PDA

View Full Version : Intonation? And Strings?



JackLuis
11-08-2016, 06:52 PM
I generally am a first position player so I don't notice intonation as being a problem. I have more glaring problems, however.

One of my tenors goes one or two marks sharp, on all stings, (on my Snark) at the first fret and doesn't recover but doesn't get much worse up to ~12.

I have this strung dGBE with D'Addario Carbon tenor strings, so maybe it's the strings?
Or could it be the height of the nut slots?

How much deviation from tuning should be allowed on a bargain Uke? My Baritone (Worth Browns) is right on up to the 12-15 fret where is varies 2-3 marks.

I guess I should try some south coasts.

Dan Gleibitz
11-08-2016, 10:06 PM
Probably just needs the nut slots filing deeper. It could be that the nut to first fret spacing is out, but I'd check the slots first.

Pirate Jim
11-08-2016, 10:11 PM
Almost certain to be the nut slots - fret spacing templates are readily available even for hobby builders so it's unlikely to be that. I file nut slots down with welding nozzle tip cleaners - has always done the job for me.

mrStones
11-08-2016, 10:32 PM
Personally, I'd prefer to remove the nut and sand it down to an acceptable height. I had that problem on an Islander tenor uke too and lowering the nut should fix your problem.
Sure, Filing just the nut slots is quicker and allows you more control on individual string intonation, but you have to do it really carefully and try always to keep the angle between string and nut slot (so the nut slot won't act as a knife on string) and keep also a V shape in the nut (so string won't move too much in the slot, but it will "fall" right in the V shape).
Hope that makes sense in english.

jollyboy
11-08-2016, 10:44 PM
One of my tenors goes one or two marks sharp, on all stings, (on my Snark) at the first fret and doesn't recover but doesn't get much worse up to ~12.

I have this strung dGBE with D'Addario Carbon tenor strings, so maybe it's the strings?
Or could it be the height of the nut slots?


From what you describe I would guess at the height at the nut as being the issue.


Personally, I'd prefer to remove the nut and sand it down to an acceptable height.

I agree with this. Filing down the individual slots is tricky without the proper tools. Removing the nut and sanding down the bottom is actually easier I would say. Plus it's an opportunity to replace a plastic nut with a bone one - and if you work on a 'spare' it's not so much of a problem if you take too much off and have to start over.

Booli
11-09-2016, 12:58 AM
To the OP, you intonation issues will be MORE severe with strings that are lower tension, which is what you will have if using GCEA 'tenor' strings and tuned down to dGBE, they will be too slack, and if you watch your tuner, you will see the pitch WAVER +/-5-7 cents each time you pluck the strings, and this is more evident the higher up the fretboard...

You may love the lower string tension for dGBE on a 17" scale, but there are strings designed for this tuning that are typically thicker or 'higher linear density' that will NOT have this intonation problem. I have the experience of string testing and 100's of string changes in the past 3 yrs as evidence of this.

Higher tension strings and/or 'tenor' dGBE strings may cure your intonation issues without needing to modify your uke.


Almost certain to be the nut slots - fret spacing templates are readily available even for hobby builders so it's unlikely to be that. I file nut slots down with welding nozzle tip cleaners - has always done the job for me.

CB Gitty sells these, and I use them to good effect on all ukes that had intonation issues and needed the nut slots modified. Just be CAREFUL to file a tiny bit at a time otherwise you will be going too far, you may need to iterate 20-30 times to get it dialed in just right, and better to take off too little per stroke than too much, otherwise you are going to either start over with a new nut blank, or shim the nut from underneath, OR fill the nut slots with superglue and bone dust (or baking powder) and yet also start over. Done them all, and all are a PITA vs. just having patience and taking off like 0.25mm at a time, once you do this on a few ukes, and see how many cents it improves the intonation, you can get a feel for how many strokes with the file...


Personally, I'd prefer to remove the nut and sand it down to an acceptable height. I had that problem on an Islander tenor uke too and lowering the nut should fix your problem.
Sure, Filing just the nut slots is quicker and allows you more control on individual string intonation, but you have to do it really carefully and try always to keep the angle between string and nut slot (so the nut slot won't act as a knife on string) and keep also a V shape in the nut (so string won't move too much in the slot, but it will "fall" right in the V shape).
Hope that makes sense in english.

Actually you want a ROUND nut slot, a V-shaped nut slot will usually bind the string in the slot and cause new problems such as not allowing the string to be pulled past the fulcrum of the nut in proportion to the tension as you turn the tuning peg. A round nut slot has the same profile as the string, and will allow the string to travel in the slot more easily when pulled or released by tension from the tuner.

Also if you are using Aquila REDS, a V-shaped nut slot is the kiss-of-death and will cause the strings to break every time due to the hysteresis from the string tension and the friction of the nut slot, V-shaped or otherwise.

One thing to note is that if you file the nut slots, you want the breakpoint of the string to be on the edge of the nut that faces the bridge, and to achieve this you file at a downward angle of about 15 degress toward the tuners. If you do NOT use this angle and the fulcrum of the string in the nut is the middle or back of the nut slot, you will have buzzing, as well as basically and completely skew the intonation into FUBAR because now all of the fret-spacing, calculated to the vibrating string length will be off. Vibrating string length is from the edge of the nut that faces the bridge, to the edge of the saddle that faces the nut, for a tenor, this is typically ~17" in imperial units. I will let the math mavens convert to metric. :)

DownUpDave
11-09-2016, 01:43 AM
Good catch Booli, I was thinking the same thing. Putting tenor strings on a tenor then tuning them all the way down to reentrant baritone tuning will give you intonation problems for sure.

jimavery
11-09-2016, 01:47 AM
Funny you should mention the dGBE tuning. On one of my soprano ukuleles the intonation is awful when tuned GCEA, but pretty good when tuned ADF#B.

Having said that, I'm with others on this thread - most likely the action is too high at the nut. I had that problem with an Ohana ukulele until I asked my local luthier to file the slots down a little.
I'm sure it's not your problem here, as you don't suffer the same problem with your other ukes, but it's worth mentioning that when fretting a chord one shouldn't press too hard. I confess I'm still un-learning that myself!

WhenDogsSing
11-09-2016, 07:13 AM
I use automotive feeler gages when filing nut slots. I have found that nearly every instrument I have checked out has frets that are .035" high above the fingerboard (crown height). I will add .005" to that and get .040" worth of feeler gages. I usually use a .025" thick gage and a .015" thick gage to come to that thickness. You stack these together and slide them under the strings right up to the nut and start filing away in each individual nut slot until your file reaches the top of the stack and PRESTO, you have reached a bottom nut slot height of .005" above the first fret. Works every time and you don't have to worry about filing too deep. You can buy a set of feeler gages at your local auto parts store for under $5.

You should check the crown height of your frets before you start filing. As I said, every instrument I've seen has frets with crown heights of .035". I have found that .005" string clearance over the first fret works great for me.

mrStones
11-09-2016, 11:54 PM
Actually you want a ROUND nut slot, a V-shaped nut slot will usually bind the string in the slot and cause new problems such as not allowing the string to be pulled past the fulcrum of the nut in proportion to the tension as you turn the tuning peg. A round nut slot has the same profile as the string, and will allow the string to travel in the slot more easily when pulled or released by tension from the tuner.

Also if you are using Aquila REDS, a V-shaped nut slot is the kiss-of-death and will cause the strings to break every time due to the hysteresis from the string tension and the friction of the nut slot, V-shaped or otherwise.

One thing to note is that if you file the nut slots, you want the breakpoint of the string to be on the edge of the nut that faces the bridge, and to achieve this you file at a downward angle of about 15 degress toward the tuners. If you do NOT use this angle and the fulcrum of the string in the nut is the middle or back of the nut slot, you will have buzzing, as well as basically and completely skew the intonation into FUBAR because now all of the fret-spacing, calculated to the vibrating string length will be off. Vibrating string length is from the edge of the nut that faces the bridge, to the edge of the saddle that faces the nut, for a tenor, this is typically ~17" in imperial units. I will let the math mavens convert to metric. :)

Hi Booli, thanks for this food for though. To shape the nut as a V while lowering down was an advice one guitar luthier I know gave me, but your statement make a lot of sense.

Dan Gleibitz
11-10-2016, 01:04 AM
V shape is fine, as long as the lowest part has a curved/rounded bottom slightly larger than the string diameter.

Tootler
11-10-2016, 09:31 AM
File down with a triangular needle file then finish off with the fine end of a round one to round off the bottom of the slot.

I like the feeler gauge tip for getting your nut slots the right height.

southcoastukes
11-10-2016, 12:28 PM
One of my tenors goes one or two marks sharp, on all stings, (on my Snark) at the first fret and doesn't recover but doesn't get much worse up to ~12.

I guess I should try some south coasts.

Jack,

The problem you describe above (sharp and progressively sharper) has to do with your saddle being too high. If the strings are off equally as you move up, then the angles on the top of the saddle are good - just reduce the height with a flat sanding from the bottom. If one or more strings are sharper or flatter than the others, start by compensating the top of the saddle (angle toward the back for the sharper strings, and or toward the front for the flatter ones). Then once they are all sharp to the same degree, string to string, go back and sand flat across the bottom until they aren't sharp anymore.

Adjusting the nut can help - you can do that first as others have suggested, but that only makes things more comfortable and improves intonation in the first positions. It won't make a dramatic improvement, so don't take it too far. Without working the saddle you'll still get sharper going up the neck. Worst case, if you've taken the saddle down and are still sharp, then you've got a bad neck angle. Time to throw in the towel on an inexpensive instrument.

But if it works out, you'll be lowering your action with all this; then as others have also suggested, you'll definitely need higher tension strings for a G tuning. Lower action and loose tension will likely start to give you some buzzing.

Finally, and most importantly, before starting any of this, get a set of strings that gives you the sound you like with a nice firm tension! Always find your strings before adjusting your bones. Listen, feel and play a bit first without regard to buzzing or intonation. It makes no sense to set up an instrument for a set of strings that aren't right for you to begin with.

And the Southcoast idea is a good one.

JackLuis
11-10-2016, 02:44 PM
Jack,

The problem you describe above -[/U][/I]

And the Southcoast idea is a good one.

What would you suggest for a dGBE Tenor and lesser tension for an unwound set? The D'Addrrio Carbons I'm using sound 'fine' if they weren't sharp. I like the lower tension but they could be tighter.

How much variation can be expected up and down the neck +/- cents?

southcoastukes
11-10-2016, 04:45 PM
What would you suggest for a dGBE Tenor and lesser tension for an unwound set? The D'Addrrio Carbons I'm using sound 'fine' if they weren't sharp. I like the lower tension but they could be tighter.

How much variation can be expected up and down the neck +/- cents?

Jack,

There is no reason to expect any variation at all.

Strings aren't the primary problem you have. It's set-up at the minimum (hopefully nothing worse). I don't have your instrument in hand so I can't give you definitive set-up parameters; for instance, I don't know about the strings you have on there now nor how much saddle you have to work with. If you don't know how to work bones, it's best to get started. If you make a mistake, bone is cheap and mistakes are part of learning. Tools are a great time saver, but to get started all you need is sandpaper.

Take a look back at my post. It's doubtful you can resolve this with a low tension. A lot of times people go to lower tensions because string to string tension is uneven on single material sets. When you take the trouble to mix materials and get sound and feel even across the fretboard like we do, then almost any tension can feel comfortable.

And finally, if you take a look at our tension charts, you'll see that the plain string sets rated for that tuning are going to be less than firm. If you prefer plain strings and loose tension, then my guess is that you might as well give up now on this paticular instrument. Sounds like on this one you'll need lower action to improve your intonation, and to then keep from buzzing you'll need something more than low tension.

southcoastukes
11-11-2016, 04:55 AM
Jack,

The problem you describe above (sharp and progressively sharper)

Woops!!

Didn't read carefully enough!


One of my tenors goes one or two marks sharp, on all stings, (on my Snark) at the first fret and doesn't recover but doesn't get much worse up to ~12.


If you aren't getting worse as you go up the fretboard, then a nut adjustment alone may very well take care of your troubles. You had some good advice already on that. Sorry for the detour.

But bear in mind that once you take things down at the nut, you may need to do the same at the saddle to keep the string angle from changing.

jer
11-11-2016, 05:49 AM
More times than not, if it's sharp at the first fret it is the nut. If it's sharp on down the board, it can be the saddle. Maybe your instrument could use some work on both sides of things.

Someone mentioned not pressing too hard. Good call. I've been playing stringed instruments for over 20 years and I STILL have to be mindful of this sometimes with ukes especially. Lower tension strings are A LOT easier to pull sharp simply by pressing too hard. You have to develop some great touch to keep that intonation in check.

There is one other possibility, which is the worst scenario. That would be that the bridge on your uke is located in the wrong place. Considering it seems like the intonation is consistently off, this is possible. It'd be ideal if you could take that bridge and move it back about 1/16" of an inch and test that. Of course that isn't possible with fixed bridges.

There is one other solution to that that can be done in addition to lowering the action, OR simply in place of lowering the action if you like the current string height.
That would be to sand the top of the saddle so the strings break point moves back some.
You'd need to remove the saddle and sand the top side that would be closest to the headstock at around a 45 degree angle, as a good starting point. Then round over the top. The thickness of the saddle will determine how much you can move the break point back. I usually just tape a piece of sandpaper to a flat table and then hold the saddle and run it back and forth over the paper. Don't apply a ton of pressure, let the paper do its job. Don't forget to round over the top a bit after finishing. I'd suggest a super fine grit for the very top after finishing. You want that to be as slick as it can be. I usually just hold the saddle and work the paper carefully back and forth over the top and sides near the top with a motion that rounds it up. It usually doesn't take much.

I'll attach a little crude drawing I just did of this in the Windows Paint program, because I'm not sure if I'm doing a great job explaining it with words. Maybe it'll help.

A little thing that helps me remember which way to move a saddle to compensate for intonation problems is: Flat is forward, sharp is back. I remember that flat needs to move the saddle forward since "flat" and "forward" both start with an "f". ha. By "forward" I mean towards the headstock. So sharp, like in your case, is back. Maybe a silly little thing there, but maybe someone else out there thinks like me and that'll help.

Click on the pic and it should enlarge:
95599

Keep in mind, as some others have already noted, switching to a different string set can change all these factors. Ideally, an instrument is setup with a particular string set in mind and you stay with it. I think that was worth repeating. Also, as strings age things change a bit too.

JackLuis
11-11-2016, 07:42 AM
Well I haven't had this uke adjusted at all, I took it to my local shop but the guy there said the action was about right, he didn't check intonation and since I hadn't either and it was still in C tuning so I was happy. However in the last ten months I have developed a more acute sense of hearing(?), and with the key shift to G, which I really like, I was looking for how to 'fix' this uke as well as I can.

My saddle is only ~3mm wide, so at most I can move the break point about 1 mm, is that really enough to change the tuning a couple of cents? In % of scale, 1 mm is not much.

String height at 1 is only about 1 mm and 12 is 2.5mm so I'm reluctant to change things until I find strings that provide better feel.

Booli
11-11-2016, 08:16 AM
Well I haven't had this uke adjusted at all, I took it to my local shop but the guy there said the action was about right, he didn't check intonation and since I hadn't either and it was still in C tuning so I was happy. However in the last ten months I have developed a more acute sense of hearing(?), and with the key shift to G, which I really like, I was looking for how to 'fix' this uke as well as I can.

My saddle is only ~3mm wide, so at most I can move the break point about 1 mm, is that really enough to change the tuning a couple of cents? In % of scale, 1 mm is not much.

String height at 1 is only about 1 mm and 12 is 2.5mm so I'm reluctant to change things until I find strings that provide better feel.

yes your hearing may improve to become more discriminating and to be better able to sense smaller increments in pitch over time, mine certainly has, and I simply cannot and will not play an instrument that is more than +/-3 cents off in the intonation

also, yes 1mm is enough to alter the intonation, and on tenor scale with strings of about 11lbs tension each, I have seen the 1mm shift in the string break-point (fulcrum) over the top of the saddle effect the intonation as much as +/- 3-4 cents on the tuner, and the change is more pronounced with strings that are higher tension and LESS pronounced with strings that are lower tension.

Keep in mind that if you plan to do any heavy strumming, lowering the action at the 12th fret to less than 2.5mm is likely to cause string buzz due to the arc of the string hitting the tops of the frets when it is vibrating after strumming, the string needs room to vibrate in a sort of parabolic ellipse both above and below the line of how it lays when it is NOT vibrating...

jollyboy
11-11-2016, 08:59 AM
String height at 1 is only about 1 mm and 12 is 2.5mm so I'm reluctant to change things until I find strings that provide better feel.

1mm above the 1st fret is pretty high. I would think about dropping that down half a mill as a first course of action. Having said that with your current tuning the low string tension might mean you get buzzing where you wouldn't normally (with regular GCEA tuning).

Dan Gleibitz
11-11-2016, 10:09 AM
My saddle is only ~3mm wide, so at most I can move the break point about 1 mm, is that really enough to change the tuning a couple of cents? In % of scale, 1 mm is not much.

Yes, it's enough. Think of it in 1200ths of half your scale, and you get a bit more than 5 cents per mm.


String height at 1 is only about 1 mm and 12 is 2.5mm so I'm reluctant to change things until I find strings that provide better feel.

Good thinking. Get the right strings on there first. But 1mm above the first fret is still a bit high. So long as you don't take it so low it buzzes on the first fret, any reduction will help your cause. Have a look how low the string sits over fret 2 when you press down at the first fret, or over fret 3 when you're pressing at fret 2 - that's all you _need_ at the first fret. Anything higher is just caution/margin for error.

Get the new strings on, settled and tuned. Then file the slots one at a time. Lift the string and set it in an adjacent slot, or off the end of the nut. File a tiny bit from the bottom of the slot. Be sure to angle the file so that the highest point is where the string leaves the slot (fretboard side). Flip the string back into its slot. Test it. Retune if needed. Rinse and repeat.

I think you'll feel and hear the results immediately, even after taking that first tiny bit off.

And finally once you've fixed the nut end, then check whether you need to adjust the saddle as well.

JackLuis
11-11-2016, 12:16 PM
Thanks guys. I'll play it like it is for a while, I have other real life projects that are taking my time. The intonation isn't too bad, to my hearing, yet. I had Worth Brown Fats on this uke and while I liked the tone, I like the D'A Carbons better. Fremont has a set for tenor dGBE I may try them as they should be higher tension. Since I have six other Ukes to play a couple of cents sharp doesn't get me too excited.