FAC Tuning Procedure for A4

Overview

When using FAC tuning to adjust A4, the process does not rely on the fundamental (1st Partial) of the A4 note. Instead, the tuning references the 4th Partial of A4, which is inherently sharp due to inharmonicity. As a result, the FAC tuning setting for A4 will never be exactly 0.0.

Locating the 4th Partial of A4

To verify that FAC tuning sets A4 to precisely A440, follow these steps:

  1. Turn on the SAT (Strobe Audio Tuner); it will first enter Calibration Mode.
  2. Press the TUNE button to exit Calibration Mode.
  3. The SAT will display: (A4 @ 0.0).
  4. Play and tune A4 until the display reads (A4 @ 0.0) and the lights stop moving. At this point, A4 is tuned to A-440.
  5. Change the SAT setting to A6 and play A4 again.
  6. Use the cents adjustment buttons to stop the lights. The resulting setting should correspond to the FAC tuning value for A4.

Correcting Discrepancies

If there is a discrepancy in the placement of A4 between the two measurement methods, it can be corrected using the Partial Change Correction (PCC) C8 tweak.