The Buzz Feiten intonation system is a series of subtle intonation offsets that stretch the tuning slightly to account for the interaction of different string gauges and scale lengths. The result is kind of like the ‘stretch tuning’ commonly used on pianos to make them sound more ‘in tune’ to our ears. Pianos have used this advanced system for 700 years. But guitars never had such an adjusted tuning until Buzz Feiten, a southern California studio musician, developed the system.
Megatar instruments sound more in tune with other instruments thanks to the improved intonation, which is a good thing. The real benefit is that the instrument is in tune with itself all over the fretboard so that individual notes, harmonies and chord structures are more pure and focused.
Here is link to the Buzz Feiten website:
http://www.buzzfeiten.com/
[Techie/Geeky Warning: Rather technical info following] -
Our factory shop recently got an email from a Buzz Feiten authorized shop in Italy, with the following question.
>I’m having trouble intonating the 4th melody string using the formula for BassBottom tuning because it keeps being sharp. I tune it C# no offset (at fret 2), then intonate +2 cents at the 14th fret, where I intonate. And then it’s increasingly sharp further up the fretboard. This bugs the owner.
Now intonations can change over time, and I cannot see the instrument, but it sounds like the owner has a misunderstanding about how Feiten works, and the authorized shop is not able to explain it to him. (Or maybe this particular shop doesn’t quite understand the Feiten system, could that be?)
Here’s our shop’s response –
Thanks for writing.
First I want to make sure I correctly understand what you said –
You have set the 4th melody string intonation to no offset at fret two.
Then you set the 4th melody string intonation to +2 cents at fret fourteen.
Then you noticed that the string is sharp *above* fret fourteen, that is frets 15-25.
Is that correct?
If I have understood you correctly, then here’s what I think is true …
Of course the string is at least 2 cents sharp above fret fourteen, because the formula tells you to make it sharp by two cents at fret fourteen.
And in fact, the string should continue to become sharper as you move further toward the bridge. For example, fret 17 or fret 20 or fret 25 should be *more* than 2 cents sharp.
And of course, any string that is set to be sharp halfway up the fretboard will be even more sharp higher up the fretboard. If you had zero offset at fret fourteen, then you’d expect zero sharpness above fret fourteen. But if you’ve sharped the string at fret fourteen, then as the string length is reduced as you move higher up the fretboard toward the bridge, so it will continue to become increasingly sharp at each successive fret as you move further up the neck.
As you go down the fretboard from fourteen toward fret two, of course the sharpness will go away until there is no sharpness at fret two. Because that’s how we set it.
Another Illustrative Example of How Buzz Feiten Intonation Works
If you had set the offset at fret 22, for example, to +2 cents, then as you came down to fret 14, then fret 14 would be "less" than 2 cents sharp. And so if you set fret 14 to be 2 cents sharp, then of course fret 18 or 21 or some higher fret will be more sharp.
In other words, that’s exactly what we set it to do. That’s what it’s doing. And that’s how it has to work.
It will not be different on any other string, and it will be exactly the same on any other string, where there is a greater sharpness at 14 than at fret 2.
Buzz Feiten Intonation and Your Ears
However, you may notice it less on some other strings. For example on bass strings and strings that are lower pitched, our ear hears less. And at lower frequencies, there will be less change one fret to the next in terms of actual frequency of vibration.
On some strings where the offset is less, there will be less additional sharpness further up the fretboard. So string #3 will be less, and there should be NO sharpness on strings #2 and #1.
Precision Fret-Placement Needed for Feiten Intonation System
Each fret is in one place, the same for all the strings, on parallel fret instruments, and so one string cannot act differently than another string. Even on fanned-fret instruments, the principle is the same.
And we use computer-controlled, high-precision machinery to cut the frets, so that we have no variance on the cutting of fret slots. That is, they’re not cut by hand, and there’s no human error when they’re cut. So we can assume that the fret is in the correct place, and of course it cannot be in the correct place for string #3 and string #5 and be in the wrong place for string #4.
String Gauges and the Buzz Feiten System
There can also be some slight differences between plain and wound strings, and between one gauge and another. These are largely the differences that the Feiten intonation improves. But the formula you have is the one given us by the Feiten folks, and the strings gauges you have are the ones we used to set up the formulas. (If Fabrizio has changed to different gauges, then that’s a new can of worms!)
So What to Do?
We are left with this –
Now, that particular string #4 is the lowest-pitched plain string.
If you ears and the owner’s ears say that string #4 is “TOO SHARP” as you go up the frets, then the two of you should TRUST YOUR EARS.
That’s how Buzz Feiten and Greg Back developed the formula. They *listened* and set the offsets to what sounds the best to their ears.
So if you think that string #4 is going TOO MUCH sharp as you go up beyond fret 14, then CHANGE THE OFFSET at fret 14 to a lower value. Do this till it sounds correct to your EARS. Test against the other strings by playing simple major triads up and down the strings, if you want to really check your ears.
That’s what Buzz Feiten did.
How to Correctly Play While Setting Intonation
Now, one last thing –
As you test the intonation and as you set the intonation, PLEASE do this by TAPPING on the string. Do NOT fret the string and pluck it. Set the intonation at fret two by tapping the string, and set the intonation at fret fourteen by tapping the string. (You can get very different results picking and tapping, and this instrument is designed to be played by tapping.)
Tap ON the fret, and turn up your amp, and tap softly to do the work.
Happy intonation!