This document explains the process and benefits of adjusting partial change locations in FAC tunings. By fine-tuning the locations of these partial changes, the accuracy and efficiency of the tuning process are improved. Optimized partial change locations make it easier to compare interval widths, especially when optimizing the piano’s stretch, resulting in a more consistent and musically pleasing 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 and can be changed. 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 partial change. Subsequent sections will evaluate the impact of lowering the B4/C5 partial change, with the tenor partial change 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 offers several important advantages in the tuning process. This modification allows A5 to be tuned using its fundamental rather than relying on its 2nd partial. As a result, the procedure for fine-tuning the treble stretch becomes much more straightforward, making it easier to observe and measure the precise width of the double octave between A3 and A5.
Benefits of Using the Fundamental for A5
Lowering the partial change simplifies the use of the D4/A5 12th interval when assessing or modifying the FAC’s treble stretch. Once D4 is tuned, it serves as a consistent and reliable reference point. This setup makes it possible to check both A5 and A6 against D4, enabling direct comparison of the D4/A5 12th and D4/A6 19th intervals. This method assists significantly in finding the optimal treble stretch for FAC tuning, and a straightforward Double Octave Beat (DOB) adjustment can be used to refine the stretch as needed.
Challenges with the Traditional Partial Change
If the treble partial change remains at B5/C6, tuning A5 requires using its 2nd partial. This approach necessitates a conversion process to adjust the treble accurately, which is more confusing and complex. It is also less precise and more time-consuming than tuning A5 with its fundamental. By adopting the lowered treble partial change, the process becomes faster, easier, and more precise, thereby improving both efficiency and accuracy in treble tuning.
Lowering the Midrange Partial Change: B4/C5 to A4/A#4
Lowering the midrange partial change, specifically moving the transition point from B4/C5 down to A4/A#4, is an important step in achieving consistency within the tuning system. Although this adjustment is considered the least critical among the three FAC partial changes, it complements the process after the treble partial change has been lowered.
Purpose and Implementation
The primary purpose of lowering the midrange partial change from B4/C5 to A4/A#4 is to ensure the partials used remain consistent throughout the instrument’s temperament range. By aligning this midrange partial change adjustment with the previously lowered treble partial change, the FAC tuning maintains a uniform approach. As a result, the 2nd partials are used from A#4 up to G#5, supporting overall consistency.
Significance and Practicality
While this change is less significant compared to the other two partial changes, it still contributes to the overall uniformity of the tuning. Moreover, implementing this adjustment is highly efficient, requiring only a few seconds. This makes it a practical step to include alongside the other partial change location adjustments to enhance the FAC tuning’s consistency.
Lowering the Tenor Partial Change: B2/C3 to G#2/A2
Lowering the tenor partial change on an FAC tuning, specifically shifting the change from the B2/C3 position to G#2/A2, represents a significant adjustment that offers distinct benefits for tuning accuracy. This technique, when applied to grand and vertical pianos, affects both the tuning process and the overall quality of the tuning outcome.
Impact on Grand Pianos
When using an FAC tuning, moving the partial change to G#2/A2 on grand pianos typically repositions it onto the bass bridge. This adjustment helps avoid problematic zones near the low end of the long bridge, which are often associated with scaling issues. In instruments with longer scales, the newly positioned partial change usually remains on the long bridge. The significance of this repositioning then lies mostly in its removal of a partial change from the critical A2-A4 temperament range. By relocating the tenor partial change, the possibility of major tuning errors and the necessity for subsequent corrections are greatly diminished.
Effect on Vertical Pianos and Smaller Grands
For most vertical pianos and almost all grands under six feet in length, the FAC’s default B2/C3 partial change is situated at the low end of the long bridge. This low end of the long bridge is susceptible to scaling challenges and transitions, such as the switch between plain wire and wound bichords, as well as the transition from the long bridge to the bass bridge. Introducing a partial change in this sensitive area can exacerbate these pre-existing problems. By lowering the partial change and moving it away from this zone, tuning results are generally improved and greater stability is achieved.
Advantages for Aural Checks and Temperament Setting
Lowering the tenor partial change also delivers considerable benefits during aural checks within the temperament region. With this adjustment, all notes within the temperament octaves (A2 to A4) utilize their 4th partials, which creates consistency throughout the range. This uniformity enhances the reliability of aural evaluations during the temperament setting process, making assessments more straightforward and dependable.
Facilitating Double Octave Measurements
Another important advantage of lowering the tenor partial change is the increased ease of evaluating the width of the A2/A4 double octave. Precision in assessing this interval is improved when A2 is tuned using its 4th partial. As noted by Al Sanderson, the A2/A4 double octave width greater than approximately 4 cents is generally considered excessive. Nevertheless, it is essential to acknowledge that certain pianos may require the A2/A4 double octave to be wider than 4.0 cents, based on the instrument’s individual scaling and tonal characteristics.
On all pianos however, using the 4th partial of A2 for tuning allows for direct measurement and adjustment of the A2/A4 double octave interval. This approach simplifies the application of DOB (Double Octave Beat) contraction or expansion when necessary, ensuring that the double octave width can be tailored to meet the specific requirements of each piano. The capacity to measure and adjust the A2/A4 double octave with accuracy contributes to a more refined and stable tuning result.
Applying and Correcting Partial Changes in Piano Tuning
The process of lowering all partial changes and/or correcting any errors that arise at those partial changes, is an essential practice for piano tuning. By consistently implementing this method, tuners can achieve noticeable improvements in both the quality and reliability of their tunings. Careful attention to partial changes ensures that the tuning remains stable and accurate throughout the instrument.
Partial Change Correction (PCC) Feature
The AccuTuner IV is equipped with a Partial Change Correction (PCC) feature, which simplifies the correction process for tuners. With PCC, only two button presses are needed to perform quick and accurate corrections. This streamlined approach greatly reduces the possibility of human error during tuning. Additionally, the PCC feature is versatile and can be utilized to address default FAC partial changes, offering tuners the flexibility to customize their corrections according to their preferences.
Benefits of Lowering and Correcting Partial Changes
Lowering and correcting partial changes significantly enhances the overall tuning by eliminating potential errors at the points where partial changes occur. This leads to a more uniform tuning and a consistent sound across the entire piano. The ability to adjust treble stretch with precision further refines the tonal qualities of the instrument.
Achieving Superior Tunings
By routinely applying and correcting partial changes, and by making careful adjustments to treble stretch and temperament octave widths as needed, tuners can produce results that are distinctly superior to those achieved without these techniques. This method ensures that each tuning benefits from the highest possible level of refinement, resulting in a piano that sounds its best.