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WO1999004599A1 - Guide d'ondes integre a trois pavillons et anneau de garniture - Google Patents

Guide d'ondes integre a trois pavillons et anneau de garniture Download PDF

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Publication number
WO1999004599A1
WO1999004599A1 PCT/US1998/014915 US9814915W WO9904599A1 WO 1999004599 A1 WO1999004599 A1 WO 1999004599A1 US 9814915 W US9814915 W US 9814915W WO 9904599 A1 WO9904599 A1 WO 9904599A1
Authority
WO
WIPO (PCT)
Prior art keywords
wave guide
throat
contour
horn
speaker
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.)
Ceased
Application number
PCT/US1998/014915
Other languages
English (en)
Inventor
Calvin C. Perkins
Terry L. Wetherbee
David D. Bie
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.)
Mackie Designs Inc
Original Assignee
Mackie Designs 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
Application filed by Mackie Designs Inc filed Critical Mackie Designs Inc
Priority to AU84970/98A priority Critical patent/AU8497098A/en
Publication of WO1999004599A1 publication Critical patent/WO1999004599A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/30—Combinations of transducers with horns, e.g. with mechanical matching means, i.e. front-loaded horns

Definitions

  • the present invention generally relates to a high frequency loudspeaker, and more specifically, to a high frequency loudspeaker that has a horn that serves as a wave guide and is shaped to control the pattern of sound emitted by the loudspeaker.
  • High frequency dome-type speakers, or tweeters typically cover a frequency range from approximately 2000 Hz to above 20 kHz.
  • the radiation of sound energy from the dome speaker into free space is hemispherical because the wavelength of the sound propagated by the radiator is considerably greater than the diameter of the radiating source.
  • the propagated wave front becomes less hemispherical and more elliptical in shape.
  • frequency of the radiated sound is sufficiently high that the wavelength of the radiated sound is about equal to the diameter of the radiating dome, the wave front becomes even more directional.
  • the preponderance of high frequency energy is concentrated along the central axis of the dome with very little sonic energy radiated to the sides, which is undesirable. Referring to FIGS.
  • FIG. 16A-16F shows the hemispherical shape as a wavelength of the sound propagated by the radiator, which is considerably greater than the diameter of the radiating source (the dome). This is typical of low frequencies.
  • FIG. 16B shows the wavelength not quite as hemispherical when the wavelength is approximately one-half the diameter of the propagating dome.
  • FIG. 16C shows the diameter equal to the wavelength such that the wave front becomes more directional and slightly more elliptical-shaped.
  • FIG. 16D shows the diameter twice as great as the wave length with a wave front decisively elliptically-shaped.
  • FIG. 16E and 16F show even more directional wave fronts where the diameter is even greater than that of the wave length. For example, the diameter is four times greater than that of the wave length. 16F shows the dome diameter six times greater than that of the wave length.
  • the frequency at which the sound waves produced by a speaker begin to beam, or narrow, is a function of the diameter of the piston d p that acts on the radiator.
  • a six to eight inch diameter piston is already beaming, or not producing hemispherical radiation, well below the lowest crossover transition frequency that can be prudently used in a two-way speaker system where the high frequency information is handled by the typical dome tweeter. This crossover frequency is usually set above 1500 Hz.
  • SPL sound pressure level
  • This technique increases efficiency by focusing a hemispherical radiation pattern produced by the device so that it has more energy on the axis. This achieves a result more commonly referred to as "pattern control.”
  • pattern control The challenge is to maintain the same pattern control over the entire operating bandwidth or frequency range, namely 2 kHz to 20 kHz.
  • a common practice is to use a conical or rectangular wave guide, which is also known as a conical horn. This conical horn is positioned in front of the dome to define and control the pattern of sound waves that the device produces.
  • FIGS. 1 and 2 illustrate the prior art approach for mating a conical wave guide to a high frequency driver.
  • the wave guide (horn) 14 has a side wall 16 of a "cone” (shown in cross-section), which is straight (and denoted at 17) for approximately 2/3 of its length L, as measured from dome 18 to the outer extent 20 of horn 14.
  • Side wall 16 terminates at a mounting surface, which is a front panel of the speaker enclosure (not shown).
  • the pattern control is established by the included angle A, which is between the side 16, horn 14, and the diameter of the mouth of horn D. Below a certain frequency, known as the intercept frequency, the radiation pattern is hemispherical, which is desirable.
  • FIG. 3 there are five basic mathematical horn contours that have been used to determine frequency bandwidth and pattern control or directivity.
  • the first one, conical, noted at 30, has already been discussed as well as its pitfalls.
  • Exponential, hyperbolic, or tractrix horn/wave guide realizations will load the driver down to the desired lowest frequency of operation, thereby increasing the efficiency of the device with a subsequent increase in power handling capacity, as shown in FIG. 17.
  • the graph of FIG. 17 shows the relationship of the acoustical resistance for a hyperbolic horn, line 52, exponential horn, line 54, parabolic horn, line 56, and a conical horn, line 58.
  • these horn/wave guide designs have very poor pattern control characteristics in of themselves.
  • the tractrix flare rate is essentially an exponential flare for the first 50° of the horn length, but thereafter flares out at an increasing rate to its fully developed mouth, at an included angle of 180°. A true exponential expansion would continue on to infinity, whereas the conical contour flare rate abruptly terminates at its finite length L, as shown in FIG. 1.
  • the present invention is directed to an integrated tri-flare wave guide for controlling directivity, increasing power handling capacity and sound pressure level of a dome high frequency speaker.
  • the wave guide includes a side wall flaring outwardly from a throat of the dome speaker to form a continuous variable flare rate from the throat to a mouth of the dome speaker.
  • the wave guide shape is such that a substantially circular cross-sectional form is generated when a place is cut through the wave guide parallel to the throat.
  • the side wall flares a three distinct contour rates.
  • the first flare rate is a conical contour adjacent the throat.
  • the second flare rate is adjacent the conical contour and contains an exponential flare contour.
  • the third flare rate is between the mouth and the second flare rate.
  • the third flare rate is a tractrix contour.
  • each of the three flare rates are approximately equally spaced along the length of the side wall such that the conical contour is a first 1/3 of the side wall length, the exponential flare contour is the second 1/3 of the side wall length, and the tractrix contour is the last 1/3 of the side wall length.
  • a subtending angle formed by the conical contour of the wave guide and the throat ranges from 45° to 150°. Preferably, the angle is 120°.
  • the throat of the dome speaker has a diameter as larger then 0.65 inches.
  • the subtending angle may be increased by further providing an outwardly flaring radius formed of the exponential flare contour.
  • the throat includes a phase compensation transition section, which is a small cylindrical transition section to equalize the pressure and time arrival difference caused by the suspension and driven piston.
  • the present invention way further include a trim ring that is adapted to the mouth of the wave guide in order to facilitate mounting within speaker enclosure.
  • the trim ring may further include an integral larger ring to adapt to an adjacent low frequency speaker, typically included in a powered speaker.
  • FIG. 1 is a cross-sectional view of a typical prior art conical wave guide
  • FIG. 2 is a plan view of the circular wave guide shown in
  • FIG. 1 A first figure.
  • FIG. 3 is a graph illustrating five different horn contours that have been used for speakers in the prior art
  • FIG. 4 is a cross-sectional view of a horn in the present invention having a wave guide of multiple flare rates
  • FIG. 5 is an enlarged partial cross-sectional view illustrating a phase compensation throat of the horn used in the present invention
  • FIG. 5 A is an enlarged view of that shown in FIG. 5;
  • FIG. 6 is a graph of an on axis amplitude vs. frequency of a one-inch diameter dome high frequency unit overlaid with a total radiated sound power response, both without the wave guide;
  • FIG. 7 is a graph comparing the on axis response of a one-inch diameter dome driver without a wave guide horn as a reference point, and the comparative effects of the phase compensation throat of FIGS. 5 and 5 A on the new wave guide horn;
  • FIG. 8 is a graph comparing the frequency response of the prior art circular horn and the multi-flare unit with phase compensation throat of the present invention;
  • FIG. 9 is a polar plot comparing the prior art circular horn with the present invention at 1250 Hz and 20 kHz;
  • FIG. 10 is a front elevational view of the present invention including a trim ring and additional clamp assembly for a trim rate over a low frequency speaker;
  • FIG. 11 is a perspective rear view of the tri-flare cone with phase compensation throats and trim ring shown in FIG. 10 and better disclosing a plurality of outwardly extending gussets from the rear of the tri-flare cone;
  • FIG. 12 is a cross-sectional side view taken substantially along line 12-12 of
  • FIG. 11 is a diagrammatic representation of FIG. 11
  • FIG. 13 is a detailed cross-sectional view of a portion of one of the gussets, taken substantially along line 13-- 13 of FIG. 10;
  • FIG. 14 is a graph illustrating the efficiency differences between a conical wave guide and an exponential horn at the same overall dimensions
  • FIG. 15 is a graph of a beamwidth vs. frequency for an ideal horn with perfect pattern control
  • FIGS. 16A-16F are six graphs of polar radiation patterns that illustrate the relationship between dome diameter and wavelength of radiated sound produced by a driver.
  • FIG. 17 is a graph illustrating the acoustical resistance at the throat of four different types (shapes) of horns.
  • the present invention relates to new multi-flare wave form or horn used for a high frequency dome typed speakers in order to achieve real theoretical frequency response and pattern control.
  • the invention also includes a compensation throat of the wave form or horn and a trim ring that supports the wave form within a powered speaker enclosure and with its additional clamp assembly ring for low frequency speaker.
  • the present invention wave form described below improves the low frequency loading over that of the prior art conical horn of FIGS. 1 and 2 by as much as 58 percent.
  • the present invention increases the power handling in the same frequency band by 58 percent.
  • the present invention also provides a smoother frequency response with smaller amplitude deviations, and provides better frequency pattern control than previously known wave forms or horns.
  • the throat diameter is about d is approximately 1.5 inches, which indicates that the sound wave beamwidth should collapse to about 90° at 9 kHz. If phase integrity is maintained across the 1.5-inch diameter of the throat, then the polar pattern will be that of a 1.5-inch piston.
  • Polar radiation patterns 2, 4, 6, 8, 10 and 12 of FIG. 16A-16F, respectively, and already discussed in the Background of the Invention, show the radiated polar response of a planar piston as a function of the wavelength of radiated sound, and diameter of the piston. For equal pattern control from 2 kHz to 20 kHz, the physical geometry of the radiating piston would suggest that the diameter of the throat d should be no larger than 0.675 inches.
  • This diameter is about half that of most existing prior art foreign designs.
  • the primary reason for the difference between this ideal throat diameter and the actual throat diameter used by others and by the present invention is that the effective opening is not determined only by the diameter of the piston.
  • Most one-inch diameter dome high frequency drivers have an effective opening of from 1.3 to 1.5 inches.
  • the effective diameter of throat d (referred to as d') because of its size difference from that of the prior art, is controlled by manufacture's design of the particular high frequency driver utilized.
  • the effective throat opening diameter is not solely determined by the diameter of the piston d p but is also affected by an inside diameter d 3 and an outside diameter d 4 of a diaphragm suspension, which is not discussed further here, and the diameter of any protective screen 46.
  • a smaller high frequency driver could be utilized, but power handling capacity would be seriously impaired using a smaller driver.
  • the present invention is a tri-flare horn/wave guide under the trademark TRI-FLARE CONPODENTIALTRAXTM.
  • the flare rate for the first third of the horn is conical and noted at 60.
  • Conical portion 60 establishes the polar radiation angle (subtending) for sound waves.
  • polar radiation angle is 120°, but can be virtually any desired angle from approximately 45° to 150°, depending on the design operating frequency range of interest.
  • the second third of the horn length is primarily exponential to provide resistive loading down to the cut-off (lowest usable) frequency of the device. This is noted as section 62.
  • the last third of the wave guide/horn length is a modified tractrix portion 64 to prevent mid-band beaming and to provide uniform pattern control. Tests have shown that the three different flare rates can be approximated by using two different radii of curvature to implement the design.
  • FIG. 15 compares an ideal beam width curve 56 is compared to a curve 68 that exhibits the phenomena of a mid-band beamwidth narrowing.
  • the high frequency driver of the preferred embodiment of the present invention exhibits non- ideal polar patter characteristics, because the suspension area is almost equal to that of the diaphragm (piston).
  • a small cylindrical transition section referred to as phase compensation throat 70, and best shown in FIGS. 4-5A, is included to equalize the pressure and the time arrival differences caused by the ring (radiator) suspension and driven piston. Without phase compensation in the throat transition section, as shown in FIG.
  • a polar response plot compares the results for the curve of the present invention 76 with that of the results of the current state of the art device or prior art device at 20 kHz (line 78) and 1250 Hz (line 79).
  • the present invention also includes a trim ring that is adapted to surround the wave guide of the present invention and also to have a second integral trim ring that is adapted to surround an adjacent low frequency speaker that is mounted in the same speaker enclosure.
  • This trim ring is shown at 80.
  • the smaller ring 82 is adapted to fit over the mount diameter D of the horn of the present invention.
  • the larger trim ring is denoted at 84.
  • the trim ring is essentially a low frequency driver trim ring that reduces high frequency diffraction from the low frequency driver cone and speaker enclosure.
  • a plurality of gussets 86 extend outwardly from the base 28 of the horn 40.
  • FIG. 13 is a cross-sectional enlarged view of an individual gusset.
  • the trim ring 80 would mount to a front panel of the speaker enclosure (not shown).

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)

Abstract

La présente invention concerne un guide d'onde/pavillon profilé permettant de régler la directivité et d'augmenter la puissance admissible et le niveau de pression acoustique d'un haut-parleur (77) haute fréquence à dôme à radiation directe muni d'une petite membrane. Le contour du guide d'ondes/pavillon combine trois taux d'ouverture différents, chacun d'eux s'étendant sur environ un tiers de la longueur comprise entre la gorge et la bouche du pavillon. Le premier tiers, adjacent à la gorge du haut-parleur, présente un profil conique (30). Le deuxième tiers de la longueur du pavillon présente un profil d'ouverture exponentiel (34) qui permet d'assurer une charge résistive. Le dernier tiers de la longueur du pavillon présente un profil de tractrice modifiée (38) qui empêche le rétrécissement dans les fréquences médianes et règle en un réseau uniforme les ondes sonores provenant du haut-parleur. Un anneau de garniture intégré (80) permet d'assembler le guide d'ondes/pavillon sur le haut-parleur. L'anneau de garniture intégré (80) comprend deux anneaux réunis (82,84), aptes à entourer le guide d'ondes et un haut-parleur basse fréquence adjacent monté à l'intérieur de la même enceinte de haut-parleur que le haut-parleur haute fréquence à dôme.
PCT/US1998/014915 1997-07-18 1998-07-17 Guide d'ondes integre a trois pavillons et anneau de garniture Ceased WO1999004599A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU84970/98A AU8497098A (en) 1997-07-18 1998-07-17 Integrated tri-flare wave guide and trim ring

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US5306897P 1997-07-18 1997-07-18
US60/053,068 1997-07-18

Publications (1)

Publication Number Publication Date
WO1999004599A1 true WO1999004599A1 (fr) 1999-01-28

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PCT/US1998/014915 Ceased WO1999004599A1 (fr) 1997-07-18 1998-07-17 Guide d'ondes integre a trois pavillons et anneau de garniture

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WO (1) WO1999004599A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005077073A3 (fr) * 2004-02-11 2006-07-27 Soundtube Entertainment Inc Systeme de haut-parleur audio
US7203329B2 (en) * 2004-02-11 2007-04-10 Soundtube Entertainment, Inc. Audio speaker system employing an axi-symmetrical horn with wide dispersion angle characteristics over an extended frequency range
US10848862B2 (en) 2016-06-29 2020-11-24 Dolby Laboratories Licensing Corporation Asymmetrical high-frequency waveguide, 3-axis rigging, and spherical enclosure for surround speakers

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2873812A (en) * 1957-09-05 1959-02-17 Electro Voice High frequency loudspeaker structure
US5284222A (en) * 1991-12-13 1994-02-08 Sony Corporation Speaker cabinet
US5548657A (en) * 1988-05-09 1996-08-20 Kef Audio (Uk) Limited Compound loudspeaker drive unit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2873812A (en) * 1957-09-05 1959-02-17 Electro Voice High frequency loudspeaker structure
US5548657A (en) * 1988-05-09 1996-08-20 Kef Audio (Uk) Limited Compound loudspeaker drive unit
US5284222A (en) * 1991-12-13 1994-02-08 Sony Corporation Speaker cabinet

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005077073A3 (fr) * 2004-02-11 2006-07-27 Soundtube Entertainment Inc Systeme de haut-parleur audio
US7203329B2 (en) * 2004-02-11 2007-04-10 Soundtube Entertainment, Inc. Audio speaker system employing an axi-symmetrical horn with wide dispersion angle characteristics over an extended frequency range
US10848862B2 (en) 2016-06-29 2020-11-24 Dolby Laboratories Licensing Corporation Asymmetrical high-frequency waveguide, 3-axis rigging, and spherical enclosure for surround speakers
US11252500B2 (en) 2016-06-29 2022-02-15 Dolby Laboratories Licensing Corporation Asymmetrical high-frequency waveguide, 3-axis rigging, and spherical enclosure for surround speakers
US11659321B2 (en) 2016-06-29 2023-05-23 Dolby Laboratories Licensing Corporation Asymmetrical high-frequency waveguide, 3-axis rigging, and spherical enclosure for surround speakers
US12356144B2 (en) 2016-06-29 2025-07-08 Dolby Laboratories Licensing Corporation Asymmetrical high-frequency waveguide, 3-axis rigging, and spherical enclosure for surround speakers

Also Published As

Publication number Publication date
AU8497098A (en) 1999-02-10

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