Kantare guitars and the "Lens resonance system"

[Mark Day]

Anybody heard of this before? I stumbled across it while googling.

http://www.kantareguitars.com/in/index.php?section=5

[Clay Schaeffer]

I've seen that before. It looks like it would lend itself to CNC and industrial methods of production, but not be conducive to voicing individual plates. I have no idea how it would sound.

[Tom Harper]

The home page on that web site loads a sound clip that I am assuming is one of the instruments using this construction. It sounds good, like a very well made classical guitar. I bet its just like every other bracing system though - you have to control the details and use good wood to take advantage of the characteristics the bracing pattern provides. Yes, how would individual voicing work? Do you glue/unglue the cap and shape the supporting structure?

Thanks for posting this, Mark. I had not heard of it before. I hope they do well with it. I prefer the sound they are getting to other recent changes, e.g. carbon fiber lattices, but that's just me. John Williams seems to disagree and I would hazard a guess that his opinion is pretty well informed. .

[Alain Bieber]

It is amusing for me to note some kind of interest for a strutting system designed around a kind of circular structure trying to set a zone of central rigidity to the top of a classical guitar. It happens I played with that idea some six or more (?) years ago. I found some advantage to that kind of strutting, sustain and separation chiefly, but I was a bit worried about a kind of dryness of the sound, specially in the trebles. As a "very classical guitar sound" oriented guy, after eight guitars built along those lines I returned to a more conventional model.
This was the topic of an experiment shared with my Maestro Thomas Norwood. We called it the ALTHO structure, AL for me and THO for him. Explained in an American Lutherie paper of some years ago, maybe five years.
Amazingly some of the guitars built along those lines, that were not my prefered production, fell in professional hands.. and they liked it much more than me.<g>
A photo shows why I feel the Finnish idea is not far away compared to the ALTHO one. I am aware of the differences too of course.

[Mark Day]

I was just curious. Any time I see some new-fangled idea in luthery I like to see what the good folks here think about it.
I didn't hear any clip on that page, and I would like to hear what these things sound like.

[Alain Bieber]

Mark,
Apparently, the "fangled" idea comes from Liikanen, a rather sucessful guitar maker in his country. The Kantare name is for a linked factory in Asia I guess.
I wish sometimes to have an idea that would allow me to start a business in China <G>.

[Simon Magennis]

I wish sometimes to have an idea that would allow me to start a business in China <G>.

+!

[Simon Magennis]

Liikanen and his guitars have a strong following. The owner of what is probably the best guitar store in Germany (has had Friedrichs, Hausers in stock at various times) got a Liikanen as his personal guitar. I see the Kantare's coming up as recommendations on various forums and never really heard anything bad about any of them.

What Alain's photo and post above confirms for me is that in this craft, it doesn't matter what system you use, it's a matter of how well you do it and the players' or listeners' tastes in sound. Well done, pretty much any system will give a good instrument which will please someone.

[Dave Cohen]

I see nothing in the term "lens resonance system" that evokes any actual physics to me, other than a few physical-sounding words strung together.

The normal modes shape of assembled guitar body modes up to about 1.5 kHz are well known, first determined by holographic interferometry about 40 years ago, and presumably well before that by things like glitter patterns, & etc. Bracing patterns have little influence on the shapes of those lower modes, though they can move the modal frequencies around a bit for some of the modes, sometimes. Those mode shapes are determined predominantly by the shape of the guitar itself. The closest Liikanen & co. could come to making a claim based on physical reality would be that their bracing pattern might tend toward lower effective masses. As I remember it, concentrating mass and/or stiffness toward the perimenter of the plates favors higher effective masses, and Bernard Richardson related lower effective mass to what he called a higher "acoustic merit". According to Richardson and (his then grad student) Howard Wright, a string more easily drives a lower effective mass. You can read a short account in Richardson's May, 2002 CASJ paper, "Simple models as a basis for guitar design", or a more comprehensive account in Howard Wright's thesis. I don't doubt that Liikanen's guitars are well regarded, though I suspect that is more due to his execution that to anything special about the bracing pattern.

[John Steele]

Did a patent search and came up with this:

http://www.google.com/patents?id=h5oRAA ... &q&f=false

There may be more connected to it but they did not show up in my search
John

[Alain Bieber]

THanks John,
So this is the thing that was patented. Originally, it seems to me a bit in the vein of the Dammann-Wagner ideas which logically met large sucess in Central Europe. But no Nomex. I suppose an important thing, that I personally overlooked in my experiment is to complement that kind of stucture with very very thin rims, both for spruce and cedar tops.
Osmo Palmu, a Finnish guitar player plays a Liikanen (but no idea what kind of Liikanen) on You_tube.

[Alan Carruth]

Dave Cohen wrote:
"The normal modes shape of assembled guitar body modes up to about 1.5 kHz are well known, first determined by holographic interferometry about 40 years ago, and presumably well before that by things like glitter patterns, & etc. "

It's interestinmg that, while Chladni's work goes back to about the mid-nineteeth century, most of the modern understanding of instrument modes started with laser holography. It was only later, when Carleen Hutchins and others started to look for 'shop' methods of getting the information that time-average holographic interferometry provided, that somebody dug out the earlier work on Chladni patterns. In Chladni's day they drove plates with a violin bow, and the problem was figuring out the exact pitch of the modes, and it wasn't really until the microelectronic revolution of the last forty years or so that that problem was solved. That's one reason the science of this stuff is so new: it was expensive and dificult to do until pretty recently.

Alan Carruth / Luthier

[Dave Cohen]

Alan, that's interesting. I was in grad school at the time the KTH holographers were first publishing their work, so interferograms were among the first results that I saw. What's really interesting about that is that prior to interferometry, there were certainly people who wanted to know what the modes were, and modal analysis isn't restricted to interferometry alone. The only requirement is that one be able to excite a mode at its' eigenfrequency (or close to it) and distribute _enough_ sensors spatially on or around the object to map the mode shape. I'm thinking f'rinstance of the Strong et al paper in "The Chicago Papers". What they called "nearfield holography" was not optical, but rather done with an array of microphones. That paper was published after the holographic interferometry of the KTH group, but it seems it could have been done earlier if someone had wanted to know the mode shapes badly enough. Another possibility would have been an array of phono cartridges on the object. So now I'm curious to know why they didn't come up with something like that??

[Michael Lewis]

Hindsight is always a bit more clear. To look forward takes inspiration and insight, and a good education can help too. You guys rock.

[Alain Bieber]

Alan,
A point of detail. I read recently on Google book the original acoustics treaty by Chladni (published in 1802 in German, 1809 for the French translatioon). He states in this book that he made his first vibrating plates experiments, with the bow, in 1785. I am surprised. Maybe it took quite a long time to be widely known, but at the end of his life, around 1820, it was among the widely "popular physics" demonstrations, in European Universities at least.

[Eric Reid]

Alan,
A point of detail. I read recently on Google book the original acoustics treaty by Chladni (published in 1802 in German, 1809 for the French translatioon). He states in this book that he made his first vibrating plates experiments, with the bow, in 1785. I am surprised. Maybe it took quite a long time to be widely known, but at the end of his life, around 1820, it was among the widely "popular physics" demonstrations, in European Universities at least.

"Chladni plate" experiments go back even further than that. Robert Hooke conducted them and wrote about it in 1680.

[Alan Carruth]

Felix Savart applied Chladni techniques to the study of violin plates early on. The big problem they had was not in exciting plates and getting patterns, it was figuring out the exact frequency! I've seen drawings of the rig they used. It was like a linen spinning wheel that was turned by a hand crank. The large wheel turned a small spindle that had spokes on it, and a card was held against those to produce a sound (just like my bike when I was a kid!). The frequency was matched with that of the plate mode in question, and the turning rate for the wheel timed with a stop watch. Knowing the gear ratio and the number of spokes you could calculate the frequency. I'm sure it was technical issues like this, as much as anything else, that kept people from using Chladni methods much earlier. They were certainly widely known.

Another thing that may have slowed the use of them was the subject of one of Carleen's stories. She had been encouraging Saunders to thing about the normal modes of a 'free' violin plate, but he said that it was such a mathematically bizarre object that they would probably be very difficult to calculate, and might not make much sense. When the first holograms of a set of her plates came back she took them up to show him. After she explained what they were, and handed the photos over, she said he spread them out on the table, and spent the next 45 minutes going from one to the other sating:"Hmmm". They were, of course, the same modes you'd see on a square isotropic plate with the 'ring' shifted up in pitch (by the arch). Sometimes the stuff that's not worth trying is worth trying...