I hooked up the dreaded Polk Cobra Cables!

madmax · May 2004

Yes, that's right, the dreaded Polk Cobra cables (also widely known as amp killers). I normally run Audioquest type IV speaker cables but a few days ago I connected the Cobra cables. I have had them for over a year but I've been too afraid to try them. So far so good. I have burned them in for about 30 hours so far and my amps are working fine with them. (they should only be used with tube amps because they are almost perfect transmission lines and without a little high frequency rolloff up in the RF region they can rip your amp apart).

They excell at soundstage and midrange detail. The lows are a little lacking in level because the cables are too long. Some reviews I've read say you need to cut them up and place 3 or 4 lengths in parallel at which point you end up with cables equal to some of the best ones in the world. The highs seemed a little more edgy to me but only in the slightest amount. (Not enough to worry about). I believe that is due to the length as well. The midrange is awesome! I plan on cutting them up and running in parallel later on this summer. At least I will if my amps still work.

This is a very unique product to say the least.

madmax

F1nut · May 2004

You're a brave man...lol.

How long are they now? I'd love to see a pic of those things since you still haven't invited me to your house.

jcaut · May 2004

I plead ignorance: I've heard of these, read several discussions in the past about them, searched the forum......I still don't quite get it.

Somebody fill me in, please. Highly capacitive WIRE? I thought low capacitance and low inductance were both desirable qualities, as far as wire goes. Are we talking about killing amps due to the complex load... impedance phase angle changes... or HF oscillation? All of the above?

I'd like to see a pic.

Jason

madmax · May 2004

I'll have to check the length but I think they are 16'. Soon enough...
madmax

VR3 · May 2004

The problem with the cables was basically this...

The signal would leave the amp, and arrive at the speakers and do a 180...and go back to the amp and KABOOOOOM

jcaut · May 2004

Man I hate when that happens!

Thanks. I was actually looking for a more technical description, and a "why this is a good thing, sound-wise" type explanation.

jdhdiggs · May 2004

Originally posted by jcaut
Man I hate when that happens!

Thanks. I was actually looking for a more technical description, and a "why this is a good thing, sound-wise" type explanation.

Google it, I got some really good info.

mantis · May 2004

16 feet should be a bad run.Runs of over 25 feet is where change will occur.

Mad,
do the cable Improve over what you where doing before???This is where Value of any cable comes in.If it's not of yuor liking,get the cables out reguardless of the name brand and sell to someone who ownes a system they will make a difference or better put Improvement.

A frame is something else you could do with them.Hanging them on the wall might yield better performance....you understand.

Dan

madmax · May 2004

Originally posted by mantis

A frame is something else you could do with them.Hanging them on the wall might yield better performance....you understand.

Dan

Waaaaaaaaaaaa....

They aren't bad with the bass and treble, just not optimum with the length. As someone else said this is fairly well documented. What they are is a litz sort of thing. Many strands with each one isolated from the other and all braided together. The word is that if you run multiple sets at 5 or 6 feet you cannot find anything better. (assuming you don't turn your amp into a radio station and blow up the whole mess).

Or, as you say it may be better to hang them on a wall...

organ · May 2004

Sounds cool. I'd like to hear what you think of them once you do it in parallel.

I had no idea Polk made speaker cables. Did they design the Cobra to work best with a particular model? When did it come out?

Oh yeah, did you install the Shaguangs yet? I just ordered a quad of EL34EH from Electro Harmonix. Tried my old(not so healthy) ones a few days ago and they sound super in triode.

Maurice

madmax · May 2004

The Shuguangs are burning in now. I cannot say what they sound like yet. Right now not too good but you know how tubes are...
madmax

George Grand · May 2004

Somebody's got a hold on some wild mind expanding stuff.

Strange reply you got there Max. I'd disregard.

George Grand (of the Jersey Grands)

PolkThug · May 2004

ARTHUR SALVATORE AND HIGH-END AUDIO LTD

POLK (COBRA) SPEAKER CABLE (IN PARALLEL ONLY!)- This speaker wire (8 cables in parallel) has proven to be superior to every other cable that I have compared with it, at all prices points, for over 20 years now. It was even far superior to the $15,000, top-of-the-line Kimber at the Las Vegas CES show a few years ago.

The Polk is very transparent, lucid, clean and extended in the highs. It is not for those audiophiles looking for something "euphonic" to complement digital or solid-state sound. It is the most revealing cable ever made and it must be used in parallel or else it will sound lean on low-impedance, or even average impedance, speakers.

Based on our collective, long-term experiences, eight cables in parallel will work with everything, and four with most speakers*. The overall length must be as short as possible.

The Polk does have one noticeable weakness; its bass transmission is not the equal of some of its rivals in both the areas of weight and impact, but its bass definition is still as good as anything made even today.

*One cable will work extremely well with tweeters.

The History
Polk Speakers did not manufacture this cable. It was designed and manufactured by a cable company in Japan (the name is unknown). Polk marketed it at the time as an alternative to the early Fulton cables (see below). According to an inside source, they were aware of what they had, the best speaker cables around, but they marketed it in the wrong manner. They sold it in single pairs and in very long lengths. Unfortunately, that is the exact opposite of the correct method for optimizing its unequalled potential.

The predictable result: Very few people ever heard this cable at its best.

If that wasn't enough, all of the reviewers at the time, with one notable exception, dismissed this cable as inferior, if not actually dangerous to use (with transistor amplifiers). This all occurred when there was the initial explosion of cable companies back in the early 1980's.

The result: The Polk was quickly forgotten.

Polk-The Science Behind It
There are no "secrets" or "magic" behind the unprecedented performance of this cable. Polk simply has the lowest inductance of any cable ever made, which means it is the "fastest" cable, and it is also the cable with the most extended high frequencies.

The actual wire is very fine and pure, and it is damped on its inside and outside by polyethylene. Both the resistance and capacitance are high. The resistance can be easily reduced by both shortening the cable and also running them in parallel. The high capacitance is not a problem for tube amplifiers, but it can be a serious problem for unstable (meaning usually older) transistor models.

Identification
The Polk is round* and about the same diameter as a common interconnect. Through the clear outer plastic, you can see the very fine green and copper wires, bundled together, and intertwined (overlapped) with each other.

(*There is also a flat version of the Polk, but it is not as good.)

The reason there is not a "short circuit", despite the numerous overlaps, is because every single wire has a clear insulation around it, which must be burnt off to make the required connections to the amplifier and speakers.

Building Polk-A True Project
Polk was never manufactured and/or marketed in its optimum form. It must be built using the original, raw, single-run cables. This will not be a simple, "fun" project. It is more accurately described as a true challenge, as I will now explain in more detail:

Caveats: The Polk is very tedious, difficult and even dangerous to build and terminate properly:

1. All the paralleled cables must be exactly the same length or you lose focus.

2. All the "greens" must be in parallel together, and so must all the "coppers", never both green and copper "runs" of the same cable.

3. All the green and copper individual wires and "bundles" must be kept totally separated from each other or there will be a "short" (use a voltmeter to verify this).

4. A very high temperature soldering iron or solder pot is required to remove the clear insulation on each tiny strand.

5. The fumes, resulting from burning off the insulation, are toxic.

6. The paralleled cables should be in as intimate contact as possible, to reduce both micro-vibrations and inductance.

Further- Amazingly, the Polk cables were made out of copper. Only one audio reviewer heard (and measured) the potential of this cable when it was available, brand new, 20 years ago; Peter Moncrieff of International Audio Review. Here is part of what he wrote in IAR Issue No #9:

"If only Polk's resistance were lower, it would be a virtually perfect speaker cable...The beautifully flat error curve of Polk suggests a plan for creating the virtually perfect cable: run many Polks in parallel."

I, and a few of my associates, just followed Peter Moncrieff's theoretical "plan", and it actually worked. That's why it is still the only cable in Class A.

F1nut · May 2004

Great read, thanks for posting it.

dcarlson · May 2004

Very interesting... So, where are the pics of these mysterious cables?

F1nut · June 2004

There is a discussion at AK about this cable, here's a link with a pic.

http://www.audiokarma.org/forums/showthread.php?s=&threadid=6918

Gary Robertson · June 2004

Oh No,
Not the ol' negative feedback syndrome..
Some companies try to create lower THD ratings with this trick--Oh hell,,, what do i know--i'll shut up while i'm still ahead..ha,ha...

VR3 · June 2004

you forgot adcom...lol

Gary Robertson · June 2004

Keep it up fellas--i enjoy the humor..
Just wait till i start ranting nd raving about my REALISTIC ( ol' radio shack receiver) and OPTIMUS speakers.........
AND MY OLD BSR McDONALD 8-TRACK........

Hey you guys forgot about "ACOUSTIC ZEN" cables..Ha,ha...

madmax · June 2004

When I first got these I was going to get a BRYSTON amp because of its GLORIOUS sound but never did. Much like ATC I think the MARTIN LOGAN speakers would work nicely with them!! The perfect system would be the BRYSTON AMP, MARTIN LOGAN speakers and a TOSHIBA 3960 DVD player. Talk about high end!
madmax

mhardy6647 · May 2020

^^^ sixteen years on* -- is this legit or just hoo-hah? I am speculating the latter...

If it's not hoo-hah (i.e., if its not spam)... tell us more about yourself @Polkcobrauser -- without blind links, if you please.

_________________
* Wasn't that an Elton John song?