OTK SHF SP Cord - AKA Polk Cobra Speaker Cable Set - 25ft x 2 -

OTK SHF SP Cord - AKA Polk Cobra Speaker Cable Set - 25ft x 2 -

OTK

Regular price $200.00 USD
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POLK (COBRA) SPEAKER CABLE (IN PARALLEL ONLY!)

 

This speaker wire (6 or 8 cables in parallel) is superior to every other cable I have compared it with, at all prices points, for over 40 years now. It was even far superior to the $15,000, top-of-the-line Kimber at the Las Vegas CES show some years ago.

The Polk is extremely transparent, lucid, clean and extended in the highs. Accordingly, it is not a good match for those audiophiles looking for something "euphonic" to compliment digital or solid-state sound. It is the most revealing cable I have ever heard and it must be used in parallel or else it will sound noticeably "lean" on low-impedance, or even average impedance, speakers. For same actual examples...

Based on our collective, long-term experiences, for a standard 6' length, eight cables in parallel will work with everything, and four cables with most speakers*. The rule is simple; The overall length must be as short as possible, with the added benefit that less cables (in parallel) are required at the same time (my own Polk cables, since 2008, are 3' long, with 6 cables in parallel).

The Polk does have one noticeable weakness; its bass transmission is not quite 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. Even more relevant, the Polk is now the finest speaker cable in only ultra-pure, minimalist systems (such as my own Reference System). The Coincident Extreme speaker cable, see below, has proven to be as good, or superior, in more typical systems, meaning those that are using push-pull amplification (and, I assume, multiple speaker drivers).

*One Polk 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 (OTK). 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 of the time). This all occurred when there was the initial explosion of cable companies back in the early 1980s. The predictable result: The Polk was quickly forgotten by almost everyone.

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 speaker cable with the most extended high frequencies.

The Polk cable has other technical advantages as well: The actual wire is very fine and pure, and it is very well damped on both 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 may 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. The flat Polk is not quite as good as the round version, but it is still noticeably superior to most other speaker cables, at any price.)

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, 30 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 in Class A after all these years.

Further (11/05)- This Japanese designed and manufactured speaker cable, only marketed by Polk in North America, was also sold in Europe by another name. This was unknown to me until I received this e-mail from a reader:

"Here in Norway, the Polk Cobra (speaker cable) was sold under the name Monitor Audio. I bought a pair of Polk Cobra on ebay last year, and they are identical to the Monitor Audio I have. I bought the Monitor Audio back in the early eighties."

Personal Note- Needless to say, my description for the Polk Speaker Cable now also applies to the equivalent Monitor Audio speaker cable, and so do all the respective caveats and warnings.

In stock

There’s something undeniably magnetic about vintage audio gear. The tactile weight of milled aluminum knobs, the warm glow of dial lamps, and—above all—the rich, analog sound that today’s sterile streaming boxes can’t quite replicate. But time is merciless: capacitors dry out, switches oxidize, and those gorgeous walnut cabinets lose their sheen. That’s where the art (and science) of our vintage audio refurbishment comes in.

Why Vintage Audio Still Matters

In the golden era of hi-fi—roughly the mid-1960s through the early 1980s—companies like Marantz, McIntosh, Pioneer, Sansui, and Technics were engaged in an arms race of build quality. This was before cost-cutting plastics and disposable designs; amplifiers were over-engineered, receivers were works of art, and turntables were precision instruments.

Owning one wasn’t just about sound; it was about status and permanence. These machines were built to last a lifetime—or two. The irony? Decades later, they often do, provided they’re given the care they deserve.

The Philosophy of Refurbishment

Refurbishment is not just about fixing; it’s about preserving authenticity while ensuring reliability. The goal is to keep that lush, analog character alive without compromising safety or sound quality.

Some enthusiasts chase museum-level originality—keeping every factory component in place. Others opt for sympathetic modernization, upgrading parts that never existed in the ’70s to improve performance. Both approaches can be valid; it depends on your vision.

The Turntable Store refurbishing process.. step by step

Step 1: The Initial Encounter

When we first meet a 40-year-old amplifier, we resist the urge to plug it in right away. That dusty Marantz 2270 might look gorgeous, but old electrolytics and brittle insulation can short instantly under full voltage.

Instead:

  • We inspect for corrosion, burnt resistors, and leaking capacitors.
  • We use a Variac (variable transformer) to bring up voltage slowly, reforming capacitors rather than shocking them back to life.
  • We check fuses—not just for continuity but for correct ratings.

Tip: A faint musty smell? That’s often the scent of old phenolic boards, not trouble. But a burnt smell? That’s trouble.


Step 2: Deep Cleaning & Control Detox

Dust is the enemy of good sound, that is why we clean the interior carefully with compressed air and a soft brush.

The real magic comes with switches and potentiometers. Over decades, oxidation builds up, causing scratchy controls and dropouts. A deep contact clean in each pot and switch, followed by vigorous cycling, often restores silky-smooth operation.

Step 3: Electrical Resurrection

This is where science meets art:

  • Capacitors: Electrolytic caps often need some attention. We replace out-of-spec caps with high-quality modern equivalents (Nichicon, Panasonic), avoiding over-capacitance unless the power supply can handle it.
  • Resistors: Carbon comp resistors drift over decades. Measure and replace out-of-spec parts.
  • Transistors: Certain vintage transistors (e.g., 2SC458) are notorious for noise. We do swap defective ones for modern low-noise equivalents.
  • Relays & Lamps: Speaker relays oxidize; replace or clean contacts. Dial lamps? Upgrade to warm LEDs for a factory glow without the heat.


Step 4: Cosmetic Glory

Refinishing the walnut cabinet can transform a unit. We do use real wood oil or Danish oil, not polyurethane. We clean the glass dial carefully; those silkscreened letters are fragile.

Knobs? We polish with metal cleaner, but never use abrasives on anodized aluminum.

Faceplate lettering? We avoid harsh chemicals—just mild soap and a microfiber cloth.


Step 5: Calibration & Sonic Check

After the repair and cleaning, it’s time to dial in the performance:

  • We do adjust bias and DC offset on amplifiers for stable operation.
  • On turntables, we re-lube bearings, replace belts, and check speed accuracy.
  • On Cassette Decks and Reel to Reels, we replace belts ( if needed ), we clean and demagnetize the heads before the alignment process ( a must ! ) 

When done right, the result is astonishing: a sound that breathes—liquid mids, velvet highs, and bass with a tactile presence that modern gear rarely matches.


Our promise for Audiophile-Level Results

  • We Avoid Cheap Parts: That $5 eBay capacitor kit? Hard pass. We use reputable brands.
  • We Don’t Over-Polish: Patina is part of the charm. We aim for “well-loved,” not “plastic surgery.”
  • We Upgrade Discreetly: If we must modernize (like adding gold-plated RCA jacks), we keep it tasteful and reversible.


Why It’s Worth It

The payoff isn’t just sonic—it’s emotional. Restoring a 1970s Marantz or Sansui is like bringing a classic car back to life. Every glowing dial lamp, every smooth rotation of a volume knob, connects you to an era when music mattered enough to build machines like this.

And when you drop the needle on your favorite record and hear that warm, enveloping sound, you’ll know: this wasn’t just a repair. It was a resurrection.

We have a 14-day return policy, which means you have 14 days after receiving your item to request a return. 

To be eligible for a return, your item must be in the same condition that you received it, unworn or unused, with tags, and in its original packaging. You’ll also need the receipt or proof of purchase.

To start a return, you can contact us at theturntablestore@gmail.com. Please note that returns will need to be sent to the following address: 

The Turntable Store
45 Market Square
Manheim PA 17545

If your return is accepted, we’ll send you a return shipping label, as well as instructions on how and where to send your package. Items sent back to us without first requesting a return will not be accepted.

You can always contact us for any return question at theturntablestore@gmail.com.


Damages and issues
Please inspect your order upon reception and contact us immediately if the item is defective, damaged or if you receive the wrong item, so that we can evaluate the issue and make it right.

Exceptions / non-returnable items
Certain types of items cannot be returned, like turntable needles and custom products (such as special orders or personalized items). We also do not accept returns for hazardous materials, flammable liquids, or gases. Please get in touch if you have questions or concerns about your specific item. 

Unfortunately, we cannot accept returns on sale items or gift cards.

Exchanges
The fastest way to ensure you get what you want is to return the item you have, and once the return is accepted, make a separate purchase for the new item.

European Union 14 day cooling off period
Notwithstanding the above, if the merchandise is being shipped into the European Union, you have the right to cancel or return your order within 14 days, for any reason and without a justification. As above, your item must be in the same condition that you received it, unworn or unused, with tags, and in its original packaging. You’ll also need the receipt or proof of purchase.

Refunds
We will notify you once we’ve received and inspected your return, and let you know if the refund was approved or not. If approved, you’ll be automatically refunded on your original payment method within 10 business days. Please remember it can take some time for your bank or credit card company to process and post the refund too.
If more than 15 business days have passed since we’ve approved your return, please contact us at theturntablestore@gmail.com.

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