Speaker system and a method for improving sound quality thereof

Abstract

A speaker system suppresses standing waves generated in the system and reproduces clear and dynamic bass sound. The system includes a cabinet formed of acoustic insulation walls, and at least one partition wall situated inside the cabinet to form a space by surrounding the space. The partition wall suppresses the standing waves generated inside the cabinet and is formed of a material having high internal loss. The space has a total capacity more than one tenth of a capacity of the cabinet, wherein a closed end of the partition wall is located between one-half and four-fifths of a distance from one end to the other end, and an opening area of the same partition wall is located at a side opposite to the closed end in a longitudinal direction of the cabinet. The opening area is located between four-fifths and five fifths of a distance from one end to the other end.The material has a density per volume greater than 0.1 g / cm3, a density per area from 0.01 g / cm2 to 0.21 g / cm2 and a characteristic of semi-transmission for the standing waves. The partition wall has a closed end portion. The closed end portion is formed of at least one of the partition wall and the acoustic isolation walls. The space is a substantially closed space<?insert-end id="INS-S-00001" ?>.

Description

[0001]This application is a continuation of application Ser. No. 08 / 373,250, filed Feb. 7, 1995 now abandoned which is a 371 of PCT / JP92 / 01721 filed Dec. 28, 1992.TECHNICAL FIELD[0002]This invention relates to a cabinet where little standing waves are generated particularly to a speaker system comprising a cabinet suitable for reproducing high fidelity sounds, and a method for improving sound quality thereof.BACKGROUND ART[0003]Hitherto, a closed type cabinet, a bass-reflex type cabinet and a non-back baffle type cabinet have been known as a speaker cabinet. In the conventional cabinets, standing waves are generated by resonance of air inside the cabinet. The standing waves cause various problem as follows:[0004](1) The standing waves interrupt movement faithful to signals of a diaphragm of a speaker unit. As a result, an output sound frequency characteristic is disturbed and reproduced sound is distorted.[0005](2) A wall surface of the cabinet resonates with standing waves to produ...

AI Technical Summary

Benefits of technology

[0013]An object of the present invention is accomplished by a speaker system wherein a cabinet has a space enclosed by partition walls therein, the partition walls are formed of a material having high internal loss and semi-transmission for a plurality of standing waves, a total capacity of the space is more then one tenth of a capacity of the cabinet, and a closed end of the space is positioned between one-half and four-fifths of a distance from a longitudinal end of the cabinet to the outer. Also, a ratio of cross-sections of the space and the cabinet is preferably larger than one to five in the cross-section crossing the longitudinal direction of the cabinet. The space may be replaced by a plurality of spaces of diff

Problems solved by technology

(1) The standing waves interrupt movement faithful to signals of a diaphragm of a speaker unit. As a result, an output sound frequency characteristic is disturbed and reproduced sound is distorted.

(2) A wall surface of the cabinet resonates with standing waves to produce sounds of the cabinet. A reproduced sound accompanied by the sounds of cabinet is different from an original sound. Also, the reproduced sound sounds as if it winds round the cabinet and has little exposition.

(3) A resonant sound of the standing waves leaks through the diaphragm of the speaker unit or a wall of the cabinet. Consequently, a specific sound of the reproduced sound has reverberation and is not clear. For solving these problems, various proposals have been made.

(1) In case the cabinet is filled with the sound absorbing material, a lively, dynamic sound can not be reproduced. With the perforated board, only a special standing wave having a wave length corresponding to a size of the perforation can be absorbed to thereby have little absorbing effect. Thus, a plurality of standing waves is generated in the cabinet, which results in no practical use. In case the performed board is used together with the sound absorbing material, various problem accompanied by mal-effects of the sound absorbing material arise. In case the sound reflecting board is used to scatter a sound it is necessary to select a material, size, shape and setting direction of the sound reflecting based according to a direction and a wave length of the Standing wave. Thus, it is difficult to cope with many standing waves. Further, in case an uneven diffusion reflecting structure comprising the sound reflecting board is formed on an inner surface of the cabinet, an effective volume of the cabinet decreases. The honeycomb type core has a large total opening area so that it has an effect only for a specific sound. When the honeycomb core is used together with a sound absorbing material, a reproduced sound is accompanied by a mal-effect of the sound absorbing material. It has been proposed that a sound absorbing cabinet is provided in tie cabinet. However, the purpose is to raise a reproduced sound pressure level by resonating with a sound of specific frequency. The sound absorbing cabinet having small internal loss makes a reproduced sound an unnatural sound accompanied by a reverberation, in resonance with a sound having a specific frequency, if used in a wide range sound reproducing speaks system.

(2) In case the wall of the speaker cabinet is thickened, since the standing waves isare not suppressed the problem of the diaphragm of the speaker unit an not be solved.

(3) In case the opening of the frame of the speaker unit is covered with the sound absorbing material, a large quantity of the sound absorbing material causes a mal-effect to a tone quality. Also, it is difficult to eliminate mal-effects of the standing waves having frequencies less than 300 Hz with only the sound absorbing material.

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