US2701025A

US2701025A - High fidelity sound system

Info

Publication number: US2701025A
Application number: US270085A
Authority: US
Inventors: George H Kuhl
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-02-05
Filing date: 1952-02-05
Publication date: 1955-02-01
Anticipated expiration: 1972-02-01

Description

Feb. 1, 1955 e. H. KUHL 2,701,025

HIGH FIDELITY SOUND SYSTEM Filed Feb. '5, 1952 IN VEN TOR.

George/ KM BY/W/ W} United States Patent HIGH FIDELITY SOUND SYSTEM George H. Kuhl, Glen Ellyn, Ill.

Application February 5, 1952, Serial No. 27 0,085

3 Claims. (Cl. 181-30) This invention relates to a high fidelity sound reproducing system.

It is the general object of this invention to produce a new and improved apparatus for the high fidelity reproduction of sound.

Recent years have seen noteworthy advances in electronic systems for accurately and faithfully reproducing sound. Amplifying equipment, sound generators such as speakers, and other equipment, have been improved to the extent where sounds can be reproduced with a faithfulness heretofore thought impossible. Similar advances have taken place in the art of recording sound for later reproduction. Long-playing records and wire and tape recordings are now being produced which can recreate, with accuracy and fidelity, music and other sounds recorded therein.

One serious drawback to the faithful reproduction of sound still remains. In ordinary sound reproducing systems the speaker or other element generating the sound is normally enclosed in a housing of some sort and all of the sound is generated from a very small area. This fact creates the illusion of music or other sound coming out of a box. This effect is quite different from the effect on the listener of hearing a live orchestra symphony or other originator of sound in actual performance. To take an extreme example, the average home listenerto recorded symphonies may purchase and install an excellent record player, a high quality pickup, preamplifier and amplifier and speakers capable of reproducing all of the notes which the human car can hear and yet, when listening to a record of a symphony orchestra, the feeling of depth which would be sensed at a live performance is lost. It is unrealistic to condense a symphony orchestra into a two cubic foot record player cabinet.

A number of attempts have been made to overcome this disadvantage, some of them extremely elaborate. For example, it has been proposed to make two recordings of, for example, a symphony orchestra with one recording instrument being located on the left side of the orchestra and the other instrument on the right side. When listening to the recordings both are played at once but one record is directed to the left ear of the listener while the other, to the right ear. In such systems earphones have been used and the listener has one earphone connected to the instrument playing one record and the other connected to the instrument playing the other record; or two speakers positioned on either side of the listener may be employed. Such systems, while helpful, are cumbersome, difiicult to synchronize and certainly undesirable for installation in a private home.

I have discovered, however, a compartively simple apparatus and method of using the same which, when properly installed, gives the illusion of depth to a sound reproducing system. In the system of this invention the sounds are divided between low frequency sounds and high frequency sounds in a manner which is common in high fidelity speakers (such as coaxial speakers or separate tweeters and woofers) which are usually employed. Rather than placing both speakers in a single box, however, they are so arranged as to cause the high frequency sound to take a different, preferably longer, path from their origin to the listener than the sounds generated by the low frequency speaker. In the preferred form of the invention illustrated, the longer path is achieved by directing the low frequency generator directly toward a listening area to provide for the sounds generated thereby a relatively short path while directing the sounds generated 2,701,025 Patented Feb. 1, 1955 by the high frequency generator against a reflector for reflection toward the listening area. This not only spreads the high frequency sound to give the illusion of sound coming from an area rather than a point, but also causes the high frequency sound to travel a longer path. This longer path gives a feeling of depth to the sound. Apparently the feeling of depth arises because of the fact that the same sound which may have a basic low frequency also has overtones in the higher frequencies. Because of the differences in paths, the basic low frequency note reaches the ears of the listener slightly in advance of the high frequency overtones and this very slight difference in the arrival times of sounds to the ear of the listener creates an illusion of depth.

A high fidelity sound reproducing system installed and operated in the manner hereinafter to be described creates the illusion of a full symphony orchestra, for example, playing behind an imaginary opaque drop, that is, as if it were playing just outside the room, and the full expanse and breadth of the orchestra can clearly be felt by the listener.

The apparatus and its use will be described in connection with the accompanying drawings, in which:

Fig. l is a front elevation of apparatus embodying the invention;

Fig. 2 is a vertical sectional view of the apparatus shown in Fig. 1; and

Fig. 3 is a horizontal sectional view taken near the upper portion of Fig. 1.

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail one specific embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

While it will be clear to those skilled in the art that the sound reproducing system of this invention can be utilized with many sound generating instruments such as electric organs and the like and that the principles of the invention can be utilized in installations of widely varying nature, for the purpose of brevity the invention will be described for use in reproducing recorded sounds from a record and is shown as installed in a room.

Referring now to the drawings, it will be noted that the apparatus is installed in the corner 10 of a

room having walls

11 and 12, meeting in the corner at an angle of approximately and a ceiling 13 and floor 14. Extending diagonally across the corner from ceiling to floor is a closure member 15 which may take the form of a plywood panel or other suitable material usable in sound reproducing systems. The closure member 15 together with the ceiling, walls and floor forms a chamber 16 isolated except for a circular opening 17 therein. For the purposes of enhancing the appearance, a suitable cloth grillwork such as the grillwork 18, which may be rectangular or any other shape, covers the opening 17.

Mounted on the interior side of the closure member 15 is a low frequency sound generator in the form of a speaker 20. The chamber 16 in which the low frequency speaker is located provides a rather large isolated volume of air. Corner space in a room is often unusable for any purpose and thus by utilizing a corner, a great deal more of isolated air space for the speaker can be obtained without detracting from the appearance of the room. The closure member 15 may be finished to resemble the other walls of the room so as to be comparatively inconspicuous. A further advantage of corner location is that the diverging walls act as extensions of the horn of the speaker and improve its performance.

High frequency speakers 21 and 22 (which are known as tweeters in the art) are located exteriorly of the chamber 16 and are directed away from the listening area, the direction of said area being in the direction faced by the low frequency speaker 20. Preferably the high frequency generators are mounted in a cabinet 23 which rests upon the floor 14 of the room. The cabinet may be provided with a suitable turntable 24, preamplifier 25 and amplifier 26 of the electronic sound reproducing equipment. The amplifier is connected to a suitable crossover network 30 which functions to divide the electrical impulses received in accordance with the frequency of the sound to be generated in a manner well known in the art. Preferably the crossover network is so constructed as to deliver to the low frequency generator 20, through line 31, electrical impulses for producing sound of 850 cycles and lower. While a single high frequency generator may be employed, I prefer to employ two and to arrange the crossover network so as to deliver to the generator 21 electrical impulses for reproducing sounds having from 850 to 2500 cycles and to utilize the lead 33 to deliver to the high frequency generator 22 electrical impulses for reproducing sounds over 2500 cycles. By the employment of a high frequency generator, such as the generator 21, and an extra high frequency generator, such as the speaker 22, a further improvement in the illusion of reality can be achieved.

The high fidelity generators are directed upwardly and away from the listening area against an angularly inclined reflector 40 located adjacent the ceiling. The reflector 40 is constructed of high fidelity sound reflecting material such as glass, steel, tile and the like and serves to reflect the high frequency sounds outwardly toward and into the listening area. Because of the circuitous path followed by the high frequency sounds, their path of movement to a listener in the listening area is longer than the path of movement of low frequency sounds from the low frequency driver 20.

The reflecting panel 40 is substantially trapezoidal in shape and cut to fit the corner in which it is installed. Thus, the shorter base 41 rests against the closure member 15 while the longer base 42 is located adjacent the ceiling of the room with the sides 43 and 44 being adjacent the

walls

11 and 12 respectively.

While improvement over ordinary installations can be accomplished by locating the reflector within the chamber 16 and also moving the high frequency speakers within the chamber, the results are inferior to those produced with the arrangement shown in the drawings inasmuch as with the latter arrangement, a far better dispersion of sound occurs which enhances the illusion referred to of the sound originating from an area rather than from a point. If the

walls

11 and 12 are of ordinary plaster, they possess some sound absorbing qualities. If the plaster is extremely hard, however, or if walls which have a high reflectivity for sound are encountered, improved sound characteristics can be obtained by insulating with sound deadening material the exterior surfaces of the walls within the chamber.

I claim:

1. Apparatus for increasing the fidelity of a roominstalled sound reproducing system comprising a closure member extending from the ceiling to the floor of the i member extending from adjacent the ceiling to the floor within the chamber and directed outwardly therefrom toward a listening area, an angularly inclined reflector positioned exteriorly of the chamber adjacent the ceiling and a high frequency generator positioned exteriorly of the chamber and substantially vertically beneath said reflector, said high frequency generator being directed upwardly toward the reflector.

2. Apparatus for increasing the fidelity of a roominstalled sound reproducing system comprising a closure of the room diagonally across a corner thereof to provide with the walls, ceiling and floor an isolated chamber, a low frequency generator mounted on the closure member within the chamber and directed outwardly therefrom toward a listening area, an angularly inclined reflector positioned exteriorly of the chamber adjacent the ceiling, and a high frequency sound generator positioned exteriorly of the chamber substantially vertically beneath the reflector and directed upwardly and away from the listening area toward the reflector.

3. Apparatus for increasing the fidelity of a roominstalled sound reproducing system comprising a closure member extending from adjacent the ceiling to the floor of the room diagonally across a corner thereof to pro vide with the walls, ceiling and floor an isolated chamber, a low frequency generator mounted on the closure member within the chamber and directed outwardly therefrom toward a listening area, an angularly inclined substantially planar reflector inclining outwardly toward the listening area and extending from the upper portion of the closure member substantially completely to the ceiling and horizontally from wall to wall in the corner, and a high frequency sound generator positioned exteriorly of the chamber substantially vertically beneath the reflector and directed upwardly and away from the listening area toward the reflector.

References Cited in the file of this patent UNITED STATES PATENTS 2,143,175. Waite Jan. 10, 1939 2,217,279 Karns Oct. 8, 1940 2,275,610 Bucky et a1 Mar. 10, 1942 2,310,243 Klipsch Feb. 9, 1943 2,539,327 Reid et a1. Ian. 23, 1951 2,610,694 De Boer Sept. 16, 1952 2,612,234 Zivadinovic Sept. 30, 1952 FOREIGN PATENTS 929,705 France Jan. 6, 1948