US1731460A - Acoustic device - Google Patents

Acoustic device Download PDF

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Publication number
US1731460A
US1731460A US308367A US30836728A US1731460A US 1731460 A US1731460 A US 1731460A US 308367 A US308367 A US 308367A US 30836728 A US30836728 A US 30836728A US 1731460 A US1731460 A US 1731460A
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United States
Prior art keywords
diaphragm
acoustic device
correcting
spaced
adjacent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US308367A
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English (en)
Inventor
Hallawell Austin Morris
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Victor Talking Machine Co
Original Assignee
Victor Talking Machine Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Victor Talking Machine Co filed Critical Victor Talking Machine Co
Application granted granted Critical
Publication of US1731460A publication Critical patent/US1731460A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/06—Loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 

Definitions

  • the present invention relates to acoustic devices such for example as loud speakers and the like of the type in which the diaphragm or other sound producing or receiving surface is substantially unthrottled. That is to say the diaphragm is either adapted to operate without a horn, or if a horn is used, the mouth opening of the horn is not appreciablysmaller than the area of the diaphragm.
  • thecurve instead of being a straight line parallel to the frequency axis as it should be in the ideal case, has one-or more pronounced irregularities.
  • the present invention provides means where'- by certain of these irregularities may be reduced or eliminated. This is accomplished according to the invention by arranging adjacent to but spaced from a part of the diaphragm a fixed surface.- In this way an air space is provided which is resonant to the frequency or range of frequencies at which it is P desired to increase the response of the device.
  • a plurality of such resonant air spaces co-operating with one diaphragm may be provided.
  • Figs. 1 and 2 are diagrammatic views in elevation and plan respectively of a loud speaker embodying the invention.
  • Fig. 1 being a section on the line 11 of Fig. 2, and
  • FIG. 3 is a diagram illustrative of the invention.
  • a diaphragm 1 v of thin aluminum is stretched and clamped in known manner between two rings 2 and 3.
  • Three radial arms 4 project inwards from the ring 3 and support (in a manner not shown) a magnet 5. having an annular air gap 6 in which is arranged a coil 7 attached to the diaphragm 1.
  • Three radial arms 8 project from the ring 2 and are united above the centre of the diaphragm 1. and threaded through the arms 8 at their junction is an adjusting screw 9 provided with a lock nut 10. Upon the lower end, of the screw 9 is tired a 308,367, and in Great Britain October 4, 1927.
  • Fig. 3 shows the response characteristic of a loud speaker, of the type above described, before and after correction with the aid of the present invention, the dotted line representing the uncorrected curve.
  • the loud speaker has two dips in its response curve reaching maxima at about 1,600 and 300 cycles per second respectively.
  • the screw 9 In orderto remove or reduce the dip at 1,600 cycles per second the screw 9 is adjusted until the resonance due to the air space between the disc 11 and the diaphragm 1 is at 1,600 cycles per second. If the amount of correction provided is too small, the size of the disc should be increased and vice versa. hen the right adjustment has been foundthe screw 9 is locked by means of the nut 10. In one actual case to produce a correcting resonance at 1,600 cycles per second an air space one-tenth of an inch long was found to be suitable.
  • annular ring 1% is adjusted by means of the screws 12 which are then locked by means of nuts 13.
  • a suitable length of air space was in practise found to be from 1 inch to 1 inches.
  • the correcting device may take the form of flat-plates as described above, or alternately it may consist of a solid body of any desired shape, provided that the surface thereof adjacent the diaphragm lies generally parallel thereto. It may be made of any suitable materiai, such for example as metal, wood or moulded material and it may be constructed with or without an aperture through the centre.
  • the invention has-been described as applied to a plane membrane it is not so limited but maybe applied equally to membranes, diaphragms or pistons of any shape. In general the effective surface of the correcting device would then conform roughly to the shape of the membrane, diaphragm or piston.
  • the one providing resonance pendent adjustment toward and away from at the highest frequency is the central one, said diaphragm. since the higher the frequency of vibration, In te tim ny f' t' 1 gn my the more does the vibration of the diaphragm 11111110 to H115 speclficatwni become confined to the central portion there- AUSTIN MORRIS HALLrUNELL. of. in order to produce a flatter resonance, that is to say one covering a wider band of 1G frequencies, the air space may be made to i '15 vary progressively in depth.
  • An acoustic device comprising :1 diaphragm or other sound producing or rccciv- 2() ing surface which is substantially unthrottled
  • a fixed surface is arranged adjacent to but spaced from a part of said diaphragm substantially as and for the purpose described.
  • a device as claimed in'claim 1 wherein said diaphragm is flat and wherein said fixed 30 surface is of annular shape.
  • An acoustic device comprising av .diaphrag'in which is substantially unthrottled, a device forming a fixed surface adjacent to but spaced from a part of said diaphragm,
  • An acoustic device comprising a diaphragm which is substantially unthrottled, a
  • a device as claimed in claim 4 includw ing means for adjusting the fixed surface toward and away from the diaphragm.
  • An acoustic device comprising a diaphragm, a support therefor, a device torm- 50 inc a fixed surface arranged adjacent to but spaced from a part of said diaphragm, and means for adjustably mounting said device on said support.
  • An acoustic device comprising a diaphragm, means forming afixed surface adjacent to out spaced from a part of said dia- 'phrag'm, an adjustable mounting for 'said' means whereby the position of said surface may be adjusted toward or away from said diaphragm, and means for locking said 1 5 mounting to prevent movement of said suri'ace from its adjusted position.
  • An acoustic device comprising a diaphragm, a plurality of devices each forming a fixed surface adjacent to but spaced from 9

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
US308367A 1927-10-04 1928-09-26 Acoustic device Expired - Lifetime US1731460A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1731460X 1927-10-04

Publications (1)

Publication Number Publication Date
US1731460A true US1731460A (en) 1929-10-15

Family

ID=10889413

Family Applications (1)

Application Number Title Priority Date Filing Date
US308367A Expired - Lifetime US1731460A (en) 1927-10-04 1928-09-26 Acoustic device

Country Status (3)

Country Link
US (1) US1731460A (fr)
FR (1) FR661129A (fr)
NL (1) NL23563C (fr)

Also Published As

Publication number Publication date
NL23563C (fr)
FR661129A (fr) 1929-07-22

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