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Posted
This was posted over on the OLF and just thought I would share - great examples of what a good guitar top should sound like when you tap it (before bracing).

NPR clip from TJ Thompson

Then - the whole idea behind brace shaving is to get as close as you can back to that nice ring.

Thanks. I had always wanted to hear what tap tone sounded like.

Posted
That was a guitar top? It sounded like a drum, that was surprisingly vibrant.

Most people have the misconception tap tone is a tone. maybe they should have renamed it.

Nice link. I believe he is taping finished tops including braces as that is when you tune a top and can get tone like that. Not mentioned in the broadcast.

Posted
That was a guitar top? It sounded like a drum, that was surprisingly vibrant.

Most people have the misconception tap tone is a tone. maybe they should have renamed it.

Nice link. I believe he is taping finished tops including braces as that is when you tune a top and can get tone like that. Not mentioned in the broadcast.

Yes that's what I was thinking too, I was under the impression in the beginning that it was just the wood but before bracing it sounds nothing like that.

Posted

After listening to this I feel that this article is very misleading because he isn't explaining what he is hearing very well at all or how it might play into the finished instrument. The way he leaves the article by tapping a piece of wood and then playing a guitar made 70 years ago offers nothing substantial to our understanding of how any of it relates to guitar building. The topic of tap tuning is misleading enough without this.

And this article is not about tap tuning. At best it is about wood selection.

This technique is mostly about wood selection but that again is meaningless without the experience to understand how each piece fits into the overall tonal picture (which is not discussed). All this guy is doing is selecting wood based on what he thinks he is hearing. But since he never explains his goals in detail I can only assume that he is just following a recipe. To begin with those are very unrefined tap tones and do not have the dynamics of a braced top. Nor does he tap around the board to show how the different ares shape the tones (you would also need to see that). So the information present is very raw and vague. If you do not have a audio-vision of where you are going then the tone you hear from a piece of wood won't help you. It is all about how certain natural characteristics fit together to make a complete tonal picture. And that takes guesswork at first and the experience of how your guesses pan out. That takes building many guitars before it starts to make sense.

Thanks. I had always wanted to hear what tap tone sounded like.

This isn't difficult. Take any piece of wood and hold it 1/4 of the way down and 1/4 of the way across and tap it in the opposite corner. That's the natural fundamental of that piece. Hold it 1/4 down and 1/2 across and that is the octave. It is extremely important to note that these tones are of the piece in it's current dimension. It will change as soon as you cut, scrape, slot, brace, glue, route, etc. You really won't be able to tell much about tap tones of raw materials unless you tap it at every step of the way and hear how the processing of wood affects this tone.

This is just the beginning of a huge topic of discussion.

~David

Posted

Thanks for you insight David. I've used two methods, one by holding it as you mention and tapping with my finger to get a rough idea of the resonant quality of a certain piece of wood (in it's current dimension). But more useful is comparing two pieces of the same wood in similar dimensions (ie. two neck blanks), to give me a much better idea of the more resonant of the two. Some just sound dead, and some ring like a bell.

The second thing I've done is to tap a tuning fork and hold the ball end to the wood to once again compare between pieces or even different woods. I've found especially with body woods, you can discern a lot about a hunk of wood and what it may do with strings attached to it.

David, I have one question for you since you have far more building experience. Regarding the first method I mentioned, have you ever had two pieces of the same wood (lets say neck blanks) where one tapped very resonant and the other not so much - then after dimensioning or rough carving the tones changed dramatically so that the less resonant became MORE resonant? I have to think that there is an inherent resonance to a piece of wood that doesn't change to this degree.

Posted

komodo, I have taken two pieces of the same species and dimension and had very different results as well. I have some mahogany that rings like a bell and some that doesn't at all. But I have never had a piece become more resonant after processing it. In my experience I have found that certain qualities (resonance, sustain, bell-like chime) are inherent in each piece and do not change much with processing. This is why it is important to hand select the woods you use. It's all subjective and impossible to special order.

The tuning fork method is very interesting. I have tried it a few times and find that I am now using it along with a finger tap. The tuning fork is vibrating metal and like a string it provides a metallic resonance and a driving force. It's a good method in my experience.

~David

Posted

I will bet that there are plenty of folks who would like to build an acoustic instrument but haven't yet - and have never heard what a top sounds like.

I've been interviewed by NPR before - their intention with a piece like this is not for it to be a tutorial, but rather to give the uninitiated a taste - a rough idea - of what goes into an acoustic instrument. I think it does that.

Posted

I saw a simillar thing on tv with Wayne Henderson tap toneing a peice for one of his acoustics. I suppose at the very least it helps someone who is just starting out and idea of what people mean by the phrase tap tone, and also and example of what they should be searching for

Posted
The tuning fork method is very interesting. I have tried it a few times and find that I am now using it along with a finger tap. The tuning fork is vibrating metal and like a string it provides a metallic resonance and a driving force. It's a good method in my experience.

I have used my tuning fork mostly on tops, and once again unless comparing directly against another board you may not notice anything. I've got some maple tops where one will ring and another will resonate like a bell. What I wonder is that after dimensioning you might change the resonant frequency of a piece of wood and it may not have that same bell like quality? Maybe the tuning fork was hitting a resonant frequency for that particular piece of wood in its current dimension? My heart says no, as there are other inherent qualities to that piece of wood and why it rings so well.

David we discussed his a bit over email talking about the piece of Madagascar rosewood I had for my personal uber neck. I decided to go ahead with the carbon bars and am shaping it now (I work VERY slow). It seems to have all of it's qualities intact, but maybe it's resonant frequency is raised? I did mess up a bit on fretting and cracked my inlay, but I'm not too worried.

Jeff

Posted

For a given material, the resonant frequency of a solid object depends only on dimensions and density. If it "rings" you may change its "ring tone", but you won't change the fact that it rings.

But glue on a drop top, or a fretboard, and yes you may (or may not) lose the ring. But its still better than the piece that doesn't ring.

Posted
For a given material, the resonant frequency of a solid object depends only on dimensions and density. If it "rings" you may change its "ring tone", but you won't change the fact that it rings.

But glue on a drop top, or a fretboard, and yes you may (or may not) lose the ring. But its still better than the piece that doesn't ring.

I have a REALLY nice piece of Madagascar Rosewood, and it rang like a marimba bar. This made me second guess putting CF bars in it, as I didn't want to lose any of it's character. David suggested that the CF bars would not ruin anything but stiffen it, eliminate dead spots and raise the frequency to avoid wolf tones. Correct me if I'm wrong on this David. I decided to go ahead and put them in, and so far it's still an awesome neck.

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