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Positive Feedback ISSUE
We sent out the same 20 questions to 50 manufacturers, the following are their responses. The intent of the survey is to address basic questions as to design along with any questions raging on various sites, while minimizing potential chest-thumping and friendly, or unfriendly, bashing of others....
Adam Blake of Pear Cable
PFO Why do cables make a difference? Interconnects, speaker, and AC cords?
Adam Blake The better question here (without trying to sound obnoxious) is: Why wouldn't cables make a difference?
The more technical answer is that audio cables are subject to all of the same electrical principles as any other electrical device. The most basic analysis begins with the fundamental electrical properties of capacitance, inductance, resistance, and conductance of the circuit the cable participates in. These parameters will control the basic frequency response of an audio system, and contrary to some claims, cables can absolutely impact even the basic frequency response. On our website we provide direct evidence of this impact with real electrical measurements of two identical systems except for the cables. The results show that cables can impact a system frequency response more than an amplifier.
Of course, the basic frequency response does not tell the entire story, it only gets you started. What happens if noise gets into the cable? What happens if noise gets out of the cable? What happens if the cable vibrates? What happens if a conductor gets corroded? The list goes on and on of mechanisms and properties that will have measurable effects on the signal going through the cable. People who claim that these things cannot be measured are very plainly wrong. All of these phenomena can be measured; what is more difficult is proving that the effects can be heard.
Old scientific papers that measure the limit of human hearing on test subjects using monotones do not apply to the limit of human hearing with regard to a complex music signal. I would argue that it is much easier to detect subtle variations in a complex music signal than in the tone generated by a tuning fork. However, perhaps this is the wrong way to try to understand the limit of human hearing. Maybe a better test is to take any decent audio system (even a high end one), digitally equalize the signal so that the frequency response is completely flat at a listeners position, and then run some blindfolded listening tests between the audio system and a musician performing live. I believe that nearly everyone (even non-audiophiles) would be able to discern the difference between the live music and recorded playback. The average person may not be able to tell you why their stereo does not sound as good as a live performance, but they still know that it is not as good. The only explanation is that very small levels of deterioration of an audio signal can be heard. Cables, like any other component of a high fidelity audio system, fight to reveal those last details.
PFO What about metals ...copper versus silver versus gold versus what? What about blends?
AB Metal choice is important for a cable, but far less important than the geometry. Take whatever metal you personally feel sounds best, construct a cable using the worst geometry you can think of, and it will sound worse than the best geometry with the worst metal.
Unfortunately, I believe that many people ascribe too much importance to metal choice in cables. It is generally a very easy property to describe when compared to something more complex such as geometry. It is difficult for consumers to compare metal choices due to the fact that very few cables are sold with identical construction except for the metal. Usually there is at the very least an insulation material change as well. As a cable manufacturer, I have the privilege of being able to make direct comparisons between cables that are identical except for the metals. In my experience, it is not the number one factor in determining sound quality.
All of that said the metal does matter. Once you get past the basic properties of resistance, the theory that guides metal choice at Pear Cable really has mostly to due with impurities/corrosion (particularly non-metallic). Non-metallic corrosion within, or on the surface of, a conductor will affect an oscillating signal the same way insulation does. However, since most of these oxides, sulfides, etc. have far worse insulating properties than a proper insulation material, they do a disproportionate amount of sonic damage. For products that require the ultimate performance such as our ANJOU analog interconnect, that leads us to use pure gold as a conductor. However, for our top of the line speaker cable, we found high purity copper to be the best solution.
I believe there are many metals that will function well for interconnects, fewer for loudspeaker cables because resistance is a major concern, and for both I would stay away from any form of plating or cladding for analog applications. Among other considerations, skin effect will cause a plated conductor to skew high frequency information because it will see a different resistance from the low frequency signal.
PFO What about dielectrics... Teflon versus what?
AB With dielectrics, I find Teflon and air to be a cable's best friend. Cotton also has its uses, but primary insulation (i.e. insulation in direct contact with the conductor) is not something I would consider using cotton for in cables.
PFO What about no dielectric?
AB No dielectric is of course the best, but not when it comes in the form of an unsupported conductor (the only way to truly have no dielectric). Cables that use conductors placed loosely in tubes are easy to make, benefit from lower dielectric interaction, but suffer from corrosion problems, mechanical problems, etc. For Pear Cable, the benefits of this type of construction do not outweigh the downsides.
PFO What about measurements... what do they tell us? what do they not tell us?
AB Anything that will affect an audio signal going through a cable can be measured in some way. You may need to infer the net effect on the sound quality from listening tests, but if it changed the audio signal, it is measurable. The complicated part of this problem is determining what measurable affect causes the most sonic damage. It could be the case that a very small high frequency inaccuracy causes a cable to be far more irritating than a relatively large bass roll-off caused by a system crossover. Determining which effects matter most to listeners is where the art meets the science.
PFO What about connectors... how important?
AB I believe that connectors can be important, but once a good connection is established, a cable becomes the dominant player. So what constitutes a good connection? First, we look for good contact pressure at each point that makes contact. Loose, or poorly defined contact surfaces can absolutely hurt sound quality. Secondly, we look for time stability. Will the connector corrode over time leading to a change in the connection quality? We stay away from un-plated silver for this reason (silver corrosion such as silver sulfides and oxides, while not insulators are not anywhere close to as conductive as metal. Anyone who disputes this should look up the electrical properties of these materials.). Thirdly, we look for a method to make a secure connection from the cable conductors to the connector. This can actually be quite a challenge.
One note I would like to add here is that we really only use name brand connectors with our cables. They can add a frustrating amount of cost to a cable, but they generally are significantly better than the no-name imports. As a manufacturer, I get to see large quantities of connectors, and we have done the comparisons. Ultimately, we keep coming back to the name brands for reliability, build quality, etc. that is generally lacking from imported copies. We would love to offer cheaper alternatives, but the quality difference is usually too great.
PFO Why this geometry... ribbon, twisted, braded, spiraled...?
AB Geometry is really the hardest design element to get right because it involves tradeoffs between so many factors (electrical properties, mechanical properties, flexibility, cost, etc.). For our highest-end ANJOU cables, we have developed 2 unique proprietary geometries that we feel offer the highest levels of performance. For each price point, we try to give the customer the most effective geometry possible. Although geometry can be a dominant cost factor, other elements such as insulation thickness can have very little bearing on cost, but a large effect on performance. We always strive to bring "free" performance benefits to the customer.
Although it is not a steadfast rule, interconnects and speaker cables generally should have different geometries. Consumers should be wary of designs that are largely the same for both the interconnect and speaker cable. Speaker cables have vastly different electrical requirements from interconnects. When the same exact geometry is used for both cables, this is a tip that at least one of the cables has not been optimized for its job.
PFO What about cryoing? What is going on with this?
AB This is a debate that has been going on in the cable industry as well as in other areas of audio for some time. I actually worked on a research project for a major manufacturer of brass instruments to characterize the differences between brass instruments that had been cryogenically treated, vs. those that had not. Musicians have been swearing by their cryo'd trumpets for years. For audio cables it is not something that I loose sleep over, but I would not discount it entirely.
PFO Why shielding? Why not shielding?
AB Some cables and electronic environments really require shielding if noise is something that the listener does not like. Of course there are a number of geometries that can help to reduce various types of noise without the use of a shield. For analog audio cables, assuming the shield is not a critical part of the cable geometry (such as a coaxial design), a shield generally will hurt the core audio quality. However, sometimes the net benefit in terms of noise reduction is justified. Power cords are the one area that I believe benefit from shielding with very few downsides.
PFO What about run-in? Why is/isn't it important?
AB With our cables, I believe you get the core element of the sound quality from the moment the cable is first used. All of the many elements of the basic cable design exist and work from the very beginning. Cables can certainly change mechanically and perhaps electrically as they settle into their homes behind your audio rack. Many of our customers believe that our cables sound better after a break-in period, and I have experienced this as well. At this time I do not claim to have a good explanation for this, but I can say that some of the explanations offered by competitors are factually flawed.
PFO What about lengths? Why are/aren't they important?
AB Matching cable length is extremely important. Everything in high fidelity audio is about making small improvements. The damage a cable does to the audio signal is proportional to its length (although not always proportional in its perceived effect). Running cables of different lengths means that damage done by each cable will not be equal. On the listening side of this equation, I find the soundstage to be the element that suffers the greatest from mismatched cable lengths.
PFO What is directionality?
AB There are two very different cases to consider when talking about the directionality of cables. The first case is that of an asymmetrical cable. The classic example is an interconnect that has a shield connected at one end only. For this type of cable it is important for the shield to have the lowest resistance path to ground, which is why these cables have directional arrows. This is a proven electrical engineering technique that should be followed.
The second case to consider is for a cable that macroscopically is completely symmetrical. It is important to understand that the audio signal in a cable does not have a direction. Although this can be difficult to visualize, as an alternating current, the audio signal truly moves in both directions the exact same way. First the voltage goes positive pushing electrons one direction, then the voltage goes negative, dragging the same electrons the opposite direction. There is no circulation the way there would be in a direct current circuit. Even if a conductor had a different resistance in each direction, (although I am not aware of any conductor that does), it wouldn't matter because the signal has to go both directions in the wire to complete a cycle.
The above paragraph considered, as an engineer, I strive to control as many variables as possible. As a result, in our ANJOU Interconnect, we have directional arrows despite the fact that the cable has no shield. This is really a product of controlling variables rather than worrying about the direction of signal. We control variables where possible, and some of our cables have directionality due to the shields, but beyond that, our cables can be hooked up however the user sees fit.
PFO How did you get into this?
AB I started the way I believe most consumers approach audio cables; as a non-believer. I think the instinctual reaction almost everyone has when they first hear someone tell them that cables will affect the sound quality of their stereo, is to dismiss the notion as garbage. Even though a cable can have a bigger impact on sound quality than something like an amplifier, people have a hard time believing that can be true. An amplifier weighs so much, and it has so many parts in it. Surely something as simple as a cable cannot matter nearly as much. However, once I experienced the difference that cables could make first hand, I, like many consumers, became hooked.
As a hobby, I began with DIY cable experimentation that gave me a good basic foundation in the effects of cable geometry. At my previous job, as the head of research and development for a high-tech fuel cell company, I gained a tremendous amount of materials knowledge, and an intricate understanding of what gets electrons excited (pun intended). Frustrated by the quality of cables on the market and the prevalence of fictitious claims giving the industry a bad name, I combined my areas of knowledge and created Pear Cable.
PFO What is your fundamental design philosophy/goal?
PFO Why this?
AB I believe most people prefer the sound quality of live music to recorded music. The only way to get recorded music to be closer to live music in terms of sound quality is accuracy.
PFO How do you approach accomplishing this philosophy/goal?
AB I take a very technical approach to cable design that I believe is the only way to move the state of the art forward. Listening tests are critical to understand the perceived importance of various changes, but the foundation for our designs is in science and engineering.
PFO How successful do you feel you have been at achieving the goals that you have set for yourself?
AB I truly believe that we have made excellent progress in two key areas. On the lower end of the price scale I believe we have succeeded in bringing out cables that offer dramatic improvements in sound quality over other moderately priced cables. Secondly, I believe we have succeeded in redefining the upper limits of accuracy with our high-end offerings.
PFO How do you plan to push beyond what you have already accomplished?
AB Developing solutions to problems that are not currently addressed, improving the performance of existing products through innovation, and improving the average cable setup in every home by bringing out better technology at lower prices.
PFO Where is this all heading?
AB Both the capability of audio playback, and the performance of cables have improved over the last 10 years. Over the next 10 years we will see further improvements. On the source side of the equation, as technology improves, I believe that the people who currently sacrifice sound quality for convenience (MP3 Players come to mind), will no longer have to make that sacrifice. Source convenience and sound quality will both be possible.
PFO Others that you admire?
AB The people I admire are those who have been able to both develop new technology, and deliver it to consumers by building successful businesses. Bill Gates, Steve Jobs, Dean Kamen (Excluding the Segway debacle), etc.