P12 in Tunelab Pro

[jason kanter]

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I've worked out the method of tuning the Brekne Perfect 12th tuning =
using Tunelab Pro. (As we know, Ric uses Tunelab 97 for this, and his =
method does not work in TuneLab Pro. Tunelab 97 crashes on my XP =
machine, and TL Pro has additional features that I like very much, so =
I've worked out this method.) Haven't tuned it yet.

I would very much appreciate, Ric, if you can verify that this =
duplicates the lovely tuning that you achieve. It should be precisely =
accurate from D3 through C8. The method for the bass is uncertain at the =
moment.

1. Take inharmonicity measurements as normal.
2. Go to the Partials window (press P) and set all partials to 1. Then =
set the following partials to 3: D3, B4, F6.
3. Click OK and now press T for the tuning curve screen. Click the =
button to allow manual adjustment of all 4 aspects of the tuning curve. =
Set both bass and treble octave types to 4:1. Now press Z to zoom out to =
be able to see the entire curve.
4. You now need to make four precise adjustments as follows (it takes =
several passes to get these exact):
     a. Toggle the H and Y keys to set the deviation for A0 to exactly =
zero (lower pane).
     b. Toggle the J and U keys to set the D3 exactly at 0.0. (This =
makes the perfect twelfth with A4).
     c. Read the offsets of B4 and F#6 (somewhere between 5 and 10 =
cents). Toggle the K and I keys to make these two offsets match exactly.
     d. Read the offsets of F6 and C8 (generally 30-35 cents). Toggle =
the O and L keys to make these two offsets match exactly.
The deviation lines (which are displaying deviations in the 4:1 octaves) =
will not be straight, because we are favoring twelfths over double =
octaves. But the deviation line does stay within +1 to -1.

5.  When done, return to the Partials screen to change them to your =
preferred partials for executing the tuning (e.g. use 6 from A0 to E1, =
etc.)

As Ric has pointed out, the bass may feel a bit shallow. It is possible =
to do the exact same procedure using 6:3 in the bass, except that D3 =
winds up a few cents south of zero to accommodate that greater stretch =
in the bass. (Also the bass deviation curve is more distorted). As I =
have not yet tuned this, I anticipate a strong need to verify the bass =
aurally and determine what works best. It will be nice when Bob Scott =
adds 3:1, 6:2 and 9:3 to the tuning curve menus.

Feedback most welcome.

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jason kanter . piano tuning/regulation/repair
bellevue, wa . 425 562 4127 . cell 425 831 1561
orcas island . 360 376 2799
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