The Basic Structure of Erhu
Tube of Erhu
The tube is an important part of the erhu, which uses the push and pull motion of the bow to vibrate the skin of the musical instrument and make it sound after the strings are rubbed. The texture and shape of the erhu tube have a direct effect on the volume and sound quality. It is generally made of red sandalwood or mahogany. The shapes are hexagonal, octagonal, circular, front octagonal and rear circular, etc., and the hexagonal shape is commonly used. A sound window (usually a carved wood window) is inlaid behind the erhu tube, which not only plays a decorative role on it, but also has certain advantages in pronunciation, sound transmission and sound filtering. The erhu tube is the resonance tube of the erhu. It is generally made of ebony, mahogany (red sandalwood is rare), but also made of rosewood or bamboo. In the 1970s, low-foaming (ABS) materials began to be used for molding. Its shape is mainly hexagonal, with a length of 13 cm and a front mouth diameter (opposite side) of 8.8 cm. In some areas, it is made into a circle or an octagon. The waist of the tube is slightly thin, and the rear mouth of the tube is open or the device has a sound window with various patterns of flower holes. The erhu tube plays the role of amplifying and rendering the string vibration.
Skin of Erhu
The python skin of the front erhu tube is called the qin skin, also called the qin membrane. It is an important device for the sound of erhu. Generally python skin, snake skin is the lowest grade Erhu Qin skin. Snake skin has fine scales, regular lines, and full of toughness, but the texture is thin. The sound quality is easily affected by factors such as climate and room temperature. The scales of the python skin are thick and flat, the color contrast is coordinated, the thickness is appropriate and elastic, it is not susceptible to insects, and the pronunciation is good. The python skin is the most ideal in the area around the anus. The python skin in this place has wide adaptability, thick and round pronunciation, and stable performance. Newly bought erhu, whether it is snake skin or python skin, often have empty and sandy pronunciation, and the volume difference between the upper and lower ends is large. This is because the vibration of the piano skin is not coordinated enough. After a period of playing, the vibration of the piano skin may gradually become normal. It is an important vocal body of erhu and the key to vibration source, which has a direct impact on sound quality and volume. The larger the scales of the python skin, the better the tone.
The erhu rod is the backbone of the erhu and also the trunk. It not only plays the supporting role of connecting up and down, but also has a certain influence on the overall vibration pronunciation. The materials used to make the rods are some sandalwood (less in quantity), ebony or mahogany. Ebony is generally used more. Ebony is cheap and good-quality, and has a certain degree of tensile resistance. It is an important pillar for supporting the strings and for pressing the strings. It has a total length of 81 cm and a diameter of approximately 0.55 inches (1.83 cm). The top is the erhu head, the upper part is equipped with two pegs, and the lower end is inserted into the piano tube. The erhu head is in the shape of a curved neck, and it is also carved into a dragon head or other shapes. To measure the purity of an erhu’s pronunciation has a lot to do with the choice of erhu rod material. Mahogany is usually regarded as top grade, ebony is also good, and other woods are inferior. In addition to carefully distinguishing the material of the piano shaft, the choice must also take into account the tight texture, fine and uniform wood rays, no knots, no scars, no obvious cracks, and a certain degree of brightness.
Shaft of Erhu
There are two upper and lower shafts (also known as Qin Zhen), which play the role of adjusting the pitch. The upper shaft binds and twists the inner strings, and the lower shaft binds and twists the outer strings. There are two types of erhu shafts: wooden shafts and mechanical shafts, both of which have advantages and disadvantages. The wooden shaft is stable after tuning, and it is not easy to run off the strings, but because the time is tight and loose, it brings difficulties to the tuning. The mechanical axis tuning is fast and free, and the pitch is good. If the production quality is not completely passed, there will be looseness and slippage from time to time, which will easily cause the strings to run out of sound.
Strings of Erhu
The string is one of the sound bodies of the erhu, and also one of the sound source bodies of the erhu. Its quality directly affects the pronunciation effect. There are two kinds of strings: one is metal string, which has the characteristics of good tension, good sound quality, good pitch and high sensitivity, and it is divided into aluminum string and silver string, silver string is the best; the other is silk string. It produces a softer and more delicate sound than metal strings, but it has poor tension, poor pitch, and is easy to break and change the tone. Metal strings are mostly used.
Bow of Erhu
An erhu bow is composed of a bow stroke and bow hair. A good bow must first be long and straight. Secondly, the bow hair must be white horsetail hair as the top grade. And the it must be numerous and uniform, and tied at the joint of the fish tail firmly. Finally, pay attention to the number of knots of the bow stroke should be few and small, and the thickness should be moderate. The length of the bow is 76~85 cm. The bow rod is a bracket to support the bow hair. The length is 2.4 feet (80 cm). It is made of Jiang Wei bamboo (also known as young bamboo). Both ends are baked and bent, and horsetails are tied. The bamboo is thick. One end of the bow is at the tail of the bow, and the ponytail is clamped between the two strings to rub the strings to produce sound. The bow hair is mostly horsetail, but it is also imitated by nylon silk. Some simple erhus use nylon thread instead of bow hair, which has poor acoustic effect. To measure the durability of bow hairs, it mainly depends on whether the bow hairs are arranged neatly and flat, the length is uniform, and the thickness is uniform. Good bow hair requires no broken ends, no slenderness, no unkempt entanglement, etc.
Qianjin, plays a role in fixing and cutting erhu strings. It also has a certain impact on intonation. It is made of cotton thread, silk thread, plexiglass, plastic and other materials. There are various forms, including fixed jacks, wire wound jacks, metal jacks and so on. The more commonly used is wire wound jacks.
Bridge of Erhu
The erhu bridge is the medium of vibration between the strings and the erhu skin, which plays an important role in sound. It uses materials such as wood, bamboo, metal and paper. Commonly used are wood pine knot bridge and maple bridge. The wood pine knot bridge has soft wood, round and honest sound. While the maple bridge is moderately soft and hard, with soft sound and low noise. Although the size of the erhu is small, it is the hub that connects the strings of the piano. Its function is to transmit the vibration of the string to the python skin. Therefore, the material, shape, and placement of the erhu bridge on the skin greatly affect the sound quality of the erhu.
In order to improve the sound of the erhu, the hoarse erhu should use paper bridge (that is, use kraft paper or other hard paper to roll it into a strict simple shape), and the sound should be softer: the dull erhu can be changed to bamboo code. The sound becomes louder, suitable for playing lively and lively tunes. The monotonous erhu adopts metal spring codes to make the sound more resonant.
Base of Erhu
The erhu base is the bottom support of the erhu body, which plays a role of decoration and stabilization of the erhu body. Some erhu supports are also equipped with adjustable bottom supports, which are adjusted with nylon buckles. It is more convenient when playing.
Under the erhu bridge, a small piece of damper pad made of flannel or felt must be inserted between the strings and the film. It can solve the “wolf sound” of the erhu, eliminate the empty sound of the erhu, and make it concentrated and full. The thickness and size of the damper pad should be moderate, too thick will affect the volume, too thin will not work. The materials used to make sound pads often include white sponge, woolen cloth, cashmere, cotton cloth, suede, flannel, etc. The most widely used are sponge and woolen cloth, and the best effect is natural suede. It should not be underestimated. There is also the ability to quickly change the timbre. If it is close to the erhu bridge, the timbre is very smooth, and at the same time it loses a part of the volume. If away from the erhu bridge, the timbre will become brighter. Besides, it must be adjusted according to the needs of the song.