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

FAC Tweaks: Which one should I do first?

This post should prescribe a general approach to applying these FAC Tweaks.   This FAC Tweak ‘ordering’ is a starting point.   As the technician becomes more familiar and adept with these tweaks, to some extent, their order can be modified and tweaked to suit the work flow of the technician.

The A Multiplier Def:   Set the A Multiplier Def to .8
(Once the A4 Multiplier Def is set, it will stay that way.   It can be called a ‘global’ or a MENU setting, similar to Auto Step Delay, or the Foot Switch U/D setting, or the Time Out setting.   Those settings can be changed thru the SAT’s MENU, but once they are set, they don’t need to be adjusted after the SAT has been turned off.

{I’m planning another video on how the MENU settings can be changed with Piano Manager too}.

Next, and this isn’t necessarily a FAC tweak at all, but the next step is to know where the 4th Partial of A4 is when A4 has been tuned to A440. 

So, before doing anything else, before measuring any FAC numbers, tune A4 to A440  (A4 @ 0.0) and then set the SAT to A6 and measure the location of A4’s 4th Partial when A4 is tuned to A440.

Write that number down somewhere, because you’ll need it later to make sure the custom tuning being created with the help of all these tweaks will be exactly A440.

Now measure the FAC numbers as usual and store the tuning to a page of memory.

Lower the tenor partial change down to G#2/A2.

Lowering the FAC Tenor Partial Change: The “How”

If you want to use a tuning sequence, now is when a tuning sequence will come in handy.   See the post here on “Using a Sequence”

A suggested sequence would be A4, A3, D4, E4, D3, E3, and A2.

Using that sequence tune those 7 notes, and listen to each new interval created with each additional note in the sequence.   Once all the notes have been tuned and checked, a decision can be made regarding any widening or contracting of that A2-A4 range width.

My first suggestion would be to try using some DOB to adjust the width of that two Octave A2-A4 range, and see if that makes it more to your and the piano’s ‘liking’.

My guideline here is to try to start with the A2/A4 4:1 octave about 2.5 c. wide.  That means the Setting for A2 would be around -2.5 c.   Just a guideline.   Of course it (A2) can be higher or lower than that -2.5 c. setting.

But start by using DOB to get A2 around that -2.5 setting.   Then tune the 7 notes in the sequence to see how the intervals created by those notes sound.   It shouldn’t take you long to be able to discern if the A2/A4 double octave is too wide or not wide enough.

You’re looking for the best sounding compromise at this point.   As you know this tenor area contains a lot of scaling changes, but what you’ll be listening for is the best sounding, or as Al would say, the ‘least bad sounding’ width for that A2-A4 range.

(Double Octave Beat:  DOB.  Each .1 DOB @ A2 alters the setting of A2 by .4 c..   So a .2 DOB setting at A2 will lower A2 by .8 c..   A  -.2 DOB setting on A2 will raise A2 by .8 c.)

I’d suggest sticking with DOB at this point for adjusting the width of this A2-A4 range.    Maybe later on, if you run into a more ‘extreme’ situation, you may want to try a different set of FAC numbers to tweak the stretch so maybe not so much DOB is needed.    But for most – 98% – pianos, DOB should give really good results, and it’s easy.

Once you have a DOB setting you want to use for the mid-range (A2-A4) write that DOB setting down.

Correct the Tenor Partial Change using PCC.
If DOB is used for the mid-range, make sure to use that same DOB setting when correcting the tenor partial change.   So, if a -.3 DOB setting is to be used when tuning the Mid-range.

Once the tenor partial change has been corrected, go ahead and tune some notes that allow you to hear how a few 3rds, 6ths, and 10ths sound going across that partial change.

If you like you could create a second sequence for this:
Something like:  G#2, A2, A#2, C3, C#3, D3, F3, F#3, G3, C4, C#4, & D4.
Tuning those notes would give you a trio of M3rds, a trio of M6ths, and a trio of M10ths.

The scaling changes in this area will probably effect some of those intervals, but the overall quality of the interval’s even progressions, should reveal if any of the tweaks so far need to be checked.   But before making a lot of adjustments, make sure the tuning of the reference notes is accurate!!   More often than not, it’s a note that has slipped.

For tuning the rest of the bass (A0 – G#2) use the same DOB setting that is being used in the Mid-Range.

So at this point, the only ‘on the fly’ tweak you will need to make is a single DOB setting that will be used for notes A0 – A4.


Don’t stop now!   Keep up the good work and finish it off by using the PCC feature to correct the two partial changes found above A4! 

But first, BEFORE using the PCC feature to correct the treble partial changes, set the DOB back to 0.0!!

Now go ahead and correct the two treble partial changes.

Check/Correct All Partial Changes Using the SAT’s Partial Change Correction feature

The last step in the PCC routine is to raise or lower the complete tuning so that A4 will be at exactly A440.

This is why you wrote down the first step, which was to tune A4 @ A440, and measure where A4’s 4 Partial is.

That’s it.

It doesn’t matter whether you start at the bottom or the top or the middle, go up or down, whenever notes A0 – A4 are tuned makes sure the DOB setting is correct.   If there is no DOB for the treble (A#4 – C8), make sure there is no DOB stored in the SAT for tuning the treble.

A final Treble Tweak using DOB: 
If you would like to add a little more stretch in the treble, I would suggest using note A6 as the guide.   Find a DOB setting that gives you the sound you want for A6, and use that DOB setting for the entire treble (A#4 – C8).

Here is another use for yet another sequence.   The idea here is to find a starting DOB setting for A6, and then tuning some notes to check it.

A starting point for A6 will be about 2.0 c. higher than the setting on A4. 

What that means is that a good starting point for the A4/A6 4:1 octave will be about 2.0 c. wide.  You can start higher or lower if you want.

For example, if the FAC numbers you measured on that piano were a bit on the high side, you might want to start with a 3 c. wide A4/A6 4:1.    I came up with the 2.0 c. wide number by averaging about 235 tunings’ A4s and A6s.   Since this 2.0 c. width is an average, some pianos will enjoy more and some less.    But that’s why you’re there.  And that’s why you’re doing this.

Doing this bit of listening and tweaking the treble is not only enjoyable, but I think you too will find it makes a big difference in how the piano sounds up there!

As I’ve said over and over again, I like a triple octave @ A7.   But FAC tunings were designed more in the double octave width up there.   But that’s OK.   You won’t be able to turn a double octave with @ A7 into a triple octave width @ A7 using DOB but you can work with the overall stretch up there and get it to sound very nice with an FAC tuning and a single DOB setting.

Find a good sounding place for A6 and then use that DOB setting for the treble (A#4-C8).

(Of course, feel free to add more DOB above A6.   If you decide you want to do that, add it incrementally, maybe .1 DOB at a time on each note or every other note or so above A6.     But for the first 50 pianos, while you are learning this and getting more and more familiar with how the pianos are sounding, your new found experience with it will give you some more personal guides for tweaking.

One of the reasons I like to have a single DOB setting for the lower half (A0 – A4) and the upper half (A#4-C8) is because it makes it easier to do a quick 2nd pass or go over a section again, for either unison cleanup or general piano ‘drift’ I guess we can call it.

Adding DOB ‘on the fly’ is great, but unless each one of those ‘on the fly’ changes is written down, knowing where the first setting was can be a little bit of a mystery to duplicate that first pass.

Here’s a sequence for tuning the treble:

A3, D4, E4, A4, A5, D5, E5, A6, D6, E6.

I like to check the tuning of the 3rd octave A, D and E, so I can use them as solid reference notes for the treble tuning.

Remember, all the partial changes in the treble have been corrected!!   That is very very important for doing this!  If the partial changes are correct it should all work and the reference notes should be really accurate and true.   But if there are unchecked and uncorrected errors at the treble partial changes, these reference notes will give false inaccurate signals as to what’s what.

So this treble tweak is really only to be used in combination with corrected treble partial changes.

After tuning A3, D4, E4, and A4 using the DOB setting used for the Mid-range, if A4’s setting is 9.0 add or subtract DOB so that the setting for A6 is around 11.0.

Now tune A5 and then D5 and E5.   Now listen to the intervals paying particular attention to the D5/A5 and the A4/E5 5ths.   If they aren’t quite as clean as you like, add another .1 or .2 DOB, retune and relisten to them.  (each .1 DOB moves A5 by .2 c.).  Once you get those 5th octave 5ths, sounding good,  check the double octave (A3/A5) and the pair of 12ths (A3/E5 & D4/A5).  Also check the octaves A4/A5, D4/D5, and E4/E5.

When you are OK with how it sounds so far, tune A6, D6 and E6.   Again, paying attention to the 5ths in that 6th octave (D6/A6, and A5/E6).   Also the double octave A4/A6, the new 12ths, and so on.   You may need to tweak the DOB setting a little bit, but it shouldn’t take much.

Again, you’re looking for the best sounding compromise up here.  A single DOB setting for the whole treble.  My general rule is that better a touch too sharp than a touch too flat @ A6.

Sometimes some pianos seem to enjoy more stretch @ A6 than they do @ A5 or vice versa.   So you’ll have to do enough listening up there to make the best sounding compromise.   But I think you will soon realize how much this improves the sound of your tunings!   And if you have to give up a little @ A5 to get a nice compromise for the treble, when you are finished with the tuning, and sit down and play your ‘finished’ piano tuning checks, you’ll be pleased at the improvements you’ve made over a standard FAC tuning.

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