davec wrote:Rickenbacker supply a twelve-string set (Compressed Round Wound, Part No. 95404):
10/10
13/13
20/10
26/13
34/20
42/26
That's clearly not of the same gauges as the "standard" Pyramid set (lighter at the bass end), and the 20/10 pairing on the third course suggests that the 0.010" string is meant for tuning to the G (1st string, 3rd fret on an "ordinary" guitar). The other string in that course is a wound 0.020" (source:
http://www.the-music-connection.com/ricpart.htm#strings) and the gauge pairing obviously precludes unison tuning.
A "10" can theoretically be tuned to the G. In fact, if viewed as the logical extension to a 56-13 set, it should even stretch - at medium gauge tension - to the A (1st string, 5th fret).
Unison tuning was often used on the third course of 12-strings in the dark days of the 1960s, when sufficiently light strings for tuning to the high G were difficult or impossible to get in the UK. But it's an unnecessary compromise...
JN