Robert Conrad, Registered Piano Tuner/Technician, Tucson, AZ

FAC Tuning Routine Using the SAT IV’s Partial Change Correction Feature

All computerized tunings have partial changes.     Every partial change in a ‘computer generated tuning is a potential error in waiting.      Correcting errors at partial changes improves the sound of the tuning.   This procedure will show how to correct all three FAC partial changes when using an AccuTuner SAT IV.

A complete 2 octave temperament range (A2-A4) with no partial changes, and all notes within that range, using the same (4th) partials, is important for making accurate aural checks in the temperament.   Lowering the partial change to this location results in an A2 – A4 temperament range with all notes using their 4th Partials.    This procedure is how to lower the FAC tuning’s tenor partial change from B2/C3 to G#2/A2.

Accurate aural checks are important for making sure the stretch in the midrange is a good fit for the piano.    This procedure will give some guidelines for the width of the  A2/A4 4:1 (double) octave and  how to use DOB to either expand or contract the A2/A4 4:1 width.

Using a 7-note ‘sequence’ speeds up the tuning of the 7 reference notes used for aurally checking and trying a few different widths for the midrange.    Using a sequence eliminates the need to scroll up and down thru the chromatic half steps in order to get to the next reference note.   This makes trying a few different widths faster and easier.  This procedure will describe how to use a ‘sequence’.

The treble stretch is addressed as well and will give a guideline for the amount of DOB to use in the treble.

1. Measure and Store FAC as usual using .8 A Multiplier Default.
       !!Make note of the A4 setting!!   It will be needed later.

2. Lower the tenor partial change to G#2/A2.
Once the tenor partial change has been lowered, it is easy to see the width of the A2/A4 double octave.

3. Using the Partial Change Corrector (PCC), correct the two treble partial changes.

Start with B5/C6 and then do B4/C5.

4.  After the partial change corrections have been made, look at the new setting for A4.

Using PCC on the partial changes above A4 effects the locations of all the notes below the partial changes – including A4.

5. Correcting A4

Go to C8 and add or subtract that difference to the setting of C8 and press STR + MSR.

For instance:   If the original setting for A4 is 9.0, but after the partial change corrections have been made, A4 is 11.0, the difference between the two A settings is 2.0 c.
Subtract the 2.0 c. difference from C8 and press STR + MSR.   (If C8 is 36 c., lower it by 2.0 c. so that C8 is now 34 c.)   This will lower the whole tuning by 2.0 c. and put A4 back to 9.0 c.

All these PCC changes are stored onto the page in the SAT. If you turn the SAT off and then on again, and then go back to that page, the tuning will be exactly as you left it, will all the partial changes corrected.

At this point, if you want to save this tuning onto a different page in your SAT, use the Copy and Paste buttons to copy it to a different page. (The Copy and Paste feature only works in the lower memory of the SAT IV’s pages 1 – 122.)

6. If you want to add a name to this tuning, here are the instruction from the SAT IV Instruction Manual:

EDITING HEADERS FROM THE KEYBOARD OF THE ACCU-TUNER IV
With a page of memory selected, hold down the DISPLAY key until the cursor starts to blink under the
first character. The NOTE up button will move the cursor to the right, NOTE down will move the cursor to
the left. The CENTS up button will move up the character sets, CENTS down button moves down the
character set. The PAGE button will move in jumps from lower case alphabet to upper case alphabet, to
the special characters. Once the desired character is displayed use the NOTE button to move to the
next location to select a character. Once the desired information is in the header, the SHIFT button will
store the new header information.

*********************************************

The rest of these tweaks will NOT be stored with the tuning and must be done ‘on the fly’.

Working with the A2-A4 midrange to find a good fit for the piano.

Since the FAC’s default partial change location has been moved from B2/C3 to G#2/A2, there is now a complete Two-Octave temperament range with all notes using the same partials – i.e. NO partial changes within that range that can cloud or confuse the aural checks.

{In this tenor area, even if the partial change has been corrected, it is best to use the same partials for the entire range.   This has to do with the ‘reliability’ or the consistency of the partials being used.   When trying to find a smooth sounding tuning in this area, the parallel is finding a smooth ‘set of numbers’ for this area.
Whatever partial is used, a smooth set of numbers is the goal.
On well scaled pianos, pianos with a well designed and well made set of wound strings, the 3rd, 4th, or 6th partials can probably be used without any problem.
But on the shorter scales, with poorer scaling, poorly designed and/or poorly made wound strings, it can make a big difference which partials are used for tuning the wound strings in the bass and tenor.
On those poorly scaled pianos, the partials on each string or each unison can be quite different from the adjacent notes.   And the higher the partial the more ‘different’ they can be, one from the other.   This is the reason why using a ‘lower’ partial is more ‘reliable’ or consistent than using one of the higher partials for tuning.  
When a tuning uses a smooth set of numbers and a lower partial, even though the upper higher partials may jump around a lot, they will not cause anywhere near the problems created when trying to use a smooth set of numbers and one of the higher partials.   
Sometimes the higher partials are so inconsistent that standard the lower partials end up being all over the place as well.   Sometimes the scaling or the wound strings are so bad that after using the 6th partials and a smooth set of numbers around A2, the 3rds, 6th, 10ths, 5ths, octaves, everything sounded awful.   But when the 4th partials were used to tune this same area on this same piano during the same tuning session, the 3rds, 6ths, 10ths, 5ths and octaves all sounded OK.   
Granted, this piano was an exception, but pianos like this are out there, and you will run into them and if your system uses partials higher than the 4th, and contains an uncorrected partial change or two down there, and you hear things not working out for you, this is a probable cause.
On these pianos, the best solution for using an FAC tuning, is to lower the tenor partial change even lower into the bass.   Try taking it down to E2/F2, and if that’s not low enough, go down to B1/C2.   You’ll have to create your own little tuning curve and store it into the SAT with all those notes using the 4th partials.   It’s not as difficult as it sounds.   The other alternative of course, is tuning the bass by ear.}

7. A2:

Look at the setting for A2.

This is taken from Al Sanderson’s ‘Instructions for Direct Interval Tuning of the Two-Octave Temperament’:

“Step 2. Tune A2 from A3 as a 3-6 octave 1 cent wide. Check the A2-A4 double octave, and if it is more
than 4 cents wide, divide the excess by three and narrow both octaves by this amount. (E.g., if double
octave is 5.5 cents wide, 5.5-4 is 1.5, divide by 3, and narrow both octaves .5 cent.)”

So if A2 it is lower than -4.0, A2 may need to be raised.   DOB can be used for this.
At A2, .1 DOB will move A2 by .4 c.

8. Before going any further, tune A2 and A4 and see how the double octave sounds.

You might like it where it is.  Use the midrange sequence and tune the rest of the reference notes: A4, A3, D4, E4, D3, E3, and A2.
Listen to see if the tuning  sounds like a good fit for the piano.

Here are as few guidelines to try: 
My average A2 setting is around -2.5 c.  But that’s not an absolute by any means.   That’s just my average.

I have had to place A2 much lower @ -5.8 c.   But that was a real exception.   I’ve also placed A2 @ -1.9 c. as well.   A2’s location just depends on the piano.

But I’d suggest trying a width of between -2.5 and -3.0 c. and working from there.

You will be able to tell by listening the the lowest 5th (A2/E3) and the highest 4th (E4/A4). Try to find a good combination for those intervals, and then check the rest of the intervals created by the reference notes.

With a little experimenting, experience and listening, a good width for the midrange section (A2-A4) can be found.   Some pianos make it easier than others, but you should soon be able to find a nice compromise fit for the piano.

9.  Make a note of the DOB setting – and the setting for A2 – you think fits this midrange area the best.
10. Check the tenor partial change again.

Now that the midrange has been more finely adjusted, check the tenor partial change again.
If a PCC correction is needed at this point, it should be minimal.   After pressing STO + MSR, the DOB will still be in the SAT, and the settings for both A2 and G#2 will be right where you want them.    The PCC works even with a DOB setting being used!

The tweaks for the lower half of the piano are now all done.

At this point, use a single DOB for the lower half – the same DOB used for the midrange will probably work just fine in the A0 – A2 range.
Tune 50 pianos using this procedure before venturing off on your own.
Only after using it on a number of different pianos, will you have a good idea as to how this sounds compared to your previous methods.   Once you have done tis a few times, it will go really quickly, and I think you’ll hear it as worth doing.

I’ve given you some guidelines here that will get you started, but I’m sure you will want to try different things and do your own listening.   Bu that’s the fun part anyway.
I like making all the decisions, what I think sounds good, and how to get there.    The actual SAT button pushing is pretty quick.  It’s the listening that takes time.

11. Write down midrange DOB setting!

I make all the measurements, and do all the aural checks, make all the decisions as to what I’m going to do, before doing the tuning.

Now that all the partial change corrections and the resetting of A4 is done and stored with the tuning onto a page of memory, the only other written notes that need to be taken are the DOB settings for both the Bass (A0-A4) and the Treble (A#4-C8).    Those DOB settings will more than likely be different.

 

Finding a good DOB setting for the Treble:

A good starting point for A6 is about 1.6 c. higher than the setting for A4.  This creates an A4/A6  4:1 (double octave),  1.6 c. wide.

Sometimes A6 may need to be a little higher or lower, but this is a good starting width for that double octave on many pianos.

For example:   If A4 on the tuning is 9.0 c., and A6 is is 9.8,  some DOB is needed to move A6 from 9.8 up to around 10.6.

Each .1 DOB will raise A6 by .4 c..      10.6 – 9.8 =  .8 c.   A DOB amount of .2 is needed to raise A6 up to 10.6 c.

After setting the DOB for the treble, use the treble sequence to tune A5, then D5, and then E5.   First listen to the D5/A5 5th.   If it needs a little more stretch, add another .1 DOB and re-tune A5 and D5 and give it another listen.

The upper 5th in that octave will indicate fairly easily and quickly if A5 is sharp enough and the lower 5th (A4/E5) will hopefully confirm.

If you think more stretch is needed, add another .1 or .2 DOB, re-tune A5, D5 and E5 and listen again.

(Just be aware that .1 DOB adjusts A5 by .2 whereas each .1 DOB adjusts A6 by .4 c.   The goal is to use a single DOB setting for the treble by finding a good sounding compromise for both A5 and A6 using a single DOB setting.   So as you adjust the DOB @ A5, keep an eye on what is being done at the A6 position.)

Once happy with A5 continue using the sequence to tune A6, D6, and E6 using the same DOB amount as when tuning A5!!

Now that there are no partial change errors, you should be able to find a good DOB setting that will sound nice for both A5 and A6.

NOW, you’re ready to tune the piano.

All the partial changes are correct, no errors there, A4 is correct and the tuning will end up @ A440, the Midrange will be a good fit and the treble stretch is a good fit for the piano.

Since your DOB settings are written down, just make sure to use the right DOB when tuning the Bass, and remember to change it @ A4 to the Treble DOB setting.

These DOB settings can’t be stored to the tuning.   If this piano is one you tune often, all you will really need to keep track of is where the tuning is in your SAT (Naming will help with that) and the DOB settings you use for the bass and the treble.    This is something you will only need to do once on each piano.

Since the standard SAT IV has 400 pages, and the SAT IV “980” has 980 pages, it might be handy for you to start using, if you aren’t already, the Piano Manager Software with your SAT.   With it, you can store these pianos to the upper memory.   Doing so will allow you to store hundreds of your favorite customers pianos in your SAT.  With Piano Manager, tunings can be named, arranged, headers can be printed, and backups can be made.   There are lots of things Piano Manager can be used for that can make this type of upper level tuning work more repeatable.

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