REVIEWING THE FAC NUMBERS
To review your FAC numbers, hold down the STRETCH button. While the STRETCH button is held, the left window will
show the note F3 and the right window will show the F3 stretch number. Release the STRETCH button and hold it again
to view the A4 stretch number. Release and hold the STRETCH button again for the C6 stretch number. After reviewing
the stretch numbers you will have to press the MEM button to get back to the FAC tuning and out of the old stretch tuing
range of C3 to F6.
It is be a good idea to write down these FAC numbers if you want to refer to them at a later date. Once the SAT is turned
off the FAC numbers can no longer be recalled using the STRETCH button.
NOTE: Some tuners have reported that the stretch numbers tend to drift lower as a piano is tuned repeatedly to the same
tuning.
Some customers have expressed a preference for starting with the A-4 measurement vs. the sequence described above.
As long as you have the correct partials set up on the SAT, you can start with any of the three F-A-C notes.
The FAC numbers are automatically inserted into the header that is part of the tuning record of each piano. If you have
an SAT II and the Piano Librarian program, you can view the FAC numbers. The format of the header is as follows:
001_________________________________10.2 8.8 7.9 FAC 000000
IF NOTHING HAPPENS
Suppose you try to store a stretch number and nothing happens? This can be disconcerting, but the problem is usually
very simple to solve. The SAT is very fussy about being on the correct note when it stores a stretch number. You must
have the SAT on F6 in the TUNE mode (by pressing the TUNE button) to store an F3 stretch number, and if you are not,
nothing at all will happen. To store an A4 stretch number you must be on A6, and to store a C6 stretch number you must
be on C7. In other words you must be on the correct note in order to store a stretch number. This requirement reduces
the possibilities for errors.
The other situation when nothing happens is if you try to transfer an FAC tuning to page zero in memory. Simply select a
valid page in memory (SHIFT and PAGE up) and repeat the STRETCH rollover to MEM procedure.
OFFSETTING AN FAC TUNING TO NON-STANDARD PITCH
Tuning and pitch-raising a piano to non-standard pitch is very easy with the FAC program. Prepare the SAT with the
RESET feature to get the SAT offset to the required pitch. For instance, to tune at 442 put 8.0 cents into the CENTS
window and then hold down SHIFT and press RST. The CENTS window is reset to zero cents, and the 8.0 cents is
stored as a pitch offset. The plus sign in the left window indicates this offset on the sharp side. Any pitch up to a
semitone sharp or flat can be used as a pitch offset this way.
Now that the pitch offset is stored, take your FAC measurements as usual. When the tuning is created, the offset will be
included in the stored number for each note, and the plus or minus sign will no longer be in the display.
AVERAGING STRETCH NUMBERS FOR HIGHER ACCURACY
The above procedure applies to one open string on each note. For greater accuracy, you may take the measurement on
each string of a note individually and average the results. If one of the strings disagrees badly (more than two or three
cents) with the others, throw out this reading before averaging.
"GOOD" FAC NUMBERS
You can tell a lot about a piano and its scale design from the FAC stretch numbers. The three numbers should be
reasonably close to each other and lie in a reasonably straight line for the best results. For example, FAC numbers such
as 10, 9, 8 or 5, 6, 7, or 8, 8, 8 represent well-scaled pianos. The lower the numbers, the lower the inharmonicity, so
spinets tend to have higher stretch numbers than grand pianos.
