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Yes, they could use as their frame of reference that one song by Metallica that had a classical guitar for 30 seconds in the intro. The classical masters could play that one 30 second part, and the listeners could decide whether the tone was good or bad based on how closely the guitar matched the recording.

People ALWAYS listen for what fits their expectation.

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Old growth, shmold growth!

This probably won't surprise anyone:

I've done these sort of tests, not always "blind" or fully controlled, but one thing always comes through. If there's a really nice guitar in the set, everyone picks it, whether experienced, half deaf or whatever. Doesn't matter whether it's SS or classical, there always seems to be a consensus around the really nice one. And ask them what they like about it, everyone will tell you something different!

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

They probably used a master grade concert classical for that 30 second Metallica intro.

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Old growth, shmold growth!

You might be onto something there.

Reversible multiple scale fretboard! Me likey! =)

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Jim Hansen

I've been off this list for 'way to long (computer trouble!), so please forgive me if I hark back to the 'string forces' bit.

I spent 'way too much time a few years ago measuring the forces that a string puts on the saddle top. I did so because I have weak math chops, and didn't want to simply cite Fletcher and Rossing without being able to back it up. You can see all the gory details on my web site: look on the 'Acoustics' page for a paper entitled 'String Theory' (I simply could not resist...).

I learned several things. One was that strings may be the simplest part of the system, but they're NOT 'simple'.

I realized that the way we usually talk about vibrating strings; the itterative sum-of-all-the-modes thing, works nicely for the usual sort of simplified mathematical treatment that pleases physics text writers, but it's not as useful for luthiers. For one thing, we're often a lot more interested in the non-linear stuff that's really hard to include in the math (like the tension change!), and, for another the actual way the string tugs on the bridge becomes a lot clearer if you use a 'time domain' view rather than the usual 'frequency domain'.

The most important thing I learned, though, was that F&R are (pretty much, within the limits of linear math) right. In general, for practical strings you would use on guitars, the 'transverse' signal greatly overpowers the 'tension change' one on the bridge top. When you add in all the other considerations that have come up on this thread (monopole motion vs torquewise, etc.) it makes no sense to try to maximise the tension change mobility/long dipole in that respect (there are other reasons for liking a long dipole, of course, but it's not a primary power producer over most of the guitars range).

Just to finish up beating the dead horse: tailpiece guitars can't be effectively driven by the 'tension change' signal. They ought, therefore, to sound an octave lower than 'fixed bridge' guitars with the same strings. The fact that they don't (compare Leadbelly's Stella 12 with a tailpiece and ladder bracing with, say, Leo Kottke's Taylor with a fixed bridge) shows that both are being primarily driven in essentially the same way; by the vertical component of the transverese force. There are more 'scientific' ways to show this, of course, but it's a guitar list and people want things they can hear.

I'm sorry to be belaboring this point. Partly, as I say, I just was not able to get into the site when it was the active discussion. More important, though, is that this is _such_ a widespread misconception, and so tenaciously held. Any time I can strike a blow for 'truth and justice', and so on, I try to do so. I know it won't change the minds of the true believers, but I keep hoping to get someplace with everybody else.

Well, I'm convinced.
Part of it is, once the math and energies are explained, guys like me then think to themselves, "Okay, that's how it looks on paper, but what does it look like physically on the instrument?".
The reason the "saddle rocking" held so much appeal for me is because it seemed like a mechanism that worked with what I thought the mechanical effects of the string should be.
The problem was, and nobody could really explain it to me because they can't read my mind, hence the long discussion and multiple explanations until it "clicked", was that in my head, I was picturing the top of the guitar as being relatively stable, and the string saddle mechanism was torquing the top inducing a twisting sort of vibration.
What was missing from my mental construct, was the fact that the top of the guitar is actually hinged ALL AROUND THE PERIMETER of the guitar, and able to be leveraged up and down as well since wood is somewhat elastic, kinda like a drum head, except the wood is not being tensioned, it simply has a measure of stiffness and elasticity built in. The link I provided to the string vibration model also has drumheads on the mainpage, which also got me thinking. Looking at the physical string model, thinking about drum heads, and reading Trevor's explanation again, solidified in my mind that when the transverse force distorted the string upwards, the string is actually tugging upwards on the saddle assembly, and when the string is distorting downwards, it is tugging the top downwards as well, inducing an up/down movement of the entire soundboard at once. This is also due to the fact that the string is anchored to the soundboard at the end of the string. I kinda picture the string as having a whip-like effect on the soundboard, except the string is anchored to the soundboard, so the string is not free to "whip around", so it pulls the soundboard in whatever direction it would have gone, in a cyclical fashion.

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Old growth, shmold growth!

Talking of the top as a drum head leaves you in grave danger of falling into banjo territory.

Hmm. (emphasis added)

I thought I made a clarifying distinction......

I think part of the problem with these forums is that people don't always read or try to fully understand a post before responding (myself included).

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Old growth, shmold growth!

There's been lot's of great posts on this thread so my thanks to everyone who's contributed.

Now, just when you thought it was safe to go out and pluck a string, has anyone really thought hard about how a wave travels across a soundboard, so producing radiated sound?

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

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MK5acoustics.com

Yes, some of it is just different language. But there's also an inclination to pick on just one feature of the sound whereas there are usually multiple causes and people will pick different ones. There's also often the "give 'em volume and they hear tone" problem. One that rarely comes out and that I always find to be a feature of a great guitar is how in-tune it plays. So many guitars are quite a way out for many different reasons and whilst it may not be immediately obvious that there's background dissonance and inharmonic partials, a guitar that plays really nicely in tune is like a cloudless day.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Trevor Gore wrote:
"One that rarely comes out and that I always find to be a feature of a great guitar is how in-tune it plays."

If you ever feel the need to demonstrate that one for yourself, put a properly compensated saddle on a 12-string. Suddenly you'll realize how bad most of them really sound.

Al, thanks for chiming in; I absolutely agree with you. It is the basis behind my Ascent Series guitars which use Ned Steinberger's bridge concept. Unfortunately when Acoustic Guitar did my interview, they got it wrong on editing. There was a correction online and in the following issue. In using the Steinberger bridge, I chose to have some break over angle to exert about 10-12# of static downward force on the top. Bracing for this put the ring+ mode in the "normal" range for a guitar. But the point is that the excitation predominately results from the vertical component of the transverse force and not by a rocking motion. Moreover, it is the dynamic force that is important, not the static force. Ned also agrees with this.

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Randy Muth
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