Best Speaker Cables? - Page 13

Maybe you can help me out then.

Yes.


That's not entirely true. Better copper and shielding do transmit better AC and that can translate with a good cord into sonic improvement.

I was skeptical on this at first as well but after working many recording sessions and experimenting with my systems and those of friends, I heard the difference.

But no one is holding a gun to anyone's head, if you don't think it makes a difference then save your money.

Yes, there are three general ways:

1. Insufficient conductivity for the current you're using. A big amp going full tilt can draw a lot of current, and can be limited in its output power by the cord. Some amps have power cords hard wired into them because they don't want people putting inadequately sized cords on them and either burning the cord or limiting the performance of the amp. Most of the time this isn't an issue as many wall outlets will limit current before a decent cord (cf. house lights dimming when you turn on some amps).

2. Power cords that have their 3rd prong lifted can solve some hum issues. This is not a generally safe thing to do unless you know what you're doing.

3. This one is a bit more exotic, but if your system has ground loop issues, the earth conductor (the wire that's connected to the 3rd prong) can exacerbate or mitigate these issues. If it's too small (not enough conductivity), there is a higher voltage drop, and this may cause noise to either cross some audible threshold, or some electrical threshold (lots of things connected to ground are pretty non-linear), and become audible. I've had equipment whose hiss got much quieter when I put a bigger (14 AWG) cord on them. This is a sign of inadequate design of the equipment BTW.

Some people claim shielded cords make a difference, and I suppose this is possible, just as wrapping tinfoil around a mic stand can in some cases make a difference. However, this is indicative of equipment that has some problem to be so sensitive to changes like that. The shielding theory generally doesn't hold much water because there are two very big holes at the end of the cables, as most cable ends are made of non-conductive plastic. Effective shielding requires a conductive material entirely surrounding the thing to be shielded.

--Andre

Shunyata has a good summary below as follows:

The most common misconceptions about power transmission and their simple technical truths follow:

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 50-60hz 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. Due to their obvious proximity, 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 a 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 EM wave and the current flow. The current itself cannot be contaminated but the EM wave can be modulated with other frequencies. We usually call these other frequencies noise or EMI. Within the various parts of a power circuit there may be EMI in certain parts that are not present in others. EM energy can be transformed or redirected to lessen their effects.

Some power cords for example, use capacitors, inductors, or ferrites in an attempt to control the EM fields around the audio component. The success of such an approach is completely dependent upon the specific power supply design and its reaction to the added reactive capacitance of the power cord.

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 PC is NOT the last 6 feet as stated in #1 and the local current and EM effects directly affect the sonic performance of the component. The power cord is not the last 6 feet, it is the first 6 feet from the perspective of the component. The further a noise source is from a component, the less of an impact it will have on the components power supply. The high-frequency noise sources that have the greatest impact on audio and video performance are the system components themselves -- which are usually all in close proximity of one another and all emit radiated fields of high-frequency noise. A well designed power cord can act as a noise-isolated extension of the primary winding of a component’s power supply and will help isolate the power supply from the fields of radiated RF and EM noise energy that is ever present in all electronics systems.

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. EM waves that travel through space dissipate in power as the square of the distance from the source and 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. Most components use FWBR (full wave bridge rectifier) power supplies that generate an incredible amount of transient noise when the rectifiers switch on and off. The design of a power cord can significantly affect the reactance of these signals within the power supply. Because the power cord is part of the primary winding of the power transformer, the transition between the various metals used in a PC can cause EM reflections and diode-like rectification of the noise impulses as they propagate away from the power supply. If the PC presents a high impedance to these signals they will be reflected back into the power supply where they will intermodulate 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 conspiracy among audio designers that keeps them from producing a “proper” power supply that is not affected by the quality and design of a power cord. This concept is like saying that if a speaker were properly designed, you wouldn’t need to use a good quality speaker cable.
Answer: Shunyata Research power cords have been tested with modest beginner and mid-fi equipment as well as the most exotic and sensitive recording devices and electronics. We have yet to find a component that cannot be improved by replacing the power cord with a high-quality design.

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.
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.
Answer: Capacitance alone cannot account for the differences in a power cord’s performance. There are some very effective aftermarket power cords that have virtually unmeasurable levels of capacitance. These power 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; the shorter the cable the better.
Answer: 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 or signal degradation.

A power cable on the other hand is not transmitting an analog 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 the specific case of Shunyata Research -- we use patented noise-isolating geometries, shielding and a patented compound that absorbs EMI in some power cord models. Increasing the length of the cable, increases the noise isolation, or coupling effect to the FeSi 1002 compounds, therefore increasing the performance of the cable.

In general, Shunyata Research does not recommend a power cord that is shorter than 3 feet or 1 meter in length for performance ease of use and, or resale reasons. Of course, subtle degrees of audio performance are not the only consideration when putting together an audio system. Aesthetics are 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.

Perhaps you heard a difference, but unless you've done a controlled test where the only changes are better copper and shielding, then I don't see how you can attribute the difference you heard to those factors.

--Andre

I can because I have done tests where only the AC cords were exchanged.

It was aluminum foil that stopped the RFI. Cheap, simple solution.

http://web.mit.edu/ariely/www/MIT/Papers/Placebo1.pdf

Blind testing eliminates any placebo effect.

Most audio equipment uses linear power supplies, so they use a bridge rectifier and big caps to make DC. More things use switching power supplies these days, and there are techniques you can use to not deal with the noise a SMPS generates. Nevertheless, the rectification induces >100% distortion on the waveform.

Also, in the circuit, you have voltage regulation that cleans up the power more, and isolates the wall from the circuit ... if it's designed correctly. And it's yet another reason power cords don't matter as far as clean power delivery goes.


That's a pretty terrible summary. It's too bad you just copy-n-paste crap instead of thinking through the claims for yourself to see if there is any correlation with reality or even with the subject matter at hand.


Total strawman. Some aspects of electricity have a direct analogy to water flow. Others don't. Nevertheless, this aspect doesn't really address why power cords should or shouldn't sound different.


Another strawman, except this one contradicts itself. AC power can be contaminated, and AC power cannot be contaminated? Make up your mind! Also, well-designed components have high levels of EMI filtration. Those that don't are susceptible to wrapped tin foil.


That's right, but I'm not sure why they said this, since this completely debunks any special filters, shielding, or filtering properties of fancy power cords. To have a chance at proper filtering or shielding, the power cord must be designed with a specific power supply input impedance in mind. This is also why balanced power doesn't work as well as it does on paper.


If you believe what they wrote before, this couldn't possibly be true. More self-contradiction.


Another self-contradiction. You cannot possibly design a power cord with predictable filtering capabilities without knowing what power supply you're going to use with it.


Strawman. Speaker-speaker-cable interactions cannot be avoided unless you have superconducting cable or infinite input impedance on the speaker. Electrical power supplies however can be designed to ignore the vagaries of wall power.

--Andre

So you've done double-blind tests on power cords?

Threads like this make me wish I cared more about elementary physics.

So the only differences between the two cords you compared were their metallurgical composition and shielding? Everything else --- construction, insulator material, position in space, etc. --- was identical? I doubt it.

--Andre

Not everything was identical but it was still valuable as one was a regular power cord and the other was more expensive power cord with better copper, shielding and connectors. If the difference was parts quality, shielding and copper then that the sonic differences we heard would indicate some impact from those factors. Therefore, the better power cord had a positive impact.

Yes, I have done DBTs on AC cords, mic cable, interconnects, and speaker cable. The latter two were especially noticeable.

When you do recordings RJ, you constantly are looking for ways to improve the signal chain. We use a "champioin-challenger" model where the best sounding gear is the champion and we try new gear to challenge that champion. We only replace the champion when 2/3 of our team or more agrees that the challenger has better sound. We upgraded mic preamps, Analog to Digital converters, microphone cable, power supplies (we now use battery power), and hard drive recording devices. And we have constantly improved playback which is fun for audiophiles.
The only thing we can't control is the hall we record in as location work is what we do although we are starting to do studio work like I did throughout the 90s.

That's not necessarily true. Things like the quality of power coming from the wall and the actual position of the cord are still different and could account for all the differences if you were swapping cords. If you were comparing two cords simultaneously, then you have to account for equipment differences, which can be significant even when comparing identical models due to component variation, as well as power cord position, and the use of different physical outlets.


It would be very interesting to see the controls and statistical analysis of your trials.


You make it sound so official and scientific, which reminds me of this:


--Andre