If anybody is interested in some modern evidence about J.S. Bach's intentions regarding a temperament for the WTC, I recommend : Bach's Keyboard Temperament Internal evidence from the WELL-TEMPERED CLAVIER by John Barnes (pub. in EARLY MUSIC, 1980) Very briefly, this is a statistical analysis of the major thirds in the preludes of the WTC, with a temperament made to order by giving the least tempering to the third that is heard most frequently,and progressively more tempering to the thirds that are heard less frequently, ie; if it sounds better, let's hear it more! One paragraph: "This article has tried to reveal the internal evidence which suggests that the WELL-TEMPERED CLAVIER was written for a temperament similar to Werckmeister III. It has also tried to show that a small modification to Werckmeister III improves the agreement between temperament and score. While this, of course, falls very far short of a proof that the WELL-TEMPERED CLAVIER was written for the temperament given in Table 6, it consideably narrows the practical search for temperaments suitable for performances of the WTC.Futher progress will probably come from playing and listening to the music on authentic instruments suitably tuned. The first matter to debate is whether the worst major thirds should be Pythagorean, with errors of 22 cents. They probably should, since this value arises naturally in a tuning using perfect fifths, and does not sound impossibly astringent in Bach's contexts. The secnod uncertainty concens a suitable value for the best major third or thirds. If the temperament makes this too pure, more error will be left for distribution among Major thirds such as E and G# which seem to need a tuning whisc is a little better than Pythagorean. Theoretically there are an infinite number of distinct temperaments to choose from. In practice, however, it will be found that the values for the best and worst major thirds and the notes on which they occur do not admit of much variation from those suggested here." This article is rich with statistics, theory, historical references, and practical tuning information. I highly recommend it. Paul Bailey
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