How I got my K brand uke back for 50c

A big swoosh of appreciation to the forum for really helping me solve a (very worrying) problem.....
I managed to materialize a beautiful Hawaiian made tenor, after years of yearning. Everything is exquisite on this uke - the koa, the build, the intonation... and every note rings like a bell, EXCEPT ONE - the D note at the 2nd fret on the C string. That's D for "Dead note" - a lifeless thud that I tried and tried to ignore but it just kept coming up (don't we do that in all our really meaningful relationships?)
Anyway, I tried all manner of fixes over the years, till I really faced up to the issue (the first step in moving forward) and did some research on dead notes in acoustic instruments....I was almost ready to go in search of another uke until, after searching through UU, I was able to solve it with an Australian 50c coin and a bit of "bluetak". The coin lives under the middle of the soundboard, just behind the brace. It has moved the dead note to some indiscernible place (could be on Mars for all I care) and left me with an instrument that I can't put down again.
God bless our little ship "UU" and all who sail in her!
Here's the solution:

I used that trick on a couple of classical guitars, and it works. One lost a bit of volume, but it was loud enough already. I had a laminated classical with a thuddy /dead open G string, along with nearly all the fretted G notes. I decided to try a sound port on that guitar, and it eliminated the thuddy G notes completely.

It's good to see that your uke is back in action.

I had thought of a soundport, but it's a radical move with random possible results - although I was frustrated enough at times to get out a power drill and rip in.
The eventual outcome is beautiful for its finesse...

How did you know where to put the money?

I tried it on several parts of the outside of the top - different coins, multiple coins etc. until I found the right coin and the right position. The best was the 50c coin between the sound-hole and the bridge. For that position it was easy to reach in and stick it on the inside - directly under where I had found the sweet spot on the outside.
I wonder how many of you have found a dead spot on their ukes. Has anybody solved it in the same way?
I can't tell you how satisfying it is to have found such a simple solution. Thanks again for the collective wisdom.

I have the very same issue! Second fret of the C string. I have to give this a try! Thanks for sharing your experience! I really appreciate it.
Randy

No worries Mate.
The Australian 50c coin weighs around 15 grams and is kind of big.
Try a few US coins, and a few positions. Hope it works for you too.

UPDATE
After some more playing I found out where the dead spot went..... up to the G, 3rd fret A string (though much more subtle than the previous D thunk).
A quick change out of the 50c coin for a 20c coin and I'm back in action! I think the trick is to try something, play with it for a while, then adjust the dead note to where it is least noticeable.

So what's the explanation behind all this? Is there some frequency at which the soundboard has an overtone or something that cancels out the note or ?

I'm also interested in understanding this one...

hmm. I/ve not had a uke with one dead note., but I;ve had a few where all the notes were dead and some where one string dominated. this is very interesting.

Explanation? I'm not exactly sure, but as OldePhart said in another thread:

"The issue pretty much had to be either a standing wave in the body or the top vibrating exactly out of phase with the string - either of which would pretty much kill the note.
As for what's going on - I 'm a software engineer not a mechanical engineer but basically when anything vibrates it does so in waves - you can see this if you look at super-slo-mo video of vibrating strings and the like. So, different parts of an object are in different phase relationships to the source (i.e. in the case of a stringed instrument each part of the top is vibrating at some phase relationship to the string). The phase relationship depends on, among other things, the frequency (and, generally speaking, multiples of it are going to result in the same relationship). So, it sounds like what was happening is the top was vibrating such that the part of it immediately under the bridge was very nearly exactly out of phase with the string, thus canceling it. Adding (or subtracting, but that's harder) weight at the right point moves the frequency at which that cancellation occurs. You probably still have a dead spot, but now it is either between notes or perhaps completely out of the range of the instrument (actually, all instruments will have dead spots, it's just that they usually are not within the range of the instrument and certainly not right on a "concert pitch" note)."

at - http://forum.ukuleleunderground.com/showthread.php?80351-A-Dead-Sound-Is-it-me/page3&highlight=dead+note

One could probably do more research on the net, but I'll take his word for it

From my research over the past several years (reading research others have done), stringed instruments have a main body resonance, and it can be measured. If the main body resonance falls on G, all/most of the G notes should sound thuddy or dead. They're not weak notes, but rather strong notes that have little sustain. Luthier Al Carruth has looked at this problem extensively, and concluded that adding a brace or weight to the soundboard is the easiest solution. He suggested the BluTack trick to me, and it worked. It took very little material placed on the wing of the bridge to shift the thud on one classical guitar and that material was then moved to the inside of the soundboard, same spot.

This isn't always without compromises, however. I recently returned a Martin C1K for two reasons, one of which was a thuddy open G string, along with an equally thuddy fretted G note on the third fret of the E string. Putting pressure on the bridge with my pinky while playing the open G string reduced the thud, but also reduced the volume significantly. I had to place a set of feeler gauges on the soundboard to shift the frequency away from G, but that had too negative an impact on volume.

You can google "Al Carruth Wolf Notes", and find quite a bit. First thing you'll find is that we're not talking about wolf notes, but that's what many people call them. Aaron Green apprenticed with Al Carruth, and wrote this:

Any time you have a booming note on the guitar, there is a resonance that is very active around that frequency, not just the main cavity (A0) resonance. Very often what is known as the cross dipole on the top comes in around A.

In any case you have to understand the underlying issue here. Guitars vibrate in many ways all at once. There are innumerable resonances that interplay between the top, back and air inside the guitar. How they all relate to each other is what determines the charecter of the guitar. What makes building such a challenge is that most desireable qualites have a contridictory relationship with each other. Evenenss of response is desirable, so is an expansive tonal pallete and a sound that is intersting to listen to. These two qualites are odds with each other. What creates an even sound is a flat frequency response, all the resonances behaving at the same level. Speak in a monotone voice and you'll get the picture. What creates an interesting sound is a lot of active resonances, what my teacher called "peaky" when we would look at a frequency plot chart (kind of like an EKG moniter).

The real trick is to strike the balance between the two, which is lots of active resonances that behave in a controlled fashion. I tend to think of this desired interplay of the resonances like a bunch of gears. Each resonance is represented by a spoke in a gear. If they all fit together well, when one resonance peaks another one will come and fill the dip it creates. The result is an even response that still has lots of charecter and tonal capabilities. Hard to do to say the least but you only hit as high as you aim.

Some designs lend themselves to one side of this more than the other, lattice and double top guitars can to be very even, but lack the pallete of a "traditional" guitar. And very often you'll see a "traditional" guitar that is quite musical and colorful with some real booming notes, particularly guitars that are underbuilt.

Some uneveness of response, in a new guitar can be expected to take care of itself, if you take the time to really work the notes around the boomer. I have heard it in my own guitars, but it wasn't a glaring problem nor were there dead notes surronding the boomer. I would still have to say though that if you don't like the guitar from the get go, it is unlikely you will like it later.


The Martin I returned had an open G string that I just couldn't live with. Strumming any chord in which the G string remained unfretted, resulted in hearing the G string make a thud. Adjusting my attack to lightly touch the G string did alleviate the obnoxious sound, but who wants to bother with that? If the thud falls on anything but an open string, I can live with it.

Strumdaddy said:

I wonder how many of you have found a dead spot on their ukes. Has anybody solved it in the same way? I can't tell you how satisfying it is to have found such a simple solution. Thanks again for the collective wisdom.

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I had this problem, in fact, it looks like you found the thread where OldPharte suggested this solution to me. Two pennies moved the thud up the neck and dissipated it a bit.

Like you, I was incredibly pleased with this simple solution!

Cheers Frank B

I love these technical threads where I can learn more about accoustics. I'm a biology teacher and love to dabble with the dark side of physics. So I'd heard all about body resonance, and I remember reading somewhere that tenor bodies generally have a resonance around a low G. I didn't realise that these notes might sound thuddy. I have noticed that on both my tenors, F sharp, always sounds thuddy compared to the rest (with very little sustain). So, would I be right to associate this observation with what you are telling me; is the body resonance of both my tenors around F sharp?

It should be around F#, and humming into the soundhole at different pitches will reveal the strongest response. You can set a digital tuner on top of the instrument, and tap it. That should also reveal a pitch response. Al Carruth has a laboratory set up in his shop for these sorts of experiments. Here is a link to his "Corker" guitar:
http://www.alcarruthluthier.com/guitars/corker.htm

Very interesting information that is a bit over my head. I don't play well enough to discern any dead spots in my ukes, but now I may have a better ear out when I'm playing. The science of sound is incredible.

Ukejenny said:

Very interesting information that is a bit over my head. I don't play well enough to discern any dead spots in my ukes, but now I may have a better ear out when I'm playing. The science of sound is incredible.

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I fear that you may now be spoiled forever! Hearing dead notes everywhere, when previously you just played. Sorry about that.

Strumdaddy said:

I fear that you may now be spoiled forever! Hearing dead notes everywhere, when previously you just played. Sorry about that.

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No problem. I always want to learn more, no matter what. Although, I may need to pester you to help me find the fix if I ever do hear any! I was a Jr. High band director, so I'm pretty darn good at selective hearing and completely tuning out or even muting what I don't like. LOL

A friend bought a baby grand piano around 10 years ago. He is quite an accomplished pianist, and had a Christmas party not long after the new piano arrived. Everyone loved his playing, and the piano. We were the last to leave, and after all the guests had left, he told me that this piano was driving him crazy. I had no idea what he was talking about, and he told me to listen while he struck a particular key. It sounded fine to me, but he kept playing it. After about 5 minutes, a buzz/fizzle/sizzle could be heard. He then played a short passage which included that key, and there was no way of not hearing it. His wife was also a pianist, and she didn't even want to deal with it any longer. The piano company sent out 3 or 4 repair techs, and they couldn't fix it. They finally brought a woman in from another state, and she found and fixed the cause of the buzzing.

My new Koaloha has a thuddy note on F. I can live with that, because it's not on an open string. Open string thuddy notes drive me mad.....