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Ram Electronics HS Measurements and Analysis

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By Gene DellaSala

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.

HS_meas_inducVfreq

Inductance vs Frequency

The Canare 4S11 has appreciably lower inductance than standard 10 or 12AWG zip cord. The series inductance was measured to be under 0.120uH/ft which is an excellently low figure for such a low gauge cable and non-fancy cable geometry.

HS_meas_ACvFreq

AC Resistance vs Frequency

The Canare 4S11 measured to have an effective gauge of 11AWG which is low just like we like it for speaker cables. The cable didn’t start to appreciably skin until well out of the audio band (>50kHz) which is more than adequate for a high performance cabling solution which will cause no audible harm to your system.

For a more detailed discussion on Skin Effect, see:

Skin Effect Relevance in Speaker Cables

HS_meas_capVfreq

Capacitance vs Frequency

The Canare 4S11 cable capacitance is under 40pF/ft which is commendably low and should not present any amplifier stability issues, even for relatively long cable runs for even the least robustly designed amplifiers.

 

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Recent Forum Posts:

gorillacooch posts on August 01, 2009 16:25
Oh and one more thing, does the WBT connector really make a difference? What does River cable use?

Does River Cable use Canare4S11?
gorillacooch posts on August 01, 2009 16:22
Can you please do a comparison with Audio Art Cables? I would love to see what you think about those. Also can you do a big comparison review of XLR connectors.
gorillacooch posts on July 28, 2009 01:52
Do the HS cables use the same gas joint termination thingy that river uses?
gorillacooch posts on July 28, 2009 01:11
How much better are the cables made by mudkat, the cat 5?
chris357 posts on July 27, 2009 14:00
i get Canare form cable solutions I like the feel and the build quality and the price is very good!!! I'm almost 100% canare through my system excpet for some used audioquest that I got for 15 bucks
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