US3662292A - Helical spring for producing artificial reverberation - Google Patents

Helical spring for producing artificial reverberation Download PDF

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Publication number
US3662292A
US3662292A US62441A US3662292DA US3662292A US 3662292 A US3662292 A US 3662292A US 62441 A US62441 A US 62441A US 3662292D A US3662292D A US 3662292DA US 3662292 A US3662292 A US 3662292A
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United States
Prior art keywords
transducer
spring
pick
helical spring
producing artificial
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Expired - Lifetime
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US62441A
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English (en)
Inventor
Werner Fidi
Bernhard A Weingartner
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AKG Acoustics GmbH
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AKG Akustische und Kino Geraete GmbH
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    • 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

  • ABSTRACT A system for producing artificial reverberation using unidimensional wave guides reflectively terminated at both ends incorporates a helical spring excited into torsional vibrations by an electro-mechanical drive transducer, and includes at least one pick-off transducer converting mechanical vibrations into electrical vibrations.
  • the drive transducer is at one end of the spring and the distance between the drive transducer and the pick-off transducer most remote therefrom corresponds to a signal transit time of substantially 50 ms.
  • the overall length of the spring is at least 4 to 5 times this distance, and corresponds to a signal transit time of at least 200 ms.
  • the surface of the helical spring is partially or wholly formed irregularly, and the spring has individual turns which are irregularly deformed.
  • the pole/zero configuration in the frequency spectrum must have a very high density.
  • the reverberation time should diminish towards low frequencies as well as towards high frequencies.
  • the mean frequency response also should have a diminishing characteristic towards low frequencies as well as towards high frequencies.
  • the signal which is to be reverberated, to be dispersively resolved in a random manner.
  • a high grade artificial reverberation can be produced with uni-dimensional structures only by such resolution or disintegration along the spring under the conditions of a high pole/zero configuration density, the pole values being statistically different over the entire transmission range.
  • the surface of the helical spring be rendered irregular, for example, by means of etching, and for the individual turns of such a spring to be irregularly deformed. While it has been shown that the quality of the reverberation thus produced is sufficient for mixing with the direct signal, the reverberation cannot be used directly by itself. The reason for this is due to the fact that, in known reverberation apparatus, the signal is impressed at one end of the delay line and is picked off at the other end.
  • the technical literature discloses that the first echo should occur with a maximum delay of 50 ms, or better still, with a smaller delay of, for example, only 30 ms. It has been found advantageous if a plurality of echoes occurs within the aforementioned interval of approximately 50 ms. It is furthermore essential that the first echoes, which are to correspond to those due to the first wall or ceiling reflections in natural vibrations, be reproduced with the least possible distortion, that is to say, with the highest possible signal fideli- Accordingly, no statistical dispersions should be present during the aforementioned time interval of 50 ms. All the requirements taken together cannot be satisfied byknown reverberation apparatus.
  • This invention relates to systems for producing artificial reverberation using uni-dimensional wave guides reflectively terminated at both ends, and, more particularly, to such a system avoiding the defects of prior art system.
  • the invention makes use of a helical spring excited into torsional vibrations by means of an electro-mechanical drive transducer, and of at least one pick-ofi transducer for converting the mechanical vibrations into electrical vibrations.
  • the drive transducer is disposed at one end of the spring, and the distance between the drive transducer and the pick-off system most remote therefrom corresponds to a signal transit time of preferably 50 ms, with the overall length of the helical-spring being from 4 to 5 times this distance but corresponding to a transit time of at least 200 ms.
  • the surface of the helical spring is wholly or partially formed irregularly, where appropriate, or individual turns of the spring are irregularly deformed, or both expedients are adopted.
  • that section of the helical spring disposed between the driving transducer and the pick-off transducer or transducers is fonned from a wire having a smooth surface.
  • the remaining part of the helical spring has a wholly or partially irregularly formed surface and, where appropriate, includes a plurality of irregularly deformed turns.
  • At least one electro-mechanical transducer disposed along the length of the helical spring, to be provided with an attenuating system.
  • a helical spring with a delay period of at least 200 ms, is provided with at least one drive transducer and one pick-ofi transducer spaced respectively by a distance corresponding to a maximum signal transit time of 50 ms, and for the substantially longer part of the spring, not provided with any pickoff transducer arrangement, to be provided with an irregularly formed surface to produce a plurality of frequencydependent, statistical reflections within this latter part of the spring.
  • An object of the invention is to provide an improved system for producing artificial reverberation using uni-dimensional wave guides reflectively terminatedat both ends.
  • Another object of the invention is to provide such a system incorporating a helical spring excited into torsional vibrations by an electro-mechanical drive transducer and having at least one pick-off transducer spaced from the drive transducer and converting mechanical vibrations into electrical vibrations.
  • a further object of the invention is to provide such a system in which the drive transducer is at or adjacent one end of the spring, and the distance between the drive transducer and the pick-off transducer most remote therefrom corresponding to a signal transit time of substantially 50 ms.
  • Another object of the invention is to provide such a system in which the overall length of the spring is at least 4 to 5 times this distance and corresponds to a signal transit time of at least 200 ms.
  • a further object of the invention is to provide such a system in which a substantially longer part of the spring, with which there are associated no pick-ofi transducers, has an irregularly formed surface to produce a plurality of frequency-dependent, statistical reflections therein.
  • FIG. la is a diagrammatic illustration of one embodiment of the invention, including electro-mechanical transducers disposed along a helical spring;
  • FIG. 1b is a view, similar to FIG. I, of another embodiment of the invention.
  • FIG. 2 is a pulse diagram of the system with the spring not having an irregularly formed surface
  • FIG. 3 is a pulse diagram of the same system but with the spring having a treated or statistically irregularly formed surface.
  • electro-mechanical transducers 1, 2 and 3 are operatively associated with a helical spring 4.
  • Transducer 1 functions as an electro-mechanical drive transducer to impress, on helical spring 4, the signal to be reverberated in the form of torsional vibrations.
  • Transducer 3 is an electro-mechanical pick-off transducer and is disposed at a distance from transducer 1 corresponding to a transit time of approximately 50 ms.
  • Transducer 2 constitutes a further pick-off transducer which may be disposed at a shorter distance from transducer 1, and corresponding to a transit time of at least 30 ms.
  • Helical spring 4 extends beyond pick-off transducer 3, and the extending section has a length, in accordance with the invention, corresponding to a signal transit time of at least 200 ms.
  • the spring For manufacturing reasons, it is often appropriate for the spring to be surface treated over its entire length. This procedure results in a certain loss of quality which may, however, be regarded, in some circumstances, as tolerable. Depending on where, and on the manner in which, the surface of the spring is formed, it is possible to produce more or less intensive changes of the tone quality.
  • the section of spring 4 between transducers 1 and 2 it is possible for the section of spring 4 between transducers 1 and 2 to be provided with a smooth surface, for the section of spring 4 between systems 2 and 3 to be provided with the surface having only slight irregularities, and for the long section of spring 4, adjoining transducer 3, to be provided with a surface having substantial changes.
  • FIG. 3 shows the pulse diagram of the same spring if the surface thereof is provided with statistical irregularities.
  • sinusoidal pulses with a mean frequency of I000 Hz were used in place of needle pulses. It can be seen that practically no periodicity is present, thus permitting a diffuse resolution of the signal.
  • the time intervals which are clearly recognizable in FIG. 2, are properly filled, in the pulse diagram of the surface treated spring as shown in FIG. 3. Accordingly, the echoes occurring at signal transit times of more than 50 ms, in the invention arrangement, cannot be distinguished, but the condition according to which the first echo appears substantially unchanged with an interval of 30 to 50 ms has been satisfied.
  • reverberation systems which, taking the form of transit time elements, employ some mechanical systems capable of vibrating, are subject to a rise of reverberation time towards the lower frequency.
  • a reverberation system of average dimensions having a reverberation period of 2 seconds at a frequency of 3 kHz, will have a reverberation period of IO seconds at a frequency of I00 Hz.
  • Such an effect is extremely undesirable and therefore must be compensated by suitable measures.
  • damping material This may be done by the attachment of damping material to the electro-mechanical transducers, but this procedure is effective only at low frequencies. Assuming suitable damping, it is possible for the reverberation time to be influenced, if desired, even over the entire frequency range to be transmitted. Normally, damping of the electro-mechanical transducer systems will be performed as indicated in FIGS. la and 1b, because this method is the simplest. However, it is also possible for the spring itself to be damped, for example by disposing it in a damping material or in oil.
  • a reverberation system embodying the invention supplies an artificial reverberation which, in practice, cannot be distinguished from the natural reverberation.
  • the illustrated embodiments described herein are those in which the drive system is disposed at one end of the helical spring and the first pick-off system is disposed at a distance corresponding to a signal transit time of approximately 30 to 50 ms.
  • the principles of the invention are not limited to such an arrangement, but also cover embodiments in which the drive system is disposed at a distance from the ends of the helical spring, and in which the first echo must arrive within the first 50 ms and which furthermore contain the other inventive features.
  • Such a system results in a reduction of the technical effort while providing approximately the same quality.
  • the wave guide comprises a helical spring excited into torsional vibrations in the audible sonic range by an electromechanical drive transducer and incorporating at least one pick-off transducer converting such torsional mechanical vibrations into electrical vibrations: the improvement comprising, in combination, said drive transducer being at least adjacent one end of said spring; the signal transit time between said drive transducer and the pick-off transducer most remote from said drive transducer, at frequencies in the audible sonic range, being substantially 50 ms; the overall length of said spring being at least 4 to 5 times the distance between said drive transducer and said pick-off transducer most remote from said drive transducer, and the overall signal transit time of said spring, at frequencies in the audible sonic range, being at least 200 ms.
  • the improvement claimed in claim 5 in which the surface of that portion of said helical spring disposed between said drive transducer and a pick-off transducer comprises a wire having a smooth surface; the surface of the remainder of said spring being formed irregularly.
  • said remainder of said spring includes a plurality of turns which are deformed irregularly with respect to a normal circular configuration.
  • said drive transducer is disposed at one end of said helical spring; said pick-off transducers including a first transducer disposed at a distance, from said drive transducer, corresponding to a signal transit time of substantially 50 ms and a second transducer disposed at a distance, from said drive transducer, corresponding to a signal transit time of at least 30 ms.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Reverberation, Karaoke And Other Acoustics (AREA)
  • Springs (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)
US62441A 1969-08-18 1970-08-10 Helical spring for producing artificial reverberation Expired - Lifetime US3662292A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT789069A AT299572B (de) 1969-08-18 1969-08-18 Anordnung zur Erzeugung künstlichen Nachhalles

Publications (1)

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US3662292A true US3662292A (en) 1972-05-09

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US62441A Expired - Lifetime US3662292A (en) 1969-08-18 1970-08-10 Helical spring for producing artificial reverberation

Country Status (6)

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US (1) US3662292A (enrdf_load_stackoverflow)
JP (1) JPS4811497B1 (enrdf_load_stackoverflow)
AT (1) AT299572B (enrdf_load_stackoverflow)
DE (1) DE2040043A1 (enrdf_load_stackoverflow)
FR (1) FR2102411A5 (enrdf_load_stackoverflow)
GB (1) GB1303203A (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4844301U (enrdf_load_stackoverflow) * 1971-09-27 1973-06-09

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2375004A (en) * 1943-05-12 1945-05-01 Josephine Knotts Knowles Training apparatus
US3136853A (en) * 1961-04-12 1964-06-09 Baldwin Co D H Music enhancing systems
US3159713A (en) * 1961-03-10 1964-12-01 Hammond Organ Co Artificial reverberation device
US3270300A (en) * 1962-04-26 1966-08-30 Hammond Organ Co Reverberation unit magnetic assembly
US3517344A (en) * 1966-12-06 1970-06-23 Akg Akustische Kino Geraete Delay device particularly for the production of artificial reverberation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2375004A (en) * 1943-05-12 1945-05-01 Josephine Knotts Knowles Training apparatus
US3159713A (en) * 1961-03-10 1964-12-01 Hammond Organ Co Artificial reverberation device
US3136853A (en) * 1961-04-12 1964-06-09 Baldwin Co D H Music enhancing systems
US3270300A (en) * 1962-04-26 1966-08-30 Hammond Organ Co Reverberation unit magnetic assembly
US3517344A (en) * 1966-12-06 1970-06-23 Akg Akustische Kino Geraete Delay device particularly for the production of artificial reverberation

Also Published As

Publication number Publication date
JPS4811497B1 (enrdf_load_stackoverflow) 1973-04-13
GB1303203A (enrdf_load_stackoverflow) 1973-01-17
FR2102411A5 (enrdf_load_stackoverflow) 1972-04-07
AT299572B (de) 1972-06-26
DE2040043A1 (de) 1971-02-25

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