“Let our rigorous testing and reviews be your guidelines to A/V equipment – not marketing slogans”
Facebook Youtube Twitter instagram pinterest

Kimber Kable 4PR & 8PR Measurements and Analysis

By

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. At low frequencies the results illustrate Rs being lower than Rdc, which is inaccurate, as Rs tends towards Rdc as frequency approaches zero or DC. The LCR measurement derives Rs from signal phase and amplitude, while a DC meter measures exactly what it is looking for, thus this discrepancy is likely due to a meter resolution issue, as the meter in AC mode does not sport the high accuracy it would in DC mode. The cable should ideally be modeled as multiple parallel resistors, and those resistors treated as a lumped element in series with an ideal inductor.

Each resistor is a frequency dependent element, and the inner ones fall out as the frequency increases. It is important to note the difference in measuring techniques, and caution the reader not to attempt to derive any relationships with the two numbers, as the absolute accuracy between the methods has not been established. However, the rising trend of Rs vs frequency is indicative of increased Rac due to skin effect and should also be noted.

kimber-inductance.jpg

Inductance vs Frequency

Both the Kimber 4PR and 8PR were among the lowest inductance cables in this comparison. Due to the braided geometry of these cables, not only are they the lowest inductance, but their inductance profile vs frequency was ruler flat for the entire audio band. By weight of comparison, the inductance of the 8PR was a mere .041uH/ft 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 .056uH/ft which is slightly higher than I measured but shows they are conservative in their ratings.

Kimber-resistance.jpg

AC Resistance vs Frequency

 

kimber-gauge.jpg

Resistance vs Gauge

The Kimber 4PR have the highest resistance out of all of the cables in this comparison. The effective gauge of these cables is around 14AWG which isn’t terrible but for considerably less cost one could get some of the competing lower resistance brands in this comparison. The Kimber 8PR’s effective gauge is around 11AWG which is significantly lower than the 4PR and close to the Bluejeans 5T00UP 10AWG cables. What is very interesting about both Kimber products is that they are the only speaker cables in this comparison with a relatively flat AC resistance profile. Both products don’t start to show appreciable signs of skin effect until arounf 50kHz which is well above the audio band. At 100kHz the AC resistance of the 14AWG Kimber 4PR cables is equivalent to the Bluejeans 5T00UP 10AWG cables. While this is purely academic, it is noteworthy that Kimber products are by design less prone to skin effect than the other cables even though they don’t post nonsensical arguments on their website about how this parameter can cause deleterious effects at audio frequencies.

For a more detailed discussion on Skin Effect, see:

Skin Effect Relevance in Speaker Cables

kimber-capacitance.jpg

Capacitance vs Frequency

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 cables that sandwich their conductors together, the Kimbers manage to keep capacitance in check without the necessity of adding a zobel network on the speaker side of the cable to assure amplifier stability. Kimbers published capacitance spec is 38pF for the 4PR and 90pF/ft for the 8PR. This is about what I measured as well as you can see from the graph above. The Kimber 8PR is about four times higher in capacitance than the Sonicwave or 5T00UP cables, and twice as high as its 4PR sibling. Again I don’t see this as a show stopper especially since most people purchasing these type 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.

 

Confused about what AV Gear to buy or how to set it up? Join our Exclusive Audioholics E-Book Membership Program!

Recent Forum Posts:

bandphan posts on May 24, 2009 15:59
foeth, post: 571564
I see. You meant ritual, not process.

I don't know what I meant, I just like Hebrew National hot hogs
foeth posts on May 24, 2009 10:18
I see. You meant ritual, not process.
Michael posts on May 24, 2009 09:24
Kosherization :-)

The meat is prepared is a special way (I mean.. on the factory), not just not mixing milk & meat.. bla bla.. Also, there are different levels…

think like HDMI Category 1 and HDMI Category 2 :-))

It is not “blessing”, if certain conditions are hold, a certificate is issued.. which is also time-limited

anyway, comparing to snake oil products to me, being very, very secular, I think is irrelevant
bandphan posts on May 24, 2009 08:03
foeth, post: 571515
Please elaborate

isn't it the process of the Rabbi blessing the food, and the way its handled prior to the faiths consumption
foeth posts on May 24, 2009 06:37
Please elaborate
Post Reply