US3777844A

US3777844A - Adjustable speaker cabinet

Info

Publication number: US3777844A
Application number: US00300177A
Authority: US
Inventors: R Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-10-24
Filing date: 1972-10-24
Publication date: 1973-12-11
Anticipated expiration: 1990-12-11

Abstract

An acoustical cabinet for housing one or more loud speakers is described. The cabinet is broken up into a plurality of separate chambers and resonance volumes by means of horizontal partitions across the rectangular chamber. Each of the horizontal dividing walls has a plurality of circular openings therein. The speaker or speakers is mounted to a horizontal baffle across the entire cross section of the chamber. The resonance volumes above the speaker are partially vented, through pluralities of circular openings in the front panels of those chambers. The chambers below the speaker are likewise vented to the back through pluralities of circular openings.

Description

[ Dec. 11, 1973 United States Patent [191 Johnson ADJUSTABLE SPEAKER CABINET Primary Examiner-Stephen J. Tomsky d u m e r 0 m fl 0 e n 0 g l U m M e d Tr a SO Bf e t H e .m R w C m a .w t m a m m 1. 7 1 A UA t S t r u 0 C 2 I w 94 7 m. mm on 9 e vwc .m u k but u c RMO n O m d w m h F l l 6 2 7 2 l [21] Appl. NO-I 300,177 speakers is described. The cabinet is broken up into a plurality of separate chambers and resonance volumes by means of horizontal partitions across the rectangular chamber. Each of the horizontal dividing walls has a plurality of circular openings therein. The speaker or speakers is mounted to a horizontal baffle across the entire cross section of the chamber. The resonance [56] References Cited UNITED STATES PATENTS volumes abovethe speaker are partially vented, through pluralities of circular openings in the front 181/31 B P nels of those chambers. The chambers below the 81/31 B speaker are likewise vented to the back through l g ralities of circular openings.'

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m" pmud. 0m TP 046 466 999 111 37 l 8384 9546 3238 9488 1 2333 4 Claims, 5 Drawing Figures 0 52 552- oooooo OOOOOOOO ADJUSTABLE SPEAKER CABINET tus. More particularly, it is concerned with loud speaker housings andcabinet arrangements in connection with sound reproduction devices to provide improved tonal quality.

Acoustical devices in the prior art have generally been inadequate and failed to presentproper tonal effects in accordance with the electrical signal supplied to the sound reproduction devices of loud speakers. In the prior art, most cabinets housing loud speakerscomprise more or less of a single resonant chamber, or a plurality of resonant tubes connected with a principal chamber. While there are many variations of this type of loud speaker chamber none of them have been completelysatisfactory in the quality of the sound emission, particularly in terms of the breadth of the frequency band permitted to be produced.

SUMMARY OF THE INVENTION- It is a primary object of this invention to provide a housing, or cabinet, for loud speakers which provide adequate opportunity for resonance and filtering and in the use of wave guides so that abroad band of sound reproduction is effected.

This and other objects of this invention are realized and the limitations of the prior art are overcome in this invention, in which the cabinet in which the loud speaker or speakers are installed, provide a plurality of separate vertically arranged volumes .formed by horizontal baffles across the entire cross section of the rectangular cabinet to allow both resonances and reflection of the entire wound waves. There are pluralities of openings in each of the horizontal baffles, and each resonant volume defined between baffles has an opening to the outside atmosphere through'the front or back panels. These openings are provided through a plurality of circular apertures of different diameters. The resonant volumes above the loud speaker are vented to the front of the chamber, and the resonant volumes below the loud speaker are vented to the back of the chamher. I The principal design factor in this cabinet lies in the fact that each of the horizontal baffles has a plurality of different size openings, arranged in different geometric patterns, but each baffle has a total area of openings equal to that of the total vibrational diaphragm area of the loud speaker. Also the vents to the front, and to the back, are of such number and size of openings that the total area to the front is equal to the total vibrational area of the loud speaker diaphragm. Likewise, the total area of the openings venting to the back are likewise equal to the total vibrational area of the loud speaker diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of this invention and a better understanding of the principles and details of the invention will be evident from the following description taken in conjunction with the appended drawings in which:

FIGS. 1 and 2 present a front and side view of the loud speaker cabinet.

FIGS. 3 and 4 show views of two of the horizontal baffles showing aperture arrangements.

FIG. 5 is an isometric view of one end of one of the wave guide tubes showing a valve by which the end of the tube may be opened or closed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, numeral 10 indicates generally the loud speaker cabinet of this invention. This comprises a rectangular cabinet having a group of

front panels

32, 34, 3 6, 38, 40, two

sides

24, 26, a top and

bottom

28 and 30, and a group of

back panels

56, 58, 60. There is a principal rigid horizontal baffle 48 across the complete cross section of the-chamber. This supports the principal speaker 52, or speakers, since there may be more than one of the different frequency band type. The aperture area of the speaker, or speakers, is represented by the numeral 53. This baffle 48 is generally positioned at some point near the lower onethird of the vertical dimension, and particularly below the middle of the chamber. The space above the loud speaker is divided into a plurality of resonance and sound reflecting volumes shown by the numerals 12, I

14, 16 and 18 although there may be more or fewer chambers, each being air tight except to that extent by which there is a controlled sound input and emission area as shown. Likewise there are a plurality of

resonance volumes

20 and 22 below the loud speaker.

The cabinet is generally made of heavy wood construction so as to provide principal chambers which are not readily flexed by the sound pressure. Thus the bottom, top and sides will be of rigid wood construction. Similarly the front and back panels can be of heavy wood construction although plastic panels of a thickness of one-quarter inch or more can be used. A single front panel is used which completely covers the front of the

chambers

32, 34, 36, 38, 40.

The two parts of the cabinet above and below the principal speaker or speakers are kept separate and air tight. The space above the speaker is vented through openings in the front panels and the space below the speaker is vented through the back panels. Each of the horizontal baffles such as 42, 44, 46 and 50 are provided with a plurality of openings of different sizes and geometrical arrangements. Horizontal baffle 42, for example, is illustrated in FIG. 3 and may comprise an opening A which may conveniently be a circular opening of five inches diameter. There are on the sides a group of six openings identified by the letter B which may conveniently be two inches in diameter. There are in addition a group of six openings identified by C which may conveniently be one inch in diameter and a plurality of four smaller openings labeled D which may conveniently be /2 inch in diameter. The

baffles

42 and 46 may be identical. Baffle 44 is illustrated in FIG. 4, for example, and comprises two large openings identified by A which may conveniently be five inches in di ameter and a group of six openings C which may conveniently be one inch in diameter. This baffle 44 may be duplicated in the position of baffle 40. Adjacent baffles will each be different in the distribution of openings. However, there is one factor which is fixed and that is, that the total areas of the openings in each of the baffles are substantially equal and are equal to the cross sectional total vibrational area of the loud speaker or speakers. This is a design requirement of this device. That is, the areas of the openings in each horizontal baffle are equal to the cross sectional area of the vibrating diaphragm of the loud speaker or speakers.

In'FIGS. l and 2 there are shown a group of

panels

32, 34, 36 and 38, each of which have a plurality of openings of different sizes and different arrangement. The sum total of openings such as B, C, and D over all of the four panels is equal to the total vibrational area of the diaphragm of the loud speaker or speakers. Similarly there are shown in FIG. I in dashed outline a plurality of openings through the

back panels

58 and 60 which, also, together total in cross sectional area to the cross sectional area of the loud speaker 53.

As a variation, some or all of the openings in one or more of the front panels such as 32, can be fitted with a plurality of resonance tubes, such as 62, of different selected lengths to act as sound wave guides for selected frequency components of the audio signals. These can be circular cylinders, cut off square, or they can be cut off at an angle such as 64 which will tend to provide a broader band of resonance, and flatten the peak of resonance, for each of the tubes so cut.

What has been described is a substantially rigid rectangular cabinet of greater height than width or thickness, with a plurality of horizontal baffles or dividers. The loud speaker or speakers is fastened to one of these rigid baffles at some point below the center of the cabinet. The baffles above the loud speaker and below the loud speaker are perforated with a plurality of circular openings of different diameters and geometric arrangement, but each of the baffles has a total area of opening which is equal to the total vibrational area of the diaphragm of the loud speaker. The resonance volumes above the speaker, formed by the horizontal baffles, each vent through the front panel of the chamber, through a plurality of openings of different diameters and arrangement. The total cross sectional areas of these openings is equal to the cross sectional area of the total vibrating area of the loud speaker diaphragm. Similarlybelow the diaphragm there are openings in the back panel which total in cross sectional area equal to the total vibrational area of the loud speaker diaphragm. Some or all of these openings can be fitted with sound wave guide tubes as desired.

FIG. 5 shows a valve, generally indicated by the numeral 55 which is preferably employed in the outer end of each or a portion of the sound wave guide tubes 62. In this'way each wave guide tube having a valve 55 therein may function as an open end or a closed end pipe, or partially opened and closed. Valves 55 permit the user to adjust tonal response by changing the harmonics which are augmented by the speaker cabinet and those which are attenuated. 1

While the invention has been described with a certain degree of particularity it is manifest that many changes may be made .in the details of construction and the arrangement of components. It is understood that the invention is not to be limited to the specific embodiments set forth herein by way of exemplifying the invention but the invention is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element or step thereof is entitled.

- What is claimed:

1. An adjustable loud speaker cabinet, comprising:

a. a rigid substantially rectangular cabinet, greater in length than in width or thickness;

b. a rigid wall across said cabinet on one side of the center thereof, forming two chambers, at least one loud speaker mounted in said wall, said loud speaker having a diaphragm area of K;

c. a plurality of spaced baffles across said cabinet in the larger of said chambers, forming a first plurality of resonance volumes; K

d. at least one baffle across said cabinet in the smaller of said chambers, forming a second plurality of resonance volumes;

e. each of said baffles having a plurality of circular openings of different diameters and geometric arrangement;

f. the total cross sectional area of the openings in each baffle substantially equal to K;

g. a plurality of openings in the front panel of said chamber, venting each of said resonance volumes in the larger of said chambers to the front, the total cross sectional area of said openings in said front panel being equal to K; and

h. a plurality of openings in the back panel of said chamber venting each of said resonance volumes in the smaller of said chambers to the rear, the total cross sectional area of said openings in said back panel being equal to K.

2. The loud speaker cabinet as in claim 1 including a plurality of wave guide tubes of selected lengths insertedinto selected ones of said openings in said front and rear panels.

3. The loud speaker cabinet as in claim 1 including means to removably mount wave guide tubes whereby they can be interchanged in position.

4. The loud speaker cabinet as in claim 3 wherein at least one of said wave guide tubes including a valve means in one end thereof.

Claims

1. An adjustable loud speaker cabinet, comprising: a. a rigid substantially rectangular cabinet, greater in length than in width or thickness; b. a rigid wall across said cabinet on one side of the center thereof, forming two chambers, at least one loud speaker mounted in said wall, said loud speaker having a diaphragm area of K; c. a plurality of spaced baffles across said cabinet in the larger of said chambers, forming a first plurality of resonance volumes; d. at least one baffle across said cabinet in the smaller of said chambers, forming a second plurality of resonance volumes; e. each of said baffles having a plurality of circular openings of different diameters and geometric arrangement; f. the total cross sectional area of the openings in each baffle substantially equal to K; g. a plurality of openings in the front panel of said chamber, venting each of said resonance volumes in the larger of said chambers to the front, the total cross sectional area of said openingS in said front panel being equal to K; and h. a plurality of openings in the back panel of said chamber venting each of said resonance volumes in the smaller of said chambers to the rear, the total cross sectional area of said openings in said back panel being equal to K.

2. The loud speaker cabinet as in claim 1 including a plurality of wave guide tubes of selected lengths inserted into selected ones of said openings in said front and rear panels.