Những Nghiên Cứu Khoa Học Về Thanh Giằng Đàn Guitar - Bracing

One of the first things that guitarists do when evaluating a guitar is to check the wood. Besides that, there are still a few people who understand the importance of bracing the guitar .

Bracing is understood as the wooden bars attached to the inside of the guitar, helping to strengthen the head - where it vibrates with each beat, and round out the overall sound of the whole instrument. Bracing in Vietnamese is called "bracing rod".

There are many different types of bracing used when making guitars, but in general, they all have to ensure a balance: reinforcing the head of the guitar moderately so as not to kill the sound vibration waves. The combination of wood, soundboard and support plate will highlight some harmonious features in the design.

Over the past four decades, Dr. Bernard Richardson, of Cardiff University, has extensively studied how the head vibrations and how bracing affects that. “The key thing about soundboard design is this: using a support plate to achieve the minimum required strength, to prevent deformation of the horse's zipper (and twisting of the soundboard). It also provides the minimum stiffness required for normal acoustic operation, but at the same time keeps the oscillating mass of the plate to a minimum. That's the art of lute making - striking a balance between stiffness and lightness."

Dr. Richardson's research helps provide in-depth new knowledge for guitarists. However, this knowledge also helps guitarists better understand their instruments, and sympathizes with the difficulties that luthiers face in the process of making guitars.

FAN BRACING GUITAR CLASSIC

According to guitarist Jose L.Romanillos, Antonio Torres, who laid the foundation for modern guitar design in the late 19th century, uses a 3-plate prop system.

Torres' best design has 7 radial struts in the shape of a propeller (with 2 crossed), while his other 2 designs have only 5 struts. Other famous guitarists have designed guitars with 4, 6, 7, 8, 9 or 11 struts.

Below is a picture of a Yamaha C40 beginner guitar, which has a propeller frame with 4 struts located at the bottom of each side. The image directly below is the Artist Guitar CL44PK AM, with 5 struts.

What we can't see in the two photos above is the thickness of the soundboard and the stiffness, to assess the impact of the prop system. This is exactly what Dr. Richardson has tested on several different soundboards, using state-of-the-art equipment.

FAN BRACING GUITAR FLAMENCO (FAN BRACING)

We can clearly see that the white pine guitars are of better quality than the two mentioned above. However, this is not a lame comparison just because the Rafael Romeo guitar costs more than the other two.

The guitar still has a fan-shaped bezel and nylon strings, but with up to 7 support bars. In addition, other guitars created by Santo Hernandez, Domingo Esteso, and Marcelo Barbero all have transparent, ultra-lightweight soundboards that are also supported by seven flamenco-style props.

According to Jose L.Romanillos: “This technique is crucial to the percussion quality required of an ideal flamenco guitar, in order to avoid reverberation of the sound from the soundboard to the strings. To be able to achieve this, flamenco guitarists have to design the guitar so that the sound of the note must occur and end simultaneously with the player's plucking gesture."

X-shaped GUITAR ACOUSTIC (X BRACING)

Because acoustic guitars use steel strings, it causes strong impact on the horse as well as the top of the guitar. The inner brace must be able to both hold firmly against the pulling of the strings and help the sound have the desired resonance. And X Bracing is considered effective for acoustic guitar. The X-frame was invented by Martin Guitar.

Engineer Luthier Trevor Gore said that the X-frame design of a large guitar helps create an extremely attractive effect: strong bass but high treble, with a deep mid-range. This design is also very suitable for bluegrass music because it creates space for the sound.

Alternatively, strumming guitarists might also consider this design, because if you have the full midrange on a strumming guitar, that guitar is often hard to hear. "Guitar players still need to be aware that each guitar is unique and that the influence of one element on the sound, such as the design of the bezel, can be balanced by another.

Realistic image of soundboard vibration captured by camera

We can judge the sound quality of a guitar by looking at the response of the body to the strings. In particular, the internal frame of the guitar is the most important factor, besides the quality of the wood, the size and thickness of the soundboard.

Dr Richardson from the acoustics group of Cardiff University's School of Physics and Astronomy has recorded the vibrating response of the bodies of different guitars. Although this motion is elusive and complex, we can decompose them into different resonant frequencies or mode frequencies. These are specific frequencies intended to amplify guitar movement.

The images below, from the 2002 paper "Input admittance and sound field measurements of ten classical guitars", show five spectrum board designs. how they vibrate in their base mode. The histogram points oscillate similar to the contour lines of the map.

Soundboard II is the standard Torres design; III : grid design; V : design by Ramirez; VI : radial design; and VII : extended Torres design.

These are subtle but important differences that affect the sound in complex ways.

One of the most exciting findings of this study is that each guitar is unique, but each produces a quality tone that is tailored to the preferences of the players.

Dr. Richardson said: “There is no one formula for a good guitar, just like wine, there are many wines that are equally good but have their own flavors. And of course there will be bad wines.”

No single bracing design can guarantee a particular type of response - on the contrary, every design aims for the correct overall balance between the stiffness and mass distribution of the soundboard itself (which the anti-vibration for shaping).

Guitars are complex instruments, and internal bracing is only one factor that affects the overall tone and quality. But it is worth considering that the inside of a guitar can reveal some fundamental elements that are not visible from the outside.