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DESCRIPTION JPS59196690

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DESCRIPTION JPS59196690
[0001]
The present invention relates to an improvement of a speaker system in which a bass speaker is
attached to a buckle surface of an enclosure. FIG. 1 shows a conventional two-way speaker
apparatus of this type, in which (1) is a rectangular parallelepiped enclosure, (2) is a baffle
surface of the enclosure (1), and (31, (4) is attached to a baffled surface (2) It was done. Each is a
bass speaker. It is a speaker for high sound. FIG. 2 shows the sound wave emitted by the above
device. Sound pressure frequency characteristics at the far front of the buckle surface (2) are
shown, the solid line a is a comprehensive characteristic and two dotted lines, c when only the
bass speaker (3) and the treble speaker (4) are driven Characteristic of By the way, in the abovementioned device, when the bass speaker (3) is driven, the resonance inherent in the enclosure
(1). That is, standing waves are known to occur. This standing wave affects the sound pressure
characteristics of the sound wave emitted from the low frequency speaker (3) to cause peaks and
dips, which causes deterioration of the sound quality. As a measure against standing waves with
the above, a sound absorbing material is attached to the inner wall of the enclosure (1), but even
then, as shown in FIG. 2, disturbance occurs in the reproduction band of the bass speaker (3).
There is. Also, it is also known that the inherent resonance frequency fv that occurs in a closed
rectangular sound field such as the enclosure (1) is as follows. Here, C is the velocity of sound, H,
W, and D are dimensions of the rectangular sound field in the upper and lower, right and left 4,
front and rear directions. NH 'nwr nD is an integer representing the standing wave mode
corresponding to H, W, D , 1, 2 ...). As can be calculated by the above equation (1), only one
direction mode (nH, nW, TaD where 0-2 is the axis where one side in the enclosure is an integral
multiple of half the wavelength of the acoustic wave) Also called modes), modes in which two or
more modes overlap (nH). Many standing waves occur at the frequency at which two or more of
ny and nD are not 0). They are sequentially generated with the frequency at which the maximum
side length becomes a half wavelength being the lowest. For example, as shown in FIG. The
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vertical dimension is the most dog-friendly enclosure. The lowest natural resonance frequency fv
is c / 2H. すなわち、nH””T、nw−nD−0である。 It is also known that the sound
pressure or particle velocity distribution in the enclosure becomes an inherent distribution when
a standing wave is generated at the frequency represented by equation (1).
FIG. 3 shows an example of first to third order distribution regarding a mode (axial mode) with
only one direction. In the figure, the horizontal axis represents the distance and both ends
correspond to the end face of the enclosure, the vertical axis is the value normalized by the
maximum value of the sound pressure or particle velocity, and the solid line 9 dotted line
represents the sound pressure 2 particle velocity, and 2% It is the distribution of the axial mode
first-order, second-order, and third-order in the order of the sex (aL (bL (c)). These sound
pressure distributions show the same distribution as that of the closed acoustic tube. In the first
order, one side is at the center, in the second order at one-quarter position from both ends, in the
third, the center and both ends There is a node (sound pressure 0) at a position of 1/6 of one
side from. As a measure against standing waves, a method considering the standing wave mode
of FIG. 3 can be taken. That is, this is a method of attaching the bass speaker at the node position
of the standing wave sound pressure mode, and the standing wave generating the mode is not
excited if the center of the bass speaker substantially matches the node of the sound pressure
mode. . Referring to FIG. 1, if the bass speaker (3) is mounted at the center of the pan full surface
(2), the bass speaker (3) is located at the top, bottom, left and right of the enclosure (1). The
standing waves are not excited at the respective frequencies which generate the 01th mode (nu+, nW "'1) in FIG. Well, as shown in Figure 3, even in the third-order mode, and even in the oddorder mode, there is a node of sound pressure at the center, so that those standing waves will not
be excited either. The same applies to the secondary and even-order modes of FIG. 3 (b).
However, as in the conventional device shown in FIG. 1, in the case where there is one low
frequency speaker (3) and the enclosure (1) is long in the vertical direction (I (> W)), primary
(odd order) and secondary It is impossible to drive each (even-order) node simultaneously. That
is, the center of the bass speaker (3) is at least off center of one of the nodes. Some low order
mode standing waves are excited. As described above, in the conventional apparatus, a standing
wave is excited in the enclosure from a low frequency. They have the disadvantage that the
sound pressure frequency characteristics are disturbed. The present invention aims to eliminate
the above-mentioned drawbacks of the prior art devices, and therefore an enclosure. The internal
dimensions H2 width W, depth H) W, H) D rectangular, and two bass speakers, each of which is a
second order generated in the enclosure in the height direction The sound pressure mode of the
standing wave is attached to each of the two nodes.
FIG. 4 shows an embodiment of the present invention, and (a) is a front view. (B) is a longitudinal
sectional view taken along 4b-4b of (a), (1) is a rectangular parallelepiped enclosure with an
internal dimension of height H2 width W, depth H> W, H> D, (2 ) Is a baffled surface. (5a) and
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(3b) are speakers for bass with the same aperture. Each of the baffle surfaces (3a) is such that its
center is H / 4 below the center of the baffle surface (2) so that the center is H / 4 above the
center of the baffle surface (2). 2) attached and driven with the same amplitude and the same
phase. The following operation is obtained in the above embodiment. すなわち。 (1) The two low
frequency speakers (3a) and (3′′o), as described in FIG. 3, generate secondary standing waves
in the vertical direction (height) in the enclosure (1) Because the sound pressure mode node is
attached, the second order standing wave in the vertical direction and the even-order standing
waves that generate nodes at the same position as the node are not excited. (2) Since the two
bass speakers (3a) and (5b) are mounted at symmetrical positions at the center of the baffle
surface (2), the inside of the enclosure (1) is driven isometrically at its center In particular, oddorder standing waves of one or more orders which produce nodes at the center in the vertical
direction are not excited. (3) Since the two bass speakers (5a) and (5b) are mounted on the center
line of the baffle surface (2) in the left and right direction, the primary order that occurs in the
left and right (width) direction in the enclosure (1) The above odd-numbered standing numbers
are also not excited. According to the above-described operation, at least the first to third
standing waves in the vertical direction in the enclosure (1) and the odd standing waves in the
horizontal direction in the enclosure (1) do not significantly affect the sound pressure
characteristics by the above operation. Since the excitation of the sound pressure is not excited,
the disturbance of the sound pressure characteristic and hence the deterioration of the sound
quality is reduced. In the above embodiment, two bass speakers (3a). These speakers (3a) are
mounted on the center line of the enclosure (1) in the left-right direction. The same operation can
be obtained even if (3b) is attached at a position equidistantly shifted in the opposite direction
from the center line. Then, as shown in FIG. 5, if the above equal distance is W / 4, the same
operation as the above (1) can be obtained for the standing waves generated in the left and right
direction of the enclosure (1). It becomes. The enclosure according to the present invention is not
limited to a rectangular parallelepiped, and may have an average height H1 width W and depth
H> W, D, not limited to a closed type, and may be a bass reflex type etc. It is.
Also, the two bass speakers of the present invention do not have to have the same diameter, and
the mounting position of the baffle surface is also within 10% of the height H2 width W of the
enclosure from the position of the node of the sound pressure mode It is good if it is in the range
of As described above, according to the present invention 2, according to the present invention,
the speaker device, which is attached to the buckle surface of the bass radio cabinet, is vertically
mounted in the enclosure. The low-order standing waves generated in the left and right
directions are not excited, so that the disturbance of the sound pressure characteristic of the bass
speaker can be reduced, and hence the deterioration of the sound quality can be reduced.
[0002]
Brief description of the drawings
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[0003]
FIG. 1 is a perspective view showing a conventional speaker device.
2 shows sound pressure frequency characteristics of the one shown in FIG. 1, and FIGS. 3 (a) to 3
(c) show first to third modes of sound pressure and particle velocity at standing wave frequency,
respectively. Figure showing. FIG. 4 shows an embodiment of the present invention, and (a) is a
front view. (B) is a longitudinal cross-sectional view along 4b-4bK of (a), FIG. 5 is a front view
which shows the other Example of this invention. (1) ... enclosure, (2) ... buckle surface, (5a). (3b)
... Loudspeaker. Fig. 1 ') Fig. 2 Fig. 3 (α) tb) (C)
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