How Much to Spend on Audio Cables

I am an electrical engineer and have studied the characteristics of wires and cables and transmission lines at both radio frequencies and low frequencies. I’ve built a lot of audio projects and played around with different setups for delivering sound into a room. I studied and researched acoustics and sound formation and propagation. I don’t claim to be the expert, but I consider myself above average when it comes to understanding the various aspects of sound generation and delivery.

I was carpooling with a friend in England during a 6 month work assignment there and we hit on the topic of audio systems and the conversation veered into cables. I made a wisecrack about the amount of money some people will spend on audio cables when most of that money is buying little more than meaningless hype. Much to my surprise, he shot back – somewhat defensively – that his system used 128 strand oxygen-free something something something sound cables to drive his loudspeakers. I surmised in that instant that all of the technical explanation in the world would not turn him from his complete and utter devotion to the great goddess of high fidelity audio. Rather than engage in a battle that would not end peacefully at truth, I steered the conversation away from that sensitive area and we chatted about less controversial topics. I continued to think about that conversation and others I’ve read or participated in since. There is such a passion by the believers about the difference that expensive speaker cabling makes. Is there something to their claims?

Testing and modeling of cables within the audio bandwidth (20Hz to 20kHz) show that they have negligible capacitive and inductive behavior and therefore can be accurately modeled with resistance. What this means in layman terms is that any ‘coloring’ or filtering of a signal driving a loudspeaker by the cable is due only to the resistance of the wire and not to any frequency dependent effects. As a signal increases in frequency, it tends to ride along the outermost layers of the wire through which it is being transmitted, a phenomenon called ‘skin effect’. This causes an increase in resistance in the signal path because the signal is traveling through a smaller cross section of wire. Fortunately, skin effect only occurs at frequencies much higher than the highest frequencies present in an audio signal.

The net result of all of this is that resistance is really the only factor to worry about with audio cabling. If it is speaker wire that you are concerned with, resistance can be an important factor because of the amount of current that travels through the wires to move the speaker cones. The primary benefit of premium speaker wire is low resistance. Other specs and features such as special dielectrics or magnetic flux tubes sound a lot like marketing hype, since a dielectric affects capacitance, and magnetic flux has to do with inductance, both of which would matter if your hearing range ran into the megahertz (most people can’t hear anything above 20 kilohertz) but have no noticeable effect on the sound. What you really want is low resistance. I actually used Romex (the wire that is in the walls of your house) to wire my home theater system. Not sure how the costs per foot would fall out against leading speaker wire, but the resistance is very low and probably significantly lower than speaker wire.

Audio cabling for delivery of signals between one box and another such as from your CD player to your Home Theater is less sensitive to resistance. The reason is because only a very small amount of current travels in the cabling. When you see gold connectors on cabling the purpose is to provide minimum resistance, as gold has lower resistance than copper, tin, nickel or other metals that might be used for the connectors. In addition to providing lower resistance out of the box, gold also does not corrode the way tin and copper do. Corrosion results when moisture enables oxidation of the surface of the metal. This oxidation is a sort of ‘rust’ on the surface of the metal which has higher resistance, causing the overall resistance of the signal path to increase. In extreme cases this oxidation can be high enough to block the signal entirely. If this occurs, the oxidation must be removed through the use of sandpaper, a sharp edge, or other tool to scrape off the oxidation layer. Gold plated connectors will reduce or eliminate this hassle. Of course, gold is quite expensive so it might be preferable to use tin and then scrape off the oxide every few years. I generally don’t buy cabling with gold connectors and I don’t believe I have suffered much loss in audio quality as a result.

In summary, if you’re buying speaker wire, almost any kind of speaker wire will get the signal to your speakers with decent sound. Lower resistance wire will deliver more power to your speakers and you may hear a slightly different ‘color’ as well. Likely you’ll prefer the sound with lower resistance. Speaker wire with a larger cross section of copper will likely be lower in resistance. If you’re buying cabling, don’t worry as much about the cross section of the wire. If you’re a purist and don’t want to have to worry about corrosion effects after several years, buy cabling with gold connectors. Otherwise, you will probably get by just fine with standard tin.

Vacuum Clothes Drier

Once while cleaning out the lint catcher in the drier, I thought about all of that cloth and how my shirts become thin over the months until they fall apart.  That led to thoughts about the amount of hot air that exits the drier.  There is a ton of wasted energy and wasted life by tumbling your clothes and running hot air over them.  Is there a more efficient approach?

The idea behind heating clothes to dry them is to cause evaporation of the water so that it can be carried out of the clothes and through the vent to the outside.  Another way to cause evaporation is to reduce the air pressure, or to generate a vacuum in the chamber holding the clothes.  Maybe the drier becomes a chamber with a rack for hangers to hang on and/or shelves or hooks to hold what you’re trying to dry.  Line up your shirts in the drier on hangers, shut the door and press go.  Most of the air is sucked out of the chamber and moisture condenses on the sides of the chamber where the temperature is kept cooler than that of the chamber.  Moisture then is captured in a chamber below where it can be drained once the vacuum is released.   This approach takes some doing to generate the vacuum but the clothes take less of a beating and less energy is spent heating the outdoors.

Golf ball finder

Finding your golf ball when you sliced into the weeds is a pain sometimes. Here are some ideas for electronically tracking the ball and leading you to it…

We talked about the problem that we amateurs have of hitting the golf ball into the rough and then spending 20 minutes searching for it before throwing out yet another ball.  Wouldn’t it be nice to have an electronic means of finding the ball?  Here are some ideas we’ve bounced around:

Passive RFID: Manufacture each ball with an RFID chip inside.  Then equip the course with RFID sensors which can triangulate and locate the position of the ball.  This information is gathered and relayed to a golf course central processor which then transmits the location coordinates of the ball to a hand held or cart mounted unit.  This unit could incorporate GPS technology, showing the golfer’s present position plus the position of the ball.  The golfer position would come from standard GPS satellite reception.  The ball location would  come from the transmitted coordinates.  Both would be indicated on the unit’s map.

One drawback of the above system is that GPS resolution is several feet and there are times when you know within that resolution where your ball is but you still can’t find it.

Active Beacon Emitter from Ball: Another approach would be to manufacture the ball with an active RF beacon emitter circuit inside.  This circuit would also include a piezoelectric accelerometer which would produce a voltage when the ball is hit with the club.  The voltage would be captured on a capacitor and with proper power management would be sufficient to power the RF emitter circuit inside.  The RF emitter would continue to emit bursts of an RF signal modulated with a unique  identifier (perhaps the chip can be programmed with this ID from outside the ball by RF near field stimulation, or manufacturers would produce balls with regularly updated ID codes) until the power harvested from the impact of the club on the ball has dissipated.  This RF beacon would then be received by a hand held or cart mounted unit that has two receivers some distance apart which triangulate the position of the beacon and generate a ‘beep’ and a direction arrow on a display.

Keeping Score: For those who golf near par this may not be as interesting but for the rest may be.  Since we have this gadgetry sensing when the ball is hit and where it goes, it wouldn’t take much to add a score keeping function that counts how many times the ball has been hit before landing in the cup which impact pattern could be detected and used to reset the counter for the next hole.  Or, maybe there is a wireless circuit in each of the cups to log the score and reset for the next hole.

Update 4/22/11: RadarGolf is a company that in 2005 was selling a golf ball finder system based on RFID tags embedded in the balls.  It may have not worked very well, as they seem to no longer be selling the system though they continue to sell the balls.  There are also other RFID oriented golf ball finding technologies for sale which can be found with a search on terms like ‘RFID golf’.