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Thread: (Another) Intonation Question…

  1. #1
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    Question (Another) Intonation Question…

    [ Concluding Post by OP ... see #56 Resolved ]

    Sometimes having good tools to measure parameters can be damaging to ones’ mental health.

    I’m reminded of an observation by a favorite college professor, “ I didn’t know I was poor as a kid until I took Economics in college!” Now that I can 'measure' my instruments tuning, the rabbit hole is enlarged...

    My two “issues” have to do 1) with being in tune further up the fretboard, and 2) what I can best call a “thunk funk."

    Three ‘ukes: 1- Fender Montecito (tenor); 2- Romero Creations Replica (Spruce/Mahogony tenor); 3-Romero ST Concert (spruce top/laminate body).

    For all three instruments I used a Korg TM-60 for initial open string tuning (analog needle gauge with digital numeric display) and used the iOS App n-Track Tuner to measure the hz/cent variations. [FWIW, the App matched the Korg for the initial open string tuning.] All strings on each ‘uke have settled.

    Starting with the STC, Worth strings (BL-lights). Open strings tuned gCEA to within ‘hundredths’ Hz on the initial pluck, slowly fading slightly flat after about 3 seconds. As I go up the fretboard things start going flat. Depending on the string, flat by 6-9 Cent. By the time I get to the 12th fret, flatness ranges from 16-27 Cent.

    Initial setup was done by UkeRepublic. Action: 1st fret 1.0+; 12th fret 2.8 with the first fret being about 0.5mm high. A few individual frets are very slightly low at 3-4 sting locations, but no buzzing. In don’t think the setup included dressing the frets as some of the edges were a little rough as well and the included Romero strings were nicked near the saddle. The saddle on the g string also had a slight groove (you could hear a click when the string was moved from side to side. Finally, the bridge is set at the proper height and distance (with the 12th within 1 mm of center).

    Now with the Romero Replica. GCEA (low G)- I started with Romero’s and switched to Clear Worths that had the same diameters as the Romero’s (I kept the Romero flat wound). I followed the same measuring process and the result was less ‘flatness’ at both the 5th and 12th frets. At the 5th the range was 5-7 Cent flat; at the 12th the range was 7-16 cent.

    AND for the Montecito. Same Worth strings as the STC. Same process for measuring… Much better results. Within 5 Cent at the 5th (slightly sharp on the E & A). At the 12th fret the G and A were “remarkable” spot on and the middle two 4-6 Cent!

    I understand that keeping intonation ‘close’ with shorter fretboards difficult. But with consistently flat intonation in this larger range I was hoping for advice on improving the deficit. Where do I start to ‘sharpen’ the notes as the scale increases. (obviously I’m keeping the ‘inferior’ Montecito as-is … wink)

    The second issue has to do with what can best be described as a ‘thunk or thud-iness’ when moving up the fret board, starting at the 5th fret…. only on the C string.

    The open string resonance on both the Romero ‘ukes is wonderful, sustaining for 4,5,6 seconds. But when I get to the 5th through 8-9th fret the sustain drops to about 2 seconds and it just sounds ‘dead’. It sounds similar to having your shirt sleeve touching the string ( it isn’t ). There is sufficient clearance at the next fret and I’m careful to press the string at either the middle or closer to the fret with the same thunk. Interestingly, the sustain starts to increase as I continue to move up the fretboard.

    Any ideas? FWIW, I don’t get the same result when I play my grandson’s Enya HPL Soprano and Concert models.

    Thanks for “listening” … here’s hoping for some ideas.

    Stu
    Last edited by Web_Parrot; 08-20-2019 at 12:17 PM. Reason: Final Edit to Conclude issue (#56)

  2. #2
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    You're definitely going down the rabbit hole. All my ukes are off at the 12th, but I decided not to be concerned, just have fun playing. I'm not a professional who records, unless you are, why worry about it? I've heard of people have the bridge moved, but a different set of strings will require that again. The only adjustable uke bridge I've seen is the TunaUke that Lanikai uses where each string sits on a small saddle that can be slid forward and back, but height to lower the action requires sanding like any other saddle.


    This is Michael Kohan in Los Angeles, Beverly West near the Beverly Center
    9 tenor cutaway ukes, 5 acoustic bass ukes, 11 solid body bass ukes, 9 mini electric bass guitars (Total: 34)

    • Donate to The Ukulele Kids Club, they provide ukuleles to children in hospital music therapy programs. www.theukc.org
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  3. #3
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    You might try a wound C string to help with the thud.

  4. #4
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    Ok, you can walk away now or go further down the rabbit hole (its fun, honestly). It's time to measure your instrument's with a rule rather than just a tuner.

    Nominally your instruments have TOO much compensation at one end of the other which leads the intonation to go flat which is opposite to the usual error in ukuleles of not having enough compensation which leads intonation to go sharp.

    Lets talk tenor to start with and a nominal 17" scale length. In a World of "perfect" strings (which don't exist) the distance from inside the nut to where the strings contact the saddle would be exactly 17" and the centre of the 12th fret would be exactly half way at 8 1/2" and every note would play in tune. Now in reality strings are too stiff to vibrate exactly as theory predicts so what happens is that notes go sharp as you fret up the neck. To correct this ukuleles/guitars/all fretted and stringed instruments have saddle compensation making the actual scale length longer than the nominal/theoretical scale length which flattens the note and corrects for the tendency to go sharp.

    The amount of compensation at the saddle needs to be reasonably precise. Now we need to talk about the positioning of the nut which also impacts the intonation of the instrument. If the nut is too far away from the 1st fret than it should be then the intonation will go sharp. If the nut is closer to the 1st fret than it should be then the intonation will go flat. A "tiny" bit of nut compensation (nut closer to frets than theory) can be good but just a tiny bit.

    One of the most common errors you see in mass manufactured/cheap ukuleles is that they have no saddle compensation (why manufacturers don't know this stuff is beyond me) so they always go sharp.
    Your problem is that you have too much compensation at one end or the other or both.

    Start by laying a rule down the fretboard from inside the nut to the saddle and comparing the distance from inside the nut to centre of the 12th fret to the distance from inside the nut to the saddle contact point.
    How much compensation do you have?
    How does the measured distance from inside the nut to centre of the 12th fret compare to the theoretical distance from inside the nut to centre of the 12th fret? THis should be 8 1/2" on a tenor ukulele however it can get more complicated than that as the instrument may have been built in metric rather than imperial.

    17" converts to 431.8mm. Tenors are still commonly built to this scale length although sometimes they are built to a metric 432mm scale length.
    A 15" Concert scale is 381mm although its common to have them built to 382mm metric as well.

    Ae you still with me?
    Last edited by anthonyg; 05-20-2019 at 07:35 PM.

  5. #5
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    Quote Originally Posted by anthonyg View Post
    ... ... Are you still with me?
    Yes! I'm not the OP but I really learned from your post.

  6. #6
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    Quote Originally Posted by bellgamin View Post
    Yes! I'm not the OP but I really learned from your post.
    Thanks. I'll keep on going.

    First we need to measure so we KNOW where the error is. My experience is that if I measure an instrument carefully then I will always find a measurable error if the intonation is out. If the instrument has great intonation then the instrument will measure accurately.

    Let me shortcut for a moment and then go back.

    If an instrument is reasonable accurate at the low frets and gradually gets worse up the neck then the nut should be correctly placed and the error is in the saddle.
    If an instrument is bad over the first few frets and gets better up the neck then its the nut at fault and the saddle is probably right.

    In reality its often both that are wrong.
    Now sometimes things can get REALLY complicated because the fault MAY be at the nut yet some tech guy tries to fix it by compensating for the error at the saddle.
    This happens a LOT and I have a bee in my bonnet about it. Now I've made this very error myself many times so I don't want to be too critical of tech guys and my attitude nowadays is to try my best to teach the theory as best I can.

    One example from me is that I own a hand made electric ukulele that was going flat over the low frets and I couldn't set the saddles short enough to fix it. I took the instrument to a shop and had them move the bridge closer. Later on I learn't/realised that it was in fact the nut that was positioned too close and in fact the bridge was just fine where it was originally. Now that I have the nut fixed the saddles need to be back as far as they can go

    So, before we do ANYTHING, first measure. All over.

    So for a 17" Tenor lay a steel rule from inside the nut to over the saddle and note where things are positioned. Is the centre of the 12th fret precisely at 8 1/2"? The saddle should be at 17" plus a little but just how much extra is there?

    That's a start.


    Now when your REALLY ready to go down the rabbit hole.

    To do this really well you must first independently establish the precise scale length that the frets are fretted to. Guessing that its 17" (431.8mm) when its really 432mm isn't close enough. We need to be precise and the way you do this is with the help of Stewart MacDonalds fret position calculator.

    https://www.stewmac.com/FretCalculator

    What you do is make an educated guess as to the scale length and put the data into the calculator.
    Then make some fret to fret distance calculations. Work out the distance from fret 16 to fret 1 and fret 12 to fret 1. You do the calculations to 3 decimal places first and any rounding is done last. Once you have your distances, carefully measure them on the fret board. Are they correct?

    I've just been working on some baritones that are nominally 19". They were measuring accurately from inside the nut to the centre of the 12th fret at 9 1/2" so I though it was spot on. Recently I figure that I had better do the right thing and measure them with the help of stewmac. To my surprise they weren't 19" ( 482.6mm) but were actually 482mm.
    You need to be this accurate.
    Last edited by anthonyg; 05-20-2019 at 08:23 PM.

  7. #7
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    Down the rabbit hole indeed. It is all right and proper to stress the need for accuracy in these essential placements, but don't take it too far. IMHO to suggest that we have to work to an accuracy of two tenths of a millimeter is unrealistic.

    John Colter.

  8. #8
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    Quote Originally Posted by ukantor View Post
    Down the rabbit hole indeed. It is all right and proper to stress the need for accuracy in these essential placements, but don't take it too far. IMHO to suggest that we have to work to an accuracy of two tenths of a millimeter is unrealistic.

    John Colter.
    Well its up to you of course. For the record a 0.2mm difference to saddle compensation WILL make a difference and is well within the range of adjustments that you could expect a tech to do when fine tuning intonation. The tech may not have measured it with a rule yet they will have likely adjusted it, restrung the instrument and tested it with a tuner. A 0.2mm error in nut placement will have an effect.

    My advice to builders and techs is to not try to fix a 0.2mm error at the nut with a 0.2mm adjustment to the saddle. The first step is to know what needs to be adjusted before you start.

    It makes a BIG difference.

  9. #9
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    Quote Originally Posted by ukantor View Post
    Down the rabbit hole indeed. It is all right and proper to stress the need for accuracy in these essential placements, but don't take it too far. IMHO to suggest that we have to work to an accuracy of two tenths of a millimeter is unrealistic.

    John Colter.
    Well written Anthony

    My few pennth’s worth as a Mechanical Engineer.

    Number 1

    The Nut has to be right, it is the Datum, the reference from which all measurements are taken.

    Screw up the Nut and you screw up the whole scale.

    Number 2

    Distances between frets have to be accurate and as per the calculator, this should not be an issue during manufacturer.

    Number 3

    Saddles fitted to the vast majority of Ukes are generally budget items with no easy adjustment to fine tune the string length.

    Joe Public may not be able to work to two tenths of a millimeter (roughly 8 thousandths of an inch) but a good Tech should be able to and certainly the fully adjustable saddle that I have on my Risa Uke can enable adjustment to far less than two tenths of a millimeter.
    Col.
    From the UK with a bad case of MIAS.
    Korg PA700, Korg Kross 2, Gibson LP, Fender Jazz Bass,
    + Amps, PA, Boss GT100, mixer.
    Ukes - Kala KA-TEME and Risa ST electric solid body.
    Uke wish list, a Bass, make and model yet to be determined

  10. #10
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    I beg to differ.

    John Colter.

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