US3742140A - Arrangement for damping torsional oscillations induced in a helical spring, particularly in artificial reverberation devices - Google Patents

Arrangement for damping torsional oscillations induced in a helical spring, particularly in artificial reverberation devices Download PDF

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Publication number
US3742140A
US3742140A US00138208A US3742140DA US3742140A US 3742140 A US3742140 A US 3742140A US 00138208 A US00138208 A US 00138208A US 3742140D A US3742140D A US 3742140DA US 3742140 A US3742140 A US 3742140A
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United States
Prior art keywords
windings
spring
helical spring
artificial reverberation
reverberation device
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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
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US00138208A
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English (en)
Inventor
B Weingartner
W Fidi
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AKG Acoustics GmbH
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AKG Akustische und Kino Geraete GmbH
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/30—Time-delay networks
    • H03H9/36—Time-delay networks with non-adjustable delay time
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K15/00—Acoustics not otherwise provided for
    • G10K15/08—Arrangements for producing a reverberation or echo sound
    • G10K15/10—Arrangements for producing a reverberation or echo sound using time-delay networks comprising electromechanical or electro-acoustic devices

Definitions

  • a spring system particularly for an artificial reverberation device, includes a helical spring in which torsional oscillations are induced, and a moving coil system connected to the helical spring for damping the oscillations electromechanically.
  • the moving coilsystem includes two electrically and magnetically decoupled windings disposed in a permanent magnetic field with one winding being electrically connected to the input of an amplifier and the other winding being electrically connected to the amplifier outpun
  • the two windings are mechanically interconnected and arranged in tandem along the turn axis of the helical spring, with the axes of the two windings being mutually perpendicular to each other.
  • the two windings may be mechanically interconnected in directly contiguous arrangement to form a rigid unit, or may be spaced apart and resiliently interconnected by a resilient coupling, such as a metal strip.
  • the moving coil system may serve either as a driving system, for inducing torsional oscillations in the helical spring, or as a pick-up system, for detecting such oscillations.
  • the two windings are rectangular, but other configurations may be used with some decrease in the quality.
  • a bridge circuit is used for this purpose, but such a bridge circuit can not provide satisfactory results over the entire frequency range extending to at least kHz, as at least one branch of the bridge contains both the driving system and the pick-up system, the electrical impedance of this arm depending greatly on the position of the coil or winding in the magnetic field. Aside from this, bridge circuits require a relatively high degree of electrical and technical sophistication, and this affects production costs.
  • This invention relates to spring systems, particularly for artificial reverberation devices, and more particularly, to a novel and improved spring system providing adequate separation between driving and pick-up systems over the entire frequency range.
  • a spring system particularly for an artificial reverberation device includes a helical spring in which torsional vibrations are to be induced, and also includes a moving coil system connected to the helical spring for electromechanically damping the oscillations of the spring.
  • the moving coil system includes two mechanically interconnected coils or windings which are electrically and magnetically decoupled and disposed in a permanent magnetic field. One of the coils is electrically connected to the input of an amplifier and the other to the output of the amplifier.
  • the two coils are arranged in tandem in the spring system along the winding or turn axis of the spring, and with their axes orthogonal, or mutually perpendicular, to each other.
  • An advantage of a system embodying the invention is that the physical position of the two coils means that the common magnetic flux necessarily is small, while the orthogonal or mutually perpendicular relation between the planes of the two coils or windings, namely the winding planes perpendicular to the coil axes, reduces this flux completely so that only a small magnetic coupling remains.
  • a system embodying the invention produced a crosstalk attenuation of more than 80 dB. in a frequency range of up to 10 kHz.
  • the coils or windings have the shape of a rectangular frame, but it is also possible that the framelike shape of each coil or winding may be elliptical, circular or other configuration, provided that a certain loss of quality is acceptable, for example, for reasons associated with easier coil winding techniques.
  • the windings are connected together in a directly contiguous arrangement to form a rigid unit.
  • the windings are spaced apart longitudinally of the spring system and are resiliently interconnected by a resilient coupling, for example, a metal strip, so that a frequency-dependent attenuation is obtained, more particularly high attenuation of the low frequencies, the degree of coupling being variable as required by appropriate choice of the strip material, length and shape.
  • a resilient coupling for example, a metal strip
  • the advantage of a resilient coupling of the two windings is that all the mechanical systems in an artificial reverberation device, from the spring system to the reverberation chamber, have better quality at the lower frequencies. Therefore, it is frequently advantageous to attenuate mainly the lower frequencies without appreciably affecting the higher frequencies.
  • the mechanical systems tend toward uncontrolled oscillations above a limiting freque cy for example, the frequency above which torsional oscillations are no longer possible, so that although there is a high crosstalk attenuation between the two windings of a spring system embodying the invention, undesirable oscillations may occur as a result of mechanical types of oscillation in the entire amplifier system. All these difficulties can be reduced, or practically eliminated, by resiliently'mechanically coupling the two windings.
  • Variations in reverberation time can be obtained, in a reverberation device embodying the invention, by making the amplification variable.
  • An object of the invention is to provide an improved spring system, particularly for artificial reverberation devices.
  • Another object of the invention is to provide such a system including a helical spring in which torsional oscillations are to be induced and a moving coil system connected to the helical spring for electromechanically damping the oscillations of the spring.
  • a further object of the invention is to provide such asystem in which the moving coil system comprises two mechanically interconnected windings which are electrically and magnetically decoupled and disposed in a permanent magnetic field.
  • Another object of the invention is to provide such a system in which the two windings are disposed in tandem along' the axis of the helical spring with their axes mutually perpendicular to each other.
  • a further object of the invention is to provide such a system in which adequate separation between driving and pickup systems can be attained.
  • Another object of the invention is to provide such a system providing satisfactory results over the entire frequency range.
  • FIG. 1 is a diagrammatic illustration of a first embodiment of a spring system in accordance with the invention
  • FIG/2 is a diagrammatic illustration of a second embodiment
  • FIG. 3 is a diagrammatic illustration of a spring system, embodying the invention, incorporated in an artificial reverberation device having separate driving and pick-up systems;
  • FIG. 4 is a diagrammatic illustration of a spring system embodying the invention, incorporated in an artificial reverberation device and serving as either a driving system, a pick-up system, or both.
  • the spring system illustrated therein includes a helical spring 1 to which is connected a moving coil system for electromechanically damping torsional oscillations of spring 1.
  • the moving coil system includes two frame-like coils or windings 3 and 4, which preferably have a rectangular form, as illustrated, although they may have other less advantageous shapes with a corresponding loss of quality.
  • Coils or windings 3 and 4 are disposed in succession, or in tandem, along the winding or turn axis 6 of spring 1, and are rigidly mechanically interconnected, for example by adhesive, to form a contiguous rigid unit in which the planes of the coils are mutually perpendicular to each other.
  • the coils or windings are disposed for rotation about axis 6 in a permanent magnetic field between a north pole N and a south pole S of a permanent magnet system 2.
  • FIG. 2 A construction of this type is shown in FIG. 2, wherein a resilient mechanical coupling 12 is provided between windings 3 and 4, and constitutes a thin resilient strip, for example a steel strip, mechanically interconnecting the two windings.
  • a resilient mechanical coupling 12 is provided between windings 3 and 4, and constitutes a thin resilient strip, for example a steel strip, mechanically interconnecting the two windings.
  • One of the two windings, illustrated as winding 3 in FIG. 2 is rigidly connected to the terminal turn of spring 1, particularly at points 10 and 11.
  • a synthetic resin adhesive is most suitable for this purpose.
  • FIG. 3 illustrates a spring system embodying the invention serving simply as an attenuating element in an artificial reverberation device.
  • Torsional .oscillations are induced in coil spring 1, at one end thereof, by a driving system E.
  • the oscillations are propagated along spring I and are picked up at the other end of spring 1 by a pick-up system A.
  • An attenuating system D embodying the invention, is incorporated, for example, at substantially the middle of coil spring 1.
  • 'Attenuating system D includes permanent magnet system 2 in the air gap of which there are situated windings 3- and 4 with their planes at, right angles to each-other.
  • the windings are rigidly interconnected, and therefore form a unit which moves about the winding or turn axis 6 of coil spring I.
  • the moving coil system isconnected as rigidly as possible at the points 5, to a turn of coil spring 1, so that the oscillations of the spring are also transmitted to the moving coil unit formed by windings 3 and 4.
  • the EMF induced in winding 3 by movement in the permanent magnetic field of permanent magnet system 2 is fed to the input of a variable gain amplifier 7.
  • the resulting amplifier output is fed to the winding 4, arranged so that the current flowingtherein interacts with the magnetic field of system 2 to transmit, to the unit formed by windings 3 and 4, a torque directed in opposition to the torque of winding 3.
  • the magnitude of the torque depends upon the amplification factor of amplifier 7. Since amplifier 7 has a variable amplification, the attenuation required for coil spring 1, and hence different reverberation times, can be finely adjusted.
  • the simple driving system E shown in FIG. 3, is replaced by a moving coil system embodying the moving coils or windings 3 and 4 in accordance with the invention.
  • the signal for reverberation is also fed to amplifier 7, whose output 9 is connected to winding 3.
  • Angular or torsional oscillations about axis 6 of coil spring 1 thus are induced in winding 3 positioned in the magnetic field of permanent magnet system 2, and are transmitted to winding 4 through the rigid connection between windings 3 and 4, and to coil spring 1 by virtue of connection of coil spring 1 to winding 4 at the points 5.
  • the EMF induced in winding 4 by its movement in the permanent magnetic field is supplied to input 8 of amplifier 7.
  • the pick-up system A is provided at the other end of coil spring 1, and its construction is identical with that of the drive system E.
  • the only difference in the circuit arises from the fact that the arrangement functions as a pick-up system rather than as a driving system.
  • the torsional oscillations arriving at pick-up system A, after travelling along coil spring 1, induce similar angular oscillations in the unit consisting of the rigidly interconnected windings 3', 4' in the magnetic field of permanent magnet system 2'.
  • the EMF induced in winding 4' is supplied to the input 8 of amplifier 7, and the reverberated signal is picked up from a second output.
  • the signal is supplied to winding 3, the polarity of which, in the permanent magnetic field, is such that it tends to counteract the angular movement of winding 4.
  • the required attenuation of .coil spring 1 can be adjusted in accordance with the magnitude of the output voltage.
  • the windings used in the spring system embodying the invention preferably have the shape of a rectangular frame, but circular, elliptical or other frame shapes for the windings also can be employed.
  • a spring system particularly for an artificial reverberation device, including a helical spring, in which torsional oscillations are to be induced, and a moving coil system connected to the helical spring for damping the oscillations electromechanically and including two electrically and magnetically decoupled windings disposed in a permanent magnetic field, with one winding being electrically connected to the input of an amplifier and the other winding being electrically connected to the amplifier output, said two windings being mechanically interconnected with each other and being arranged in tandem along the turn axis of said helical spring, with the axes of said windings being mutually perpendicular to each other.
  • a spring system particularly for an artificial reverberation device, as claimed in claim 1, in which said two windings are fixedly connected together in directly contiguous relation, to form a rigid unit.
  • a spring system particularly for an artificial reverberation device, as claimed in claim 1, in which said two windings are spaced apart along the turn axis of said spring; and a resilient coupling resiliently interconnecting said two windings.
  • a spring system particularly for an artificial reverberation device, as claimed in claim 3, in which said resilient coupling is a metal strip.
  • a spring system particularly for an artificial rever beration device, as claimed in claim 1, in which said windings have substantially identical shapes.
  • a spring system particularly for an artificial reverberation device, as claimed in claim 1, in which said windings have substantially identical electrical properties.
  • a spring system particularly for an artificial reverberation device, as claimed in claim 1, in which said windings have the shape of a rectangular frame.
  • a spring system particularly for an artificial rever beration device, as claimed in claim 1, wherein said two windings serve additionally as a driving system for inducing torsional oscillations in said helical spring.
  • a spring system particularly for an artificial reverberation device, as claimed in claim 1, wherein said two windings serve additionally as a pick-up system detecting the torsional oscillations in said helical spring.
  • a spring system particularly for an artificial reverberation device, as claimed in claim 1, in which said two windings are disposed at substantially the middle of said helical spring; a moving coil drive system connected to one end of said helical spring; and a moving coil pick-up system connected to the opposite end of said helical spring.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
  • Reverberation, Karaoke And Other Acoustics (AREA)
US00138208A 1970-05-19 1971-04-28 Arrangement for damping torsional oscillations induced in a helical spring, particularly in artificial reverberation devices Expired - Lifetime US3742140A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT448670A AT298826B (de) 1970-05-19 1970-05-19 Anordnung zur Dämpfung von zu Torsionsschwingungen angeregten Schraubenfedern, zur Erzeugung künstlichen Nachhalles

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US3742140A true US3742140A (en) 1973-06-26

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US (1) US3742140A (enrdf_load_stackoverflow)
JP (1) JPS5412781B1 (enrdf_load_stackoverflow)
AT (1) AT298826B (enrdf_load_stackoverflow)
DE (1) DE2124164A1 (enrdf_load_stackoverflow)
GB (1) GB1306194A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4007332A (en) * 1975-07-18 1977-02-08 Berg Arne L Artificial reverberation system

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1757193A (en) * 1930-05-06 hotopp
FR886491A (fr) * 1939-09-05 1943-10-15 Licentia Gmbh Dispositif de compensation transformant une valeur de mesure en courant continu
US2560257A (en) * 1951-07-10 Instrument damping system
US2866935A (en) * 1956-02-06 1958-12-30 Robillard Jean Jules Achille Transient measuring apparatus
DE1537605A1 (de) * 1967-12-27 1970-01-08 Geraetebau Hempel Kg Nachhallgeraet
US3526793A (en) * 1968-11-25 1970-09-01 Akg Akustische Kino Geraete Transducer for converting electrical oscillations into torsional vibration and vice versa
US3634595A (en) * 1969-03-31 1972-01-11 Giorgio Pasquali A generator of harmonic signals with a helical spring

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1757193A (en) * 1930-05-06 hotopp
US2560257A (en) * 1951-07-10 Instrument damping system
FR886491A (fr) * 1939-09-05 1943-10-15 Licentia Gmbh Dispositif de compensation transformant une valeur de mesure en courant continu
US2866935A (en) * 1956-02-06 1958-12-30 Robillard Jean Jules Achille Transient measuring apparatus
DE1537605A1 (de) * 1967-12-27 1970-01-08 Geraetebau Hempel Kg Nachhallgeraet
US3526793A (en) * 1968-11-25 1970-09-01 Akg Akustische Kino Geraete Transducer for converting electrical oscillations into torsional vibration and vice versa
US3634595A (en) * 1969-03-31 1972-01-11 Giorgio Pasquali A generator of harmonic signals with a helical spring

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4007332A (en) * 1975-07-18 1977-02-08 Berg Arne L Artificial reverberation system

Also Published As

Publication number Publication date
DE2124164A1 (de) 1971-12-02
GB1306194A (enrdf_load_stackoverflow) 1973-02-07
JPS5412781B1 (enrdf_load_stackoverflow) 1979-05-25
AT298826B (de) 1972-05-25

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