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Allen
03-28-2017, 03:37 PM
It's amazing how many ukes that I'm asked to work on that have intonation issues, and many times we're not talking about a little. But the saddle not even close to where it's suppose to be.

I can only assume that it comes down to a few things on the part of the builder.


Not knowing anything about compensation
Not knowing the scale length (yes on 2 occasions the wrong scale length)
Complete stuff up. This probably applies to the second one listed.


I use a tapered template that follows the same taper of my fret board. Makes it's easy to locate on the fret board and assures that the strings will follow the correct path up to the nut. One end butts up agains the nut, and as you can see the other end locates the front edge of my saddle.

Once I have the bridge located I will do a sanity check with a string running from each outside nut slot to the corresponding bridge position....just to be sure.

98925

sequoia
03-28-2017, 05:36 PM
This discussion about bridge/saddle location in relation to scale length is an old chestnut on the forum but still so interesting but I think people are still basically confused...

A few things to understand: As the string is pushed down and fretted it tends to proportionally decrease the length of the sting and make the note sound slightly higher (sharper) than it theoretically should be at a given position. This effect increases exponentially as one moves up the neck. By moving the saddle slightly further away from the nut it compensates for this tendency by making the string slightly longer than the theoretical perfect scale length and thus it compensates for this change in the string length when fretting a note.

Second, the tendency for a string to sharpen depends on its diameter. Obviously the diameter of the strings on the four strings of an ukulele is not equal and thus for perfect compensation, the saddle would have to be compensated slightly differently for each string diameter. This can be done but is not really practical since each part of the saddle would have to be divided up into four separate pieces each exactly compensated for the difference in string diameter. It can actually be done done and I've seen it, but the question is: does it really matter? With a slight intonation difference across the stings with a straight saddle most people will accept or not even hear the discrepancies. Thus intonation compensation is an "average approximation" across the four strings with each being slightly off but closer than an uncompensated saddle.

And if that wasn't enough, the height of the string off the fretboard (action) will effect the degree that a string will sharpen off its theoretical intonation. The higher the action, the more the string is stretched thus increasing the sharpness of the note. This is one reason that really cheap ukes with ridiculously high action sound so bad. Go up even 4 or 5 frets and the tuning becomes sharper and sharper sounding... really icky and out of tune.

So scale compensation is a series of compromises that gets us close to the ideal, but never quite makes it. Close enough. At certain point you have to just tune up and shut up and play your ukulele. I used to compensate my straight saddled 17 inch scale length tenors by 3/32 of an inch which is the rule of thumb distance that gives "good enough" compensation across all four strings with a medium to medium low action. Recently I have increased this to a full 1/8 inch which I think works better considering the medium action I like on my ukes. Plus, after awhile I find the bridge tends to rotate forward under string tension bringing it back towards the 3/32 mark. Much as we would like to think and hope, the ukulele tends to change shape over time and this needs to be kept in mind. Thus I tend to over compensate just a little bit. It is all a bit of a moving target.

It is all a compromise in the end and it just depends on the amount of error we are willing to accept. The smaller the error the better, but perfection is impossible. Just get it close as you can and then just shut up play the goddamned thang.

Timbuck
03-28-2017, 08:34 PM
That gauge is almost the same as mine Allen ...only mine has a hook at the end that drops in the saddle slot.

ProfChris
03-28-2017, 11:37 PM
... the question is: does it really matter? With a slight intonation difference across the stings with a straight saddle most people will accept or not even hear the discrepancies. Thus intonation compensation is an "average approximation" across the four strings with each being slightly off but closer than an uncompensated saddle.

I think it does matter to a player who goes above, say, the 5th fret. I don't spend a lot of time there, but when I do I would like to be as in tune as possible.

For example, if I'm playing a song in F then a nice finish can be to play and hold 5558 as the final chord. If the saddle isn't individually compensated, but just "average" compensated with a straight saddle, then the C string rings noticeably sharp. I like Aquilas, which are thicker than most, so that makes the sharpness very noticeable. It's OK if the chord is held for just a couple of beats, but as the final chord it detracts from the song if it doesn't ring true enough for most not to notice.

Individual compensation is quite easy, using a narrow file for example. But if I were building for the general market I wouldn't individually compensate strings because the amount of compensation depends in part on string choice and action height - these need to be settled first. If you're building for an individual and can get the recipient over to try the uke, decide on strings and set action height, then individual compensation is in my mind worth it.

anthonyg
03-29-2017, 02:27 AM
Don't forget the nut placement either. I'f I'm having intonation issues with an instrument then I will measure the instrument for errors and quite often the error is in the nut placement. This is particularly relevant if the intonation problems are in the open position.

Anthony

Kayak Jim
03-29-2017, 04:28 AM
Don't forget the nut placement either. I'f I'm having intonation issues with an instrument then I will measure the instrument for errors and quite often the error is in the nut placement. This is particularly relevant if the intonation problems are in the open position.

Anthony

Can you expand on this please. I'm in the process of putting together a cigar box uke, my first "build" (and I hesitate to call it that) attempt.

Do you mean the nut is not square with the centerline? Or wrong distance to first fret (but this wouldn't affect open intonation)?

anthonyg
03-29-2017, 08:47 PM
Can you expand on this please. I'm in the process of putting together a cigar box uke, my first "build" (and I hesitate to call it that) attempt.

Do you mean the nut is not square with the centerline? Or wrong distance to first fret (but this wouldn't affect open intonation)?

Both factors are relevant. It's kind of like blueprinting. If a plan states that something should be in this place, make sure its exactly in this place. Having said that, its complicated. As far as "blueprinting" goes this means that if say you have a 15" scale instrument, the distance from where the string leaves the nut to the centre of the 12th fret should be precisely 7 1/2". If you get this spot on then your 95% of the way there.

What I have found though is that the two outer strings travel a tiny fraction further than the two inner strings and this DOES make a difference to the intonation as small as the difference is. This is how accurate you need to be. Usually a builder will measure nut placement down the centreline of the neck which is reasonable enough and if done correctly this will have the inner two strings pretty right but the outer two strings going a fraction sharp.

My two bobs worth. Please measure the nut placement so that the outer two strings line up at the 7 1/2 " mark and don't go sharp and then ever so carefully file the nut contact point back for the inner two strings so that the intonation doesn't go flat on those strings.

I'm being fussy I know yet nut compensation is a done thing in the world of handmade guitars.

Even if your not going to go to this much trouble, if the nut is carelessly placed further away from the 12th fret than its supposed to then the intonation will be sharp. If it is placed closer to the centre of the 12th fret than it should be then the intonation will go flat.

I have mostly fixed sharp intonation on inaccurately built ukuleles by placing a matchstick on the fretboard, under the strings and up against the nut thereby flattening the sharp intonation.

And to the "open" intonation question. I said open position which usually means the first 3-5 frets. We are talking about non barre chords.

Anthony

Kayak Jim
03-30-2017, 04:15 AM
Great information. Thanks Anthony.

sproutguitars
01-20-2018, 06:30 AM
HI
Im new to building ukuleles. I built several electric guitars and 1 acoustic . Im at the point to position the saddle on a tenor ukulee and a concert ukulele. do I have to set the sadlle slightly off from the 'G" string to the "A' string to get the proper intonation ?

Allen
01-20-2018, 09:09 AM
On ukes the saddle is set straight across. Not at an angle like on steel string guitars.

You get your room for compensation from the width of the saddle. I make mine 4.0mm wide for several reasons. Compensation being one. It's way more amount than is required though.