Chess, the Allen article was interesting and for the most part very well written, but I suspect that John may have drawn the wrong conclusion on p.6 from the favorable result he measured. Although it was a bit difficult to follow exactly what was being compared, I gathered that two 6ga THHN single conductor wires somewhat loosely twisted together were compared with a 10ga 4 conductor solid wire cable with each pair joined to form the equivalent of two 7ga conductors. He comments that one effect of joining the pairs would be to "cancel inductance", and of course this isn't the case, but rather that closely spaced conductors minimize inductance. Note for example Gene DellaSalla's
article on measuring speaker wire inductance which points out that it's directly proportional to the distance between the centers of the two conductors and for that reason the spacing should be minimized. Allen had the closely spaced conductors in the 4 conductor cable compared with the wider and variable spacing of the two THHNs. Presumably the wider spacing significantly increased the inductance, which would have resulted in a greater high-frequency rolloff. He comments that "In addition to flat frequency response, the inductance was also minimized", but it would appear that the latter caused the former and that the solid/stranded factor may have been irrelevant.
