Dick Olsher returned to the Lindsay-Geyer interconnects in August 1991 (Vol.14 No.8):
The Lindsay-Geyer Highly Magnetic Interconnects (Vol.14 No.2) continue to occupy center stage in my reference system. My opinion of the sound of these cables has not changed. They continue to impress me mightily in the areas of textural purity, treble smoothness, and image definition (footnote 1). The purpose of this short note is to relate some further thoughts concerning David Lindsay's cable hypothesis.
Lindsay correctly describes the skin effect in terms of the propagation of two signal components along and within the wire. The primary signal travels along the periphery of the wire close to the speed of light depending on the particular dielectric used for insulation. The transverse component sinks into the wire at a leisurely speed and is retarded in phase and intensity as it penetrates deeper and deeper into the wire. Lindsay hypothesizes that the transverse signal emerges from the wire, at which time it continues to propagate down the wire. It is this sort of "echo," he argues, that contributes to transient smearing and distortion by nonmagnetic cable. The modus operandi of magnetic cable is based on ensuring that the wire diameter is equivalent to a large number of skin depths so that the emergent signal is greatly reduced in intensity.
This hypothesis predicts a large echo for ordinary wire; an echo, as JA has argued, that should be readily measurable. It is important to note that the fact that the cable sounds the way it does is not at issue here. Rather, it is the reason for its sonic excellence that is thrown into question by measurements. John Atkinson's inability, under carefully controlled conditions, to measure the sort of delayed pulses predicted by Lindsay (Vol.14 No.6, p.215) prompted me to take a closer look at Lindsay's hypothesis. The problem is this: Why should the transverse signal emerge from the wire? Is there any reason here to believe that it actually crosses the cable/dielectric boundary?
The answer that I arrived at was that the transverse signal does not emerge from the wire. Instead it continues to circulate within the conductor until it is dissipated ohmically—that is, by heating of the conductor. Why this happens can be appreciated by considering two different approaches.
First, to solve the problem rigorously one would have to solve Maxwell's equations for the specific geometry of the wire/dielectric interface. This is a difficult calculation, which I, for one, do not have the stomach for. But the clear indication from framing the problem in this way is that because of the considerable impedance mismatch at the interface, essentially all of the transverse signal will be reflected back into the wire.
Another way to look at this is to invoke antenna theory. To ask the transverse signal to leave the wire is equivalent to having it radiate out of the wire. The wire would, in effect, be acting as an antenna. It is well known that the radiation resistance of a conductor at audio frequencies is negligible. It is only at radio frequencies that substantial energy can be radiated by a conductor. Assuming the conductor to be a loop antenna, I calculated that at 1kHz, the radiated signal will be at least 160dB down from the main signal. Such amplitudes are, to my mind, clearly in the "don't matter" category.
Thus, Lindsay's hypothesis for why his cable sounds the way it does would appear not to hold water. If Lindsay were right, ordinary copper cable would not work as well as it does.—Dick Olsher
Footnote 1: Other audiophiles seem to concur that the L-G interconnect is extremely smooth-sounding. See this month's "Letters" on the next page—John Atkinson
Footnote 1: Other audiophiles seem to concur that the L-G interconnect is extremely smooth-sounding. See this month's "Letters" on the next page—John Atkinson
