Interconnects implementing the Eichmann Ratio™.

For a long time my interconnects used to be of the TNT-Audi X-Cable kind. But then I started using interconnects based on Chris VenHaus' DIY Silver Interconnects, except that the cables are made from copper wire instead of silver. These cables quite definetely sound better than the X-Cables.

Silver is difficult to work with. It tarnishes easily, and needs to be protected from air. The sound is also said to be on the bright side, and brightness is what I don't like in my system. And I've been wondering: With speaker cables made from copper, and internal wiring in amplifiers beeing copper, why is it important for the interconnects to be made from silver?

So, copper it is. It's cheap, and enameled copper (according to Jon Risch's Web Site the next best material to use after bare copper), is easy to work with. And being enameled, it is already protected against tarnishing (and accidental shorts inside the cable).

And then there is the Eichmann Bullet Plug. This new plug has gained a reputation of good sound in a short time. The plug is almost all plastic, with only enough metal for the plug to make contact. This way the signal does not wander around in a huge mass of copper (or even worse, brass) when it leaves the cable and enteres the plug. In addition, the Eichmann Ratio™ specifies that the return pin should be of larger cross section than the signal pin.

"The Ratio forces the return conductor to respond rapidly to signals being transmitted through the signal conductor, at the same time providing a balance of reactance between signal and return. This ensures that all frequencies and their harmonics are transmitted in a more perfect state. The result is cleaner signal transfer. Which translates to better sound quality."

The exact ratio is not specified, but according to various pictures and diagrams, the ratio seems to be about 2:1 in cross sectional area. I'm not really sure if I believe in this, but if it works, that's good, and if it doesn't, it probably doesn't do any harm either. Having the ratio only in the plug can't make much difference, but let the whole cable have it, and the results should be forthcoming.

Combine the Eichmann Ratio™ with Chris VenHaus' topology, and you get an excellent interconnect. And here's how you can make it.

The cable itself is made from a teflon tube. I use a AWG 8 sized tube, which is 3.38 mm inside diameter. It is virtually impossible to handle this tube without some sort of jig, something to hold the tube straight with, and which the tube can be turned around. One example can be found on Chris VenHaus' page. For myself, I created a jig that will hold a string or piece of electric wire (on which the tube has been placed) tight, with a hasp to tighten it. I prefer electric wire (one cord from a zip cord), since it is less elastic than string, and makes a tauter holder than a string does. The electric cord will unfortunately tear and have to be replaced after a few uses - the copper strands inside snap under the tension.

To satisfy the Eichmann Ratio™, the ground wire should be 1.4 times thicker than the signal wire. 0.20 mm (AWG 32) for the signal, and 0.30 mm (AWG 29) for the ground is close enough and will do nicely. Having two different diameters of the wires also makes it easy to see which is which when the time comes to solder them to the plug.

Start with the thin wire. Tape it to the end of the tube. While holding the wire, turn the tube, and move your hand with the wire down the tube while turning to lay down an evenly spaced helix. Tape the wire to the other end. Do the same with the thicker wire, and make sure that the helixes are evenly spaced, so that at any point down the tube the two wires are on opposite sides of the tube.

Now wrap the cable with teflon tape (plumbers wrap). Lay down the layers with a liberal amount of overlap. Use extra layers on the ends, to protect the cable from the strain relief.

The body of the Bullet Plugs is quite wide, so extra electricians tape has been added to make the cable wide enough inside the housing for the restraining screw to get something to hold on to.

The Bullet Plug is a very tight fit first time it is used. It is recommended that a hair dryer is used to heat it before use, to make the plastic softer before insertion, whereafter it will set in the new size once it cools. My hair dryer was too weak, so I put the plugs on a desk with a 20 W halogen lamp just above. Keep watch for overheating - this is plastic.

Use a piece of folded emery paper to remove the enamel on the wire ends prior to soldering.

Insert the Bullet Plug into a chassis plug before soldering. This keeps the plug in place, and will also lead off excess heat so the plug is not damaged. The thin wire goes into the signal pin (center), and the thick one onto the ground pin (edge). Use only a little solder, and don't let it heat up the soldering platforms too much. Remember to put the body of the plug onto the cable before soldering the second plug.

Screw on the bodies of the plugs. Push the cable slightly into the plug before securing the cable with the restraining screw, to remove any tension there might be on the wires.

Finished! You now have a very good sounding interconnect for just a little money - the plugs are the largest part of the total cost.

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