The Difference Between Copper and Copper Clad Aluminum Cable

[Duran 387]

Audio manufacturers around the globe are waging an unseen battle. Most people have no idea that the war is going on, much less who is winning. You see, a significant percentage of the cost of the electronics and loudspeakers we enjoy and, in particular the wiring that interconnects them, is linked to the price of copper.

Since 2004, the price of raw copper has more than doubled and manufacturers have been fighting to keep the cost of products low, as one must do in a highly competitive marketplace. Although the price of raw copper has a direct affect on amplifiers (PCBs have copper traces and copper windings in transformers) and loudspeakers (most voice coils are copper), no category of car audio has been as directly affected as cable and wire. You may have noticed that a quality "amp kit" that used to sell for $49.95 a few years ago is now $99.95 or more. This increase is directly attributable to the amount of copper in those products and the rising cost of the raw material.

In an effort to reduce "sticker shock" for those shopping for amp kits, several companies began producing a different kind of wire as a more cost-conscious alternative. The new wire isn't really new; it was used occasionally in past automotive applications. But high prices make for innovation and now we have "Copper-Clad Aluminum" (CCA) wire that costs about half the price of pure copper cables. While this can be a great alternative to expensive copper, it can also lead to problems if misapplied and its limitations aren't fully understood. Here is how to find out if it's right for your system.

Description

CCA wire is an aluminum wire or many strands of aluminum wire coated with a very thin layer of copper. In practice, the "copper-clad" part of the nomenclature is mainly there to assuage potential buyers' doubts, as the amount of copper used is inconsequential to the actual performance.

The construction and gauge sizes of CCA wire are the same as copper wire. The strand size and count can differ just like various qualities of copper wire, as will the flexibility of the conductor. The insulating material is the same PVC or silicone-based material found on copper wire.

The big difference between pure copper wire and CCA wire is resistance. If you look up the conductivity of common metals used as electrical conductors, some facts might surprise you.

The best metal for conducting electricity isn't gold, as many believe. The absolute best conductor is pure silver. The second best is copper, with a very good conductivity at 97.6 percent that of silver. This is the main reason that copper has been the most popular material for an electrical conductor—it's a fraction of the cost of silver with almost equal performance. Gold ranks third, with 76.6 percent the performance rating of silver (the real benefit to gold is its ability to resist corrosion and oxidization). Aluminum, however, is a distant fourth at the 63 percent mark, or about two-thirds the conductivity of copper. Stated another way, and when we include the tiny bit of copper applied, CCA cable has about 34 percent greater resistance than a pure copper cable of the same gauge and construction. Let's take a look at what that additional resistance can mean in the real world or car audio.

If you're reading CA&E, you probably already know that resistance in a conductor causes a loss of power in that conductor, in terms of voltage and/or current. It also can become a source of heat if the resistance and amount of power delivered are high enough.

A quick Ohm's law refresher reminds us that E*I = P or, for those not familiar with the symbols, voltage multiplied by current equals power. So if we want to maximize the ability of our amplifier to make power, we need to maximize the voltage and current that supplies it. Any amount of resistance in the conductor delivering that voltage and current becomes a limiting factor to maximum power delivery.

It's not essential to go into the mathematics here. The point is that for optimum performance with a given supply voltage and a known current delivery requirement, we can calculate how much resistance in the conducting cable is acceptable. Since most of us have been taught the general rule of thumb for selecting wire gauge in systems of various power levels using pure copper cables, it's very important to rethink those requirements when using a less effective conductor, like the CCA cable. While some of you already have your mental light bulb coming on, for those of you new to CCA cable, I provided some additional data to explain what goes on from a technical perspective.

Lab Measurements

As we discussed earlier, additional resistance will increase the heating in the conductor and decrease the amount of power delivered. Let's look at safety first and examine the heat developed in the cables.

Why is the heating important? In most vehicles a portion of this conductor must "live" in the vehicle's engine compartment. Vehicle underhood temperatures here in Arizona often exceed 180F. The insulating jacket on most cables is only rated at 105C, or about 221F. That doesn't leave much of a safety margin for internally developed heat and, in extreme cases, can lead to softened or even melted insulation on the conductor.

They say a picture is worth a thousand words. Here at Cogent Audio Labs, we're fortunate enough to have a special camera that allows us to photograph heat. In the accompanying photos (see below) you'll see radiometric images of three different cables, all sold as 4-gauge and measured under identical test conditions.

A pure copper cable and a CCA cable were measured and proved to be "full-spec" 4-gauge as determined by the American Wire Gauge chart. The second pure copper cable is sold as 4-gauge but is about 10 percent under spec in strand count and diameter. It's also less expensive than the full-spec copper, so that may be an indication for the buyer to pay attention.

Each cable was exactly 20' in length and the heating test involved passing 100A of current through it for a 30-minute duration. This is a severe condition but not impossible to duplicate in large systems. The ambient temperature and the start temp of each cable was 76F (see measurements below).

Conclusion

At this point you might be thinking that CCA wire is bad and shouldn't be used, but that's not the case. We've done extensive testing on CCA wire for several manufacturers and our results show that it can work very well for all but the highest current applications. Because of the additional resistance you simply can't substitute the same gauge CCA wire for the traditional gauge copper wire. Our strong recommendation would be to simply use one gauge larger size of the CCA cable than the copper cable.

That being said, if you compensate for the increased resistance in the CCA cable by going to the next larger gauge size, you'll probably end up with equal or maybe even less resistance than the smaller gauge pure copper. But along with an increase in cable size comes an increase in price. This could mean little difference in bottom line prices between comparable copper and a +1-gauge in CCA, so be aware of what you're buying. —Garry Springgay

Garry Springgay is the owner of Cogent Audio Labs, and a former contributing tech editor for Car Audio and Electronics magazine.

http://caraudiomag.com/articles/copper-wire-vs-copper-clad-aluminum-wire-wire-warnings

[Duran 387]

I'll stick to welding cable

[bassahaulic 155]

I'll just over compensate. I'll do 4 runs of CCA 1/0 for the price of a single run of pure copper 1/0.

[Randal Johnson 544]

I'll stick to welding cable

I agree. Welding Cable is the best Bang for the Buck !!!

[Julian 641]

I'll just over compensate. I'll do 4 runs of CCA 1/0 for the price of a single run of pure copper 1/0.

x2222222222222222222

[bassahaulic 155]

I'll just over compensate. I'll do 4 runs of CCA 1/0 for the price of a single run of pure copper 1/0.

x2222222222222222222

My new friend.

P.S.

More like a triple team on this forum.

P.P.S.

8,19,10,2,18,27,22,5,27,14,2,16

[Julian 641]

I'll just over compensate. I'll do 4 runs of CCA 1/0 for the price of a single run of pure copper 1/0.

x2222222222222222222

My new friend.

P.S.

More like a triple team on this forum.

P.P.S.

8,19,10,2,18,27,22,5,27,14,2,16

hahah!

two runs of CCA from KK 2.50 single run of 1/0 3-10 dollars/ft

[Duran 387]

Even most of the other mainstream companies are CCA.

[cedartowndawg 3]

While you guys are being cheapos, I'm gonna get the max efficency and run PURE silver!

(God help me with the cost. )

[CrazyKenKid 64]

cool read! thanks for posting and spreading the knowledge!

the next build will not include cca wire! lol

[sandt38 448]

Great article, Duran! Thanks for the read.

I guess there really isn't anything wrong with CCA if you simply don't have the money. But that also gives rise to my opinion that if you simply can't afford the cable, you can't afford the system you intend to install. But, for those of use with bigger dreams than wallets, I would advise that you get yourself at least 1 size up from the standard cable required for the system. I considered using the 1/0 CCA from Knukonceptz, as my system really only needs 4Ga to run it, but instead I opted to use their 1/0 Kolossus Fleks cable. I figured I might wind up upgrading my sub stage to a ShivaX or 2, and it would be nice to have sufficient cable already installed. When I really thought about it I concluded that I just didn't see any reason to cheap out on the cable, after all it should outlast the vehicle it is installed in... so why be cheap about it?

Seriously, if you can't afford $100 for a 1/0 pure copper cable, you shouldn't be running a system that demands 250-300 amps of supply side current.

[slim2fattycake 85]

I think I got something else out of this than everyone else. Next time, I'll buy CCA. Do understand that this is way overkill for what we do in car audio. 100 amps of current for 30 minutes? Who has the equipment to even handle that. KK's wires are oversized as well so their CCA is the best bang for the buck.

"if you compensate for the increased resistance in the CCA cable by going to the next larger gauge size, you'll probably end up with equal or maybe even less resistance than the smaller gauge pure copper."

[Sir-Lancelot 216]

Meah, after helping someone install some of the Knu CCA cable, I will stick to welding cable thank you very much.

That Knu CCA is pure shit IMO.

[Maddenkid2011 3]

Is this copper or CCA?

Knu 4 Gauge Amp Kit

[jcarter1885 995]

I only use Knukonceptz Kolossus Fleks Kable from my distribution block to my amplifiers for there power and ground wires. Everything else in the car is welding cable, just how I roll

[jcarter1885 995]

Is this copper or CCA?

Knu 4 Gauge Amp Kit

It tells you in the description of the product if you read it.

[Maddenkid2011 3]

Is this copper or CCA?

Knu 4 Gauge Amp Kit

It tells you in the description of the product if you read it.

I knew it was the OFC but the strands on the ground wires look more like the CCA example picture than the copper example picture

[sandt38 448]

Is this copper or CCA?

Knu 4 Gauge Amp Kit

That is copper. The CCA is not really a transparent covering, it is opaque pearl blue, and the CCA ground is pearl white.

this is the 4ga CCA kit:

http://www.knukonceptz.com/productDetail.cfm?prodID=KLM-K8

[Kanaworm$ 292]

I will stick to Stinger HPM silver tinned OFC. It doesn't corrode as easy as non tinned copper, especially under the hood.

Great post btw Duran! Thanks!

[cobra93 47]

I will stick to Stinger HPM silver tinned OFC. It doesn't corrode as easy as non tinned copper, especially under the hood.

Great post btw Duran! Thanks!

I don't remember where I read about it, but with silver tinned copper wire the signal/voltage will travel the path of least resistance (obviously).

In this case the silver has a lower resistance than the copper and this signal/volts/amps will travel down the out side of the wire more so than the copper itself.

Does this matter? Probably not to my ears, but to some people they can hear the difference. I remember seeing a company that had home theater cable (diy) for more than $1200.00 per foot.

I realize this is way off topic, but.....

This was a quick search Audioquest cable

Edited July 30, 2010 by cobra93

[Kanaworm$ 292]

I will stick to Stinger HPM silver tinned OFC. It doesn't corrode as easy as non tinned copper, especially under the hood.

Great post btw Duran! Thanks!

I don't remember where I read about it, but with silver tinned copper wire the signal/voltage will travel the path of least resistance (obviously).

In this case the silver has a lower resistance than the copper and this signal/volts/amps will travel down the out side of the wire more so than the copper itself.

Does this matter? Probably not to my ears, but to some people they can hear the difference. I remember seeing a company that had home theater cable (diy) for more than $1200.00 per foot.

I realize this is way off topic, but.....

This was a quick search Audioquest cable

Wow! Really wouldn't know about all that. I just stick with Stinger as I can get it local and cheap!

[cobra93 47]

I would like to say I read this in a home stereo magazine many years ago, not sure. Whoever was reviewing the different cables worked for this magazine, The funny part was that he struggled to hear any difference, while his wife would walk in from another room and say something like "The highs sound better, did you get new speakers?". I'm sure this irritated the crap out of him.

He also said that different frequencies travel through different parts of the wire (the skin or the core of the wire) and arrive at the speaker at different times. Is this true, I don't know. I would have the means to test it, but it was an interesting read.

In the 90's, I was told that twisted/braided rca's would reject outside noise from being introduced into the signal. Is that true, I don't know, but I never had any more issues with buzzing or other noise in my systems after i switched to them.

Edited July 30, 2010 by cobra93

[sandt38 448]

Actually unshielded twisted pairs are not really designed to eliminate ground loops or induced noise, such as we see from car audio environments. They are intended to eliminate crosstalk. BUT! In a car we really are not terribly concerned about crosstalk.

Rarely in a car audio environment will we see UTPs used correctly. Ideal usage of UTP usually involves multiple runs of twisted pairs in a single insulator sleeve. In order to reduce, or eliminate crosstalk transmission between the 2 twisted pair in the same sleeve, the twist rates (and in some cases, direction) need to be different. Considering that most manufacturers twisted pair RCAs for in car use are all the same twist rate (it may vary by mfg, but who is going to use multiple mfgs, as they typically don't match?), their ability to eliminate crosstalk is nearly nil. However, outside EMI/RFI and ground loops really are what cause the noise issues we hear in a car. The noisy environment in a car really makes crosstalk a non-issue, as it is generally a very fine distortion compared to typical ambient noise in a vehicle.

A lot of people figure that twisted pair was the ingenious development that was cause for better noise rejection in car audio systems. In reality we saw better noise rejection technology introduced to our equipment including but not limited to increased low line voltages which help reduce noise on the input side by increasing the desired signal to interfering signal ratios. The best RCA to use for RFI/EMI noise rejection in a car is really good old fashioned shielded RCA cables. However, for the best of both worlds you can find shielded twisted pairs (STPs). But actually because today's noise rejection technology in our devices you could just about run your power cable next to an old school speaker wire type RCA cable without much noise issue, as long as the system is well gounded that is.

[Impious 1,476]

I don't remember where I read about it, but with silver tinned copper wire the signal/voltage will travel the path of least resistance (obviously).

In this case the silver has a lower resistance than the copper and this signal/volts/amps will travel down the out side of the wire more so than the copper itself.

Does this matter? Probably not to my ears, but to some people they can hear the difference. I remember seeing a company that had home theater cable (diy) for more than $1200.00 per foot.

I would like to say I read this in a home stereo magazine many years ago, not sure. Whoever was reviewing the different cables worked for this magazine, The funny part was that he struggled to hear any difference, while his wife would walk in from another room and say something like "The highs sound better, did you get new speakers?". I'm sure this irritated the crap out of him.

He also said that different frequencies travel through different parts of the wire (the skin or the core of the wire) and arrive at the speaker at different times. Is this true, I don't know. I would have the means to test it, but it was an interesting read.

Really, just from what you've said, I would guess that the article you read was filled with techno-babble bullshit. It sounds like they were taking some general facts and extrapolating out useless or possibly incorrect theories. Stereophile'ish, for lack of a better word.

Silver has less resistance than copper, no doubt about it. And while I haven't done any mathematics at all, this is a pure guesstimation, I would have a hard time imagining the silver tinning having less resistance than the copper wire of comparatively much greater thickness.

Skin effect is real, and wire does have group delay. However, within the audible spectrum and with speaker wire the length we use in car audio (and in most homes), both of these issues can be completely ignored. The change in speaker wire "performance" as a result of these two items within the 20hz - 20khz bandwidth is well below the threshold of audibility. We are talking about hundredths of a decibel and nanoseconds. Nothing to concern yourself with. Now if we were talking RF frequencies, then it's something to consider. Nobody can hear the difference, but many people like to trick themselves into believing the can so they can justify either 1) spending more on speaker cable than most spend on a new car, or 2) to justify their other closely held but largely unfounded beliefs. It's a little like religion, really.....a loss of rational thinking so that irrational thinking can attempt to be justified. Also, skin effect only affects AC not DC. So no worries with your power/ground cables.

In the 90's, I was told that twisted/braided rca's would reject outside noise from being introduced into the signal. Is that true, I don't know, but I never had any more issues with buzzing or other noise in my systems after i switched to them.

This is actually a long standing debate. Some people swear by UTP (unshielded twisted pair), including the likes of Richard Clark.......others swear by shielded cable. This and amplifier sonics are probably the two most hotly debated topics.

[Impious 1,476]

But actually because today's noise rejection technology in our devices you could just about run your power cable next to an old school speaker wire type RCA cable without much noise issue, as long as the system is well gounded that is.

You've been able to do that without issue for a couple decades. I know I've been doing it for over a decade without a single issue.

Power cable induced noise is an old wives tale in car audio