2 Questions About a Recent Build

I recently finished a soprano. It has two issues for which I'm hoping the group might offer some direction. 1) The A string sounds a little punky, doesn't resonate as long or loud when played open as the others do. It is a bit better when played fretted, but I'm not convinced even then that it resonates to the same extent that the other strings do when fretted. My first inclination was that it is a nut problem. The slots were cut using nut files, so they are rounded at the bottom. The slot is shallow on the A string, i.e., the string does not sink into the nut very far. BTW, what's the rule of thumb for this, all other things being equal. What I'm asking is does one want to have the strings fully in the nut or the slot just deep enough to keep the string from popping out notwithstanding the other concerns about height of strings or nut in general? Since the string also sounds thin when fretted, it may not be the slot at all. Any other suggestions?

2) The C string buzzes a lot. It does so when played open and between the 1st and 4th fret, then again further up the neck. I've checked the frets for level and can't find any rocking with a straight edge, plus it buzzes open. I don't think it's the nut because it buzzes in the same way when played fretted, as I've said. I don't know if it's the saddle, or (I'm hoping not) a loose brace or bridge plate. I don't hear any noise when I tap the top. If it is something loose, how do I go about figuring that out and then fixing it on a soprano uke?

Thanks in advance for your help.

Here is a quote from MBU in the past about the c string. I'm sure pics will help. How's the bridge angle? I know that I had one where there wasn't enough so the string moved too much...anyways, here's the quote.

Forget about geometry and math for a second. I agree with Aaron in that I'm doubtful the buzz is from the saddle. I know that it sounds like it's coming from the bridge but it's more likely vibrating against one of the frets due to uneven frets, insufficient relief, improper tension of the string, etc. The C strings is always the most problematic due to it's thicker diameter and wider vibrating arc.

nongdam said:

Here is a quote from MBU in the past about the c string. I'm sure pics will help. How's the bridge angle? I know that I had one where there wasn't enough so the string moved too much...anyways, here's the quote.

Forget about geometry and math for a second. I agree with Aaron in that I'm doubtful the buzz is from the saddle. I know that it sounds like it's coming from the bridge but it's more likely vibrating against one of the frets due to uneven frets, insufficient relief, improper tension of the string, etc. The C strings is always the most problematic due to it's thicker diameter and wider vibrating arc.

Click to expand...

Thanks. The bridge angle, if I understand to what you refer (the break angle of the string over the saddle?), should be okay, I've made about half a dozen just the same without trouble. I have not rounded the saddle at all (it's flat on top) and perhaps that is affecting the way the string contacts with it, but it is only a problem on the C string. The quote may be right, however, because I have a troublesome buzz when I use Worth strings and a real nasty buzz with heavier gauge Aquila strings. If "insufficient relief" has to do with the height of strings above frets, that shouldn't be it - it's about 3mm at the 12th fret. If it refers to the height of the saddle above the bridge, that should be fine too, there's lots of clearance. I'm not sure what to do about the possibility of improper string tension.

Any ideas about the A string issue?

The first thing I would do is to shape the top of the saddle so the intonation is correct. The saddle top should not be flat, this could cause all the strings to rattle and buzz. Next is to make sure the nut slots are wide enough for each string and that the string is in contact with the bottom of the slot. The string slot on the nut should also be slightly slanted back so the string is resting on the nut next to the fingerboard, and not in the middle somewhere. If the height of your string is good, doing all the above should correct all the problems. Let us know.

BlackBearUkes said:

The first thing I would do is to shape the top of the saddle so the intonation is correct. The saddle top should not be flat, this could cause all the strings to rattle and buzz. Next is to make sure the nut slots are wide enough for each string and that the string is in contact with the bottom of the slot. The string slot on the nut should also be slightly slanted back so the string is resting on the nut next to the fingerboard, and not in the middle somewhere. If the height of your string is good, doing all the above should correct all the problems. Let us know.

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Thanks, Duane. The nut slots are angled down toward the headstock, slightly, but the A slot is so shallow in may not be sitting right. I think the saddle may be the biggest offender. I'll give you suggestion a try and let everyone know.

It's 4:00 AM and this thing is keeping me up. So, I look at the saddle again. It is angled slightly down toward the tail and the back edge is softened, but what I meant by the top of the saddle being flat is that it is not rounded and the front edge is sharp. Then I play the C string and the buzz is not there any more. Then I play it hard, then harder, and the buzz comes back, barely. Aaaagh! The A string is still punky. I do think the saddle and the nut need work, as Duane but now I'm tired and cranky about this and I don't want to attack the thing in this frame of mind. I'll work on it again next week, when I've got a better attitude, and post again.

Sometimes it's best to let them sit for a week before loosing any sleep over this. It's going to take a bit of time for the instrument to adjust to it's new stress's and tension. I find many times that a buzz or what not that drives me mad in the initial stages just vanishes after a week. But also at times when I think everything is sweet, a week later something might pop up on another instrument that will need some attention.

You have to be systematic trying to track these things down. Eliminate things that are possibilities until there is only one or at the most two likely causes. If it buzzes on an open string, and sounds the same when you fret the same string, then it's not the nut. So systematically check each fret by moving up the fret board.

If it's a saddle causing the problem then if it's possible for you to press the string down a little firmer on the saddle with say your thumb nail while plucking the string, and the note is cleaner then it's most likely a saddle problem. Deal with the round over of the saddle. Making a nice clean contact area.The C string is the worst problem being thicker it doesn't want to bend cleanly over a too wide contact area without some issues possible presenting themselves.

If there isn't a good clean contact on the saddle you can also have a dull or dead sound to a string. Same solution to the one with a buzz on the saddle. Make that beak over point a nice clean contact.

I've also had saddles that were not making even contact on the bottom of a saddle slot causing a buzz that were really difficult to track down. At least the first time. Now I know that if the other solutions don't address the problem then I need to pop out the saddle and check the slot and bottom of the saddle to make sure of a good fit.

Let us know how you go.

Duane and Allen have covered the bases pretty thoroughly. FYI, relief refers to the straightness of the fret tops (or fingerboard, if you like). If all the fret tops are perfectly level with each other there is no neck relief. Negative relief is a back bow. Big trouble there. If a string is fretted at 1st and 12th frets and there is a gap between the string and the middle frets, then you have positive relief. We generally try for zero relief, but some instruments just don't like it. Or rather, a fret that is just barely too high can cause buzzing but may be hard to locate. Building in a bit of relief is fine and will usually keep you out of trouble if weather changes cause the neck to move. A good straight edge that's the length of the fingerboard (and careful examination) is useful for checking relief. A shorter one may not disclose the problems.

Thanks, John, Allen, and Duane. All of this is very helpful and informative. I know how to proceed and am at least a little more confident about everything. You guys are a tremendous resource and I really appreciate it.

Okay, I'm ready to update. Thanks again, guys, for your replies. As you will see, they helped...

First, I wondered if the saddle was not fitted properly. It fell a little loose, not falling out looks, but easy to pull out loose. So, I put a little CA on one side ... I know, but it was just to find out if that was the source of the problem. I restrung the ukulele. Alas, still buzzing at the C, punky at the A. So, I changed strings (again) just to make sure it wasn't the strings. Hooray, no buzzing at the C, but the A was still punky. Then after about an hour of noodling around,
the buzz came back on the C.

Next, I followed Duane's recommendation and worked on the saddle a little, compensating it to proper intonation realizing I would have to do this anyway. Tightened up the strings, voila, proper intonation - still buzzing, still punky.
However, now the problems were only apparent when the stings were played open. I figured, then, the source of these problems had to be at the nut, then, or possibly even the tuners. I had checked the frets for level, anyway.

Although I had used the same nut file on other ukuleles without problems, it seemed reasonable to me that the A string slot might be a little too tight. I opened it just a little, and the sound improved. On to the C. I held first the nut and then the headstock at the tuner to my ear as I played the C open. The buzz was loud at both, but a little louder at the nut itself. Further, holding the tuner had no effect whatsoever. The slot was angled down toward the tuners. I pressed the C string down between the nut and the tuners as I played the C, and the buzz went away. I had used different tuners on this ukulele. Upon examination, I saw that the stem of the tuners was higher than on the other tuners I had been using. That is, the parts of the tuner between the headstock and the stem, overall were higher, so the angle of the string to the nut was not as steep. I rewound the string in such a way that it was as low on the tuner stem as possible. The buzz was gone.

I can only conclude that I had angled the slot too much and that the string was buzzing against the top part (headstock side) of the slot. It's still kind of odd to me that regardless of the strings I used, the buzz didn't start until I played the ukulele for a while. In other words, it happened once the strings began to settle in and not the other way around. I do have some room to cut the slot closer to level, but I may wait a little to make sure the buzz doesn't come back.

Thanks again for your input. I learned a lot.