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When 12 Gauge Wire is Not 12 Gauge

amirm

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#1
I know a lot of members here use premium speaker wires. But I thought I share this testing I did on common low cost 12 gauge wires. As always, comments and questions are welcome.

Introduction
Why test 12 gauge (AWG) wire? 12 AWG speaker wire is a “safe bet” from performance point of view because anything thinner may interact with the low impedance of your speakers and cause the frequency response to vary beyond threshold of hearing (-0.5 dB). That change can “color” the sound.

Once you get to 12 AWG and in reasonable (shorter) lengths, you should be good. This conclusion however only holds if the wire you buy is actually 12 gauge wire and has the nominal resistance that is used in the computation of dB drop. For this reason, it is useful to see if the wires that one can readily buy online or from local sources in US complies with the nominal values for 12 AWG. The measurement in question is “DC resistance” where we measure the resistance of the wire when it is being fed direct current (DC). This is the most basic parameter for cables.

I plan to keep updating this data. So if you like your favorite speaker wire measured, PM me for address and be ready to mail a 4 foot/1.5 meter section of your wire and I will measure and add its value to the measurement table below.

Test Methodology
The purpose of a good speaker cable is to transfer energy with very little drop. That very characteristic makes it very hard to measure the resistance by definition, that is a very small value. Typical (DC) resistance of speaker wire is in the area of 0.0015 ohm/1.5 milliohm per foot. This small resistance puts typical multimeters out of business since they become inaccurate in single digit ohm let alone in thousands of an ohm.

There are different solutions to this problem. The one I opted for is the so called 4-wire or Kelvin measurement invented by Lord Kelvin 100+ years ago. At high level, the 4-wire system separates the leads that provide power to the load (i.e. our speaker wire) from the leads that measure the voltage drop across it (which given the current, tells us the resistance using Ohm’s law). Because the leads are separated, we are now free to provide much more current and as a result, create a larger voltage drop. Not only that, but we also eliminate the effect of meter probe because the current that is going through them is a fraction of what we are feeding the load. Please look online if you like to have more details about its operation.

Unfortunately high-end milliohm meters are quite expensive, some going for as much as $5,000. I don’t do enough of this work to justify investing in them. The unit I have used here is a portable unit which has resolution down to 0.1 milliohm and accuracy of 1% (plus 5d). Its output current is rather low at 200 milliamps since it runs on batteries. That however, is still 200+ times more than standard multimeters which use 1 microamp to 1 milliamp typically for resistance measurements.

In my test fixture, I am using a common, 2-probe system. There are still 4 leads going to the load but they attach to the load in pairs. This removes one of the sources of mistakes (using the wrong probes for high current and voltage measurements) and makes it much faster to test multiple items. Accuracy is still quite high.

As is always the case, the reality and theory are different. A milliohm meter is a very sensitive device. This means that it will actually measure the contact resistance of its own probes. This is easy to back out however by zeroing out its lead resistance first which is what I did. What is not so easy is to guarantee that you put the same contact pressure on the wires in question. There is an easy solution to this which is to use a much longer length of cable and hence, have its resistance swamp the connection load. Problem with that is the wire will coil every which way and won’t match from sample to sample. I wanted a predictable setup where every wire was tested the same way which meant straight and flat.

My solution to the problem was to use a ~3 foot segment of wire that I could hold flat on my desk but then short out one end and measure the resistance as seen from the other end. This does create a new problem in that the twisted end again has certain resistance and variability. To counter that, I put “clamping” load on it in the form of a beefy paper clip. I tested that fix by pushing hard on the connection while the clip was holding it and the difference was negligible. Without that clip, there would be considerable change when I put force on it.

Here is what the final fixture and my test setup looks like:



Sample Wires Tested
Here are the samples that I managed to acquire during a two week or so period:

Monoprice 12 AWG Speaker Wire: I bought a 50 foot spool through Amazon third-party service. I paid $25.35 and shipping was “free” (Prime). Monoprice’s own price is lower but you have to pay shipping and I prefer to not create accounts online any more than I have to.



The cable itself has a blue stripe on one of the wires which is useful in identifying which wire is which. The reel was cardboard and the overall impression screamed budget/low-end. The stripped wire did not hold well together due to many soft strands. Stripping it resulted in loosing fair number of strands.

RadioShack 12 AWG “AUVIO” speaker wire: I bought a 50 foot spool this on sale for $39. With tax it came up to $43 or so. Since I picked it up locally there was no shipping.



This is one good looking cable and spool! It oozes quality. The spool is blue and substantial. Likewise the wire looks thick and beautifully wound. I weighed the spool and wire and it was 4.51 pounds. In comparison, the Monoprice was 2.68 pounds. If I put the two next to each other and put the price tag on them, I am pretty sure most people would go for the RadioShack wire. The visual difference is unmistakable.

Parts Express Wired Home SKRL-12-50: I bought a 50 foot spool again through Amazon for $24.20. Shipping was an additional $7.69 for a total of $31.89. I went to their site and it was similar in price with shipping so I bought it from Amazon. It took over 7 days to get this wire. They shipped it quickly but they used economy service to send it to me. Being spoiled by free Prime shipping from Amazon, it was quite annoying to pay nearly $8 and have to wait a week.



As the listing indicates, this is from a company called Wired Home. It came in a nice blue plastic spool. It was not nearly as substantial as the RadioShack wire but definitely a step above lower end stuff.

Belden 5000UP 12 AWG: This is an in-wall speaker cable. As one of the largest cable suppliers in the world, and set of measured specifications, I thought this would provide a nice baseline to compare others. I could not find 50 foot spool of this wire on Amazon. All that was available through third-parties was 100+. Parts Express sold it however by foot though so I ordered 20 feet. The cost for that was $19.60 and shipping was $14.00 for express delivery.



The outer wrapping in this cable is thick and substantial. Not to the level of RadioShack wire but still above average. The individual wires inside strip easily and hold their form strongly. It is the closest thing to electrical wire.

Fry’s 12 AWG Wire: It was hard finding this wire at Fry’s Electronic as it was not with the rest of the speaker wires in the AV department. This is what it looks like:



Price was a reasonable $15.99 for the 50 foot spool. The spool is very light and the wire pretty flexible.

Electrical Wire: This is your typical stranded 12 gauge electrical wire that I had bought from Home Depot. It is a single conductor wire so not very suitable as speaker wire. But I thought I include it as a reference since I had it in my drawer of electrical parts. I don’t have the label handy but it is similar to this:



It strips easy because it matches the gradations in the a typical wire stripper but is very stiff.

Colman in-wall 12 AWG: I have a few hundred feet of this in my house. My then contractor (before I started Madrona Digital) selected it without my involvement. I told the contractor to pick “good quality cable” and this is what he bought. The application is non-critical (background music in the kitchen and feeding power to other devices). This is what it kind of looks like:



As you can see, it is a typical in-wall (CL3) cable with outer insulation and Belden like inside wires.

ICE 12 AWG Speaker Cable: ICE is one of the “go to” brands of cables for custom AV installers. We use a number of different speaker cables at Madrona and I found this left over reel in the shop and thought I should test it:



BestBuy 12 AWG Cable: As with Fry’s, the speaker area had a bunch of wires from Monster and their own house brand but nothing that went up to 12 AWG. I remembered that the automotive section often has heavier gauge wires and that was the case. They had a non-descript 20 foot spool. One conductor is copper colored and the other “silver.” I suspect it is actually aluminum wire.

Canare 4s11: This is a premium in-wall cable. It has four 14 gauge conductors. You can use two of the 14 gauge wires together if you only need one speaker feed which is the way I tested it. Alternatively you can use it as redundancy in case during construction a nail or screw went into it.



Coat Hanger: No, you don’t new glasses; I did say coat hanger! :D There is an online fish story that says someone performed blind testing of coat hanger against monster cable and nobody could tell the difference. There are other issues with that story but here, I thought I focus on the DC resistance.



The specimen I used has no brand or label. It is awfully thick though and was very hard to unwind into a straight “wire.” To combat contact resistance, I zeroed my meter by putting the probes next to each other and using that as the new “zero.” In a real situation that contact resistance would also be part of the equation.

Measurements
OK, enough rambling; let’s get into the measurements as shown in the table below. The first column is the length of the wire I was testing. I was not anal about keeping the length exactly 3 foot. So instead, I measured the actual segment and used that in the computation. In some cases I had a fixed length already and I used that.

The second column is our key data, the measured resistance in milliohms. Since this would vary based on the length of the wire being tested, I divided its value by the length and arrived at the industry standard milliohms/ft.

Next is the claimed DCR if available. Yes, there are discrepancies between my measurement and theirs. Since these are stranded wires, it is hard to get the exact number the resistance is supposed to be. Likely there are differences between my fixture and the one cable manufacturer used. So the best use of the measurements is as a relative value to compare one wire against another, rather than attempting to match it to any published spec. To that end, I used the measured DC Resistance of Belden cable as the baseline and used that to create a ratio in the next column (“Ratio to Standard”).

The Relative Difference column takes out the value of the Belden cable giving us a “pure” percentage of how much higher or lower the DCR is relative to Belden. In that regard, Belden gets a reference of 0. Negative numbers now mean a wire has higher resistance than Belden and positive numbers the other way around.

Weight KG indicated the weight of the sample wire I tested in kilograms. It is in metric because my scale seemed to give better accuracy there. I then normalized that per industry standards to weight/1000 meters.

Next is the thickness of the conductors. This is hard to measure as some of the stranded wires flatten when you try to squeeze them with micrometer. But I did my best anyway to give you a sense of how thick the conductors are.

While this report is mostly focused on DC resistance, I thought I include a couple of AC parameters such as Capacitance and Inductance per foot. These are not a factor in short speaker runs in the room but can be if you have long runs behind the walls.

The bottom row in green is the Geometric Mean (Geomean) of the column of data above it. Geomean is an average of a set of numbers that doesn’t get thrown off badly by one or more samples being way off the scale. Since that is what I am dealing with here, it makes for a better value than simple average. The number then provides a statistic average of the samples I tested.



And the Relative Difference charted as bar graphs:



I have color coded the underperforming wires in orange. As you can see, Monoprice, Fry’s, BestBuy and Coat Hanger fall in this bucket. The coat hanger actually went past the bottom of the graph so whatever story there is on how it sounds is quite suspect.

Fry’s and BestBuy wires must be aluminum cored to have such high resistance. They are not thin enough for the difference to be due to that. I would certainly avoid using both in any high fidelity application.

Of the none-in-wall wires, the RadioShack by far leads the pack on both subjective quality and measured DC Resistance. It managed to slightly outperformed our Belden reference. At $40, that is not much of a premium cost wise considering that you can pick it up in person and be able to instantly use it.

The Monoprice’s resistance is almost twice as high as RadioShack wire but not nearly as bad as the BestBuy and Fry’s no name wires. But being least bad doesn’t translate to good in my book :). My recommendation is that if you want to go the mail order route, go with the Parts Express Wired Home cable. It outperforms Monoprice both subjectively and in measured resistance (50% lower than Monoprice).

Conclusions
So there it is. Clearly 12 AWG wire is not 12 AWG when you buy a no-name brands. The notion then that you should buy any old wire that says 12 AWG and shopping purely based on price is not a wise one. Where you can, buy branded cable that comes with proper specification.
 
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Blumlein 88

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#2
If only the news of RS wire quality was out sooner they might not be pretty much out of business. :)

Thanks for the measurements Amir.
 

amirm

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Hehe :). When I wanted to post this article here, the old link I had to their site had vanished. I was worried I could no longer find it but was surprised to do so. It is really good quality wire for the price.
 

DonH56

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#4
One other consideration is that some wire is aluminum or copper-clad aluminum. While Al is higher resistance than copper, the real devil in the details is usually oxidation. Al and Cu do not play all that well together, and when Al oxidizes it forms a fairly hard grey sheen more difficult to recognize (and remove) than the greenish color copper typically changes to as it oxidizes. Al oxide raises the resistance considerably, at least relative to the ideal conductance, and has been a problem for house wiring.
 

DonH56

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The oxidation does almost nothing to the conductance as long as you make good contact to the actual wire. The exceptions are when, for whatever reasons, the wire continues to oxidize instead of forming a thin coating and stopping. Metallurgy is not my field, however. The problem for us is when the connections are not tight. I suspect a lot of perceived cable differences are due to simple wiping action that clears the oxidation when cables are swapped. Assuming they aren't just hearing things.
 
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NorthSky

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#7
A long long time ago I bought speaker wires from Radio Shack; 16AWG and 14AWG. The labels said "Copper OFC".
I used them for my eight surround speakers @ the time.
I was living about 300-400 feet from the ocean.
After roughly 3-5 years I noticed a sound degradation (I think, but did not measure, so all subjective here), and I looked @ all the "green" inside their transparent plastic jackets. The terminations were very bad, disintegrating, radically. I had to re-terminate all the end connectors, thirty-two of them.
That helped, but not too long after I decided to simply get rid of them all...there was just too much of that green oxidation all across the length of the wires.

That was no big deal because the total investment was roughly less than $150 (tax included). ...Cheap for roughly 200 feet.
I could also see "silverish" color in some sections and near the ends, as if the copper content was very minimal, like copper plated.
Aluminum copper plated? It really looked like it.

Now I look for solid copper, with 4-nines (Ns). ...Or more. Best interconnects: 6-nines.
Three front main speakers: Purity solid copper → http://www.audioholics.com/gadget-reviews/kimber-kable-8tc-speaker-cable/measurements

♦ Bonus: http://jazztimes.com/articles/14915-cable-guy

https://en.wikipedia.org/wiki/Oxygen-free_copper
https://en.wikipedia.org/wiki/List_of_copper_alloys
https://en.wikipedia.org/wiki/Copper_wire_and_cable

"It does not seem likely that standards for copper wire purity will increase beyond the current minimum value of 101% IACS. Although 6-nines copper (99.9999% pure) has been produced in small quantities, it is extremely expensive and probably unnecessary for most commercial applications such as magnet, telecommunications, and building wire. The electrical conductivity of 6-nines copper and 4-nines copper (99.99% pure) is nearly the same at ambient temperature, although the higher-purity copper has a higher conductivity at cryogenic temperatures. Therefore, for non-cryogenic temperatures, 4-nines copper will probably remain the dominant material for most commercial wire applications.[3]"
 
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#9
I found this VERY interesting. Since I am a Belden fan, I'm good.

But the real key would be in a blind test, could anyone hear the difference between the best and the worst?
 

amirm

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The worst was really worst! In sufficient lengths, we can cause 1 db or so drop in the part of the frequency band where the speaker impedance is lowest and have ourselves an EQ! The ones that are nominally 12 gauge would do fine in any reasonable length in a room.
 

RayDunzl

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#12
While perusing the recent Masterbuilt thread at the other place, and then roaming a bit using the alternate thread suggestions that that forum software provides, I came upon this (somewhat) remarkable post in a thread that asked "What are you using for cables?":

upload_2016-9-26_18-7-40.png


I was just curious if you would care or dare to expand upon this a bit, or whether any measurement came into play....

Are you still using them?

Do they have a little network box on them?
 

amirm

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#13
I have a pretty good sized collection of them (speaker cable, balanced/unbalanced interconnects). None are in use right now though. Last bit that I took out was their balanced interconnect that I was using with my Reel to Reel. Took out the Transparent and put in the Mogami. FYI, I received all of the Transparent cables for "free." When buying gear, the sales people always pushed cables. My answer always was, "if you want to throw them in for free, I will take them." They would proceed by reducing the price of the gear and put in the cables for the same total since they received more commision that way.

FYI for the project in this thread, I measured both transparent and monster cables briefly. Despite the fact that they are thicker overall than any cable I tested, both failed to have as low a resistance than belden 12 gauge wire!
 

RayDunzl

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Despite the fact that they are thicker overall than any cable I tested, both failed to have as low a resistance than belden 12 gauge wire!
They all fail compared to my 2AWG, with which I still intend to biwire, but haven't done so yet.

For the record, I find them punchy*.


*2. vigorously effective; forceful.
 

amirm

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They all fail compared to my 2AWG, with which I still intend to biwire, but haven't done so yet.
Funny you should say that. I recently totally rewired/redesigned my RV's electrical system. Due to requirement for over 200 amps current carrying, the main wiring is 2/0 (four gauges thicker than 2 above). As I was terminating them, I kept remembering the pictures you posted of your speaker cables!

These are very fine stranded though. I think the 2/0 wire has 600+ strands. That is needed in mobile applications due to vibration fatigue. And of course being able to bend these massive cables.

For lower 6 gauge wire, I bought these wonderful silicone wires from China, rated at 200 degree C (as opposed to common 105), that is insanely stranded:



The 6 gauge has 3,200 strands!!! It is so soft to play with that you want to go to bed with them! :D

Here is the seller: http://www.ebay.ca/itm/6-7-8-10AWG-Flexible-Silicone-Wire-Color-Selectable-5M-Lot-/201671324779?

The drawback is that they are expensive even from China. Of course that is compared to common wire. Compared to high-end wire, it is a bargain. Tempted to build speaker wires out of them and sell them at a premium. :D
 

fas42

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#16
I go completely in the other direction! For various reasons I'm agin multistranding - solid core all the way! I have a decent roll of the heaviest home wiring cable, which has been regularly used in my experiments - flexibility is for wimps!!!
 

tomelex

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#17
A long long time ago I bought speaker wires from Radio Shack; 16AWG and 14AWG. The labels said "Copper OFC".
I used them for my eight surround speakers @ the time.
I was living about 300-400 feet from the ocean.
After roughly 3-5 years I noticed a sound degradation (I think, but did not measure, so all subjective here), and I looked @ all the "green" inside their transparent plastic jackets. The terminations were very bad, disintegrating, radically. I had to re-terminate all the end connectors, thirty-two of them.
That helped, but not too long after I decided to simply get rid of them all...there was just too much of that green oxidation all across the length of the wires.

That was no big deal because the total investment was roughly less than $150 (tax included). ...Cheap for roughly 200 feet.
I could also see "silverish" color in some sections and near the ends, as if the copper content was very minimal, like copper plated.
Aluminum copper plated? It really looked like it.

Now I look for solid copper, with 4-nines (Ns). ...Or more. Best interconnects: 6-nines.
Three front main speakers: Purity solid copper → http://www.audioholics.com/gadget-reviews/kimber-kable-8tc-speaker-cable/measurements

♦ Bonus: http://jazztimes.com/articles/14915-cable-guy

https://en.wikipedia.org/wiki/Oxygen-free_copper
https://en.wikipedia.org/wiki/List_of_copper_alloys
https://en.wikipedia.org/wiki/Copper_wire_and_cable

"It does not seem likely that standards for copper wire purity will increase beyond the current minimum value of 101% IACS. Although 6-nines copper (99.9999% pure) has been produced in small quantities, it is extremely expensive and probably unnecessary for most commercial applications such as magnet, telecommunications, and building wire. The electrical conductivity of 6-nines copper and 4-nines copper (99.99% pure) is nearly the same at ambient temperature, although the higher-purity copper has a higher conductivity at cryogenic temperatures. Therefore, for non-cryogenic temperatures, 4-nines copper will probably remain the dominant material for most commercial wire applications.[3]"

I have 30 year old copper MONSTER thick cables, no green oxidation whatsover, jackets are clear and pliable. Amazing. Guess I just got lucky.
 

amirm

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I have 30 year old copper MONSTER thick cables, no green oxidation whatsover, jackets are clear and pliable. Amazing. Guess I just got lucky.
I have one that turned green that I bought around 1997, so less than 20 years. It was however stored in our basement that is open to outside of air.
 

RayDunzl

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#19
The 6 gauge has 3,200 strands!!!
Did you count 'em?

6 awg is 26,300 circular mils / 3200 strands = about 41 awg each.


I snipped an end off my 2 awg THHN.

18 strands of what works out to be between 14 and 15 awg each.

Not quite solid core, maybe I could advertise it as "solid multi-cores".

 

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