Speaker materials

1. High-quality wood such as mahogany, rosewood, peach, sandalwood and other precious hardwoods, preferably seamless whole boards, are the top quality for speaker production< /p>

Materials, but the materials are difficult to find, expensive, and difficult to process, so they are often used in top-quality speakers. Followed by sedge, jujube, catalpa, etc., with the largest specific gravity

, wood The one that is uniform is better. New materials are easy to deform when wet and need to be dried before application.

2. Medium density fiberboard is the most commonly used board, with low cost, easy purchase of materials and convenient processing. But in actual production It was found that its strength is poor,

it is easy to produce sound staining and noise, and the material is fine and soft, so it cannot be combined with wood screws, but can only be driven with iron nails, which may be shaken under high sound pressure

It is loose and has poor rigidity, which is not conducive to the sturdiness of the box.

3. Medium-density particleboard is also called a pressure plate. It has high strength, low cost, and is not convenient to process. There are many Commercial speakers, including many Japanese

speakers for this kit, all use this material, but some people report that it is not compacted tightly, contains many air gaps, and has poor sound insulation performance. It is best to make special ones

Processing to improve sound insulation capabilities.

4. High-density fiberboard, particle board and plywood have high strength, good sound insulation performance and easy-to-find materials, making them high-quality amateur products

The preferred material for speakers, but the cost is slightly higher, and processing is not easy, requiring special tools. Especially high-density particleboard, which is very hard and difficult to nail. I often break the tips of screws during production. If you don't mind, use an electric hand drill to pre-drill a small hole before tightening the screws.

5. If the inorganic material is cast into concrete, use stone plates (marble, concrete slabs, granite slabs, gypsum slabs) boards, etc.) are formed with special processes, or simply use large, heavy clay pots as the box body. It has the advantages of small sound coloration and stable sound field, and is often used by audiophiles, only

< p> is too heavy, and it is very inconvenient to move and tune. And the walls of the box must be specially treated. 6. High-density polymers (polymer polymers) such as engineering plastics, polypropylene, reinforced modified epoxy resin, and thick organic glass plates Materials) Adhering to

modern advanced scientific and technological material technology, many European and American professional speaker manufacturers use this technology to create high-end, high-quality speakers, such as JBL MM

series speakers made of high-density plastic As a cabinet, the famous JBLPROJECT K2 actually uses organic glass several inches thick to make a high-pitched voice. It is difficult to achieve under amateur conditions.

7. Metal materials are mainly used It is suitable for professional speakers and special occasions, such as stage speakers, mobile speakers, all-weather speakers for sports, all-weather mobile speakers for military use... Amateurs use it because of the high resonant frequency of its metal box, which causes sound staining. It is difficult to handle and is rarely used.

8. Paper materials are mostly used by those who are new to the burning industry and have financial constraints. There are also experts who use them to make boxes and enhance them with special techniques

Treatment, such as impregnating with epoxy resin. If made properly, the effect will be good.

Manufacturing method

1. The combination of plates is the best solution for most speakers, including some of the best. The method used in the speaker is mature, simple and suitable for factory production.

2. Casting This method is most suitable for concrete (called seamless concrete in Hong Kong) ) and polymers.

3. Cavity-cutting method 1. For top-grade fever speakers, dig out the cavity of a whole piece of precious hardwood or solid stone as the box body. You can imagine the difficulty of this method

Very large and expensive. Occasionally seen in commemorative products in Europe and the United States. 2. Earth speakers of the earth-cannon family. The ground should be hollowed out, dried and moisture-proofed

and then the panel and The speaker unit is low in cost and has very good sound quality. It is perfect for subwoofer reproduction, but it cannot be moved and has certain restrictions on living conditions

. With a high fever, it can be said that it has reached "home".

Manufacturing process

Hi-fi speaker cabinets are often exposed to rapidly changing high sound pressures, which can easily induce noise, resonance, sound coloration, and affect the playback of music

The pure beauty. Therefore, the production process is very important. "Reinforce vibration damping and avoid sound staining" is the eight-character "guideline" of the production process.

1. Extensive and reasonable use of reinforcing ribs for weak links in the speaker box. At the joint angles formed by the various surfaces in the body, use enough glue, preferably more

but not too little, to stick

Use thick hard triangular wood or square wood rods and tighten them with wood screws. The sound pressure level on the back of the woofer is the highest and can easily induce box sound.

Add a round piece to the back panel directly opposite this point. Reinforced with shaped hardwood boards, the material can use the remaining material under the panel opening. For a relatively long and narrow box,

Because the aspect ratio of the board is large, the strength and rigidity become worse, the resonance point becomes lower, and the asymptotic If the resonant frequency of the speaker or box is high, the risk of sound staining is extremely high.

Please glue a few hard square wooden rods on the ground asymmetrically. This is to eliminate air leakage in the gaps, strengthen the rigidity of the box, destroy resonance, and avoid Inducing noise

and stimulating box vibration.

2. Add appropriate amount of sound-absorbing materials such as ultra-fine glass wool, slag wool, fiber spray-coated cotton, vacuum cotton, etc. into the box, the next best Such as foam sponge, cotton

wadding, tissue paper, and soft toilet paper, which absorb sound energy, control the Q value of the speaker, and reduce box vibration. For a sealed box, the entire box must be filled.

For the phase inverter box, apply three fingers of thick sound-absorbing material on the front, rear, left, right, upper and lower walls, and increase or decrease it appropriately during monitoring to just suppress the resonant peak

For the transmission line type ( That is, the labyrinth type), which is laid at the turning point of the sound channel where standing waves are prone to occur. For the horn type (mainly refers to the propagation path of the rear-loaded signal box and greatly reduces the Q value of the box wall, it is even less effective

< p>It is very effective to eliminate sound staining. Boxes made of inorganic materials must undergo this treatment.

4. Box support and reinforcement here refers to hard square wood, porous wood board or round steel The rods firmly support the front and rear walls and/or side walls, so that

the box walls will not be excited by high sound pressure to produce annoying box sound staining. The porous plate also has the function of Q-switching. Steel rods It can be made of steel with No. 40 or above

It is machined from Φ45mm or above, and Φ8mm fixing screw holes are drilled at both ends. If necessary (if the box is larger), a flange can be welded and tightened with screws

Fixed between two walls that need to be supported. According to some seniors, this method is particularly effective in eliminating box sound caused by poor strength of the board, so it is listed separately.

p>

5. The speaker unit should be fixed from the outside to the inside to reduce the front cavity effect. It is best to make the installation holes countersunk to avoid the basin

frame from protruding and causing windage. The basin frame and the cabinet are sealed and isolated with a 5-10mm rubber gasket to avoid sound short circuit, and to prevent the vibration of the basin frame from being transmitted to the panel

and interfering with direct radiation of sound.

6. Adopt a special cabinet shape and shape. This is not to discuss the acoustics of the speaker, but to effectively prevent standing waves.

The generation of standing waves will seriously affect the performance of the acoustic system. .In order to eliminate standing waves, it is key to destroy the parallelism in the cabinet. For example,

TANNOY SIX series adopts a hexagonal body design. Many professional speakers adopt a fan-shaped design (JBL MM-SERIES,

AC, etc.). The shape of the cabinet also has a great influence on the radiation characteristics. Too many sharp edges and corners will cause diffraction and interference, so a blunt

surface transition angle can be used. The shape of the front panel will affect the service angle and phase characteristics, which can be improved by specially designed panels, including curved designs, stepped designs and other special shapes. The front panel of JBL 4208 has been computer-aided analysis , design, contrary to the tradition of flat surfaces

Using curved surfaces, which effectively improves the phase characteristics of the near sound field. BOSE301 was launched after the careful research of direct and reflected sound technology

A masterpiece of HI-FI, it adopts a unique shape design, cutting out a slope on the top of the bass speaker, and installing two tweeters for radiation in different directions at the front and rear, effectively creating a uniform sound. Sound field, it is said that listening to stereo sound is no longer just a "selfish" enjoyment when sitting on the throne of the emperor. There is news that a new type of speaker that looks like a big snail will soon be used as a new product of the British company B&W The flagship is launched. Therefore, when designing speakers, we should also emancipate our minds, break traditions, boldly imagine, be diligent in doing things, and be good at thinking.

7. Apply strong sound absorption and The residual vibration of the basin frame made of strong sound damping material can be transmitted to the panel. Direct sound radiation will be reflected to the panel. The vibration caused by the stiffness of the air in the box will also be reflected on the front panel. All of these are reflected by the panel. Radiation, superposition and interference with direct sound, cause more peaks and valleys to appear on the frequency characteristic curve, and the phase characteristics

Deterioration, especially at high frequencies, is an effective way to improve it by pasting "acoustic damping" material on the panel. Acoustic damping materials include high-density foamed foam, special felt, and factory-made Special audio

Use sound-absorbing felt, etc.