Introduction
This section provides a detailed overview of the process and benefits associated with adjusting the locations of partial changes in an FAC tuning.
Process of Adjusting Partial Change Locations
In FAC tunings, the positions of partial changes can be modified for improved results. Lowering these positions is an important step in achieving more accurate and efficient tuning outcomes. By carefully adjusting where these partial changes occur, the overall tuning process becomes more precise.
Advantages of Improved Partial Change Locations
When the partial change locations are optimized, it facilitates easier comparison of octave and other interval widths during the tuning process. This improvement is particularly valuable when working to optimize the piano’s stretch, as it allows for more straightforward evaluation of interval relationships and results in a more consistent and pleasing musical outcome.
Default Partial Changes in an FAC Tuning
An FAC tuning incorporates three primary partial changes, positioned from the highest to the lowest as follows:
- B5/C6 – The Treble Partial Change
- B4/C5 – The Midrange Partial Change
- B2/C3 – The Tenor Partial Change
Exploring the Impact of Adjusting Default Locations
While these are the default locations, they can be shifted to slightly different positions that can provide significant benefits. The following sections discuss the advantages of lowering each partial change, beginning with the treble and concluding with the tenor.
Benefits of Shifting Default Positions
The standard, or default, positions serve as a useful starting point, but they are not fixed. Making slight adjustments to these positions can result in considerable improvements. By carefully lowering each partial change, it is possible to enhance the overall outcome in meaningful ways.
The discussion of benefits will proceed in a specific order. It will start with an examination of the effects of lowering the treble. Subsequent sections will evaluate the impact of lowering each additional partial, with the tenor being considered last. This structured approach allows for a clear understanding of how each change contributes to the overall advantages.
Lowering the Treble Partial Change: B5/C6 to G#5/A5
Adjusting the treble partial change from B5/C6 to G#5/A5 introduces significant benefits. With this modification, A5 is tuned using its fundamental rather than the 2nd partial. This change greatly simplifies the process of tweaking the treble stretch, making it much easier to observe and measure the width of the double octave between A3 and A5 with precision.
Lowering the partial change also streamlines the use of the D4/A5 12th interval for assessing or modifying the FAC’s treble stretch. Since D4 is already tuned, it serves as a reliable reference point. Both A5 and A6 can be checked using D4 as a reference note for stretch adjustments, allowing for straightforward comparison of the D4/A5 12th and D4/A6 19th intervals. This approach significantly aids in determining the ideal treble stretch for an FAC tuning. A simple Double Octave Beat (DOB) adjustment can be employed to modify the stretch to facilitate these adjustments.
If the treble partial change remains at B5/C6, A5 must be tuned using its 2nd partial. This method requires a conversion process to accurately tweak the treble, which is more confusing, complicated, and less precise. It also consumes more time compared to lowering the treble partial change. By tuning A5 with its fundamental, the process becomes faster, easier, and more accurate, enhancing both efficiency and precision in treble tuning.
Lowering the Midrange Partial Change: B4/C5 to A4/A#4
The adjustment of the midrange partial change, specifically moving the transition point from B4/C5 to A4/A#4, plays a role in maintaining consistency within the tuning system. While this particular change is considered the least critical among the three main partial changes, its implementation is complimentary after the treble partial change has been lowered.
By shifting the midrange partial change from B4/C5 to A4/A#4, the process ensures the partials used remains consistent throughout the instrument’s range. This consistency is achieved by aligning the midrange adjustment with the previously lowered treble partial change. As a result, from A#4 up to G#5, the 2nd partials are employed.
Although this change is less significant compared to the others, it contributes to overall uniformity in the tuning process. Additionally, implementing this adjustment is efficient and requires only a few seconds, making it a practical step to include alongside other changes.
Lowering the Tenor Partial Change: B2/C3 to G#2/A2
Lowering the tenor partial change on a piano, specifically from B2/C3 to G#2/A2, represents a significant adjustment with notable benefits for tuning stability and accuracy.
This adjustment is especially impactful on many grand pianos, as moving the partial change to G#2/A2 typically places it onto the bass bridge. This relocation helps avoid problematic areas near the low end of the long bridge, where scaling concerns are common. On longer scales, the new partial change location generally remains on the long bridge, but crucially, it removes a partial change from the A2-A4 temperament range. This change minimizes the risk of significant tuning errors and the need for subsequent corrections.
On most vertical pianos and nearly all grands under six feet, the default B2/C3 partial change is found at the low end of the long bridge. This area is often subject to scaling challenges and transitions, such as between plain wire and wound bichords, and from the long bridge to the bass bridge. Placing a partial change in this sensitive region can intensify these existing problems. By lowering the partial change and moving it away from this zone, tuning results are generally improved.
Another advantage of lowering the tenor partial change is observed during aural checks within the temperament region. With this adjustment, all notes in the temperament octaves (A2 to A4) utilize their 4th partials. This consistency enhances the reliability of aural evaluations throughout the temperament setting process.
Additionally, lowering the partial change facilitates easier assessment of the width of the A2/A4 double octave. As noted by Al Sanderson, a double octave width exceeding approximately 4 cents is likely too wide. When A2 is tuned using its 4th partial, the width of this double octave can be readily measured and adjusted as needed, employing DOB contraction when necessary.
Applying and Correcting Partial Changes
Adopting the habit of lowering all partial changes—and correcting any resulting errors—yields significant benefits. The AccuTuner IV includes a Partial Change Correction (PCC) feature, which simplifies the correction process to just two button presses, ensuring quick and accurate results. PCC can also be used to correct the default FAC partial changes if desired.
Benefits of Lowered and Corrected Partial Changes
Once partial changes are lowered and corrected, the overall tuning quality improves due to the elimination of potential errors at the partial change points. The ability to easily and accurately adjust treble stretch further enhances the piano’s sound. This flexibility is unique to the Sanderson AccuTuner; other tuning software typically employs five partial changes and lacks an equivalent correction feature.
By consistently lowering and correcting partial changes and fine-tuning treble stretch and temperament octave widths as needed, tunings can be noticeably superior compared to those that do not employ these refinements.