US1642040A - Public-address system - Google Patents

Description

Patented Sept. 13, 1927.

UNITED STATES iii-ii, if]

PATET OFFICE.

IBRUNSON s. MoCUTCHEN, or, NORTH PLAINE -EL D, NEW JERSEY,- nssIGNoR To AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION on NEW YORK. I

PUBLIC-ADDRESS SYSTEM.

Application filed December 12, 1925. Serial No. 75,116.

instances wherein a loud speaker might be; located at a considerable distance from the platform this .acoustic delay in the air path of the speech might cause a bad'blurrin or echo effect to a listener near the loud spea er. Accordingly it is one of the primary objects of this invention to introduce an electrical delay invthe circuit of the loud speaker to compensate for the acoustic delay to the, speech existing in the air path.- With such an arran ementthe listener will not receive the speec from the horn in advance of the direct speech from the speaker with the attendant bad effect, but will receive the Speech from the horn in the same phase with and at the same time as the direct speech from the speaker. The arrangements of the invention also rovide distinct advantages from the stan point of flexibility of w location of the loud speakers for with the arrangements of the invention the loud speakers ma belocated at much greater distances than eretofore from the speaker. The greater distance at which the loud speaker may be located tends to-reduce the existence of singing in the apparatus and hence the loud speakers may be 0 erated at higher volume levels. Adcordin y, the arrangements of the invention ten to reduce singing, allow increased volume in'the operation of the loud speakers, and also afior greater flexibihty in their location. Other objects and tures of the invention will appear more fully from the detailed description thereof herein rgiven. e invention ma be more fully understood .from- .the 0 owing description, to-

ther with the accompanying drawing, m 6 Figures 1 and 2 of which the invent1on 5o iBillustrl-ted. In Fig. 1 is a circuit diagram of one form of the arrangements of the invention'andin 2 are shown details of the electrical reta devlces. p

In Fi 1 is shown "a microphone, or transll mitter, which might, be'located at a platfea- - form or any desirable spot of an auditorium,

or grounds, on which an address or other message or musical composition is to'be de- -l1vered. The microphone may be connected; to an amplifier 2. The output circuit of the coamp llfier .is shown as circuit 3. Connected to circuit 3 is the circuit 5 leading 'tothe loud speaker 7 which would be located at some distanec away from the microphone and s eaker. If the distance from the mlcrop one at which the loud speaker 7 is located is found to be great enough so "that an acoustic'dela in the air path will cause the direct speec to, arrive at this position sufliciently later than the speech from. the loud speaker 7 to cause a blurring or echo e-' f feet, the delay network 6'will be inserted in circuit 5 to com ensate for this delay. In the case of a lou speaker, such as'A located in close proximity to the micro one-no such delay circuit would be provi ed. The loudspeaker 4 might even be omitted if desired. Associated with; circuit 3 might be other circuits, such as the circuit 8, leading to other loud speakers, such as 10, located at otherpositions on the grounds. A delay network, such as 9, might be'iound desirable in the circuit 8 if the loudspeaker L0. were located at a suflicientdistance from the speaker and microphone 1. In. Fig. 2 is shown a suitable type of delay network to .be utilized in the-loud speaker circuits, such as 5 and 8. The delay networks consist of a number of sections comprisin inductance and capacity in series. The in 'vidual sections are shown between the dotted lines a, b. The delay networks, such as 6 and 9, comprise a variable number of these sections 1 depending upon the amount of acoustic delay in the air path which they are desired to compensate. 7 0

'While the arrangements of the invention have been illustrated in certain specific forms which are deemed desirable, it is understood that they are capable of embodiment 1n many other widely varied forms without departms 'from the spirit of the inventlon as define by the appended claims. J. a

What isclaimed is;

1. In a public -a'ddress systema trans mitter. circuit, a plurahty of cucmtsassociated therewith including loud speakmgoreceivers --located at various distances m said transmitter, and delay networks m cer- 91 said cincuita.

2. In a public address system a'circuit including a, transmitter, a loud speaklng receiver in said circuit located in close proximity to said transmitter, a second circuit associated with said first circuit and including a. loud speaking receiver located at a relatively greater distance from said transmitter than said first loud speaking receiver, and electrical retarding means in said second circuit.

3. A circuit including a transmitter, an. amplifier and a loud speakin receiver, said loud speaking receiver being coated in relatively close roximity to sald transmitter, a second circuit associated with said first C11- cuit and including aloud speaking receiver located at a relatively greater distance from said transmitter than said first receiver, and means in said second circuit to-so retard the currents transmitted thereover that both of said loud speaking receivers will operate in the same phase.

4. A circuit including a transmitter and a loud speaking receiver, said loud speaking receiver being located at a distance from said transmitter so great that an appreciable difference will exist between the acoustic delay in the air path between said transmitter and said loud speaking receiver and the electrical delay in said circuit interconnecting said transmitter and said loud speaking receiver, and means for introducing electrical delay in said circuit to compensate for the acoustic delay in the air ath.

In testimony whereof, I have signe my name to this specification this 10th day of December, 1925. v

BRUNSON S. MGCUTCHEN.

Images