US1981793A - Sound reproducer - Google Patents

Sound reproducer Download PDF

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Publication number
US1981793A
US1981793A US402128A US40212829A US1981793A US 1981793 A US1981793 A US 1981793A US 402128 A US402128 A US 402128A US 40212829 A US40212829 A US 40212829A US 1981793 A US1981793 A US 1981793A
Authority
US
United States
Prior art keywords
reproducer
stylus
record
records
groove
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
US402128A
Other languages
English (en)
Inventor
Arthur C Keller
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.)
AT&T Corp
Original Assignee
Bell Telephone Laboratories Inc
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
Priority to BE383667D priority Critical patent/BE383667A/xx
Priority to NL33960D priority patent/NL33960C/xx
Priority to BE374410D priority patent/BE374410A/xx
Priority to US402128A priority patent/US1981793A/en
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to GB30996/30A priority patent/GB363449A/en
Priority to FR704651D priority patent/FR704651A/fr
Priority to DE1930599965D priority patent/DE599965C/de
Priority to FR41017D priority patent/FR41017E/fr
Priority to FR44045D priority patent/FR44045E/fr
Application granted granted Critical
Publication of US1981793A publication Critical patent/US1981793A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • H04R1/16—Mounting or connecting stylus to transducer with or without damping means
    • 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
    • H04R9/12—Gramophone pick-ups using a stylus; Recorders using a stylus

Definitions

  • This invention relates to sound reproducing devices and is principally concerned with the general features of phonograph reproducer design which are applicable to both electric and acoustic types adapted for usewith hill and dale records.
  • the .object of the invention is to provide a reproducer structure which may be proportioned for efficient and substantially uniform response over the full frequency range of speech and music or for an even greater range if desired.
  • a feature of the invention is an elastic mounting for the moving system which deilects when the reproducer is set on a record, thereby setting up a restoring force of the proper magnitude which supplements the action of gravity so that the stylus can be made to follow the grooves accurately with a moving system of any -desired mass.
  • a further feature of the invention is the reduction of record wear by proportioning the mass and stiffness of the reproducer to obtain the reproducer of Fig. 1 showing particularly the mounting therefor;
  • Fig. 3 is a general view of an acoustic reproducer in accordance with the general features of this invention.
  • Fig. 4 is a schematic showing the mechanical elements of a reproducer according to this invention considered as analogs of the elements of a corresponding electrical system;
  • Fig. 5 is a schematic of a portion of a record groove of the hill and dale type
  • Fig. 6 is a graph showing the effect on the cutoff frequencies of varying the mass of the vibrating system.
  • Fig. 7 is a similar graph showing the effect of varying the initial displacement of the mounting of the moving system.
  • a U-shaped magnet 1 havlng legs of unequal length is held in position against one wall of the casing 2 by a bracket 3.
  • the pole pieces 4 and 5 are so shaped and positioned that the central piece 6 of the pole Ypiece 5 projects into an opening in the reduced end portion 7 of the pole piece 4 to form an air gap ⁇ 8. While it is preferable that this be an annular air gap, obviously it may be made elliptical or any other desired shape.
  • the pole piece 5 is made hollow so in assembling a mandrel may be used for accurately aligning pole piece 5 with respect to pole piece 4.
  • coil 13 Arranged within the air gap 8 is a. coil 13 which Ymay consist of about 40 turns of fine ribbon wire,j
  • the diaphragm 27 comprises a stiff dishshaped piston portion 28, a flexible corrugated portion 29 and a flat portion 30 which is clamped between rings 31, 31 on the housing structure 32.
  • the stylus 26 may be tted directly into a pressed out portion of the diaphragm, or may be attached to it as shown by means of a piece of amber or other suitable lightweight substance 33.
  • the initial deflection of the diaphragm when the reproducer is set on the record will, as in the previous case, provide the required restoring force for supplementing the mass in keeping the stylus on the record groove.
  • the metallic plug 34 serves the same purpose as in the Wente patent, namely to improve the transmission of high frequency diaphragm vibrations, but inasmuch as this and the other features required to make up a complete reproducer form no part of the present invention, it is believed that no further description of them need be given.
  • this reproducer should be mounted on a properly balanced tone arm so that the stylus will exert only sucient pressure on the record to produce the necessary deflection in the elastic mounting member.
  • the operation of the reproducer is similar in principle to 'those well-known'in the art, that is to say, the stylus being in contact with the rotating record having grooves of the hill and dale type, the diaphragm will be vibrated in accordance with the grooves and these vibrations will be transmitted through the structure shown to a suitable horn in the well-known manner.
  • mass and stiiness as applied to mechanical vibrating systems such as the moving system of the reproducer under discussion are commonly understood in the art to mean, not the static values obtained for example by weighing the mass and defiecting a spring element to determine the force required to produce a unit deflection, but rather the dynamic values effective at the driving point (the stylus in this case) when the system is vibrated.
  • These effective values which are often quite different from the static values are conveniently measured by means of mechanical impedance bridges of the'types disclosed'in Patent 1,880,425 and in a copending application of P. B. Flanders Serial No. 664,308 filed April 4, 1933.
  • Equation (7) and (8) yield values of f1 and f2 of 34 and 100,000 cycles respectively, which means that insofar as ability to follow therecord groove, is concerned a reproducer according to this invention having these constants will reproduce all frequencies between these values.
  • Figs. 6 and 7 indicate how the cut-off frequencies, that is to say, the undistorted frequency band covered by the reproducer varies when the values of the mass and the initial displacement are varied. Having developed general formulae of Equations 5, 7 and 8, it will be obvious that it is a simple matter to so proportion the constants of the proposed reproducer that it will respond to any desired range of frequencies.
  • the curves of Fig. 6 which have been based on the values of S, Q and V already given show clearly howdecreasing the mass of the moving system increases the undistorted band by raising the upper cut-off frequency.
  • Fig. 6 which have been based on the values of S, Q and V already given show clearly howdecreasing the mass of the moving system increases the undistorted band by raising the upper cut-off frequency.
  • the resonant frequency of the structure of the moving system can have no effect on the response of the device so that uniform response is obtained throughout the range for which it is designed. It should be noted however that the resonant frequency does have a bearing upon the amount offrecord wear. To cover a given lrange with the least possible presure on the record with a moving system of given mass, the stiffness should be such that the resonant frequency ,fo is the geometric mean of the limiting frequencies of the range to be covered as shown in Fig. 7. When this is so the steady A. C.
  • force on the record represented by SQ may be such that is just counteracted by the sum of the reactions of Equation (2) at both the limiting frequencies of the band. If the resonant frequency occurs at any other frequency the A. C. force-frequency curve will notbe symmetrical with respect to the band so that the A. C. force .will be greater at one than at the other and the steady force will of necessity be large enough to balance the greater force and therefore will cause greater wear than in the previous case.
  • a reproducer for sound records embracing all frequencies within the audible range comprising a magnetic circuit having an air-gap and other, elements including a member in the airgap, an elastic support for the member and a stylus needle connected to and adapted to vibrate the member, the elements being soproportioned that the mechanical impedance of the reproducer for audible frequencies does not exceed
  • S is the effective stiffness ofthe elastic kan support
  • Q is the displacement of the stylus from its normal position when the reproducer is resting in a groove of average depth
  • V is the maximum velocity imparted to the stylus by the groove of the record and so that the pressure required to keep the reproducer in contact with the grooves of records is of the order of 10 grams.
  • a reproducer for hill and dale records comprising a magnetic circuit, a generating element Within the circuit, a stylus associated With the generating element and elastic mounting means for the element, the mechanical constants of the reproducer being so proportioned that its mechanical impedance over any desired frequency range does not exceed
  • S is the stiffness of the elastic mounting
  • Q is the average displacement of the stylus from its normal position
  • V is the maximum velocity imparted to the stylus by the grooves of the records.
  • a phonograph reproducer in accordance with claim 2 having values of effective mounting stiffness S and effete mass M such that the resonant frequency of the reproducer 1 fram/1T' occurs in the neighborhood of the geometric mean of the limiting frequencies of ⁇ the frequency range of the reproducer.
  • a moving system for reproducers of the hill and dale type comprising a movable element, a stylus for driving the element and means for mounting the element, the mechanical constants of the system being so proportioned that its mechanical impedance over any desired frequency range does not exceed
  • S is the stiffness of the mounting
  • Q is the average displacement of the stylus from its free position
  • V is the maximum velocity imparted to the stylus by the grooves of the records.
  • An acoustic phonograph reproducer for hill and dale records comprising a casing and a moving system for vibrating the air Within the casing comprising a diaphragm and a stylus for driving the diaphragm, the mechanical constants of the system being so proportioned that its mechanical impedance over any desired frequency range does not exceed where S is thestiffness of the mounting, Q'is the average displacement of the stylus from its free position and V is the maximum velocity imparted to the stylus by the grooves of the records.
  • a moving system comprising a movable element, a stylus for driving the element and means for mounting the element the system being so proportioned that its mechanical impedance over any desired frequency range does not exceed
  • S is the stiffness of the elastic mounting
  • Q is the average displacement of the stylus from its normal position
  • V is the maximum velocity imparted to the stylus by the grooves of the record and so'that the pressure required to keep the reproducer in contact with the grooves of the records is of the order of 10 grams.
  • a reproducer having a moving system including a stylus, a mass element and a resilient supporting member for the element, the mechanical constants of the system being so proportioned that its mechanical impedance over any desired frequency range does not exceed where S is the stillness of the mounting, Q is the average displacement of the stylus from its free position and V is the maximum velocity imparted to the stylus by the grooves of the record.
  • a phonograph reproducer for high quality 1 hill and dale records comprising a magnetic circuit including an air gap and a moving systemcomprising a coil in the air gap, an elastic support therefor, and a stylus for driving the coil,

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Moving Of Heads (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
US402128A 1929-10-24 1929-10-24 Sound reproducer Expired - Lifetime US1981793A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
BE383667D BE383667A (xx) 1929-10-24
NL33960D NL33960C (xx) 1929-10-24
BE374410D BE374410A (xx) 1929-10-24
US402128A US1981793A (en) 1929-10-24 1929-10-24 Sound reproducer
GB30996/30A GB363449A (en) 1929-10-24 1930-10-16 Improvements in or relating to sound reproducers
FR704651D FR704651A (fr) 1929-10-24 1930-10-20 Perfectionnements aux reproducteurs de son
DE1930599965D DE599965C (de) 1929-10-24 1930-10-21 Elektrischer Tonabnehmer fuer Schallplatten mit Tiefschrift
FR41017D FR41017E (fr) 1929-10-24 1931-11-25 Perfectionnements aux reproducteurs de son
FR44045D FR44045E (fr) 1929-10-24 1933-10-26 Perfectionnements aux reproducteurs de son

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US402128A US1981793A (en) 1929-10-24 1929-10-24 Sound reproducer

Publications (1)

Publication Number Publication Date
US1981793A true US1981793A (en) 1934-11-20

Family

ID=23590646

Family Applications (1)

Application Number Title Priority Date Filing Date
US402128A Expired - Lifetime US1981793A (en) 1929-10-24 1929-10-24 Sound reproducer

Country Status (6)

Country Link
US (1) US1981793A (xx)
BE (1) BE374410A (xx)
DE (1) DE599965C (xx)
FR (1) FR704651A (xx)
GB (1) GB363449A (xx)
NL (1) NL33960C (xx)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2640888A (en) * 1949-11-07 1953-06-02 Edward E Combs Phonograph pickup

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2640888A (en) * 1949-11-07 1953-06-02 Edward E Combs Phonograph pickup

Also Published As

Publication number Publication date
FR704651A (fr) 1931-05-23
GB363449A (en) 1931-12-24
DE599965C (de) 1934-07-12
BE374410A (xx)
NL33960C (xx)

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