bi-wiring

[Thomas_A]

JNeutron,

I have corresponded previously with Supra Cables regarding their measurements as depicted at:

http://www.jenving.se/ply.htm

As shown, their measurements of a cable with its conductors wide-spaced, they find a loss of around 4 dB at 20 kHz, while standard "zip" is below 1 dB. In my specific question, I asked for the lenght of the cables and the answer was 10 meters ended with a 8 ohm resistor (but he was not sure, since it was such a long time since the measurements were made). It seems however, that the test was performed on longer cables, perhaps 20-30 meter.

Now, Supra might appear to be "exotic" high-end cables abroad; the price for their "zip"-cord like cables (Classic) is about 2 times that of a no-name brand here in Sweden. The Ply cable is more expensive though.

Although some of their claims are not scientific (i.e. bs), I regard Supra as being less bs among AudioCable Makers. Also, they are one of the few that actually braid their own cables at their factory, perhaps one of the reasons why prices are a little bit higher.

http://www.tnt-audio.com/intervis/suprae.html

T

[jneutron]

JNeutron,

I have corresponded previously with Supra Cables before regarding their measurements as depicted at:

As shown, their measurements of a cable with its conductors wide-spaced, they find a loss of around 4 dB at 20 kHz, while standard "zip" is below 1 dB. In my specific question, I asked for the lenght of the cables and the answer was 10 meters ended with a 8 ohm resistor (but he was not sure, since it was such a long time since the measurements were made). It seems however, that the test was performed on longer cables, perhaps 20-30 meter.

Although some of their claims are not scientific (i.e. bs), I regard Supra as being less bs among AudioCable Makers. Also, they are one of the few that actually braid their own cables at their factory, perhaps one of the reasons why prices are a little bit higher.

T

Thanks for the link..interesting read. The format was a PITA, because the three long columns fold over to page two when printed..rather discontinuous...

I'll address the simple errors..

""Conventionally, fat conductors’ high loop inductance (which raises impedance at +6dB/octave) is further raised due to internal eddy currents causing ’Skin effect’. This acts like ’the square root of an inductor’, i.e. progressively adds a +3dB/octave component to the cable’s series inductance. ""

NO...NO...NO...

The skin effect will only remove the internal inductance from the wire as the frequency goes up. The internal inductance of any wire is 15 nanohenries per foot, when skin effect does NOT occur...As skin effect occurs, the inductance will start to go down, and in the limit, the internal, 15 nanohenry inductance (per foot, per wire) is gone.. Skin effect does NOT cause additional inductance, it makes the internal go away.

It will, however, start to increase the cable resistance by cross section reduction and current re-distribution.

Geeze...this is not rocket science...it's very easy stuff....how come these guys can't get the easy stuff right!!! :-)

""Supra Ply is able to be a large-section, low resistance cable, while also overcoming skin effect and transversal distortion, by using a proprietary, pure tin plating. This has the double benefit that tin and copper meld without forming a diodic barrier (as with many silver-plated copper ’audiograde’ conductors) and that tin strongly resists most common causes of metal corrosion, and hermetically protects the copper""

NO...NO...NO..First, tin plating is never pure..And, the plating process does NOT make the copper and tin "meld". Tin plating is porous..to make it hermetic requires fusing the tin, bringing it over 231 C to reflow it. At that point, it will form two intermetallic compounds, a non solderable one against the copper (using R type flux), and a second one over that, with the pure tin over that (assuming there is any free tin left over after the heating).

The tin overcoat will have a higher resistivity than copper, and will contribute very little to the reduction or increase of skin effect. It is entirely used as a barrier metal. Fused, it will indeed provide a hermetic protection layer for the copper..

The diode explanation does not even warrant discussion..(beyond the scope of this text)

The scope photo's...

Why is it the flat DC portion of the signals is inching up? They have done something very wrong in the measurement technique. Without more details, I suspect that the IA circuitry they use to get the difference signal may be saturating during the transient portion of the waveform, and that upward slope is the recovery of the IA (many high speed circuits will take a very long time to recover from a transient overload)..not some signal abberation from the cable..If it is truly a circuitry problem, I would question all the waveforms..

Overall, a rather professional looking presentation..I liked it..

Given the errors found in Hawksford's essex echo skin effect analysis paper....I would be concerned about citing any of his HI-FI based papers, as his skin theory, test setup, and test results are not consistent with what has been known about wire inductance since the mid 40's.

Cheers, John