<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> <title></title> </head> <body bgcolor="#ffffff" text="#000000"> Hi Jason.  To take your thought a step further, The guy who first put me on the trail of the P-12ths idea showed me a series of test intervals. A major third, major sixth, octave 10th and double octave 10th. For tuning C6 for example,  the relevant notes would be Ab3, C4, F4, C5, and C6, with the Ab3 being the control note the whole way.  The Third should be slowest, but just slightly slower then the 10th. The 6th should be fastest, again by a very slight amount, and the note you are tuning... the double 10th should be just inbetween the 6th and the other two. This makes the 12th below C6 just very slightly off pure. Just got me thinking back then that it would be easy to use Tunelab to do this directly David Anderson using the clean fourths this way moves in a very similar direction. Cheers RicB <blockquote> </blockquote> <blockquote>Yes. As I think about it, I recall that David Andersen puts great emphasis on the fourths, especially on the way down through the tenor. Now fourths do happen to have the coincident partial that is a P12 from the upper note. So in a manner of hearing, David is emphasizing P12 in his own way. Hmm. Jason</blockquote> </body> </html>