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An amazing set of coverage about all things horn by the late and greatly missed Jean Michel Le Cléac’h.
Citation preview
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wavegu esJean-Michel Le Clach
1
,
toutes illustrations droits rservs sauf spcifi
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etymology: Greek : karnon,
Latin : cornu.the horn of an animal
a "wind instrument
(originally made from animal horns)
reference to car horns is first recorded in1901.
cornucopia
2
Neolithic carving
Laussel cave, France
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(in French)
Pavillon de loreille = part of the external ear which looks like a butterfly=
3
,
An automatic translation may also lead to surprising results like "small house" or "flag"...
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a horn is a tube whose cross-section increases from throat to mouth in order
to increase the overall efficiency of the driving element = the diaphragm. Thehorn itself is a passive component and does not amplify the sound from thedriving element as such, but rather improves the coupling efficiency betweenthe speaker driver and the air. The horn can be thought of as an "acoustictransformer" that provides impedance matching between the relatively dense
.
This is important because the difference in densities and motional.
the horn next to the speaker cone "driver" is called the "throat" and the largepart farthest away from the speaker cone is called the "mouth.
4
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Historical milestones
1876 ____________ Bells Telephone
1877 ____________ Edisons Phonograph
1906 ____________ Lee de Forests triode
1920_____________first commercial radio broadcast
_____________
1926 ____________ First commercial talking movie
1953 ____________ Transistor commercialization
5
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Oliphant
Shofar hornbelarussia
6
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Shell from Nepalwith the Godess
Mandala.
Tahitian Pu-Toka
7Turbinella PyrumIndia
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megaphones
Echo Lake megaphoneFisherman using amegaphone
Giant megaphone in BrusselsAnd now she beats her heart, whereat it groans,That all the neighbour caves, as seeming troubled,Make verbal repetition of her moans;
Ay me, she cries, and twenty times, Woe, woe,And twenty echoes twenty times cry so.
Venus and Adonis , Shakespeare
8
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horns as musicinstruments
First horns China
Oxus
Egypt Greece
Alphorns and thibetan horns
Strings instruments with horns
9
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4000
BC
in
China
3000 BC inOxus(AfghanistanRussiafrontier)
Oxuscivilization
300 BCin Greece
300
BC
in
America
10
Peru
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ancientGreece
Tutankhamuns
trumpets
"tuuut.....!"
11
ancientEgypt
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Thibetan
Alphorn
12
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from the 19th
13
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127dB!
vuvuzela
14brass horn used to load aloudspeaker by SusumuSakuma
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violophone
hornviolin
When strings meet horns
15
vioara cu goarnastrohcello
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Non musical
purposes architectural acoustics
og orns
firemen sirens
car horns and Klaxon m ary megap ones
acoustic locatorsPropagation Horns
16
(Kempten 1673)
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Architectural ur oses
the princelistening to thecourtiers speaking
outside the
Athanasius Kircherinvented the megaphone
(1608 Germany - 1680 Italy)
Horns used in ancient architecture
Today in Mexico
17
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JohnTyndall1820-93
Circa 1873
18foghorns designed by Lord Rayleigh
Trevose Head Lighthouse, Cornwall (1913)
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Firemen siren
sirens andKlaxons
a siren playing trumpet
19
victim of pollution
Kopenhagen siren
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military
20
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before radar:
acoustic
21
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Hearing aids
Athanasius KIRCHER
(1673)
, ,O would thou hadst not, or I had no hearing.Thy mermaids voice hath done me double wrong;I had my load before, now pressed with bearing;Melodious discord, heavenly tune harsh sounding,
22
, .
Shakespeare
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Recording and
reproducing soundsThe very first recording of sound was made by Edouard Lon
,
probably 1854 as written in his writting Fixation graphique de lavoix (1857) . He didnt know how to reproduce those sounds
First successful recording followed by its reproducing (1877) is
due to Thomas Alva Edison with his phonograph .
23
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Phonautograph1860-Scott-Au-Clair-de-la-Lune_2.mp3
a simplistic horn
24
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In December of 1877, Edisons machinistpresented him with the completed prototype.
Edison leaned toward the recording horn ands ou e ou e wor s ary a a e am ,it's fleece was white as snow, and everywherethat Mary went, the lamb was sure to go.
It was hardly a moving speech, but thennobodynot even Edisonexpected the
.
To his great surprise, a highly distorted but
out of the machine when the tinfoil was crankedunder the needle once again.
25
mary_jas_a_little_lamb.mp3
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at the French Academy
Phonograph
Edison Thomas.mp3
,
recording of a piano on a cylinder recording at Smithsonian
26
Dickson first
Experimental soundfilm (1894)
for recording through the horn,
the head was replaced by a"recording head"
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Cylinder version
27
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The E.M.G.Mark Xa
gramophone
28see: Horn theory and the gramophone Percy Wilson in JAES 1974
Trapezoidal Horn Fitted to an "Expert" GramophoneBalmain Gramophone with 5ft. StraightHorn
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The world's first commercial electrical recording
The setup for Guest and Merriman's pioneering
electrical recording of the Burial of the UnknownSoldier in Westminster Abbey on 11 November 1920.
On February 25, 1925, Art Gillham recorded"You May Be Lonesome, a song written by Art
.
It was the first master recordedto be released using Western Electric's
29
e ectr ca recor ng system.
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times
1920In Pittsburgh, Westinghouseradio station KDKA schedules the
The first radio
30
first commercial radiobroadcastthe Harding-Coxpresidential election results.
microphone
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a question of conversion efficiency of the energy
between air and
water.Im edance match
o move e oa sfar more efficient to
the water than in the
air.
Impedance mismatch
characteristic impedance of air is about 420 Pa s/m
31
.
(nearly 3600 times higher)
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- to progressively adapt the acoustical impedance
from the throat to the mouth
- to control the dis ersion of the waves out oin
32from the horn
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The specific acoustic impedance z of an acoustic component
n s mis the ratio of sound pressure p to particle velocity v at its
Where:
is the sound ressure N/m or Pav is the particle velocity (m/s), andI is the sound intensity (W/m)
33
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Sound power:
no oss ns e t e orn:
Sound intensit :it is the sound power per
unit area
It = Pt / At
=
Thus:
For a given sound intensity
It / Im = Am/ At
proportionnal to the ratio ofthe mouth area on the throat
34
area
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the horn creates a higher acoustic impedance for the transducer to work
into thus allowin more ower to be transferred to the air.
- increase of efficiency (up to 50% )
use of low ower am lifiersuse of low ower am lifierslower distortion due to smaller displacement of the membranelower distortion due to smaller displacement of the membrane
- acoustical gain (10dB and more)
- depends on the need of a narrow or a wide spread of
35
the sound in the room
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Webster's e uationWebster's e uationWebster's equation for a constant bulk modulus:
where :
The only assumption which has been made is that the.
isophase surfaces. Plane waves, spherical waves, orother wavefront shapes can be assumed within the
36
framework of Webster's equation.
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1) pressure p depends only on a single coordinate
2) only longitudinal waves propagates from throat to
mouth
Theor tells us:
only 3 shapes for the wavefront and for theinfinitesimal sound duct obey to the 1P hypothesis:
wavefront shape: duct shape:
spherical cap conical hornc linder toroidal horn
37
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isophase surfaces are parallel
iso hase surfaces are er endicular to horn wall
38 isobare (= isopressure) surfaces are parallel to isophase
William Hall (1932)
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William Hall (1932)
39
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For horns for which p depends on 2 or 3
coordinates we have to take in accounthi h order modes HOM .
40
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Isobare curves inside a horn
to take in account the
not sufficient to relysimulation to measurement
41
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The quest for efficiency,the quest for loading
42
R.P.G. Denman, "In Search of Quality", Wireless World, Vol. 25 pp97-101 (July 31, 1929)
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Mr. Kei Ikedas listening room
In 1926, the
Vita hone s stem
Julien Sullerots
uses the famousdriver WE 555-Wcoupled to the
43
of an Onken Wenclosure
WE15A horn
(100Hz to 5kHz)
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Acoustic studies using theWE15A .See on right Wente's planar waves
tube he used to measure the powerresponse of the WE555 driver
development of theStereophonic system
44
1933)
H ll d f d
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Holl wood oes for sound David FisherMajors' fi lm releases in 1928 Majors' fi lm releases in 1929
In1928thesevenHollywoodmajorsreleased220 In1929thebalancehadshiftedradically.
,
only synchronisedmusicandsoundeffects,23
were parttalkieandonly10,allfromWarner
Bros,were alltalkie.UniversalandParamountin
,
parttalkieand36withonly musicandeffects.
Silentreleaseshaddwindledtoonly38outofa
totalof290.
productions.
silent films synchronized music part talkie all talkieand sound effects
45
1926 "Don Juan" first talking movie, 1927 "The Jazz Singer"
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46
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1929 - 1935
47Sid Graumans Chinese theater in Hollywood inaugurated in 1927
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VOT A2
48VOT A7
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1960s
60080 X JBL375
+
acous cwattsGenerator
vibrationanalysis
multiple
49
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diffractor couplers (Karlson coupler)
reflectors
50
JBL "potatoe crusher"
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Acoustic
lenses
51Klanfilm horn with acoustic lens at mouth JBL acoustic lens
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JBL
52
JBL
JBL
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Karlson coupler
53
Elliptical reflectors = acoustic shells
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Elliptical reflectors acoustic shells1673
doctor andpatient
oca ors
Elipson loudspeakers
54
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55
old folded horns
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old folded horns
56
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WE 13A horn
571929 - 1935
WE the Tub , circa 1938
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58WE collector in Japan
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59Fletcher system (1933-1940)
modern folded horns
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60
YL folded horns (Japan)
Technics folded horns
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Yoshimura Laboratory, Ale and Goto horns
61
Yamamura fullrange
Churchill and Dionisio 32Nelson Passs fullrange Kleinhorn
First folded bass horns
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WE TA7396, 1936 -1937The Shearersys em rece ve atechnicalachievement
award at the 1936Academy of MotionPicture Arts andSciences
62RCA
ceremony.
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63
Early exponential straight horns
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e ore
my home made crystal radio with a Vitavox E190 horn
64
Horn tweeters
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65
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Klangfilm20 hz Tractrix horn
Germany, 1951
66
Strai ht bass horns
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Bjorn Kolbreks long throw bass horns
67
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Vincent Brients 30Hz basshorns (France)
68
Klaus Speth, full horns with Goto drivers (Germany)
Quasi cylindrical waves bass horns in France
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Jean-Paul
Marcel Roggero
Frdric Lebas
69
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Salmon family (exponential, hypex, etc.)
Tractrix, Kugelwellen and Spherical
oblate spheroidal Le Clac'h
70
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hyperbolical Le Clac'h
+ Kugelwellen
71
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resistive art
from catenoidal (T = 0)
< 1)reactive part
of theacousticalimpedance
72
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Western Electric exponential horn
73
Normal rangeof T valuebetween
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0 and 1 For T>>1 the profile becomes progressively conical
rofiles of h erbolic famil horns with T value variation between 0 and 128
74
the Tractrix hornthe Tractrix horn
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Paul G.A.H. Voigt
the mathematical pseudosphere
-
principle
a square tractrix horn built by
75
son e n ng an
"The onl wa that he could fi ure out to makehis driver sound good was to horn load it, but he
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his driver sound good was to horn load it, but he
couldn't understand the mathematics behind theexponential, so he said, "Well, the exponentialtheor redicts that the wave form oin downthe horn is plane or flat, but if you look at thephysics of the situation, the wave front has todrag along the horn walls. So naturally it's going
to be curved. What if I eometricall desi ned ahorn that has curved wave fronts all the waythrough the horn and see what happens?"
So he did a geometrical construction of a horn that would give him.
done and said, "Oh, that's a Tractrix curve." The Tractrix curve comesabout because if you have one airplane chasing another on a different
,other plane, and it turns out that's a Tractrix curve."
Bruce Ed ar on Voi t's tractrix
76
expansion law of the Tractrix horn A = 2 R h = 2 R [1-cos( )]
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77
KugelwellenKugelwellenRsch ( KLANGFILM laboratories )
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Rsch ( KLANGFILM laboratories )
radius is the double of the radius used in the tractrix horn
78see also : H.Schmidt: "ber eine neue Lautsprecherkombination" Funk und Ton N5, 1950, p.226-232
Ku elwellen
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re ne v ew oa Kugelwellen horn
79
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radiation diagram of the Kugelwellen horn
80
" ' "
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81
Le Clachs method to calculate the profile of an horn knowing therelation between the area of the wavefront and its distance to throat
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82
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Wireline 3D view of
83
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Current driven
Current driven
Voltage driven
Voltage driven
84analysis by Jacek Zagaja
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J321 (Fc = 320Hz)
rec v y pa ern o ewLe Clac'h horns
85
J871 (Fc = 870Hz)
compared profiles of exponential, spherical, Le Clac'h,, ,
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Note how the profiles of the Kugelwellen
and Le Clach horns are ver similar
86
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waveguidesThe benefits of the directivity of a waveguide
levels within the included angle of thewave uide within the o eratin fre uencband of the waveguide.
In addition, sidewall and floor bouncereflections are reduced by the controlled
87
conical hornconical horn
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88
Oblate spheroidal waveguideOblate spheroidal waveguide
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Earl Geddes
"The concept of a waveguide asa rec so u on o e waveequation was shown to becapable of exact solution, free
of Webster'equation. "
89
oblate spheroidal
system of coordinates
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90
While the summed power responsedi t d b th OS id i f ll
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radiated by the OS waveguide in fulls ace is ver smooth the fre uencresponse curve at any given anglefrom the axis is never smooth
See measurements of Earl
Geddes loudspeaker on.
91
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and simulation
of horns
92
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above: the first models used atank filled of water.
93
on right : later finite elementsmethods were used
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one of the first ublication on FEM results of the simulation of soundfields
94
in horns
easuremen s
performed
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performed
an exponential horn by JohnSheerin
Anal sis usin Caraperformed my MichaelGertsgrasser
wavetank analysis in
95David McBeans Hornresp
software.
Radiation from a
differentfrequencies
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Pressure map
Polar graph witha 3D
presentation
Various simulations of theradiation of a iston and of
a horn.
96
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conical horn Le Clac'h horn
FEM simulations performed by John Sheerin
Note the distortion of the shape of the wavefronts Note the very smooth wavefronts
97(Half horn represented only)
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s mu a ons o an wavegu e a eren requenc es
Note the wavy isobare curves over 2000Hz
98
Copyright John Sheerin
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Note the smoothness and the linarity of the
isolevel contours.
polars obtained by FEA of a 275Hz tractrix
'
99FEM simulations performed by John Sheerin
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simulation by
John Sheerin
my
e achorn
the J321 horn
100
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backreflected waves,
g r er o es (HOMs)
101
from mouth tothroat inside a
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from mouth tothroat inside ahorn.
Single reflection
Double reflection
Triple reflection
102
When the pathlength between the direct wave ande re ec e wave s equa o a mu p e o e
wavelength at the considered frequency, we
observe a summation of their pressure.
Wh th thl th b t th di t d
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When the pathlength between the direct wave andthe reflected wave is equal to a odd multiple of thehalf wavelength at the considered frequency, weobserve a subtraction of their pressure.
easy demonstration of backre ec e waves w aloudspeaker, a magazineforming a cone and a towel
103
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104
large diffraction low diffraction
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large reflection low reflection
- on left, high reflectance
- on ri ht ver low reflectance
105
measuremen s
performed at ETF2010
HOMs absorptionHOMs?
Effect of the
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wavelets graph of the oblate subtraction of the
sp ero a wavegu e
OSWGD without its foamplug and with its foam HOMs have non axial
106
rave ns e e orn
HOMs ? HOMs ?
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Jmmlc OSWgd econowave
the wavelets graph may be used in order to show the
107existence of sub-millisecond delayed energy (HOMs?)
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optimization with the goal
o a ow re ectance
108
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109
horns having a lower reflectance at mouth havesmoother frequency response curves
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increasedopening angle at
110optimized profile for the lowest reflectance at 27 frequencies
In search of a more constant
radiation angle
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radiation angle
Multicellular horns
Constant directivityorns
Wave uidesQuadratic throat waveguideOblate spheroidal waveguide
111
mu ce u ar orns
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with curved dividers
the idea is to split the wavefront near the throat of the hornthrough several ducts before the wavefront at HF begins to
separate from the walls of the horn.
112
multicellular horns with
curved thin dividers
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The dividers follow flow lines .Different shapes of cell coexist.
WE 24A,1936 - 1967
Flat mouth
113
multicellularhornswithidenticalcells
Altec
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Onken 255 wood and Onken 455
114Onken 255wood Altec LansingH1804B
bass reflex enclosure
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eta othe assembly
of cells
115
t i l h h li ( i l )
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sectorial horns have linear ( conical )expansion in one plane and
exponential expansion in the other.
Dividers can be flat (e.g. Altec 511 and. .
JBL2397)
116
n en
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e
117
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The TAD
TH4001 hornhas a Smith horndesign at throat
118
A300horn
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Altec
the Mantara horn
119
from diffraction horns to biradial horns
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JBL
Electro Voice
120
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its goal:
to obtain a more constantfrequency response over a
chosen solid an le
121
Oblate spheroidal
waveguide
Note the rather constant
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directivity over 1kHz andthe wavy contours
horn calculated by the
"Le Clac'h" methodNote the directivity regularlyincreasing with frequencyand the smooth contours
simulations using
122
ornresp
2 ways enclosure
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See also:
Acoustic waveguide for controlled
sound radiation
123
United States Patent 7068805
mode 00
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mode 00
mode 00 mode 01
mode 01
mode 10 mode 11
only modes 00, 0i, j0
124exist with round horns
each High Order Mode has its own cut-off
frequency
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Michael Gerstgrasser'minphase horn is a good
Le Clac'h horn and the
125
profile of the
mouth of an OSwave uide iscurved at a
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nearer distancefrom the throat
3 4
simulations
MichaelGerstgrasserusing AxiDriver
126from 1 to 4, note the more evenly distributed pressure field
frequency response from 0 on axis to 90off axis by 5 steps
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without e ualization with e ualization
Le Clac'h horn Min-Phase horn
The Min-Phase horn provides a better directivity control than the Le Clac'hhorn while kee in the smoothness of the fre uenc res onse curves on and
127off axis.
5/19/2018 JMMLC Lecture on Horns
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(France), 1903
a new Le Clac'h horn (2007)