Lutherie Demystified Ep. 16 | Guest Lecture: Guitarists, Luthiers and Physics
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- čas přidán 13. 04. 2024
- Guest lecture for PHY 115, Physics of Music at Wake Forest University, April 9, 2024.
Lutherie Demystified is a video series hosted by Garrett Lee that explores the world of classical guitar building--from techniques and theory to commentary and perspectives about the instruments, players and lutherie profession. GarrettLeeGuitars.com - Hudba
Thanks a lot for sharing your knowledge. It's really important for me.
Seeing the experience on chladni patterns, and the result on opposing the movement with a transversal bar... I'm wondering.. so, the bridge fixed on top is kind of a problem on frequencies response? How do you deal with this?
Very astute question! In many cases, adding stiffness with a brace or increased plate thickness will not completely eliminate a mode of vibration, but move its peak to a higher frequency. In the case of a brace, the stiffness increase rises much faster than the weight increase, but in the case of a bridge, both stiffness and weight significantly increase, so the effects won't be the same as a light brace, especially when you consider that pitches are proportional to stifffness divided by weight. In our brace thought experiment, it's evident that the stiffness in that direction went too far, and it probably more than doubled the stiffness of the existing brace (which evolved to be that size because it's been successful in past guitars with the bridge that will eventually attached). You can see how certain plate thickness/bracing scheme/bridge design combinations have evolved because they generally work well to give the proper response across many ranges of pitch. Some guitars are better at this than others because the combination of many variables is spot on.
Thank you for talking to our students Gary, and glad to see you made this presentation available to all!
Incredible video. Thanks a lot for the idea and the pedagogy !
Yourself and Jim Lil have done so much to sidestep the bullsh1t and clearly demonstrate facts.
Bravo, simple to understand and elegantly demonstrated.
Sweet builds too!
The first guitar I ever played was purchased new in Franco’s Spain in the late 50s-my dad paid $20 for it. It was a folk instrument with toolmarks on the back of the head stock, etc. And it had gut strings-the only instrument I’ve ever played with such.
He bought it for my mother-but was a classical pianist (her father conducted the CBC Symphony Orchestra-virtually identical to the Toronto Symphony Orchestra) and she summarily hung it on the wall like an ornament. It stayed there for years until the table split up the middle-right about the time Johnny Horton’s “Battle of New Orleans” was topping the charts and a school chum’s visiting cousin showed us how to play it on his big western guitar. Much to my mother’s horror (my grandmother, too, who used to play piano with the CBC Symphony live-to-air and was very snooty-and wouldn’t even mention what she thought of pop guitar music) I came home and started to practice the G, C, D like I was shown. But I loved rock-a-billy so the E, A, and part of a B came along serendipitously. My folks thought I was too young to be playing the Blues on my ma’s wall ornament.
I was supposed to be doing my piano lessons. My dad walked through the room one day as I played hooky on the ivories: “That’s the Blues,” he said, and I didn’t have a clue what he meant. Later a friend’s dad made me an electric guitar out of spare parts (only a few of them actual guitar parts); I eventually bought another big electric guitar from a pawnshop in “Hogtown” (how we called Toronto-or “Toronna”) with more pickups, knobs and switches than I can remember. Then I hit the road…
I was a prodigal son; I didn’t play guitar for a few years of mouth-organ itinerancy out on the West Coast, but every time I came back for a visit that little Spanish classical was still hanging on the wall-it kept looking like it was shrinking over the years, and that crack got wider and wider. Last I saw it there was a reefknot on a green E-string-but the gut strings were still there until that very time-mustard been over two decades old! Eventually I’d come home with a low-end Fender acoustic and I think I broke its heart. I still have the F-35 fifty years later but I don’t know what became of my first little guitar with the gut strings.
Love your channel. What led me here is a perennial question I have for luthiers: why not western hemlock for an acoustic guitar top? I’ve never heard of or seen one. Is there a reason for this?
Great show. Thnx!
You just overwelmed me. I'm a wanabe luthier on my free time. I've built about 10 string instruments. Each and every time there is something new to take in consideration. I had a narrow view of the sound and physics universe before. Now I'll have to take all of this in consideration too. Thanks so much for your time and effort. Loved the video. Explained it perfectly understandable for an idiot like me. Idiot for ideas... Best regards from Portugal
Awesome video! I'm a violinist learning guitar, and I wonder why violin has soundpost that connects the soundboard to the back, but guitar doesn't? Guitar has a lot of bracing, but violin only has one bass bar. And I find it interesting that your fingerboard is not glued to the soundboard, but the neck runs all the way to the soundhole.
Thx for sharing your findings Garrett, very interesting.
Great introduction to top resonance and tap response.
Thanks, Garrett, for sharing.
Man, I love your videos. Great info break down and great demonstration of resonant frequencies. I would love to learn how to manipulate the higher order resonant frequencies you discussed (after playing the A note) as opposed to the lower order three (main air, main top, and main back). Those are a little easier to understand and manipulate. But those elusive higher order resonant frequencies are trickier. Haha! Thanks again. I will be following along for future videos!
I'm really glad these videos are of value to you. Wouldn't we all love to be able to manipulate the higher frequency modes on command?! Unfortunately, things get very complex in the upper register of the first string as the sectors of the modes get smaller and superimpose with the sectors of the lower frequency modes. As you know, it's increasingly difficult to surgically manipulate the upper modes in any rational way. Over time, it's possible to empically find successful combinations of design/process (plate, brace and bridge flex and weight) that avoid problems and give you a pleasing voice. Successful builders find combinations that are robust, as opposed to always being on the edge of creating faulty notes. However, in Ep. 18, I'll briefly demonstrate how strategically placed weights can be used to probe and alter modes of vibration. This technique can be used to move peaks of higher order modes without causing faults in lower-pitched notes.
@@GarrettLeeLuthier What a great response, Garrett! We all appreciate it. Really looking forward to Ep. 18. The information from your videos can only improve the build quality and sound of guitars going forward. And betters guitars make better music :)
very informative thank you
9:35 such a great view, i dont think ive seen that before
I love this video, but I would also love to hear you talking about Carbon Fiber and some other similar composites used in making acoustic instruments. There is videos of Carbon Fiber violins and violas, which do sound amazing, so I could imagine this would also apply for guitar, it does have a different sound, but is not a bad one at all. There is "acoustic" guitars made out of this material, but I haven't seen classical ones being made with it. I am talking about the shape of the guitar and also about the type of string it uses when I refer to classical and acoustic, since at the end they are both acoustic
Great video, making the mysterious guitar voice so clear.
That huge utility knife is completely useless! They didn't add the ever important spray can of shark repellent!
very interesting info, thank you! However, i now have cravings for enchiladas.......
Great video!
This was excellent!!
I wonder if you could run a tone through the body with sensors at various places to allow you to know which part of the top is stiffer, allowing further balancing of tone.
In his book Left Brain Lutherie, David Hurd describes a method to measure local stiffness in different areas of the soundboard. It may prove difficult to predict exactly how that local stiffness correlates with the movements observed in the different modes of vibration, to the point that you could manipulate specific modes over others. However, if you took enough data, you might be able to discover the relationships.
@GarrettLeeLuthier l was thinking along the lines of using the information to know where and how much to adjust strength (scalloping) of bracing so as to balance and maximize vibrational potential of the top. I sort of envision a way of building in which you put the back on last so that you can make bracing adjustments before you seal it for the last time. Kind of trading the artistic for scientific method lol.
Maybe it should be kept an art..
Hello sir.
Does the string tension affect the natural frequency patterns of the guitar?.
Does it also affect the membranes, as skin on banjo?
If yes, can we add braces to the membrane to craft some sound, or it that just not as usefull?
✨🙏🏼✨
Highly interesting video !! How did you do to get the sound specter of the box ? Just putting a microphone in front of the hole and tapping one time on the box and using any software ? I want to test on my guitar aha Thanks you !
I give an introduction to the technique in Episode 15 here: czcams.com/video/BVPgZtiPk_Q/video.htmlsi=r5ssj2H__9CNBgKE&t=3192 . You can learn the specifics in Trevor Gore and Gerard Gilet's book, or in an excerpt generously provided by Trevor Gore here: goreguitars.com.au/wp/wp-content/uploads/2021/existing/Tech_note_on_data_collection_R1_2018_A4-1.pdf
Thank you for a wonderful video. I have a problem with the G note played on the open G string or on the D string. It produces a buzzing sound. I have been told it has something to do with the body resonance of the guitar. Do you have any thoughts on this issue? Can it be rectified?
It's very possible that the G (196 Hz) falls at the the peak frequency of the main top resonance so that the note vibrates with such high efficiency that the up and down movement of the top brings the string very close to a fret (probably the 6th fret on the 4th string or 1st fret on the 3rd. I show how you can move resonances in the upcoming Episode 18, but it will be about a month or more before I find time to edit the video. The techiniqe involves using a pair of magnets, one on the outside and one on the inside of the top, to add mass. By moving the pair around to test different locations, you can find a spot that primarily affects the faulty note, and less so others. Once you have the spot, you can glue a block of wood on the inside with similar weight.
@@GarrettLeeLuthier Thank you very much for this information. Incidentally, I really love the sound of the guitar that you made for Simon Powis.
I saw the thumbnail and I tought it was another video about debunking "tone woods" on electrical guitars, great video nevertheless
I remember seing Torres "cardboard" guitar in a museum, he basically made the guitar to make a point about only the top(tapa) soundboard being important, the sides and back could literally be made of cardboard(paper maché) and would still sound 90% like a normal guitar.
The bridge is essentially a brace so I guess you would suspect that you will get the results of your taped on horizontal brace once you glue the bridge on.
This is a great question which someone else also asked. I'll just repeat the answer I wrote: In many cases, adding stiffness with a brace or increased plate thickness will not completely eliminate a mode of vibration, but move its peak to a higher frequency. In the case of a brace, the stiffness increase rises much faster than the weight increase, but in the case of a bridge, both stiffness and weight significantly increase, so the effects won't be the same as a light brace, especially when you consider that pitches are proportional to stifffness divided by weight. In our brace thought experiment, it's evident that the stiffness in that direction went too far, and it probably more than doubled the stiffness of the existing brace (which evolved to be that size because it's been successful in past guitars with the bridge that will eventually attached). You can see how certain plate thickness/bracing scheme/bridge design combinations have evolved because they generally work well to give the proper response across many ranges of pitch. Some guitars are better at this than others because the combination of many variables is spot on.
please make a link to your website
Besides influencing the sustain by reflecting back a proportion of the string energy, can the physics of the guitar influence the resonant peaks in the vibrating strings itself? For example, if a guitar pick up is only "hearing" the vibration of the strings, can the wood and other features of a solid-body electric guitar influence the "tone" that results from only the string?
This is a really perceptive question. I'm not an expert in resonating systems, but I think I have experienced unruly guitars that respond as if the box starts to drive the behavior of the strings in a retroactive way. These guitars seem unfocused at certain pitches. I think this makes sense because the whole system, which includes the strings and the body, never achieves steady state after the strings are plucked, so the top etc., which can filter as well as accentuate different frequencies, should be able to influence the motion of the strings. I think really lively tops run this risk. I don't know much about solid body electrics, but conceivably it could happen with them, although much less so compared to acoustic guitars. It's an interesting thing to ponder.
@@GarrettLeeLuthier Thanks
Hi, Garrett.Thank you for the informative and useful videos for luthier. But I didn't say anything about the first peak of 88 hz. As I understand it, these are air fluctuations
In Episode 18, I'll go into detail describing the air, top and back resonances, and how they interact with one another.
@@GarrettLeeLuthier Oh, great! Looking forward to it :)
12:29 Since a banjo is basically a snare drum which works ‘in reverse’ (with the strings activating the snare head rather than the snare head activating snare wires) the word ‘percussive’ is hardly wrong!
10 minute intro in a 30 minute presentation, really?
Fabulous video Garrett.
Many thanks, Michael. I really appreciate the comment.