Not another stupid question - Part 2; string tension and intonation

thereshopeyet
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Mon Oct 01, 2012 8:47 am

I had a loose bridge on my guitar a couple of years ago.
So I can relate to the tuning issues with a loose bridge.
I got a luthier to re-glue it.
It's Rock Solid now!


michelew
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Mon Oct 01, 2012 6:05 pm

wrench wrote:
michelew wrote:
Wrench,

Thanks so much for responding with such detail. That's very enlightening.

Is there anything I can do to improve the intonation of my ukulele at the lower tuning without making any physical changes (which can't be removed when I want to return to std tuning)?

Crazy idea - would tuning it down another half step and then placing a capo at the first fret help to compensate at all? Obviously you'd need to retune to the desired pitch at the first fret.

I'm open to suggestions. Otherwise I'm assuming I just have to find a tuning of the open strings that gives the least increase in pitch from the desired note at each subsequent fret. That sounds like a trial and error exercise to be sure. Are there any good rules of thumb for dealing with these sort of intonation issues when trying to achieve a good average tuning for a string. For example, should I be aiming to have the tuning exactly at the correct pitch at say the fourth or sixth fret?

Thanks again.

M.
I think tuning down further will make the problem worse because it lowers the tension, which is changing your compensation values away from your current saddle geometry. The capo certainly gets you back to the desired key, but doesn't change the intonation because it doesn't change the tension. If you plan to play frequently in an altered tuning, I would consider a different saddle to use for that tuning. Another approach is a compromise saddle, meaning take intonation measurements in standard tuning and altered tuning, then intonate the saddle in between. Neither tuning will be in perfect tune, but neither will be in worst-case tune either.

Just to clarify a question you asked in your original post about intonation and fret location - no, frets have no effect on intonation. Intonation is strictly a function of string physics and saddle (and nut) geometry.

It sounds to me like your ears of such quality that you can hear these differences. A curse or a blessing, depending on how you look at it. I work on intonation issues for folks, and I readily admit I cannot always hear what they do. In fact sometimes they hear what my electronic tuners can't. On the plus side, straight uncompensated saddles are working just great in my guitars. :laugh:

A tip I will offer if you are messing with saddles and intonation issues is to make sure you have a fast and steep clearance angle on the back side of the saddle. Start this clearance angle just .3 or .4 mm behind the contact point on the saddle. I have seen several saddles where the contact point was mistaken by interference on the back side radius of the saddle. In fact I don't use a radius on the back side - I cut a flat plane for clearance. In fact, as I think about it, try this first, as it may resolve your original problem.
Wrench,

Thanks for all the expert advice. I suggested the capo in case it took the nut and any nut compensation issues out of the equation. Sometimes it takes a 100 crazy ideas before a good one comes along. :)

If I do end up playing the ukulele tuned a step down a fair bit, I will definitely investigate getting a new compensated saddle made. There is a Plek machine in my guitar set up shop and that's what it does (amongst other things) make bone saddles that are specific to the guitar, strings and tuning you play, so that its at its best. But, it's not cheap so I'll wait and see how much I do it first.

The break angle does in fact look very low and no where near as sharp as on my classical. The saddle is also rounded in the direct that the strings cross it. So you may well have hit a couple of the nails on the head there. I'll start looking for ukulele saddles.

As it happens, the tuning and intonation along the neck seems to have improved. I've been away for a few days. It's been colder, perhaps that's affected it. The High G string (tuned down to F) is still the worst affected. It's 20% and 30% of a semitone out (according to my Cleartune tuner) at subsequent frets even thought the open string is at F. At the 12th fret it's 40% of a semitone out. Yikes!

I'll return it to standard some time this week and let you know what happens there. I'll also source a straight bone saddle.

Thanks for your help. You obviously know your stuff.

Michele


michelew
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Tue Oct 02, 2012 3:00 am

And here's a photo of the saddle and bridge.

Image

Image

Update - pitch at standard tuning

Well I've just returned the ukulele to standard tuning and the good news is that the pitch at each fret is darn close to what it should be when the open strings are in standard ukulele tuning. At the twelfth fret that are also very close. The high G has the biggest change.

So yeh!!! my ukulele is OK. phew! B) :) :)

So it's the loss in string tension due to dropping the tuning a whole step that is definitely causing the changes in pitch from what they should be at each fret. Perhaps high tension strings would help - but that would also be a major pain in the butt, having to change strings if I want to be in a lower tuning for a while. Changing to a compensated saddle that I could switch to for dropped tuning would be simpler I think. Hmmm...I think I have a spare classical saddle around here somewhere... :)


willem
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Tue Oct 02, 2012 4:31 am

michelew wrote:
And here's a photo of the saddle and bridge.

Image

Image

Update - pitch at standard tuning

Well I've just returned the ukulele to standard tuning and the good news is that the pitch at each fret is darn close to what it should be when the open strings are in standard ukulele tuning. At the twelfth fret that are also very close. The high G has the biggest change.

So yeh!!! my ukulele is OK. phew! B) :) :)

So it's the loss in string tension due to dropping the tuning a whole step that is definitely causing the changes in pitch from what they should be at each fret. Perhaps high tension strings would help - but that would also be a major pain in the butt, having to change strings if I want to be in a lower tuning for a while. Changing to a compensated saddle that I could switch to for dropped tuning would be simpler I think. Hmmm...I think I have a spare classical saddle around here somewhere... :)

This THREAD is very useful,,,I have wonderings of a few things but first a little story,,,A year a go I bought a new guiter(Tanglewood) and it was very nice to play till I wanted to do a experiment with other strings(clearetone) and that was bad 'cos the bass strings were thikker and i was not happy with it cos my whole pleasant setup action was totally to the moon..so I went to the luthier for other strings and new adjustments,,he told me when I wanted thikker string you must always make new adjustments at it too..now I wonder if you use other tunings its maybe the best way to have that tuning on one guitar and leave it that way and maybe let the luthier do adjustments,,what i mean is,tune it in the tuning you want with the luthiers adjustments..well I don't know,,maybe..

Willem


thereshopeyet
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Tue Oct 02, 2012 8:42 am

Michelle and Willem

When you watch folk use alternate tunings.

That's probably why some musicians have several guitars on stage,
some setup for different alternate tunings.

Thanks.


michelew
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Tue Oct 02, 2012 4:14 pm

Dermot,

I suspect that the shorter scale length of the ukulele makes it more susceptible to changes in intonation than a guitar, basically that the guitar is more forgiving because the scale length is longer and the strings thicker. This may be even more true of steel string guitars since the string tension is so much greater.

I think I'm the only one of this site who talks about their ukulele. Others like Nessa, Suzi, Pierre and Jim are more people of action. :). They just get on with the job of playing and making them sound good. And perhaps the others haven't changed the tuning of their ukes.

When I started reading a bit about compensated saddles, ukes and string types, it seems that intonation can be an issue and people are using compensated saddles for ukes too.

Of course, I know almost nothing about the physics of stringed instruments so there may be other factors at play too.


M.


thereshopeyet
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Tue Oct 02, 2012 5:32 pm

Thanks.


michelew
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Wed Oct 03, 2012 10:02 pm

Hey Dermot!

Whatever makes you happy mate. :)

I'm also a curious soul. And sometimes when you start getting into a subject the info you receive just raises more questions. For example, this morning I read that ukuleles have less intonation issues (potentially) because of their smaller scale (and therefore should be fine with straight saddles). It didn't mention tension. So...

I guess the trick is to take what you understand and then let the rest soak in. You may not get it yet, but at some point it will just start to solidify, the jigsaw will make itself in your brain. If it's making you crazy move on to something else for a while, like playing (note to self). I often find that a new area of study will help me to fill in the gaps I had in another area.

Be sweet to yourself. There's no problem with asking questions. Just don't make yourself crazy by expecting to understand it all at once.

String you up? Haha! I reckon you're doing a good enough job at tying yourself up in knots. Perhaps you should cut yourself some slack. :)

Shel


thereshopeyet
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Thu Oct 04, 2012 4:48 am

Michelle Wrote:
Perhaps you should cut yourself some slack.
Thanks.


michelew
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Sun Oct 07, 2012 2:19 am

Story update. I made a new saddle for my ukulele today. It's not fancy since I only had a hack saw, pencil, metal file, flat diamond file and nail care stuff. But, it's working OK.

It's made from a bone blank, and it's mostly raises the action especially on the bottom strings. The F still isn't perfect but the intonation is a little better I think, probably due to the increased tension. The point of contact on the saddle with the F string (high G) is sitting as far back as it can I think without leaving a sharp edge that may fray the string. The other strings are pretty good along the neck and at the 12th fret.

The sound of the bone is a bit sharper, maybe louder?, slightly more brilliant. I hear ebony saddles give a more mellow tone so I may try that at some point.
Anyway, for a make-shift, low-tech, amateur attempt it seems to be working well enough. The uke doesn't sound so strange at the lower tuning. The action isn't ideal, but it's OK given that it does seem to compensate for the whole step drop. I've uploaded me playing it in the busking threads.

So the experiment is over for the moment. And it's easy enough to change out the saddle when I want to go back to standard tuning. All I need to do is loosen the strings enough to slide the saddle out and the original one back in.

Thanks for the advice again Wrench. If I find I'm uding this tuning a fair bit and playing the ukulele enough, I'll consider paying a professional to make a proper one for me.

Shel


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