Try Vallotti by ear like this:
A from the tuning fork.
A down to tenor A, below middle C.
A to F major third in tenor, wide about 3 beats per second. (A tempo you can memorize from a piece of music.)
All pure fifths or fourths: F - Bb - Eb - Ab - Db - Gb - Cb.
To establish F-C-G-D-A as evenly tempered fifths and fourths, use the technique that I mentioned last week:
C fourth under tenor F temporarily pure. D fifth under tenor A temporarily pure.
Use that C and that D to set tenor G evenly balanced by quality. (If you want to check it by beats: the D-G fourth is triplets against the C-G fifth’s duplets.) This step is placing G halfway between F and A. Your C-G and your D-G will both sound rough, 1/3 comma, but don’t worry. The next steps will take care of that.
Use F and G to correct the C to where it really belongs: same quality from both of them, which means slightly lower in pitch than the temporary C built earlier.
Use G and A to correct the C to where it really belongs: same quality from both of them, which means slightly higher than the earlier temporary D.
Check that all of F-C-G-D-A are smoothly the same quality.
Get middle C and middle D as octaves, plus the F and G, and check that everything is still smoothly even with them in the qualities of F-C-G-D-A.
Everything is now done except for E. Balance your E evenly against A and the B (Cb) that are already done. This quality of the fifths and fourths is the same: F-C-G-D-A-E-B.
And all the other fifths and fourths are pure, as done earlier.
This same F-C-G-D-A-E-B can be used to build a complete 1/6 Pythagorean meantone, or whatever.
If you want to make it Bach/Lehman…
Raise the B to be pure from E. Make E-B-F#-C# all pure from there.
Make C#-G# nearly pure, very slightly narrow.
Make G#-D# nearly pure, very slightly narrow.
Make A# slightly lower than the point where it would have been pure from both D# and F. Scarcely enough to notice that D#-A# is narrow, and A#-F is wide.
Play your music.
Bradley Lehman