the use of thicker gauge copper. No one has ever proven that silver has a sonic signature. Never seen a study that shows people can identify a silver cable versus copper in a DBT or ABX as long as they are precisely level matched. |
>>Lossy energy transfer can impact.<<
I don't dispute that low inductance and capacitance are desirable.
But, the question remains ---
How are you measuring dynamics?
At what point does an increase in inductance and capacitance cause an
audible impact on dynamics?
>>As to the evidence etc & alia, I believe Aball answered your questions<<
Uh.....no. Also, the poster asked about materials, not configuration. I'm not
sure how this relates to the original question.
|
Rsbeck -- "dynamics" are energy related. Lossy energy transfer can impact.
Frequency response measurement is time-related.
As to the evidence etc & alia, I believe Aball answered your questions, above. Cheers |
Sliver is slightly less resistive than copper, but you can overcome that by using a thicker gauge of copper. |
>>the higher the inductance and capacitance, the slower the signal will travel through the cable. This obviously impacts dynamics.<<
This is too general to be useful and also quite a leap.
How are you measuring dynamics?
At what point does an increase in inductance and capacitance cause an audible impact on dynamics?
What is the evidence for the audibility of this impact?
Are we talking about anecdotal testimonial or something more solid?
|
This obviously impacts dynamics. It seems the 'speed' of the cable is usually stated between 60-90% the speed of light, depending on dielectric constant od the insulator used. How does this affect dynamics? I thought dynamic range is based on the noise floor... steve |
Thank you, The various cable combos use silver & copper, silver & carbon and copper & carbon. If each conductor brings its own transmission signature would the broadest spectrum be derived from the use of all three? I am mainly thinking about speaker wires. |
TIme delay is also caused by wives and girlfriends. |
The "counter voltage" is actually a traveling wave and doesnt only go counter to the signal. When a signal passes through the cable, waves are induced by the electromagnetic image of the wire and are dependant on the reference ground - which is generally very nebulous in a mess of wires behind a stereo and winds up using system parasitic capacitances to sink the voltage (typically).
The problem is that the voltage and current proportionality MUST BE MAINTAINED in any system, from input to output. This is the key to understanding what I am talking about and some of you are probably already familiar with this since it is a direct repercussion of Ohms Law. When there is a discontinuity in the line - like a connection to an amp or speaker with differing impedances - the signal has to maintain this proportionality and to do this, it compensates for the differing interface resistances by creating traveling waves which are duplicate signals but travel at different speeds from the original one and go in both directions. This means you can have multiple signals, all phase shifted and arriving at different times at the speaker! All this is havoc on an audio system and is why low capacitance and inductance are desirable.
However, you still have impedance problems at the ends regardless of the cable properties. I believe that the majority of the problem lies in these impedance mismatches. I was very surprised to see the DarTZeel 108 amp and matching preamp use 50 Ohm cable connections between them to precisely eliminate this problem. Finally, a hifi equipment manufacturer trying to correct this obvious issue! It will be very interesting to see if other manufactures adopt this concept in the future. I think they will.
The vacuum cleaner spark is actually a somewhat different reason. The spark is not strictly due to traveling waves but because the vacuum cleaner motor is very inductive, you cannot interrupt the current instantaneously. When you pull the plug (without switching it off first), you see the uninterrupted current continue to flow until it goes through a zero crossing and extinguishes itself.
Anyhow, it is all very interesting and I plan on looking into these issues a lot more. It is turning into (yet another!) hobby for me. Arthur |
Aball is right - there always is a time delay in all Inductive and/or Capacitive circuits with AC signals passing through them. This is because the electromagnetic/electrostatic fields induce a counter voltage back in the wire After the original signal has passed. A good example is when you pull the plug on a running vacuum cleaner, you get a spark at the socket because the magnetic field collapses when you pull the cord and it induces a high voltage in the wire. Also, this is basically how your computer monitor gets its high voltage to power the CRT. |
Wow...questions, questions ;)
Ok, I will simplify things to keep it under control so bear in mind that it is more complex than I am making it sound.
I am doing some work right now involving modeling of cables and their impact with various loads (mostly inductive ones like motors and speakers). All cables have what is called the "characteristic impedance" which is a function of the series parasitic inductance (L) and parallel parasitic capacitance (C). The former is mostly wire-material dependant and the latter is dielectric/sheath-material dependant.
The speed is the "signal propagation speed" which theoretically is the speed of light but (also) due to the L and C of the cable, it is lower in actuality. The speed is inversely proportional to the product of inductance and capacitance - in other words, the higher the inductance and capacitance, the slower the signal will travel through the cable. This obviously impacts dynamics.
Now, here is the fine line that causes confusion. The frequency issues due to these parameters are mostly in the MHz to GHz regime which is of course not audible by humans. However, harmonics are produced by electrical interactions between the L and C which will produce sidebands that theoretically extend ad infinitum in both directions which means they reach the 20-20kHz region as well. Whether or not they are large enough in signal magnitude to be heard is still under hot debate everywhere. My personal opinion is that in some freaky way, we are able to hear this effect which accounts for the differences in sound between various cables and equipment.
The frequency response really doesnt register these effects because it is a time-domain function. If you look at it in the frequency domain (via the often mentioned Fourier transform), you can see the harmonics involved in the signal. BUT, current measurement techniques dont really have good enough resolution to get everything so part of the information is missing.
This leads to my infinite variable dictum which goes something like this: everything affects everything all the time. All we can see is our resolution capability very similar to our stereos. The information is infinite in quantity and so the amount we experience is a factor of this resolution. What happens outside the resolution is unknown. What we do know is that the effects of parasitic L and C of cables (and dont forget all the wires in your components too) add up to something that falls within human ear resolution.
Anyway, I blab about this forever so if you have any questions, feel free, but dont forget that no one knows everything that goes on in our systems. Arthur |
Aball, please enlighten us:
How do materials used in cables affect frequencies and speed?
What is speed?
Which materials affect frequencies, the conductor or dielectric or both?
If both, in what measure are such effects produced by one or the other?
Are we dealing here with measured differences in frequency response or subjectively perceived ones?
Thanks. |
Materials absolutely do alter frequencies and speed. It is a very complex process. I haven't heard of anyone using pure carbon though. Did you mean all 3 together? Copper and silver are used all the time. |
Tou may believe in anything your heart so desires. I doubt electrons care though. |
