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Cable Asylum Interconnects, speaker wire, power cords. Ask the Cable Guys. |
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Cable Asylum Interconnects, speaker wire, power cords. Ask the Cable Guys. |
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In Reply to: Re: Best wall recepticle in your experience? Oyaide or? posted by mtrot on December 2, 2006 at 19:11:53:
I can't speak to whether the Oyaide receptacles are the absolute best for all systems, but they certainly contain parts designed to overcome the obvious problems in the USA domestic power system standard receptacles. They are beautifully made and objects of industrial art in themselves.The purpose of a receptacle is to deliver up to 20 amperes of 60 Hz current at 120 volts without setting your house on fire. Loads such as vacuum cleaners and floor lamps are insensitive to minor imperfections in current and voltage linearity caused by the receptacle. However, most audio equipment at the present state of acceptable design is sensitive to these imperfections.
The first and most obvious problem is the security of the electrical contact. The plug blades are inserted into spring-loaded contacts. The contact metal has to maintain the spring pressure over a life of thousands of insertions as well as conduct electricity. There is a conflict between these two requirements. The metal composition, forming process, finish, and annealing all affect how well the contacts perform both these tasks.
The second problem, related to the first, is the acoustic response of the receptacle. The receptacle is typically mounted in a wall exposed to the audio system output, so it is subjected to a delayed and filtered version of the signal. If the electrical contact resistance is modulated by the acoustic input, there will be some sort of unwanted feedback through the power circuit. The receptacle body and contact design help determine the acoustic response.
The third problem is the metal spine that supports the insulating body (very cheap receptacles do not have such a spine). The hot and neutral wires pass on either side of this spine, so it can be a participant in the electrical circuit. If it is steel, then it acts like the core of a one-turn inductor. Any nonlinearity in the steel's magnetic response over the range of magnetic field strength generated by the supply current will induce distortion in the power wave form. Further, if the receptacle is mounted in a metal box, the spine will complete an electrical circuit that forms a one-turn transformer with the hot and neutral wires. The screws are typically steel and also cause audio problems.
Better outlets will have brass instead of steel spines and screws, but it is still a good idea to break the spine circuit at one end of the receptacle with an insulating screw and washer if the junction box is metal.
I've found by experimenting that acoustic vibration and magnetic nonlinearity in the receptacle parts cause audible degradation. Receptacles that are acoustically damped and made of non-ferrous materials give better sound.
Another problem with most receptacles is the break-away tab used to join the two outlets. One of the outlets will have the highly-stressed scored metal of the tab in series with the power connection. If you need to use both outlets, it is good to break off the tabs and wire both outlets separately.
There is a further issue of the metal finish. Various plating recipes are used in different receptacles. I don't have experience with plated metal plugs and receptacles, so I can't speak to which plating recipe would give improved performance, if any. However, it is obvious that clean contacts give better sound. Please be careful with live outlets if you attempt to clean the contacts: some cleaning tools and materials may conduct electricity.
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Follow Ups
- The scope of the problem and some findings. - Al Sekela 21:23:02 12/02/06 (0)
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