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Kimber Kable 8TC Speaker Cable Measurements and Analysis

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Using our Wayne Kerr 6420 Impedance Analyzer which graces our Test Equipment Laboratory, I measured all of the critical metrics which directly affect cable performance. I charted the results with some of the most recent speaker cables we’ve reviewed for comparative purposes.

Cable Metric Definitions

  • Rdc - Commonly referred to DCR which is the series resistance of a cable at zero frequency.

  • Rac -The resistive portion of the cables series resistance as a function of frequency due to skin effect.

  • Rs - Total Series Resistance (mohms) measured tip to tip at one end of the cable while the other end is shorted. Note: Rs = Rac + Rdc (minus instrumentation inaccuracies identified below)

  • Ls - Series Inductance (uH) measured tip to tip at one end of the cable while the other end is shorted.

  • Cp - Parallel Capacitance (pF) measured tip to tip at one end of the cable while the other end is open circuited.

Note about electrical cable resonance

Editorial Note on Cable Measurement Test Set-up

All of the measurements were completed on a fully calibrated and certified Wayne Kerr 6420 Impedance Analyzer. The 6420 was calibrated for full frequency bandwidths and for greater accuracy, the measurements and calibration process was repeated twice for consistency.

All cable lengths measured were 20 feet and divided by their length for a normalized per foot measurement.

Kimber8TC-inductance.jpg

Inductance vs Frequency for Kimber 8TC, 8PR & 4PR

All 3 Kimber models of cable exhibit very low inductance. Due to the braided geometry of these cables, not only are they low inductance, but their inductance profile vs. frequency is ruler flat for the entire audio band. By weight of comparison, the inductance of the 8TC and 8PR was a mere .037 uF/ft and .041uH/ft, respectively; which was nearly four times lower than the 10AWG Bluejeans speaker cables that I revere so much. Interestingly Kimber rates the inductance of these cables as .042uH/ft which is slightly higher than I measured but shows they are conservative in their ratings.

Kimber8TC-resistance.jpg

AC Resistance vs Frequency for Kimber 8TC, 8PR & 4PR

Kimber rates the DC resistance of the 8TC cable to be 2.19 mohms/ft while I measured slightly less at 1.72 mohms/ft.

Kimber8TC-gauge.jpg

Resistance vs Gauge for Kimber 8TC, 8PR & 4PR

The Kimber 4PR effective gauge is about 14AWG while the 8PR is 11AWG and the 8TC is slightly below 10AWG; the lowest of the bunch. The Kimber speaker cables exhibit a very flat AC resistance profile for the entire audio band. These cables don’t start to show appreciable signs of skin effect (increased AC resistance) until around 50kHz which is well above the 20kHz audio band. At 100kHz, the AC resistance of the 14AWG Kimber 4PR cables is equivalent to the Bluejeans 5T00UP 10AWG cables while the 8PR and 8TC cables exhibit much lower AC resistance. While this is purely academic, it is noteworthy that Kimber products are by design less prone to skin effect than conventional zip cord cables. It’s refreshing that Kimber doesn’t post nonsensical arguments on their website overemphasizing how this parameter can cause deleterious effects at audio frequencies.

For a more detailed discussion see:: Skin Effect Relevance in Speaker Cables

Kimber8TC-capacitance.jpg

Capacitance vs Frequency for Kimber 8TC, 8PR & 4PR

It is no surprise that when a cable is designed to be low inductance that its capacitance will be proportionally higher as a result. Unlike other cables that sandwich their conductors together, the Kimber manages to keep capacitance in check without the necessity of adding a zobel network on the speaker side of the cable to assure amplifier stability. Kimber’s published capacitance spec is 38pF for the 4PR and 90pF/ft for the 8PR and 100pF/ft for the 8TC. This is about what I measured as well, as you can see from the graph above. The Kimber 8TC and 8PR cables exhibit about four times higher capacitance than standard 10-12AWG zip cord, and twice as high as its 4PR sibling. Again I don’t see this as a show stopper especially since most people purchasing these types of cables are doing so for short runs (under 50 ft) and are likely using high quality amplification that doesn’t have stability issues driving moderately high capacitive cables.

 

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Recent Forum Posts:

Pogre posts on April 18, 2017 22:28
Rats can be cuddly once you get to know them.
Strum und Drang posts on April 18, 2017 21:46
Good question. The rat is a multi-purpose tool. It not only can accurately judge the best speaker cables, it will also provide companionship in lieu of a dog or a cat. Plus, if you have leftovers that are about to go bad, the rat also functions as a self-powered, self-propelled portable garbage disposal. (or, you can just rent a 14 year old)

I actually did a growth curve on a white rat in high school science. Amazing how much they can eat and how fast they grow. And they do like baloney. Something that life is full of.

I'm very happy my Polk towers do not need $700 speaker wire to sound wonderful.
Bizarro_Stormy posts on April 18, 2017 19:23
Why not just wrap the speaker wire in baloney..?
Should be cheaper than the rat in the long run…
and you get nifty baloney scented wire…

It's a win win…
Strum und Drang posts on April 17, 2017 21:00
Maybe I can go to Pet smart, buy a baby white rat, start feeding it baloney, do a growth curve on it, and see if it can discern minor sounds produced by my new, $700 speaker wires. The fully fledged, full of baloney rat should be able to hear how great those speaker wires are, and accurately describe just how nuanced they are. I can then set up my own ABX test with my skilled operator, great listener, rat. I should get excellent test results. After all, that rat will be full of baloney.
Speedskater posts on April 17, 2017 17:58
Strum und Drang, post: 1182980, member: 82454
What is a “sensitive ABX test?” I don't measure any of this stuff except with my ears and use them to determine if speaker A sounds better or not than speaker B, etc. You can scientifically measure many differences that go beyond human hearing abilities. Many people that advocate for very expensive speaker wires claim they can hear a big difference for the better. This is subjective and it does enter into purchasing decisions.
A “sensitive ABX test?” is one that is setup by skilled operators with experienced listeners and using very demanding test signals. An ABX test is about hearing very, very small differences. The differences are too small to have a preference. It's not a preference test that might apply to most loudspeakers.
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