The A Targets:
Every A on the piano – including A0 and A7 – is mapped and used in the LC spreadsheet for creating the tuning. The Secondary or ‘mini’ targets are the D’s and E’s in the 3rd and 4th octaves.
Creating a tuning using the LC Spreadsheet requires entering the ‘main’ targets into the spreadsheet. The secondary targets are not entered into LC but are used later. These secondary targets are used for balancing of the prime 5ths. The goal is to have the prime 5ths exactly the same width for every tuning. Balancing the prime 5ths is accomplished in LC by moving the midpoint of the octave (D#) either up or down by the amount needed to balance the 5ths.
If the widths of the pair of prime 5ths are different, they will beat unevenly. But when they’re balanced, the slight difference in their beating will be due to inharmonicity – the upper prime 5th ever so slightly faster than the lower one. Exactly the same are the M3rds in this area: if each M3rd is exactly the same width, their beating will progress evenly and correctly as they move higher up in the temperament. That’s as it should be.
Since the prime 4ths beat a little faster than the prime 5ths, if there is an unbalance in the prime 5ths, the ‘unbalance’ is easier to hear in the resultant prime 4ths (A3/D4 & E4/A4). As with the prime 5ths, even when balanced, the resultant upper prime 4th will beat ever so slightly faster than the lower prime 4th. That too is as it should be, due to inharmonicity.
It’s here, in all this balancing, where the secondary targets are used. Establishing the secondary target locations is done during mapping of the prime octave. Templates are used for this. But an FAC tuning will work just as well. As long as both A4 and A3 locations are exactly correct for the piano, an FAC tuning can be used as a template for balancing the prime 5ths.
Being able to tailor the shape of the curve within the prime octave allows us to more accurately fit the curve of the tuning to the scaling of the piano. Tunings sound so much better.
Secondary Targets within the Sub-prime Octave:
In the Sub-Prime octave the secondary targets of D3 and E3 are not necessarily used for ‘balancing’ the sub-prime 5ths. Due to all the scaling issues that occur within that A2-A3 range, instead of ‘balancing’ the secondary targets of D3 and E3 are used for accurately determining the location of A2 as well as adjusting the shape of the curve to accurately fit the scaling in that sub-prime octave.
In this are of the piano the pair of sub prime 5ths (A2/E3 and D3/A3) are rarely the same width. Of course this depends on the piano, and on the larger scales, the sub prime 5th widths may be more equal. But on the shorter scales with all the scaling issues in this area and stretching lower that starts in this A3/A2 range, the lower sub prime 5th will often be less narrow than the upper sub prime 5th. But this too is all piano dependent. All of this is discovered and determined during mapping.
Using the secondary targets in the sub prime will again allow for more accurate ‘shaping’ of the tuning curve in this area. And as in the prime octave, once the settings for D3 and E3 are known, they are then incorporated into the tuning that will be created by the LC Spreadsheet.
As an example, sometimes a piano’s D3 is a wound bichord and E3 is a plain wire trichord. Using these sub-prime as well as the prime octave mini targets really allow for a much better fitting tuning that will be created by the LC spreadsheet.
Being able to map both main and mini targets in both the prime and sub-prime octaves, gives us the capability to create a super custom midrange tuning for any piano.
Of course there are exceptions, but they are rare. But I must mention one here as an aside. A few years ago I was visiting another tuner/technician in England who owned a 3 Bridge Steinway Model A. I believe the break going from plain wire trichords to the top note on that little tenor bridge with it’s wound trichords was between C#3 and D3? Is that right? I think it is. I think C#3 was the top note on that little tenor bridge and it was a wound trichord. Terrible terrible terrible scale as anyone knows who’s tuned one knows.
But since our mini targets are D3 and E3, the issue with the transition going from D3 to C#3 didn’t get picked up in the mapping. And of course A2 was on the bass bridge on that piano.
But as soon as he started tuning and got to that C#3, that C#3 didn’t wok with anything above it! It was really awful. The C#3/C#4 octave was bad, the C#3/G#3 5th was terrible, the C#3/E#3 3rd was terrible too! Nothing worked.
We eventually used our ears as well as some technical information to get a bearable compromise in there, but it took some fairly thoughtful compromising. What made me happy was that we were able to make it work OK and only changed 4 notes or so: A#2, B2, C3 and C#3 I think they were. We didn’t want to change any more than we absolutely had to. The rest of the tuning above that break sounded great and we didn’t want to change any of that part.
So make sure to check things in this area – especially on pianos with that little tenor bridge! There is not a tuning system alive that could have covered that break ‘out of the can’ – aural-only tuning included. I doubt there’s another tuning system that could have found a more agreeable compromise by only moving 4 notes either.
Another example is much more common for most of us. Tuning shorter scales with really poor scaling. Getting everything as balanced as possible makes a huge difference in how these super challenging pianos sound. But as will all pianos, it’s just a matter of finding the best sounding compromise. The balancing act on these must be widened and include a wider area of the keyboard, mostly in the midrange of course. It involves a balanced compromise between the A3/A4 4:2 and 2:1, and the widths of the prime 5ths that best fits that A3/A4 octave compromise. And then in the subprime area, finding the best balanced compromise between the prime octave’s settings and widths and the sub prime octave’s settings and widths. But this system is up for it. It’s that combination of super technical and aural skills that make it work. It’s just not enough to rely on only one. The compromises here require some major technical skills and experience.
But it’s worth it. Not only are these situations a fulfilling learning experience, the pianos do sound much better, Surprisingly so, actually.