Wire and Connectors (Tips)
Sometimes we get asked what kind of wire to use with a speaker system, how good a patch cord is needed to hook up line level components, and so forth. This is not a bad question: Over the years we have seen a lot of systems, with audible problems due to insufficient wire, poor connections, and so on. We also know a lot of people are overspending on wire: We don’t see this directly, very much, ourselves, but, there are plenty of high end stores and suppliers, and even what you’d think would be “middle of the road” mail order and online sources selling wire and accessories for absolutely outrageous prices. $1200 for a 5 ft. patch cord? $148 for an AC wall outlet? Somebody must be buying this stuff, or you wouldn’t see so much of it being offered for sale. And that means someone is making a bundle, if they can sell just a few of these items.
Now, I myself can see that if someone shells out big bucks to run some new, exotic speaker cables, they are going to want to believe that those cables made a worthwhile improvement. That belief then becomes reality in the mind of the customer. The seller also has an emotional stake in all this, and may also come to believe “genuinely” that this kind of expenditure is worth it to their customers. This can be true especially if the customer comes back, saying, “wow those cable are great!” Further, the old cables may actually have had a subtle problem (such a bit of a poor connection, most likely — see below). However, you’ll find darn few degreed electrical engineers who get sucked in by this marketing of emotional comfort, over actual physical / electrical improvements in a system.
So… What is really needed to do a good job? Ok, let’s get down to basics: The old rule of thumb for speakers was that you wanted to keep the resistance in the wires to the speakers down to not over 1/10th of the speaker’s impedance. This would keep any losses down to 1 dB or less, and, in theory, any frequency response changes in the speaker down to 1 dB or less. This rule, though, is probably a bit TOO old. For one thing, there’s another old rule that said to keep the resistance in the low pass crossover to the woofer down to 1/10th the woofer’s impedance. Now, wait a minute… Add that up and we now have a 20% resistance, in line with the woofer. Response changes, good or bad, aside, that could be close to a 2 dB loss (especially at the speaker’s minimum impedance point(s), which is / are likely to be a bit lower than the nominal impedance.) Looking at that another way, the power to the woofer would be reduced just over 30%. Let’s see… how much more money was an amplifier with 30% more power??? This doesn’t even get into what happens to the damping, overall shape of the woofer’s response curve, etc.*
Even assuming, however, that crossover losses are a “given” (speaker system builders are free to put the lie to this!), or can be eliminated by going to electronic crossovers & multiple amps, the 1/10th rule for the wires to the speakers is probably a bit too generous for a good system. A shift of 1 dB over a wide band is audible to some listeners. And, there are further, easily measurable effects, in the audio band, that I haven’t discussed above.*
*Simple resistance effects on a woofer can be plugged into a Thiele-Small analysis program like PRo-Response for a quick look. However, there is even more going on: An audio generator and a good RMS voltmeter will get you started, if interested. An audio measurement system like LMS will take you even further, and for even more detailed measurements, modeling, and analysis, Smith and Larson Audio’s WT-2 , Speaker Tester , and WT-Pro , are terrific.
So, what is a good rule of thumb? Generally, “PR’s rule of thumb” is to measure a speaker system’s DCR or (if you have the equipment) it’s minimum impedance. Then, consulting a wire table, keep your speaker wires’ resistance to not over 1/20th of that figure. (Be sure to figure resistance “both ways” — a 20 ft. run of 12 ga. zip cord is 40 feet of 12 ga. wire.) Also remember to tin the ends of the wires with lead free solder to prevent oxidation of the exposed copper ends and prevent frays that could lead to a short. Indeed, in most cases 12 ga. zip cord, with tinned ends, will work just great, and that’s what I usually run to my speakers, Just be sure you are actually getting the wire you think you are — there are a lot of sellers marketing wire, most of it made in China, that is 2 or even 3 gauge sizes smaller than what it’s marked! (If you are not sure, measure the wire CONDUCTOR overall diameter, and consult a wire table.) If you are “on the fence” and on a tight budget, don’t sweat it if you want to go “one gauge size “too small”. If you have the money, and want to go a couple gauge sizes bigger, I can’t really argue against that either. But, beyond that, the extra money is better spent elsewhere. And let the bats worry about effects over 20kHz…
Then, there are patch cords and connectors. I usually try to go a little better than “cheapo” patch cords for line level connections to “critical” sources. A 1 meter, $5-$10 retail patch cord, with gold plated connectors, is good enough for me for most usages! I often make my own, simply to ensure there is a secure solder connection inside, and that the wire itself has decent shielding, but only for those reasons, or because I need a custom length. (I find that the biggest thing wrong with cheapo’s is that sometimes those solder connections hidden inside the molded plug-ends are poor. I’ve also found crimped connections that went bad from corrosion with age, due to no solder at all!) Regularly checking and cleaning connections themselves is also important, but, most readers here know that, I’m sure.
A smart buyer might do well to buy one inexpensive cable set, tear it apart to check the assembly quality, and the shielding (if noise picked up in the cables is a problem), and then stick with that brand for at least a while, if all checks out well. Oh, and yes, in addition to checking / cleaning my connections to equipment fairly regularly, several years ago I upgraded from conventional contact cleaners and went to using the Caig products such as DeOxIt — a far better expenditure than expensive cables!
Another smart thing to do is to buy a meter capable of reliable resistance measurements down to 0.01 ohm or so, to check the contact resistance in connections, wherever possible. You probably don’t actually need to get down to 0.01 ohms, BUT, being able to see a small variation when you wiggle your plugs, wires into speaker connectors, etc., around, is important. Believe me, it’ll likely be worse when you are actually playing your system, instead of hunched in back, checking connections. The distortion from a poor connection is often a lot worse than distortion in even budget amps. (One caveat on that, though - many amps are filled with questionable internal connectors. That’s why I like my modified Hafler 220K: It’s a simple design, and every connection is well-soldered. I did replace the poor quality RCA jacks when I did the mod though, as those really deteriorate with age. Even Hafler slipped up now and then…)
One other little detail, especially if you have speaker connections in places that are not particularly convenient to get to, is that it may be a good idea to use a good spring-loaded terminal as opposed to a screw down type. Screw-downs usually have superior (low) contact resistance at first, but sometimes the screw-downs loosen with time and as the copper wire “flows” a little under the pressure of the screw and vibration supplied by the speaker. A good spring loaded terminal will, essentially, “not let the wire get away”, and, if it is one with a good strong spring in it, contact resistance should still be pretty good / low. Caution, however: If contact resistance is not low, or the spring is weak enough that the vibration of the speaker can cause the contact to “break and make” in tune with the music, the heat and /or arcing will damage the contact surfaces, causing even poorer contact / more arcing. That in turn causes progressive contact deterioration heading toward total failure (and progressive deterioration of the sound, in the meantime.) I have even seen those plastic cup type spring terminals partially MELT at high powers — they can be fine at modest power levels, but are not suitable for either audiophile or high power usage.
Note: We are thinking of importing some good, high quality (strong spring, gold plating, will take large wire, etc.) push terminals, if there is enough demand. Please let us know if you are interested.
We also don’t think much of those $148 AC outlet (duplex receptacles) some people are selling. But, if your AC power outlets are more than several years old, and especially if they have seen quite a bit of plugging in and out type use, or use at currents at or near their maximum ratings (space heaters, medium size room …air conditioners, etc.), then replacement is not a bad idea. The same is true if anything has ever caused any arcing at all, or if there could be any issue with corrosion of the contacts inside them… (This is true of any power outlet, not just the ones for your stereo.) If you are really particular, or very safety minded), medical grade AC outlets and plugs are not too terribly expensive, in the overall scheme of things audio. In addition, you may want to check out the Hubbell and other Hubbell type products, as well.
Caution (again): If you are not sure you are qualified to do such work, hire an electrician.
In the end, sure, $1200 cables, or even $200 cables, should guarantee a good connection. (We assume they are hooked up to your $5000 amp (etc.), and that it’s manufacturer(s) didn’t skimp on it’s connectors!) But, the things I mention above are a lot better investment. Unless, of course, your time is worth $1000 per hour.