WHY POWER CABLES MAKE A DIFFERENCE - Galen Carol Audio

Every audiophile who has experimented with better power cables has heard the performance advantage they offer. Indeed, the amount of improvement can be astounding, often transforming a system from good to amazing. As audiophiles, we trust our ears but it’s hard to understand how replacing just one short link in a long chain of the power delivery system can have such a dramatic impact. The following article is intended to answer those questions.
 
To follow is a response from Mr. Gabriel that appeared in an on line forum addressing question why power can be such an influential addition to a system.

Introduction: “There are a lot of misconceptions about power transmission and power quality that make it difficult for some people to understand why a power cord makes a sonic difference. The first question is – do power cords make any difference at all? There is no sense in talking about theories of operation if we can't agree that there is an audible effect. Most of the thousands of people that use our power cords started out as skeptics and have answered that question for themselves and have found that power cables and power conditioners can have a profound impact on performance. And no - I do not care to debate with people that have not done the simplest of tests about whether power cords work or not. The only cases where a high quality cord does not have significant effects is when it is used with a poor quality power conditioner that acts as a high impedance to instantaneous current flow. “

For more information, please visit our website.

Misconception #1: AC Power is like water coming from a large power tank, flowing through several 10s of feet of power hose into a component. This implies that the component is at the end of this system.

Answer: “Actually, the component sits between two power conductors: the hot and the neutral. AC power oscillates (alternates) back and forth at a 50-60 Hz rate. So power does not pour into the component at all. The component's power supply is within a complex network of wires and connectors. ALL of the wire and connectors can and do affect the performance of the component's power supply.”

Misconception #2: AC power can be contaminated just like water in a hose. This implies that once the water is contaminated at some point up stream, that is must be cleansed before it arrives at the audio component.

Answer: “As stated in #1, the component is not at the end of the power hose. It is between two power hoses and the current is oscillating back and forth. Further, current is not like water at all. Electrons cannot be contaminated. There are two aspects to power transmission: the electromagnetic wave and the current flow. The current itself cannot be contaminated but the electromagnetic wave can be modulated with other frequencies. We usually call these other frequencies noise or Electromagnetic Interference (EMI). Within the various parts of a power circuit there may be EMI in certain parts that is not present in others. Electromagnetic energy can be transformed or redirected to lessen their effects.

"Some power cords use capacitors, inductors, or ferrites in an attempt to control the electromagnetic fields around the audio component. The success of such an approach is completely dependent upon the specific design and the reactance of the power supply of the component to which the power cable is attached.”

Misconception #3: There is up to a hundred feet of wire in the walls, so the last 6 feet of power cord can't possibly make any difference.

Answer: “The power cord is not the last 6 feet, it is the first 6 feet from the perspective of the component. As stated in #1 the local current and electromagnetic effects directly affect the sonic performance of the component.”

Misconception #4: There is a tremendous amount of electrical interference and EMI coming from outside the home that we need to protect our equipment from. This implies that we need some sort of power conditioner or filter to protect the equipment.

Answer: “Most of the EMI that affects the audio quality of a system is generated by the audio components themselves. Electromagnetic waves that traveling through space dissipate in power at the square of the distance from the source. Further, very high frequencies that propagate through the power circuit do not survive for long. Power lines present a high impedance to MHz and GHz signals due to the relatively high inductance of power lines.

"A primary source of audible sonic degradation is caused by the power supplies in our audio/video components. Most components use FWBR (full wave bridge rectifier) power supplies that generate an incredible amount of transient noise when the rectifiers switch off. The design of a power cable can significantly affect the reactance of these signals within the power supply. The power cable is effectively part of the primary winding of the power transformer. The transition between the various metals used in a power cable and its connectors can cause electromagnetic reflections and diode-like rectification of the noise impulses as they propagate away from the power supply. If the power cable presents a high impedance to these signals they will be reflected back into the power supply where they will intermodulate, thus increasing the high frequency noise levels of the component. Most power supply filters are ineffective at blocking very high frequency noise components and much of it is passed through to the DC rails. The sonic effects of this include: high background noise levels, blurred or slurred transients and a general lack of clarity and purity of the sound or visual image.”

Misconception #5: There is some sort of conspiracy among audio designers that keeps them from producing a "proper" power supply that is not affect by power cable quality.

Answer: “This concept is like saying that if a speaker where properly designed, you wouldn't need to use a good quality speaker cable. PowerSnakes have been tested with the most modest of mid-fi equipment and the most exotic state of the art components. We have yet to find a component that cannot be improved by replacing the power cord.

"As long as power supply design is based upon FWBRs or switching supplies, the power cord will always be significant.”

Misconception #6: High-end power cords just increase the circuit capacitance acting as a high-frequency shunt

Answer: “There are some power cords that ARE designed this way. Some even insert capacitors within the cable to further increase capacitance. This approach has some positives and many negatives including the reactive interference with the way many power supplies are designed.

"Capacitance alone cannot account for the differences in a power cord's performance. There are some high-end power cords that are very effective that have virtually immeasurable levels of capacitance. These cables are usually designed around hollow tubes with the conductors inside. The conductors are several inches apart and cannot significantly affect the capacitance of the power circuit.”

Misconception #7: Power cords are just like speaker cables; always the shorter the cable the better.

Answer: “Some speaker cable designers would argue that a speaker cable below a certain length is not better. We will let them address the issue if they desire.

"A speaker cable conducts an audio signal from the power amplifier to the speaker. The distance is quite small, on the order of a couple of feet to several feet. The quality of a speaker cable is determined by how well it can transmit the signal from the amplifier to the speaker without alteration.

"A power cable on the other hand is not transmitting a signal. It is conducting A.C. power and its sonic superiority will be determined by its ability to deliver current (steady-state and instantaneous) and its ability to deal with the EMI effects of the components to which it is attached.

"Since a power cord is composed of a hot and neutral wire that the component sits between, a change in the length of the cord will increase the size of the "buffer" around the component. In general, I would not recommend a power cord that is shorter than 3 feet or 1 meter in length. But subtle degrees of audio performance are not the only consideration when putting together an audio system. Esthetics is also important especially when the system is located in a beautiful home. I just point out the performance differences so that people can make an informed decision when determining the optimum length for their cables.

"There is much more that can be discussed about power delivery but for the sake of brevity I'll cut it short at this point. On a personal note I would like to say that I was an audiophile long before I was a manufacturer of audio products. Before Shunyata Research I designed high speed networking devices and can tell you that there is a lot more money to be made in the computer industry. Like many of the manufacturers of high-end audio components, I design my products for myself and for the love of music. If other people like what I have created - great. If after trying our product you prefer another - great. There is a wide diversity of preference and subjective perception among individuals. Thank goodness there is also a wide diversity of manufacturers that create products to serve a variety of tastes.”

Caelin Gabriel
Shunyata Research Inc.

Addendum:

“Before we produced our first power cord, we did extensive testing of the audible effects of a variety of devices and materials associated with power transmission. We created many jigs and test apparatus that allowed us to test wire types, dielectric materials, connector contacts, dampening materials and a variety of transformers, chokes, coils, ferrites, capacitors, triacs and diacs. After 3 years of testing, we concluded that just about anything and everything that is inserted in or around the electromagnetic field of a power circuit has an audible effect. Some of the effects are quite small and are relatively insignificant. Others are dramatically profound and sometimes surprising in their behavior. Obviously we are not going to "give away the farm" and discuss all of our findings, but there are some very basic observations that I can share with you.

"First would be that wire type and size in a power cord is highly overrated. Every wire type (I am talking about the metal itself) has a specific sonic characteristic. Silver, copper, brass, gold and others all "sound" different. The difference in sound is not related to conductivity capacity because we adjusted the sizes during testing to account for this. Each of the metal's inherent "sonics" can be ameliorated by careful adjustment of the other materials used in the construction of the final cable. We have a warehouse full of various prototype cables that never made it to production. Some of these use a relatively small wire size of ~18ga, that sounds surprising full in the bass. Intuitively, you might think that a small wire would sound thin in the bass region. This is not always the case. Conversely, we have some cables with wire as large as 1gauge that sound powerful in the bass but are also flabby and irregular sounding. So, just increasing the wire size is not the easy answer that some might think.

"Most of what I have to say here are my "conclusions" based upon observation through trial and error testing. Furthermore, there are no perfect components and there are no perfect parts. Everything is relative and the designer must weigh the sonic value of each part when designing a product. Our philosophy is to create a product that is a faithful musical component as opposed to striving for excellence in any single performance area.

"Our tests with coils and chokes indicate that (in general, with exceptions) that any coil or choke that is placed in-line with the power circuit is harmful to dynamics. Many of them will also induce a subtle smearing or blurring of transients. This is naturally dependent upon the power supply design of the unit that the coil is used with. Coils and chokes are necessary in most components and I prefer "single layer wound" types such as the foil designs. Cost of production will always mitigate against the use of these types of coils due to the expense. We definitely do not believe in placing coils or capacitors within a power cable. These devices belong in the component or in a dedicated power conditioner.

"Many components use a power inlet IEC that has an integrated "L" or "pi" filter. The quality of these devices varies dramatically. Generally speaking, the more capacitors and inductors that you have in a circuit, the more complex the dynamic interactions will be between the devices. This will also make the component they are used in more reactive and the possibility of negative sonic effects increase. Multiple filter networks can resonate and generate unintended results that have subtle but audible ringing / pinging sounds. Many of these IEC packages were created for office and computer products and are required to pass certification tests for EMI emissions. All I can say is that what is good for a fax machine is not necessarily good for a pre-amplifier.

"Shielding can be a two-edged sword. On one hand, it can reduce radiated fields from impacting other components. On the other hand, the shielding may induce re-radiated fields onto the cable or component that it is being used in. Sometimes the cure may be worse than the illness. As always - you must know your materials and tools and apply intelligence with a small dose of intuition to create a world class product. There is no silver bullet and there is no rote formula that works in all cases. There is just hard work, occasional inspiration and lots of testing.”

Caelin Gabriel
Shunyata Research Inc.

zhuhaicable supply professional and honest service.

Bundle of wires for transmitting electricity This article is about electric power conductors. For portable equipment, see power cord.

A power cable is an electrical cable used specifically for transmission of electrical power. It is an assembly of one or more electrical conductors, usually held together in a single bundle with an insulating sheath, although some power cables are simply rigged as exposed live wires. Power cables may be detachable portable cords (typically coupled with adaptors), or installed as permanent wirings within buildings and structures, buried in the ground, laid underwater or run overhead. Power cables that are bundled inside thermoplastic sheathing and that are intended to be run inside a building are known as NM-B (nonmetallic sheathed building cable).

Small flexible power cables are used for electrical devices such as computers and peripherals, mobile devices, home appliances, light fixtures, power tools and machinery, as well as household lighting, heating, air conditioning and rooftop photovoltaic and home energy storage systems. Larger power cables are used for transmission of grid electricity to supply industrial, commercial and residential demands, as well as a significant portion of mass transit and freight transport (particularly rail transport).

The first power distribution system developed by Thomas Edison in in New York City used copper rods, wrapped in jute and placed in rigid pipes filled with a bituminous compound.[1] Although vulcanized rubber had been patented by Charles Goodyear in , it was not applied to cable insulation until the s, when it was used for lighting circuits.[2] Rubber-insulated cable was used for 11,000-volt circuits in installed for the Niagara Falls power project.

Mass-impregnated paper-insulated medium voltage cables were commercially practical by . During World War II several varieties of synthetic rubber and polyethylene insulation were applied to cables.[3]

Typical residential and office construction in North America has gone through several technologies:

• Early bare and cloth-covered wires installed with staples
• Knob and tube wiring, s–s, using asphalt-saturated cloth or later rubber insulation
• Armored cable, known by the genericized trademark "BX" - flexible steel sheath with two cloth-covered, rubber-insulated conductors[4] - introduced in but more expensive than open single conductors
• Rubber-insulated wires with jackets of woven cotton cloth (usually impregnated with tar), waxed paper filler - introduced in
• Modern two or three-wire+ground PVC-insulated cable (e.g., NM-B), produced by such brands as Romex [citation needed]
• Aluminum wire was used in the s and s as a cheap replacement for copper and is still used today, but this is now considered[by whom?] unsafe, without proper installation, due to corrosion, softness and creeping of connection.[5]
• Asbestos was used as an electrical insulator in some cloth wires from the s to s, but discontinued due to its health risk.[6][7]
• Teck cable, a PVC-sheathed armored cable

Further information: Electrical wiring

Modern power cables come in a variety of sizes, materials, and types, each particularly adapted to its uses.[8] Large single insulated conductors are also sometimes called power cables in the industry.[9]

Cables consist of three major components: conductors, insulation, protective jacket. The makeup of individual cables varies according to application. The construction and material are determined by three main factors:

• Working voltage, determining the thickness of the insulation;
• Current-carrying capacity, determining the cross-sectional size of the conductor(s);
• Environmental conditions such as temperature, water, chemical or sunlight exposure, and mechanical impact, determining the form and composition of the outer cable jacket.

Cables for direct burial or for exposed installations may also include metal armor in the form of wires spiraled around the cable, or a corrugated tape wrapped around it. The armor may be made of steel or aluminum, and although connected to earth ground is not intended to carry current during normal operation. Electrical power cables are sometimes installed in raceways, including electrical conduit and cable trays, which may contain one or more conductors. When it is intended to be used inside a building, nonmetallic sheathed building cable (NM-B) consists of two or more wire conductors (plus a grounding conductor) enclosed inside a thermoplastic insulation sheath that is heat-resistant. It has advantages over armored building cable because it is lighter, easier to handle, and its sheathing is easier to work with.[10]

Power cables use stranded copper or aluminum conductors, although small power cables may use solid conductors in sizes of up to 1/0. (For a detailed discussion on copper cables, see: Copper wire and cable.). The cable may include uninsulated conductors used for the circuit neutral or for ground (earth) connection. The grounding conductor connects the equipment's enclosure/chassis to ground for protection from electric shock. These uninsulated versions are known are bare conductors or tinned bare conductors. The overall assembly may be round or flat. Non-conducting filler strands may be added to the assembly to maintain its shape. Filler materials can be made in non-hydroscopic versions if required for the application.

Special purpose power cables for overhead applications are often bound to a high strength alloy, ACSR, or alumoweld messenger. This cable is called aerial cable or pre-assembled aerial cable (PAC). PAC can be ordered unjacketed, however, this is less common in recent years due to the low added cost of supplying a polymeric jacket. For vertical applications the cable may include armor wires on top of the jacket, steel or Kevlar. The armor wires are attached to supporting plates periodically to help support the weight of the cable. A supporting plate may be included on each floor of the building, tower, or structure. This cable would be called an armored riser cable. For shorter vertical transitions (perhaps 30–150 feet) an unarmored cable can be used in conjunction with basket (Kellum) grips or even specially designed duct plugs.

Material specification for the cable's jacket will often consider resistance to water, oil, sunlight, underground conditions, chemical vapors, impact, fire, or high temperatures. In nuclear industry applications the cable may have special requirements for ionizing radiation resistance. Cable materials for a transit application may be specified not to produce large amounts of smoke if burned (low smoke zero halogen). Cables intended for direct burial must consider damage from backfill or dig-ins. HDPE or polypropylene jackets are common for this use. Cables intended for subway (underground vaults) may consider oil, fire resistance, or low smoke as a priority. Few cables these days still employ an overall lead sheath. However, some utilities may still install paper insulated lead covered cable in distribution circuits. Transmission or submarine cables are more likely to use lead sheaths. However, lead is in decline and few manufacturers exist today to produce such items. When cables must run where exposed to mechanical damage (industrial sites), they may be protected with flexible steel tape or wire armor, which may also be covered by a water-resistant jacket.

A hybrid cable can include conductors for control signals or may also include optical fibers for data.

Main article: High-voltage cable

For circuits operating at or above  volts between conductors, a conductive shield should surround the conductor's insulation. This equalizes electrical stress on the cable insulation. This technique was patented by Martin Hochstadter in ;[2] the shield is sometimes called a Hochstadter shield. Aside from the semiconductive ("semicon") insulation shield, there will also be a conductor shield. The conductor shield may be semiconductive (usually) or nonconducting. The purpose of the conductor shield is similar to the insulation shield: It is a void filler and voltage stress equalizer.

To drain off stray voltage, a metallic shield will be placed over the "semicon." This shield is intended to "make safe" the cable by pulling the voltage on the outside of the insulation down to zero (or at least under the OSHA limit of 50 volts). This metallic shield can consist of a thin copper tape, concentric drain wires, flat straps, lead sheath, or other designs. The metallic shields of a cable are connected to earth ground at the ends of the cable, and possibly locations along the length if voltage rise during faults would be dangerous. Multi-point grounding is the most common way to ground the cable's shield. Some special applications require shield breaks to limit circulating currents during the normal operations of the circuit. Circuits with shield breaks could be single or multi point grounded. Special engineering situations may require cross bonding.

Liquid or gas filled cables are still employed in distribution and transmission systems today. Cables of 10 kV or higher may be insulated with oil and paper, and are run in a rigid steel pipe, semi-rigid aluminum or lead sheath. For higher voltages the oil may be kept under pressure to prevent formation of voids that would allow partial discharges within the cable insulation.

Liquid filled cables are known for extremely long service lives with little to no outages. Unfortunately, oil leaks into soil and bodies of water are of grave concern and maintaining a fleet of the needed pumping stations is a drain on the O+M budget of most power utilities. Pipe type cables are often converted to solid insulation circuit at the end of their service life despite a shorter expected service life.

Modern high-voltage cables use polyethylene or other polymers, including XLPE, for insulation, and require special techniques for jointing and terminating.

Main article: Wire § Solid versus stranded

All electrical cables are somewhat flexible, allowing them to be shipped to installation sites wound on reels, drums or hand coils. Flexibility is an important factor in determining the appropriate stranding class of the cable as it directly affects the minimum bending radius. Power cables are generally stranding class A, B, or C. These classes allow for the cable to be trained into a final installed position where the cable will generally not be disturbed. Class A, B, and C offer more durability, especially when pulling cable, and are generally cheaper. Power utilities generally order Class B stranded wire for primary and secondary voltage applications. At times, a solid conductor medium voltage cable can be used when flexibility is not a concern but low cost and water blocking are prioritized.

Applications requiring a cable to be moved repeatedly, such as for portable equipment, more flexible cables called "cords" or "flex" are used (stranding class G-M). Flexible cords contain fine stranded conductors, rope lay or bunch stranded. They feature overall jackets with appropriate amounts of filler materials to improve their flexibility, trainability, and durability. Heavy duty flexible power cords such as those feeding a mine face cutting machine are carefully engineered — their life is measured in weeks. Very flexible power cables are used in automated machinery, robotics, and machine tools. See power cord and extension cable for further description of flexible power cables. Other types of flexible cable include twisted pair, extensible, coaxial, shielded, and communication cable.

For more information, please visit Power Cable.