(C) 2004 Hank Wallace
I remember when solid state amplifiers first came onto the market in the 1970’s. We had Distortion Wars. First, harmonic distortion dropped to 0.1%. Next year it was 0.05%. The next it was 0.01%, and then a rash of 0.001% distortion amplifiers. No matter that humanoids cannot tell the difference between 0.05% and 0.001%!
After that, in the 1980’s started the Cable Wars. Copper wire was not good enough to connect amplifier A to speaker B. We had to have oxygen free copper and gold plated connectors, special insulators, and impedance controlled geometries.
I design industrial equipment for a living. I specify gold plated connectors when the equipment is going to be used in a dirty or humid environment. Gold is a great material because it does not corrode. It’s a bit soft and does not stand repeated mating cycles as well as other metals, but especially for connectors that are mated at the factory and will never be moved, gold is great.
One interesting fact that you will observe in industrial equipment is that engineers specify gold connectors in pairs. No self respecting engineer specifies a gold connector on one side and nickel plated connector on the other. That’s a waste of money because gold connectors cost about twice that of nickel plated connectors. I have seen a couple such mispatched pairs where the nickel side corroded and the gold side was pristine, but the connection failed.
Today, I can buy guitar and signal cables with gold plated connectors, and they sure look great. The gold ensures that they will never corrode (until the gold wears off). However, if you are plugging that gold plated cable into a cheap jack on your ’57 Les Paul, you are still going to have problems.
Don’t think for a minute that a vintage guitar is going to have a high quality jack! The jacks that manufacturers put in guitars years ago were the least expensive ones they could find. Typically nickel plated brass, the nickel wears off after a few years, leaving the brass to tarnish in the air. The most common repair I have performed on guitars is replacement of the jack. If you are investing in gold plated cables, invest a few more bucks and have your guitar tech install a gold plated jack to match. Then you will enjoy the low noise, reliable service that gold has to offer.
The same is true of amplifiers. Peer into the chassis of your vintage amplifier and you will find no gold whatsoever. Stereo gear is worse, designed to minimize cost, and even though the connectors on the outside may have some gold flashing the guts plumb the very depths of skimpy design. People are plugging $100 cables into $1000 stereo amplifiers that contain only tin and nickel plated connectors.
What’s better than gold plating? I think that the best thing since electricity is the compression ring 1/4″ phone plug. Planet Waves puts these on their cables, and they really stabilize the plug and make a solid ground connection to the barrel of the phone jack. They are gold plated, but would be a killer improvement even if only nickel plated.
Oxygen Free Copper
Did you know that high-oxygen-content copper drawn into a wire becomes brittle? Oxygen has the effect of reducing the ductility of the material because it attracts hydrogen. The two form water and that creates bubbles near the surface. For this reason, most copper wire is drawn from stock that has low oxygen content.
Let’s say you are in a grocery, shopping for ketchup. You see two brands. Brand A is labeled “Great Tasting!”. Brand B is labeled “Contains NO Nuclear Waste”. What’s your choice?
Labeling commercially available copper wire “oxygen free” is like labeling ketchup “NO Nuclear Waste”. Duh!
Now there will be several readers who will email me with their estimations of exactly how oxygen free brand X cables are. A few will tell me that they can hear the difference between two cables with 0.1% oxygen content variation. Fact is, if you bought some less expensive copper wire from Home Depot and soldered on some connectors yourself, you would have a good set of cables and would still be able to make your car payment this month!
For those readers who cannot solder, the megamoney cables do an excellent job conveying electric current from amplifier A to speaker B, you are just overpaying a bit.
Inside the amplifier, one would think that the copper clad circuit boards would be touted as “oxygen free”, and would be silver plated to maximize the mobility of those sluggish little electrons. One would think that there would be a whole industry of printed circuit board vendors who cater to high end audio manufacturers and designers of high performance equipment.
Curiously, this is not the case. Within electronics design circles, there is no mention of “oxygen free”. If I asked a circuit board vendor for oxygen free copper on my next order he would laugh. Major wire and cable manufacturers’ catalogs make no mention of oxygen free copper. I suppose you could buy a silver plated circuit board from someone, but it is not a commonly available option. You see, the whole oxygen free copper trip starts at the consumer level, and engineers are not buying into it at all. Doesn’t that make you slightly suspicious?
I called Belden, perhaps the most well respected manufacturer of wire and cable, whose products are specified in military, industrial and commercial equipment. (They make speaker cable, too.) They said that their wire and cable is not oxygen free! They specify a purity level for their copper speaker cables of 99.95% and claim that the conductivity is “comparable to oxygen free copper,” but do not participate in the oxygen free frenzy. Isn’t that interesting? Belden cables are used by the mile in applications much more critical than hooking up your stereo, such as medical electronics, military systems, high power gear, very low level measurement devices, and low noise systems. In my opinion as an engineer, they make the best wire and cable on the planet.
There’s also a catalog that engineers use called Electronic Engineer’s Master (or EEM). Printed, it is about six inches thick and contains information on tens of thousands of electronic components from thousands of manufacturers. I did a search for “oxygen free” and found zero instances. Not one, not two, but zero.
What about oxygen free copper signal cables? Oxygen free copper is more conductive than “regular” copper, but not by much. Using such a cable in a signal path, such as on a guitar or keyboard, offers zero benefit because there is so little current flowing in the cable that the wire resistance could be multiplied by a factor of ten and still be unnoticeable.
What about silver plated cables? Silver is the best common metal conductor at room temperature, with copper a close second. Silver plating a copper wire reduces the resistance at high frequencies due to the skin effect, where much of the current flows near the surface of the wire.
Where is silver plating used, other than in your speaker cables? It is used mostly at microwave frequencies, like in the radar system at your local airport, where the skin effect is much more pronounced than at audio frequencies. Power levels are also in the one thousand to ten thousand watt range in radar applications.
Is silver plated copper cable used in other power hungry applications such as power lines, automobile wiring, broadcast transmitter transmission lines (1,000 to 20,000 watts typically), welding gear, and industrial equipment? NO! Why? Because of cost. It is less expensive to use more copper than to plate with silver, so the designers of these wires and cables simply do that. You can do that, too, with your speaker cables. Every decrease of two wire gauge numbers (say, from 14 to 12) gives you about 50% more copper and about 25% more conductor surface area. That beats silver plating on cost.
Cable resistance is the most important factor regarding speaker cables, and you don’t have to worry about inductance, capacitance, velocity factor, charcteristic impedance, dielectric constant, or any of the other technical terms, as long as you keep your cables short, say, 50 feet or less, with each cable the same length!
Speaker Cables and the Speed of Light
How fast do electrons travel in a wire? At the speed of light, right? No, the astute reader will say. There is a thing called “velocity factor” that reduces the speed of light to some smaller fraction in air or metals, perhaps 95% of 186,000 miles per second. So then the speed of electrons in a wire is 0.95 * 186,000, or 176,700 miles per second? Wrong still!
Actually, the speed of electrons in a speaker cable is characterized by something called the drift velocity, and is only a few centimeters per second. You heard me right. That slow. The vibrations in the cloud of electrons move back and forth at a significant fraction of the speed of light, but the electrons themselves are rather sluggish.
Splitting hairs, you say? Well, not according to some of the copper hype I have read, hype implying that electrons gleefully scream through your speaker cables until they unexpectedly crash into (ohmygosh!) an OXYGEN atom! That supposedly creates distortion that you can hear. Silly.
There’s a reason why you don’t find engineers and physicists buying $100 speaker cables.
Your Ticket to Fortune
I’m going to give away an idea right here, right now. You are the recipient. Email your patent attorney. Get ready to strike it rich.
In broadcast transmitters, a lot of power has to move from the radio or TV transmitter to the antenna, tens of thousands of watts. To get the power up the tower to the antenna, large diameter coaxial cables are used. These cables are really concentric copper pipes, with some low loss insulator spacing the pipes apart. The picture shows a popular coax made by Andrew called Heliax. This example has foam insulation.
The larger cables actually have mostly air between the two pipes. Air is a great insulator because it is low loss and results in low capacitance. However, air has a tendency to absorb water, so the manufacturers of these high power cables also sell pressurization systems.
The connectors on the coax have pressure ports, similar to the air ports on your automobile tires. These are connected to dry nitrogen or dry air gas suppilies. The cables are pressurized to prevent moisture from accumulating in the cable and increasing its loss and capacitance.
Why not take a tip from the big boys and apply that great technology to guitar cables? Pictured is an image that I edited together depicting a sealed guitar cable with a gas injection port. Here’s the idea. After you use the cable, connect it to a source of dry gas, say a small bottle of dry nitrogen. In the hours between gigs, your cable is repressurized and conditioned for the next show, drying out the dielectric for a super low loss performance.
Loads of ancillary ideas come to mind. We’ll have guitarists soon using designer gasses to pressurize their cables, talking them up on the newsgroups. “I prefer CO2 to dry N2 because it gives me a more meaty tone.” “My cable is loaded only with gaseous helium, because I like a lighter sound.” “I avoid dry air because it contaminates my oxygen free copper.”
We might even have cables filled with propane, set to detonate at the end of the show with all the other pyrotechnics (don’t try this at home). Soon, boutique gasses will appear, some of questionable origin, and you (yes you) will have a piece of the action.
There it is. Get on the phone right away and get that patent application filed.
Do you know that power propagates with a certain polarization, regarding the intertwining electric and magnetic fields? For example, television stations transmit their signal with horizontal polarization, and that’s why a TV antenna works best when it is mounted with the elements horizontal. Public safety base station antennas are vertically polarized, so the vertical antennas on the vehicles work optimally with them.
But we also have circular polarization, if you can get your mind around that. You probably have not seen circularly polarized antennas, but a common type has a coil of wire wound in a cylindrical / spiral shape. Two radios talking together have to use the same polarization for maximum signal strength. And there is actually left- and right-hand polarization to consider.
What if we could make a guitar cable that was circularly polarized? Noise coming off the AC line is typically not circularly polarized, so such a cable would be extremely low noise.
I’m a right handed player, so right hand circular polarization would be a natural for me. Lefties would use cables employing left hand circular polarization, just to avoid interference with their right handed bretheren, and to ensure optimum tone matching. Imagine what that would do for live stereo separation!
(I’ve seen a picture of Hendrix at Woodstock playing through one of those cheap coiled guitar cables. I wonder if it was a counterclockwise coil?)
Of course, our friends in the Southern Hemisphere would have to use oppositely polarized cables. Don’t you know that water swirls in the other direction down there?
So there’s another patent for you. All you have to do is figure out the polarization mechanism. You’re welcome.
Look, if you have the money for gold connectors and oxygen free copper designer cables, go for it! These products are certainly not junk, just expensive. I use gold plated cables and jacks on my instruments, but for speaker cables I buy the largest stranded copper wire I can afford and ensure that the connectors are soldered (not crimped) and stabilized with heat shrink tubing.
If you want to build your own cables, you can find the parts you need at DigiKey or Newark Electronics. In the past, as a starving college student I resorted to buying less expensive cables and working over the connectors, resoldering the connections and adding heat shrink tubing as a strain relief. I have never had one of these cables fail!