Outline Butterfly's White by thaiv2012


									                                                   White Paper
                                                       Guido Noselli                                               System

                                                                               The reason for t his and it s int rinsic charact erist ics,
I n t he Sound Reinforcem ent world in recent years, a
                                                                               which m ade it and st ill m akes it an enclosure able t o
great deal has been said and writ t en about vert ical
                                                                               reproduce wit h a virt ual dispersion of a cylindrical
line arrays. All m anufact urers, from t he sm allest t o
                                                                               nature, wit h an adequat e sound level and qualit y, a
t he largest , have brought out in a m ore or less
                                                                               rat her sm all port ion of t he audio spect rum , i.e. t he
efficient and objective manner these particular sound
                                                                               frequency range norm ally described as Vocal or
syst em s, each t rying t o influence list eners or readers
                                                                               Telephone Band .
as t o how his const ruct ion choices were t he right
The proliferation of "com m ents" certainly inform ed
members of the public, educating them on this particular
issue, and avoided people like myself (among the last to
talk about them ) having to dedicate endless pages to a
detailed description of the theory behind vertical line
arrays. This also eliminated any temptation I might have
had to criticize other m anufacturers products, because a
lot of others have already done so in the com m ents
circulating in the audio community for some time.

On t he cont rary, I ll offer as exam ples t he product s
of som e m anufact urers, dedicat ing som e space t o
t hem , because t heir part icular product s in t his field
give indispensable help in underst anding t he work
and result s achieved by Out line, described in t his
publicat ion. A great deal of what is writ t en in t his
whit e paper is t aken direct ly from t he t ext and
designs cont ained in som e pat ent s for t he But t erfly                     This is also t he case wit h t he colum ns called
system, applied for in 2002.                                                    I nt ellivox designed during recent years by Duran
                                                                               Audio ( Ref.2) , for which a sophist icat ed DPS
                                                                               cont roller was im plem ent ed enabling t o achieve very
Preliminary remarks                                                            high direct ivit y values on t he vert ical plane, even if
                                                                               in a narrow band of t he audio spect rum ,
Before Christ ian Heil ( Ref.1) , Vert ical Line Array                         nevert heless m ore t han sufficient for solving speech
was sim ply t he definit ion used t o appropriat ely                           int elligibilit y problem s in environm ent s wit h high
describe a part icular t ype of enclosure: a speaker                           reverb levels.
colum n. An enclosure st ill used t oday several                               Going back t o t he field which int erest s us, in spit e of
decades after its demise, for the speech reproduction                          all his denigrators and the sceptics who attacked him
in reverberant environm ent s and all t hose places in                         in every way, everybody has t o at t ribut e t o Heil, t he
which it s necessary t o proj ect speech over a                                invent or of t he V- DOSC, t he rediscovery and m odern
considerable distance with good intelligibility.                               profitable application from the acoustic point of view,
To dat e, t hese colum ns haven t undergone any                                of the principles which are at the basis of vertical line
furt her t echnical developm ent t o m ake t hem suit able                     arrays, t hanks t o which t hey can be used in wide-
for wider m ore dem anding use, such as t he wide                              range applications, in sound reinforcement in general
range reproduct ion of t he whole audio spect rum in                           and in particular in the high performance high quality
the pro audio reinforcement field.                                             market.

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                                                                       - page 1
Nowadays, the term vertical line array is used to                              From t he point of view of t heory, t here s cert ainly
describe a particular sound reproduction system , which                        not hing new t hat ( even if in a different less st ylish
has nothing to do with the classic vocal speaker column,                       way perhaps) hadn t already been explained fift y
apart from construction sim ilarities, which consist the                       years ago in the books quoted.
colum n s use of a num ber of norm ally sm all                                 From t he point of view of pract ical realizat ions
loudspeakers, m ounted alongside and one above each                            however, Heil int roduced a new elem ent , for which
other and, in the case of the m odern line array, the use                      he deposited the patent in France in far- off 1988 and
of a num ber of com plete enclosures, also m ounted                            lat er in Europe and Am erica ( Ref. 8) , t he im port ance
alongside and one above each other and able to                                 of which was such as t o relaunch t he vert ical line
reproduce the entire audio band or, m ore generally                            array as a highly effect ive const ruct ive solut ion for
speaking, a very wide part of it (norm ally without the                        professional high- powered enclosures; t he sam e one
low frequencies).                                                              t hat had been abandoned aft er t he first at t em pt s
I n t his configurat ion, t he syst em has a virt ual                          m any year before in t he pro audio world and lim it ed,
  cylindrical acoust ic em ission caused by t he effect of                     as we ve seen, t o a m ore rest rict ed use in t he
t he vert ical coupling of t he m ult i- way enclosure                         aforementioned speaker columns.
elements forming the array.                                                    The new elem ent is a special wave guide - t he
I n fact , t he use of several channels, wit h each                              D OSC w a ve guide , which resolves a problem
loudspeaker dedicat ed t o a specific audio range, for                         which up unt il t hen had been insurm ount able, of
t he const ruct ion of vert ical line arrays isn t a idea                      obt aining from a high frequency loudspeaker a high
recent ly int roduced by Heil, but had already been                            sound level em ission, suit ed t o building vert ical
experim ent ed and used for m any years in various                             sound colum ns for use at concert s and in general for
models of speaker columns.                                                     sound reinforcem ent in large areas .
0ne good example is described in Ref.3                                         Before describing Heil s invent ion and it s peculiarit y,
Merit t herefore shouldn't go t o Heil for having                              it s necessary t o out line, at least briefly ( t he books
int roduced t he use of m ult i- way syst em s form ing                        m ent ioned can be consult ed for t he det ails) , t he
vert ical sound line arrays, but rat her t he fact of                          m ost im port ant feat ures of a line array, wort hy of
having clearly described and dem onst rat ed t he                              being defined as such wit h reference t o t he elem ent s
crit eria t hat govern t hese configurat ions, arriving at                     that form it.
t he form ulat ion of a com plet e t heory, based on t he
sim ilarit ies bet ween acoust ics and opt ics wit h
reference t o t he Fresnel and Fraunhofer diffract ion.                        Vertical Line Arrays work
( Ref.4 and 5).
This is t he acknowledgm ent t hat t he int ernat ional                        Since vertical line arrays for sound reinforcement are
audio com m unit y m ust right ly and obj ect ively give                       form ed by a cert ain num ber of elem ent s/ enclosures
Heil and this, at the same time, is the contribution of                        assem bled one above t he ot her but operat ing
knowledge he m ade t o t his sect or and can now be                            individually, it s clear t hat t he operat ion of a syst em
used by everybody.                                                             like t hat is closely linked wit h t he acoust ic coupling
I n fact , like ot hers in t he past , such as Olson and                       achieved bet ween all t he elem ent s wit h reference t o
Beranek, to mention the most famous (Ref. 6 and 7),                            the audio range to be reproduced.
his work once again clarifies how difficult or                                 I n short , one can t alk of acoust ic coupling when t he
im possible it is, using ort hodox m et hods, t o build a                      em ission of t he elem ent s form ing t he line array
vert ical line array which works well over t he ent ire                        ( com parable t o t he em ission t ypical of point sources,
audio band, up t o high frequencies of t he order of                           wit h reference t o t he highest frequency t o be
15/20 kHz.                                                                     reproduced) int eract , sum m ing t he energy em it t ed
                                                                               I n order for t his t o occur, which is at t he basis of t he
                                                                               syst em s efficient operat ion, t wo fundam ent al crit eria
                                                                               m ust be respect ed ( Heil cit es t hree m ore, which in
                                                                               this cont ext it s superfluous t o m ent ion and of which,
                                                                               t hose of you who wish can easily find t he descript ion
                                                                               in his publications):

                                                                               a) The sur fa ce occupie d by t he a ct ive sour ce s
                                                                               for m ing t he a r r a y e le m e nt s m ust n t be le ss
                                                                               than 80% of the total surface of the array.

                                                                               b) The sour ce s m ust t h e r e for e be close ly
                                                                               coupled and separated by a distance of no more
                                                                               t ha n ha lf a w a ve le ngt h r e fe r r e d t o t he highe st
                                                                               frequency they have to reproduce.

                                                                               These t wo requisit es, if sat isfied sim ult aneously,
                                                                               m ean t hat a cert ain num ber of sources ( com parable
                                                                               wit h t he point sources at t he frequencies t hey have
So didn t H e il s w or k give a nyt hing ne w , j ust a                       to reproduce) generate in the coupling plane a sound
be t t e r k now le dge of w ha t w a s t he st a t e of t he                  wave similar or equal to the planar wave, as happens
art?                                                                           in a sound source which is effectively planar with the

Outline - via Leonardo da Vinci, 56 - 25020 Flero (Brescia) - Italy - tel. +39-030.358.1351 fax +39-030.358.0431 - www.outline.it - info@outline.it
                                                                       - page 2
sam e dim ensions, a fundam ent al condit ion for
obtaining a virtually cylindrical wavefront.
When t he second of t hese condit ion can t be
achieved for geom et rical reasons illust rat ed furt her
ahead, as it s im possible t o obt ain t he necessary
coupling which m akes t he group of em issions
com parable wit h t he em ission of a planar wave
source, at least am ong t he em ission of t he single
elem ent s form ing t he array, it s necessary t hat no
dest ruct ive int erference is generat ed in t he band of
frequencies for which t he aforem ent ioned coupling
couldn t be achieved.
I f t he requisit es list ed so far are easily achieved for
low frequencies, it s m ore difficult for m id
frequencies, t o avoid dest ruct ive int erference at
1000Hz,       for     exam ple     ( 1/ 2 wavelengt h    =
approxim at ely 17cm .) , t his would im ply t he use of
sources t hat don t exceed t he dim ensions of 17cm ( a
6.5 speaker) , wit h all t he result s in t erm s of poor
Then, for frequencies above 1000Hz, t he dim ensions                           Fla t  dia ph r a gm lou dspe a k e r s                         in
of the sources must gradually diminish to values that
are only t heoret ical and m at erially im possible t o
                                                                               vertical line arrays
achieve with real sources such as loudspeakers.
                                                                               I f however one decides t o use loudspeaker t hat are
                                                                               slight ly less t radit ional, such as t hose wit h a flat
Ve r t ica l line a r r a ys w e a k poin t                                    diaphragm , in one of t he versions m anufact ured
                                                                               t oday ( elect rost at ic, isodynam ic, et c.) , it wouldn t be
I t can be seen from all t his t hat t he form at ion of a                     difficult t o obt ain correct behaviour even at high
vert ical line array has it s weakest point in t he high                       frequencies.
frequencies or rat her in how t he act ive com ponent,                         I n fact , it s easy t o im agine how t he behaviour of
loudspeaker or ot her it em t hat has t o reproduce                            t hese loudspeakers, wit h reference t o t heir sound
them is made and used.                                                         em ission, is t he best t hat could be im agined for
I n fact , for exam ple, t o reproduce frequencies up t o                      forming a line of vert ical sound em ission. I n fact ,
10000Hz ( 1/ 2 wavelengt h = 1.7 cm ) , sources t hat                          t hese loudspeakers, being m ade up of flat
don t physically exceed t his dim ension would have t o                        diaphragm s t hat m ove in phase wit h all t he
be coupled closely.                                                            frequencies t hey reproduce, are com parable t o sm all
Even supposing t hat such sm all loudspeakers                                  line array, and t he inst allat ion of one sm all line array
( m agnet ic circuit ry included) can be built , it s easy t o                 on anot her sm all line array can only result in t he
im agine t hat it would be a wast e of t im e, due t o t he                    form at ion of a higher line array wit h em ission of
pract ically non- exist ent efficiency of loudspeakers of                      planar sound waves on t he coupling plane.
that type.                                                                     Unfort unat ely, due t o t he current st at e of t his
Creat ing vert ical line arrays t hat operat e well at high                    technique, their intrinsic construction means that this
frequencies       t herefore   becom es     a     pract ically                 t ype of loudspeaker doesn t have sufficient power
insurm ount able physical quest ion if one want s t o use                      handling capacit y for t he high sound pressure levels
t radit ional loudspeakers such as for exam ple cone or                        required from pro line arrays able t o cover large
dome units.                                                                    areas as far as both width and depth are concerned.
                                                                               For t his reason t hey re not widely used, and can
Refer again to Fig. 2A, 2B, 2C, 2D.                                            generally only be seen in m odels wit h lower
And also all kinds of horns are by t heir very nat ure
flared duct s whose sides are divergent according t o
t he required sound dispersion, and whose m out h
surface dim ensions aren t negligible as t hey re suit ed
t o t he lowest frequency t hat has t o pass t hrough
This m eans t hat even reducing t he dist ance bet ween
the horns, the emission centres (the throats) can still
be a considerable dist ance apart , so for all t hese
reasons can t be built wit h dim ensions and t ype of
dispersion m ore suit ed t o form ing a line array
operating correctly according to the requisites listed.

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                                                                       - page 3
                                                                               This em ission slot can in t urn becom e t he t hroat of a
                                                                               furt her coupled horn or wave guide, in order t o
                                                                               control dispersion on the horizontal plane.
Com pr e ssion dr ive r s in ve r t ica l lin e                                The aim of t he phasing plug is t o get t he em ission
arrays                                                                         of every point of t he circular t hroat plane of t he
                                                                               driver t o reach t he new rect angular t hroat plane at
So, what can be used t o reproduce high frequencies                            t he end of t he wave guide, t he diffract ion slot ,
that meets the necessary requisites?                                           covering t he sam e dist ance, in such as way as t o
Since t he m ost im port ant requisit e, as has been                           reproduce t he sam e planar wave found at t he t hroat
seen, is the capacity to reproduce sound pressure, of                          of a com pression driver in rect angular rat her t han
all t oday s known com ponent s t he m ost efficient and                       circular form.
t hat which is m ost suit ed t o obt aining it are                             The dim ensions of t he annular duct are very sm all
com pression driver. However, like ot her t radit ional                        and t herefore avoid creat ing dest ruct ive int erference
loudspeakers, it doesn t have negligible dim ensions,                          due t o int ernal reflect ions bet ween t he walls of t he
or sound em ission com parable wit h t hat of a                                wave guide and t he phasing plug . Fig. 6A, 6B, 6C
rectangular flat diaphragm.                                                    and 6D schem at ize Heil's innovat ion. I t s obvious
Therefore, m any m anufact urers t ried t heir skill at                        t hat t his elem ent sim ulat es t he cylindrical wavefront
m aking special wave guides or part icular acoust ic                           of a rectangular flat diaphragm very closely.
adapt ors     t hat enabled    t he  easily    available                       I n part icular, Fig. 6 A shows a horizont al cross
com pression drivers in m ult iples t o reproduce t he                         sect ion of a driver wit h phasing plug; Fig. 6 B shows
high frequencies in line array systems.                                        a vert ical sect ion of t he sam e driver wit h phasing
                                                                               plus; Fig. 6 C is an axonom et ric view showing t he
                                                                               driver wit h phasing plug wit h t he out put slot coupled
                                                                               t o a front horn or wave guide; Fig. 6 D is t he
                                                                               diagram of t wo unit s wit h phasing plug aligned one
                                                                               above the other to give a cylindrical wavefront.
                                                                               I t seem s clear t hat Heil s syst em is geom et rically
                                                                               exem plary and essent ially correct for achieving t he
                                                                               result , com pared t o t hose less correct ones based on
                                                                               coupling various wave guides, horns, et c. And in
                                                                               fact , t he perform ance of t his syst em , in m y opinion
                                                                               is at the basis of the success achieved by the product
                                                                               on which it s used.

But as can be easily deduced from t he schem at ic
exam ples on t hese pages, apart from t he m ore or
less good acoust ic result s obt ained, no device
inspired by t hem fully achieves what is required by
t he line array t heory: sound em ission by a
rect angular flat diaphragm . The sim plest m ost
efficient solution for generating planar waves.

I s t h e D OSC w a ve gu ide t h e on ly
possible solution?
The t echniques illust rat ed up t o now or sim ilar ones
sim ply enable t o reduce t he effect of int erference
t hat occurs bet ween t he elem ent s, t aking t hem t o
t he highest possible frequencies t heir physical
dimensions will allow.
Heil s wave guide on t he ot her hand offers an                                Other valid solutions?
innovative valid way of achieving the aim described:                           The Reflective Wave Guide
 Sim ula t ing t he be ha viour of a r e ct a ngula r fla t                    Only recent ly, a new solut ion was found. Aft er
dia phr a gm using a cla ssic com pr e ssion dr ive r                          several years during which t here was first ly
                                                                               confusion in t he pro audio sound reinforcem ent
The syst em foresees a wave guide t hat receives t he                          m arket on behalf of t he m aj orit y of t he world s
com pression driver s em ission via a phasing plug                             m anufact urers regarding t he use of line arrays and
elem ent , which in t urn creat es wit h t he sides of t he                    later t heir m obilisat ion in t he search for new m ore or
wave guide a narrow circular duct at the throat plane                          less valid products to be put on the market, following
where the sound is emitted, transforming it gradually                          up on t he success t hat Heil s product s cont inued t o
int o a rect angular annular duct finishing in t he sound                      have year after year.
output slot.

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                                                                       - page 4
Perhaps        t his new        solut ion     isn t  as t ot ally
irreprehensible from a geom et rical point of view as
Heil s invent ion, but anyway in m y opinion it s m ore
valid t han t he ot hers t hat have been put forward up
unt il now since, based on a com plet ely different
principle, it enables t o realize a high frequency
sect ion which perform s very sim ilarly t o a source
wit h a rect angular flat diaphragm , which I wish t o
repeat, is the solution most suited to use in a vertical
line array.
I n fact , if one looks closely, t he solut ion found allows
t he form at ion of sound em ission not only for planar
waves, but also convergent and divergent waves
according to construction needs.
At t his point , I d like t o st at e t hat t his innovat ion was
t he alm ost sim ult aneous subj ect , unbeknown t o it s
invent ors, of t wo pat ent applicat ions, bot h valid for
pat ent law, as t he m ost recent was present ed before
t he publicat ion of t he previous one, during t he so-
called lat ency period which, unless expressly
request ed by t he invent or, norm ally last s for 18
One applicat ion is I t alian, N ° BS2 0 0 1 A0 0 0 0 7 3
da t e d 0 3 / 1 0 / 2 0 0 1 , deposit ed by Out line, which I
represent , t he ot her is t he French N ° 0 0 1 1 4 9 of
08/09/2000, deposit ed by Eric Vincenot and
Francois Deffarges, t wo nam es t hat don t require any
The operating principle of this wave guide, which can
generally be defined as reflect ive , suit ed t o be used
t o advant age not only in vert ical line arrays, is
schem at ized respect ively in t he group of diagram s
from 7A t o 7E, as far as t he designs illust rat ing t he
application for an Italian patent are concerned,

                                                                               in t he Fig. 8 group, as far as t he designs illust rat ing
                                                                               the French patent application are concerned,

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                                                                       - page 5
The operat ing principle is based on t he reflect ion of
t he sound em it t ed by t he com pression driver s t hroat
by m eans of a flat , parabolic, hyperbolic or ellipt ical
surface, according to the type of dispersion required.
Before being reflect ed, t he sound em it t ed by t he
driver s circular t hroat passes t hrough a wave guide                         However, closely analysing t he geom et ry of t he
form ed on one side by parallel, convergent or                                 device proposed in t he aforesaid pat ent applicat ions,
divergent walls and on t he ot her by walls which                              one realizes t hat t he im it at ion of flat diaphragm
diverge conically or wit h anot her geom et ric flair, in                      em ission isn t com plet ely successful and doesn t
order t o form ( at a given dist ance from t he init ial                       achieve t he degree of perfect ion t hat on t he cont rary
t hroat ) anot her so- called diffract ion t hroat wit h a                     t he geom et ry used by Heil enables his device t o
rect angular shape ( a slot ) , posit ioned j ust before or                    achieve.
j ust aft er t he reflect ing surface port ion, creat ing                      I n fact , t he reflect ing parabolic surface, described as
planar, divergent or convergent sound waves.                                   being able t o t ransform t he spherical planar sound
As well as advant ages which can be easily im agined                           wave em it t ed by t he com pression driver int o a
by looking at t hese illust rat ions, t his solut ion offers                   rect angular planar sound wave, which is t he
doubtless advantages of a geometric nature, because                            prerequisit e for form ing          vert ical line arrays
folding t he high frequency wave guide ( norm ally                             perform ing well at high frequencies, needs, for t his
st raight t o avoid creat ing dest ruct ive int ernal                          to t ake place, a source which is e ffe ct ive ly a point
interference) close to the reflecting surface facilitates                      source and doesn t have dim ensions such as t hat of
reduction of the dimensions of the enclosure in which                          a driver s t hroat .
its fitted.                                                                    I n fact , analysing t he parabola by m eans of t he
What s m ore, it s acoust ic operat ion, at least in t he                      schem at ic designs, it can be not iced t hat , due t o it s
case of t he parabolic reflect ing surface, resem bles                         shape, it can t reflect in parallel beam s t he sound
t hat of t he flat diaphragm it t ries t o im it at e. I n fact ,              em it t ed by any source ot her t han a point source
a parabola works according t o t he diagram shown                              posit ioned in it s focus and t herefore, in t his case,
here,                                                                          can t com e close t o flat diaphragm s operat ion for
                                                                               planar waves.
                                                                               I t also seem s clear t hat t he pat hs from every point
                                                                               of t he source t o t he em ission surface ( shown wit h a
                                                                               darker line in t he illust rat ions) can t rem ain t he
                                                                               sam e, as is necessary t o avoid t he occurrence of t he
                                                                               t ypical int erference caused by different arrival t im es
                                                                               of the signal reproduced by the device.

and is able t o concent rat e planar sound waves
cut t ing it s surface in it s focus and/ or em it planar
waves st art ing from a point source put in t he sam e
focus, m aint aining an ident ical signal pat h from t he
source to the emission plane in question

                                                                               This also happens in t he case of t he reflect ing wave
                                                                               guide in the aforementioned patent applications.

Outline - via Leonardo da Vinci, 56 - 25020 Flero (Brescia) - Italy - tel. +39-030.358.1351 fax +39-030.358.0431 - www.outline.it - info@outline.it
                                                                       - page 6
I n fact , since t he real sound em ission is not point
source em ission, virt ual point source em ission can t
be form ed out side t he wave guide for any of t he
possible reflecting surfaces, including parabolic.

A glance at Fig. 9 B1 , 9 B2 , 9 B3 , regarding a
hyperbola, will clarify t he concept bet t er t han any
more written explanations.

                                                                               Then, wit h reference t o t he ellipse, see Fig. 9 C1 ,
                                                                               9C2, 9C3.

Outline - via Leonardo da Vinci, 56 - 25020 Flero (Brescia) - Italy - tel. +39-030.358.1351 fax +39-030.358.0431 - www.outline.it - info@outline.it
                                                                       - page 7
                                                                               wit hout      using   t he    sam e     const ruct ion  logic
                                                                               safeguarded by its patent?
                                                                               I n recent years, t he search for t his device has been
                                                                               t he obj ect of research and const ant work at Out line
                                                                               wit h count less prot ot ypes being built , of bot h very
                                                                               com plicat ed individual devices and equally com plex
                                                                               complete units containing these devices, as the latter
                                                                               were necessary for carrying out measurements which
                                                                               are really indicat ive of t he acoust ic result s obt ained
                                                                               using them in line arrays.
                                                                               This int ense work led t o t he discovery of a new
                                                                               solut ion t o t he problem , wit h t he invent ion of a
                                                                               device whose pat ent applicat ion, regist ered in I t aly
                                                                               som e t im e ago, has been ext ended t o international
                                                                               level (PCT).
                                                                               The device s operat ion is ext rem ely sim ilar t o t hat of
                                                                               a flat diaphragm , at least t o t he sam e ext ent as
                                                                               Heil s wave guide, wit h which it has no principles in
I n shor t , t he condit ions for opt im um sound
                                                                               In fact, the new device combines operation similar to
r e fle ct ion, t hose st r ict ly com pa r a ble w it h
                                                                               t hat of a flat diaphragm wit h t he m uch wider
t he or e t ica l condit ions,    pa r t icula r ly t hose
                                                                               versat ilit y and pot ent ial of t he reflect ing wave guide
a llow e d by a pa r a bola , w hich is t he r e fle ct ing
                                                                               already described, as it exceeds it in precision,
sur fa ce by m e a ns of w hich it s possible t o
                                                                               emission coherence and overall performance.
a ppr oa ch t he e m ission condit ions of a fla t
dia phr a gm , a r e only e ffe ct ive ly a nd t ot a lly
achieved if the source is a point source.
                                                                               N ose lli s D PRW G, D ou ble Pa r a bolic
When t he real source has dim ensions can t be                                 Re fle ct ive   W a ve    Gu ide       as  an
overlooked ( in t he professional sound reinforcem ent                         altern a t ive solu t ion t o H e il s D OSC
sect or, t hese dim ension can t be reduced below a
cert ain lim it for reasons of power) , t he sound
                                                                               wave guide.
emission obtained using the reflection method gets
                                                                               The solut ion, which had been sought for so long and
furt her and furt her from achieving t he em ission
                                                                               has at last been found, like all valid solut ions, is of
charact erist ics of a flat diaphragm t he larger t he
                                                                               disarming simplicity.
source s dim ension and t he higher t he frequency
                                                                               I t s applicat ion allows loudspeaker syst em designers
band to be reproduced by reflection.
                                                                               wide working m argins from t he const ruct ion point of
I t can be deduced t hat from a t heoret ical and
                                                                               view and m uch great er creat ivit y regarding
pract ical point of view, t his m et hod doesn t have t he
                                                                               enclosures shapes, up unt il now based on t he classic
geom et ric precision of Heil s wave guide and
                                                                               solution imposed by well- known techniques.
t herefore it s use in m ult iples for HF sect ions in
                                                                               I n short , t his device, built on t he basis of t he
vert ical line arrays will increase t he im perfect ions
                                                                               invent ion, allows t o overcom e t he int rinsic lim it s of a
which occur in t he syst em for physical reasons which
                                                                               geom et rical and dim ension nat ure of t radit ional cone
can t be overcom e, even if t he result is st ill
                                                                               speakers, dom e t weet ers and com pression drivers
pot ent ially bet t er t hat t hat which can be achieved
                                                                               also and above all used t o build line arrays, or t hose
adopt ing ot her classic solut ions found up unt il now,
                                                                               syst em s in which t he correct acoust ic coupling of
as t hey re also condit ioned t o a great er ext ent by
                                                                               m ult iple sources is indispensable t o achieve t he
unavoidable geometric/physical questions.
I n m y opinion, t he solut ion described t o far, based
on folding t he wave guide t o achieve t he required
                                                                               The inve nt ion is ba se d on t he t r a nsfor m a t ion of
t ype of reflect ion having a real source like t he t hroat
                                                                               a sour ce w it h t he t ypica l dim e nsions of r e a l
of a driver, can be bet t er exploit ed t o build
                                                                               loudspe a k e r s, fir st ly int o a vir t ua l point sour ce
  part icular single enclosures which don t necessarily
                                                                               w it h cha r a ct e r ist ics ide nt ica l t o a r e a l point
have t o be coupled in m ult iples, such as for exam ple
                                                                               sour ce a nd la t e r , in a se cond st a ge , obt a ining
very low profile wedge m onit ors , in which it s
                                                                               fr om t his      real       point sour ce t he r e quir e d
im port ant t o keep t he physical dim ensions wit hin
                                                                               sound dispe r sion by m e a ns of r e fle ct ion w it h
necessary limits.
                                                                               va r ious t ype s of sur fa ce s w it h diffe r e nt sha pe s,
I personally used t his syst em for our H.A.R.D. 212,
                                                                               k e e ping t he sound pa t hs e x a ct ly t he sa m e fr om
  no com prom ise wedge m onit ors wit h a very low
                                                                               a ny point of t he a ct ive sour ce t o t he
profile      and       wit h     ideal    acoust ic/ direct ive
                                                                               m e a sur e m e nt or list e ning posit ion via t he
characteristics for short/medium throw applications.
                                                                               reflecting surface.
Aft er t hese observat ions, if I ve m anaged t o explain
                                                                               This r e fle ct ing sur fa ce ca n be fla t , pa r a bolic,
m yself sufficient ly clearly, it 's obvious t hat in spit e of
                                                                               hype r bolic or e llipt ica l, or m or e ge ne r a lly
t he lat est ( nevert heless valid) solut ions t o t he
                                                                               speaking, flat, concave or convex.
problem of reproducing high frequencies in vert ical
line arrays , t he DOSC wave guide offers great er
                                                                               I t s m uch harder t o describe t he device in words t han
precision and it s perform ance is m uch closer t o t hat
                                                                               with the following diagrams.
of a flat diaphragm.
                                                                               Fig. 1 0 A, 1 0 B, 1 0 C, 1 0 D a n d 1 0 E schem at ize t he
Is there therefore absolutely no possibility of building
                                                                               t ransform at ion of a real flat source ( represent ed in
a device t hat perform s in t he sam e way as Heil s

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all t he diagram s by a cont inuous segm ent on a
dot t ed st raight line) int o a real point source by
m eans of a parabolic concave reflect ing surface and
also schem at ize t he sound diffusion in t he direct ion
of t he arrows by m eans of t he sam e parabolic
(convex) surface (Fig. 10A), a flat surface (Fig. 10B),
a hyperbolic ( concave) surface ( Fig. 10C) , a
parabolic ( concave) surface ( Fig. 10D) and an
elliptical (concave) surface (Fig. 10E);

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                                                                               Fig. 11C shows the cross-section of a practical example
                                                                               of the double reflective wave guide in which separators
                                                                               have also been m ounted in the duct to elim inate any
                                                                               possible internal interference at high frequencies.

                                                                               Fig. 1 1 D shows yet another exam ple, which can be
                                                                               achieved by the revolution of the section of the wave
                                                                               guide shown in Fig. 11A

From a graphic point of view, t he behaviour of t he
device can be seen in t he following diagram s. 11A,
11B schem at ize axonom etric diagram s of som e
exam ples of acoustic reflectors which reproduce the
various aspects of the invention.

                                                                               Fig. 1 2 schem at izes anot her possibilit y offered by
                                                                               t he invent ed syst em , showing it s great pot ent ial: t he
                                                                               t ransform at ion of a real signal source int o a real
                                                                               point source which, by m eans of ot her t wo com bined
                                                                               reflect ing surfaces, is t ransform ed int o a source
                                                                               which is planar or of anot her t ype, but nevert heless
                                                                               keeping the signal paths the same length.

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There are a lot m ore possible com binat ions which, in
order t o increase t he sound pressure level, use
several real sources simultaneously, whose emission,
using t he sam e m echanism , is           direct ed  and
reflected outwards with the required dispersion.
But , aft er what has been described up unt il t his
point , I ll leave it t o you t o im agine t he num erous
possible configurations this technique offers.
The first practical application of the device described,
the DPRWG- Double Parabolic Reflect ive Wave
Guide, in one of it s possible variat ions, is found in
the C.D.H. 483 Butterfly Hi- Pack.
Here below t here is a pict ure of part ially
disassembled one.

Definit ely t he m ost int erest ing part t o be found in
t his elem ent / enclosure, built by Out line for m ult iple                   The first t hing one not ices looking a t he above
use in vert ical line arrays, because, as I t hink I ve                        design is the external shape of the Hi- Pack, for which
clearly shown, it s a good solut ion t o t he problem of                       applicat ion has been m ade for an int ernat ional
reproducing high frequencies in this type of system.                           indust rial design pat ent , result ing in t he product
However, with the Butterfly Hi- Pack all the necessary                         being called But t erfly for t wo reasons; first ly,
geom et ric and m echanical solut ions have obviously                          because t he shape brings t o m ind t hat of a but t erfly
also been adopt ed t o ensure t hat t he rest of t he                          and secondly because it is also very light weight : in
audio spect rum , not ent rust ed t o t he high frequency                      fact , considering t he fact t hat it s equipped wit h no
sect ion, is reproduced wit h t he sam e qualit y and                          less t han five loudspeakers, it s weight                 is
precision.                                                                     approxim at ely 33kg, including flying hardware fit t ed
So all t he const ruct ion st rat agem s were chosen and                       as standard.
applied in order t o m eet t he requisit es im posed by                        The second innovat ive fact , also t he subj ect of an
line array t heory, even exceeding t hem wherever                              indust rial design pat ent applicat ion and also an
possible.                                                                      applicat ion for an invent ion pat ent along wit h t he
                                                                               DPRWG wave guide, consist s in t he t ot al lack of t op
The following designs show t he definit ive single and                         and bot t om panel defining t he horn cavit y in front
array versions of the Butterfly C.D.H. 483.                                    of the diffraction slot.
                                                                               The aim of t his was clearly t o facilit at e t he coupling
                                                                               of t he arrays com ponent s up t o t he highest
                                                                               frequencies, keeping t he sm allest possible dist ance
                                                                               bet ween t he sources and at t he sam e t im e offering
                                                                               t hem a loading baffle wit h appropriat e unint errupt ed
                                                                               lines, an effect ive st rat agem         for m inim izing
                                                                               diffract ion and alt erat ion of t he response in t he
                                                                               m id/ high range due t o gaps which can t be
                                                                               The horn itself, or rather the sides of the horn, which
                                                                               est ablish t he syst em s horizont al dispersion, finish
                                                                               wit h sm oot h curves m eet ing up wit h t he box s
                                                                               ext ernal sides, which are also rounded and raked

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                                                                      - page 11
t owards t he rear of t he cabinet and anot her                                Horizont al dispersion is 90° in t he definit ive syst em ,
innovat ion from a design and t echnical point of view.                        while t he prot ot ypes were built wit h a slight ly
I n fact , t hese geom et ric and const ruct ion feat ures                     narrower angle.
have t wo aim s: m inim izing any diffract ion at t he                         The horn used for t his has rat her enviable dispersion
m out h of t he horn and at t he sam e t im e great ly                         behaviour: for one t hing, it s const ant over t he ent ire
st rengt hening t he side walls of t he box, which ( as                        frequency range reproduced and t he off- axis level
well as all t he rest ) also cont ains a bass sect ion wit h                   rem ains high up t o nom inal dispersion, indicat ed in
bandpass configuration and two dedicated speakers.                             t he case of t he prot ot ypes as approxim at ely 80° ,
The box is built in com posit e plywood, obtained                              aft er which it drops decidedly; t his indicat es it s
alm ost ent irely via m oulding and high frequency                             efficiency as far as directivity is concerned.
gluing. The panels t hickness has been lim it ed t o                           There again, t he m out h has am ple dim ensions
14m m . t o reduce t he enclosures weight , but at t he                        (approxim at ely 50cm . before it curves round t o j oin
sam e t im e im prove overall rigidit y and elim inat e any                    t he rear panel, which m eans t hat at 700Hz t he horn
resonance t hat m ight be caused by t he low                                   already has a suit able dim ension for t he cont rol of
frequency section.                                                             dispersion and at 1400 ( 1/ 2 ) , cont rol is com plet ely
The flying hardware allows t o vary t he angle                                 achieved. Vert ical dispersion is obviously est ablished
bet ween t he elem ent s wit h m inim um st eps of as                          by the height and aperture of the array element.
lit t le as 0.1 degrees if necessary; t he m inim um                           I ve included a polar plot m easured on t he horizont al
standard step is 0.25 degrees.                                                 and vert ical plane on a prot ot ype, t o highlight
The dimensions and the materials used have enabled                             behaviour      at   som e      significant   band- centre
t he unit s t o be cert ified, according t o t he st rict est                  frequencies.
int ernat ional norm s, for flying up t o 32 Hi- Pack
syst em s in a Vert ical Line Array reaching a height of
almost 8 metres.
From t he acoust ic point of view, as well as t he
groundbreaking DPRWG- Double Parabolic Reflect ive
Wave Guide, it s wort h m ent ioning t hat it s a 3- way
system, but only requires active biamping.
One channel for t he com pression driver wit h 3
diaphragm and 1.41 t hroat , t he ot her for t he
m id/ low and m id sect ions, connect ed in parallel t o
passive components without any kind of crossover.
By m eans of a m echanical break, achieved by m eans
of t he precise rest rict ing geom et ry of t he resonance
cham bers and t he respect ive t uning of t he m id/ low
and m id sect ions, t he em issions phase was shift ed in
order t o obt ain a coherent sum over t he ent ire
reproduced bandwidt h t he t wo sect ions have in
This technique, which required fine adjustment of the
cabinet s volum es and t uning, has a great
advant age, above all regarding t he array elem ent s
com pact dim ensions ( 240m m . high, 700m m . wide
and 600m m . deep) : in fact , it s able t o produce great
energy bet ween 80 and 400Hz, which is oft en very
poor in ot her syst em s wit h com parable dim ensions.
An advant age which is even m ore effect ive because
as it s been achieved wit h a m inim um increase in
overall cost and weight.
I n fact , t wo ext rem ely light 8 neodym ium speakers
are use in t he m id/ low sect ion in a rat her unusual
posit ion and wit h t he m agnet facing out int o t he
t uned cham ber t o ensure efficient m agnet ic circuit ry
cooling by m eans of t he vent ilat ion creat ed by t he
movement of the cone itself.
The sound em ission of t hese speakers, which are in
bandpass configurat ion, has been fed int o t wo large
front slot s at t he ext rem it ies of t he box, in such a                     The prelim inary charact erist ics for a single elem ent
way as t o be sum m ed evenly and perfect ly wit h t he                        in its standard version are as follows:
em ission of t he m id sect ion, which in t urn faces out
from t he sides of t he horn in a posit ion which is                           Operating frequency range
symmetric with the sides of the diffraction slot.                                                    80÷18000 Hz
The sect ion com prises t wo m ore 8 speakers, in t his
case in ferrit e for bet t er heat dissipat ion, since                         Nominal dispersion
t hey ve t o m ove less t han t hose already described,                                                         90° horizontal
as t hey re dam ped by a sm all rear loading volum e                           Loudspeakers
t uned t o raise t heir resonance, in order t o obt ain                              low range                  2) 8 Neodym ium
greater efficiency in the mid range reproduced by the                                mid range                  2) 8 Ferrite
two cones.                                                                           high range                 1) 3 com pression driver
                                                                                                                   - 1.41 t hroat

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                                                                      - page 12
Sensitivity 1W/1 m                                                             configured t o bet t er reproduce t he required band,
        low                      98 dB                                         from t he deepest low frequencies t o t he highest
        mid                      103 dB                                        m id/ lows, and adapt it t o t he m ost varied sound
        high                     110 dB                                        reinforcem ent       requirem ent s,      highlight ing   t he
                                                                               versatility of the entire vertical line array.
Continuous power handling - Hi- pass enabled                                   These charact erist ics alone would be sufficient t o
       low           400WAES                                                   make it a worthy match for a product such as the Hi-
       mid           400WAES                                                   Pack C.D.H. 483, but Out line, t hanks t o t he int ense
       high          120WAES                                                   act ivit y in recent years and t he result s of on- going
                                                                               experimentat ion, decided t o added a furt her useful
Continuous spl calculated - 1m                                                 det ail t o t he product : Cardioid or Hypercardioid
       Low/mid         132 dB SPL                                              dispersion.
       High            131 dB SPL                                              Designing t his t ype of enclosure for low frequencies
                                                                               cert ainly isn t exact ly som et hing new, even if
Peak spl calculated - 1m                                                       generally speaking t he t echnology necessary for
       Low/mid          138 dB SPL                                             obtaining t his dispersion has been widely applied for
       High             137 dB SPL                                             many years to microphones.
                                                                               I n fact , obt aining t his dispersion pat t ern from low
Up unt il t his point , I ve illust rat ed as sim ply as                       frequency enclosures isn t exact ly an easy j ob ( on
possible and wit h t he m ost underst andable im ages                          t his t opic, I suggest som e int erest ing reading - Ref.
t he innovat ive original t echnology t hat Out line uses                      9).
for this new product.                                                          The       dim ensions involved,        linked    wit h  large
                                                                               loudspeakers and t he relat ive boxes t o cont ain and
                                                                                 load      t hem   wit h an adequat e volum e for
 But t e r fly Low - Pa ck C.D .L. 1 8 1 5                                     reproducing low frequencies, don t allow im m ediat e
                                                                               com pact solut ions, so t hrough t im e t here haven t
From t he prelim inary charact erist ics given for t he Hi-                    been products with any real commercial success.
Pack, it s obvious t hat t he syst em m ust be used wit h                      Const ruct ion difficult ies result ing from t he reasons
a bass system matching its characteristics.                                    m ent ioned in fact inevit ably lead t o high cost s,
The Out line range has at least t wo product s t hat                           worsened by t he fact t hat for t his t ype syst em it s
could excellent ly com plem ent t he syst em , wit h                           also necessary t o use sophist icat ed elect ronics,
perform ance definit ely up t o t he sam e st andard;                          normally digital.
t hey re Vict or Live and TopSub Plus. Bot h are fit t ed                      As far as I know, t o t his day on t he professional
wit h t wo 18 w oofers in classic reflex configurat ion in                     m arket , t here are only t wo brands whose product
enclosures t hat are very com pact in spit e of t he                           ranges include low frequency enclosures wit h
reproduction high level of very low frequencies; if                            cardioid dispersion or sim ilar: one is US firm Meyer
necessary, Vict or Live can be flown for great er                              Sound Laborat ory, which m anufact ures a couple of
versatility.                                                                   self- powered m odels; t he best known and first on
Perform ance specs can be found in Out line s                                  t he pro m arket a few years ago was t he PSW- 6, in
technical documentation.                                                       which no less than six large loudspeakers are used in
I n spit e of t his, it was decided t o include in t he                        reflex configurat ion: four for front radiat ion ( t wo 18
But t erfly series a new low frequency syst em for use                         and t wo 15 ) , ot her t wo 15              speakers facing
along wit h t he Hi- Pack, sharing it s funct ionalit ies. I n                 backwards to annul rear emission.
fact , t he new syst em s box is designed and built wit h                      Declared perform ance is considerable, as usual wit h
m ult iple dim ensions as far as height is concerned                           t his brand, wit h a 143dB m axim um peak spl in half-
and it has t he sam e foot print alt hough it obviously                        space at 1 m et re, a 30÷ 125Hz operat ing frequency
doesn t have t he Hi- Pack s horn cavit y .                                    range, and net weight of 200kg. it s dim ensions are
I t has t he sam e flying hardware, which m akes it                            1083m m . ( W) , 1089m m . ( H) and 794m m ( D) : all
perfect ly com pat ible and enables it t o also be                             t his wit h a front - t o- back rat io which is on average
included in main line arrays. In multiple arrays, up to                        15dB for the stated range.
16 can be flown one above t he ot her ( if t here s                            The second m odel, also of t he cardioid t ype,
sufficient space even 24! ! ! ! ! ) for a height of                            designed and built expressly as a line array elem ent ,
approxim at ely 8 m et res and a t ot al weight of                             has four speakers ( t wo 18 for front radiat ion and
approxim at ely 700kg, which can be handled by t he                            t wo 15 t o annul rear radiat ion) and, even if m ore
flying system without any difficulty.                                          com pact and light er ( 1372m m . wide, 508m m . high,
To all effect s, it s an elem ent built wit h t he crit eria                   775mm deep and a net weight of 180kg.), it also has
necessary for form ing a real vert ical line array suit ed                     a considerable declared perform ance, wit h 140dB of
to reproducing low frequencies.                                                m axim um peak spl and sim ilar operat ing frequency
I n act ual fact , since t he syst em was designed wit h                       range (28÷100Hz).
som e special feat ures which facilit at e replacem ent of                     The t echnology used for t hese t wo product s is
t he speakers wit h ot hers wit h a sm aller diam et er                        relat ively sim ple from a physical point of view; in
t han 18 ( t he size fit t ed as st andard) , such as for                      fact , t he loading syst em used in bot h t he
exam ple 15 or even 12 speakers, and since the box                             loudspeaker sect ions, front and rear, is t he classic
has t ruly com pact dim ensions which occupy j ust t he                        phase shift set- up, com m only known as bass
space of t wo Hi- Packs one on t op of t he ot her,                            reflex , while t he elect ronic cont rol applied t o ensure
( 480m m . high, 700m m . wide and 600m m . deep) ,                            t he syst em s cardioid dispersion is com plicat ed.
wit h a net w eight of 43.5k g including it s flying                           The Meyer Sound unit was recently joined by another
hardware, t he But t erfly C.D.L. 1815 ( t he code                             brand s syst em          wit h low frequency cardioid
num ber of t he basic version) , can be easily                                 dispersion - Nexo.

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I n fact , t his French firm s product range already has
a couple of m odels: t he CD 12, which is fit t ed wit h
t wo 12 and t he brand new CD 18, which has t wo
18 .
Rather than choosing a classic method from the point
of view of t he configurat ion ( bass reflex) , t he French
m anufact urer obt ained good result s, considering t he
declared charact erist ics, from t he applicat ion of what
t o an out sider appears t o be a com plicat ed              t win
reflex       configurat ion,     also      called    high- order
bandpass , whose operat ion regarding cardioid
dispersion is necessarily cont rolled by digit al
electronics which are complex and sophisticated.
I n fact , a glance at t he syst em s shows t he presence
on t he front of t he t uning and sound em ission port s
of t he t wo cham bers foreseen by t win reflex
configurat ion,       st ressing     t hat     t his  part icular
enclosure s        direct ivit y  is     som ehow      obt ained
exclusively using digit al elect ronics; in short ,
elect ronic delay and phase shift of t he t wo individual
loudspeakers em ission. This sam e configurat ion is
also used for the CD 18.
The declared specs for t he CD 12 are 102dB ( + / -
3dB) sensitivity and 134 dB (+/ - 3dB) maximum peak
at 1m in half- space, t o obt ain t he which, m aking a
quick calculation, peak power of no less than 1,700W
is required, an operat ing frequency range from 39 t o
250Hz, a weight of 36kg, including flying hardware
and a box which is 600m m . wide, 400m m high and
754mm. deep.
Figures declared for t he CD 18 on t he ot her hand
are: m axim um sensit ivit y 105dB ( + / - 3dB) and
m axim um peak spl in half- space of no less t han
145dB ( + / - 3dB) , t o obt ain which an am plifier able t o
feed out no less t han 10,000W Peak will be
Having seen t hat t he m arket s supply of cardioid
syst em s was rat her lim it ed, Out line decided t o
design it s own Cardioid syst em for t he reproduct ion
of low frequencies.
What bet t er opport unit y t o design and build it t han
t o m at ch it wit h a vert ical line array syst em , wit h
which it has very high directivity in common?

Here s t he design of t he definit ive version of t he
Butterfly C.D.L. 1815.

                                                                               The box is built in com posit e plywood, m ainly
                                                                               manufact ured via m oulding and high frequency
                                                                               gluing. The t hickness, in spit e of what one m ight
                                                                               expect for a low frequency box, is decidedly lim it ed
                                                                               (14mm.), to keep the weight down.
                                                                               The egg shape of t he sides and t he split layout of
                                                                               t he t op and bot t om give t he box great st urdiness,
                                                                               t aking residue resonance out of t he syst em s
                                                                               operat ing range and t herefore not excitable even at
                                                                               the highest sound emission levels.
                                                                               The flying syst em enables t o vary t he reciprocal
                                                                               angle     bet ween    elem ent s and    is com plet ely
                                                                               compatible with that of the Hi- Pack, with which it has
                                                                               many mechanical parts in common.
                                                                               Up t o now I ve explained t he physical and
                                                                               m echanical     charact erist ics which   m ake it    a
                                                                               t echnically advanced product , but t hese favourable
                                                                               feat ures are com bined wit h it s cardioid or
                                                                               hypercardioid sound dispersion.

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Like all Out line product s, t he t echnique used t o
obt ain it is essent ially based on t he applicat ion of
physical and geom et rical principles t o acoust ics
rather than intensive use of electronic correction.
I personally believe t hat t he acoust ic phenom enon is
a com plet ely physical phenom enon and t herefore
before using elect ronics, every possible configurat ion
which could lead t o t he achievem ent of t he required
perform ance is pat ient ly and generally successfully
tried out for each project.
The sam e crit erion was also used for t he Low- Pack
and aft er num erous prot ot ypes, assessm ent s and
m easurem ent on t he field, a new t ype of hybrid
acoust ic loading was found, of which ( following in-
dept h search) no t race has been found in
internat ional t echnical lit erat ure regarding speaker
enclosures, in particular the special type of enclosure
for low frequencies wit h cardioid o sim ilar dispersion.                      I n it s st andard configurat ion, t he syst em uses an 18
For t his new configurat ion, a hybrid from t he                               speaker for front emission and the speaker inside the
physical point of view using a com plex com binat ion                          box, whose em ission is used t o recreat e t he required
of int eract ing m echanical bandpass and high- pass                           cardioid or hypercardioid dispersion in t he syst em , is
to load the two loudspeakers, which are in a common                            a 15 speaker. Norm alized polar response in half-
air space, I t alian and an I nt ernat ional pat ent s ( PCT)                  space obt ained from t he syst em are shown below
have been applied for, support ed by frequency                                 (valid for the horizontal plane.
response polar plots and an equivalent electric circuit                        On t he vert ical plane, t he syst em has a dispersion of
diagram which, as well as specifying t he t ype                                approximately 90°, extending from the plane the box
pat ent ed,      m akes    it s     operat ing      principle                  is st anding on t o an im aginary vert ical plane which
com prehensible, ot herwise difficult t o explain due t o                      int ersect s it perpendicularly behind t he enclosure ( in
the lack of specific publications.                                             t his case, t he cardioid dispersion is m odified by t he
To highlight t he versat ilit y t hat t he t echnology used                    plane the box is standing on, which in fact eliminates
by t he syst em offers, regarding possible variat ions,                        em ission in t he bot t om left quadrant of t he polar
in t he passband reproduced wit h t he replacem ent of                         pattern).
t he speakers, and in t he dispersion pat t ern, wit hout                      I t s wort h not ing t he uniform reduct ion of rear
any part icular elect ronic processing apart from t he                         em ission for all frequency bands involved and t he
use of a norm al delay , a funct ion included in t he                          rem arkable       front - to- back  rat io which, from a
st andard GENI US 6 cont roller, t he following acronym                        m inim um of 12 dB at 120Hz ( t he t op cut - off
has been coined:                                                               frequency suggest ed) at t enuat es t he rear em ission
                                                                               by over 15dB for all other frequency bands.
 AD LS  Adj ust m e nt          D ir e ct ivit y   Loudspe a k e r

I m port ant diagram s and designs are shown below,
including a very detailed concept diagram.

                                                                               The prelim inary charact erist ics for a single elem ent
                                                                               in its standard version are as follows:

                                                                               Operating frequency range

                                                                               Nominal dispersion            Free- field
                                                                                                               180° horizontal/vertical
The subst ant ial com plexit y from t he point of view of                      Nominal dispersion - Half- space
the elect roacoust ic circuit used is expressed wit h                                                180° horizontal
ext rem e sem plicit y from t he const ruct ion point of                                             90° vertical

Outline - via Leonardo da Vinci, 56 - 25020 Flero (Brescia) - Italy - tel. +39-030.358.1351 fax +39-030.358.0431 - www.outline.it - info@outline.it
                                                                      - page 15
                                                                               safe array flying, t hus reducing t he risk of bad
Loudspeakers                                                                   results.
      front                      1) 18 Ferrit e                                The t ools offered by t he various m anufact urers of
      rear                       1) 15 Neodym ium                              line arrays are generally developed by using classic
                                                                               spreadsheet such as Microsoft s Excel.
Sensitivity 1W/1 m                                                             This great ly lim it s t he program s graphic precision,
        Half- space              102 dB                                        not so m uch as far as t he act ual resolut ion is
                                                                               concerned, but rat her for t he level of logic/ visual
Continuous power handling capacity                    Hi- Pass                 correlat ion t hat languages born for calculat ion and
enabled                                                                        at the most for statistic graphs allow to achieve.
       front 18      1000WAES                                                  For    t his reason,       but   also  considering   t he
       rear 15       500WAES                                                   developm ent of t hese          t ools  in perspect ive,
                                                                               Out line s R&D t eam put a great deal of effort and
Continuous spl calculated - 1m                                                 work into developing and designing:
Microphone in front at 4 metres
       Half- space      132 dB SPL                                             V.I.P.         Ve ct or I m ple m e nt a t ion Pr ot ocol

Peak spl calculated - 1m                                                       The first software dedicated to a determinate product
       Half- space      138 dB SPL                                             developed        com plet ely   wit h   a   cut t ing  edge
                                                                               program m ing language using powerful Open GL
Front- to- back dB SPL ratio 1m                                                graphic libraries.
Rear microphone at 4 metres                                                    List ing all t he funct ions found in t he soft ware s Bet a
         Average         15 dB SPL                                             Version and t hose forecast for fut ure developm ent
         Passband        40÷100Hz                                              would be a hard j ob here. so I ll j ust list a few of t he
                                                                               most important and include a few screen shots:

What else can be said about the Butterfly Series?

We could probably list endless ot her im port ant
  det ails t o illust rat e it s design philosophy and t he
result s obt ained, but I t hink t he cont ent s of t his
white paper are more than sufficient.
I t is however wort hwhile giving a m ent ion t o t he
aim ing and acoust ic/ m echanical calculat ion soft ware
supplied with the system.
Everybody agrees t hat current requirem ent s as far
as perform ance and sound qualit y of a sound
reinforcement systems are concerned have increased
logarit hm ically com pared t o t hose of j ust t en years
ago, when t hey would have seem ed unat t ainable.
Mat erial t echnology, new ideas and ( why not ?) old                          Creat ion, set t ing and m anual/ aut om at ic aim ing of
ideas t hat have been updat ed t o m at ch present - day                       eight vert ical line arrays sim ult aneously, wit h t wo
const ruct ion possibilit ies, have enabled t his j um p in                    different t ypes of Hi- Pack or Low- Pack enclosures or
quality and performance.                                                       a third type which is a combination of the two.
There hasn t unfort unat ely also been a sim ilar j um p
in perform ance in t he behaviour of t hose in charge
of audio syst em s, whet her t hey re t he sound
engineers who use them or those in charge of rigging
and flying. When t his rift occurs and isn t solved, it
leads t o m ediocre or even pit iful result s regarding
t he sole aim for which a sound reinforcem ent syst em
should be used:

Ensuring audiences the maximum sound quality
t ha t  t he e nvir onm e nt a l condit ions a llow ,
w it hout ove r look ing t he a chie ve m e nt of a n
adequate sound level.

To avoid one of these environmental conditions being
left t o chance and subj ect ed t o m ist akes or lack of
experience, often the aspects with the greatest effect
on result s, m anufact urers of sophist icat ed syst em s
which are t herefore difficult t o set , such as vert ical
line arrays, have all developed so- called t ools
which, by m eans of relat ively use- friendly soft ware                        Creat ion and free posit ioning of eight different
dedicat ed t o a specific product , guides t he person in                      simultaneous list ening areas on which t he arrays
charge of inst alling t he syst em t hrough t he correct                       creat ed are t o be aim ed. The cross- sect ion and
procedure, from t he point of view of aim ing,                                 designed listening area can be seen simultaneously.
m echanical aspect s and problem s which occur for

Outline - via Leonardo da Vinci, 56 - 25020 Flero (Brescia) - Italy - tel. +39-030.358.1351 fax +39-030.358.0431 - www.outline.it - info@outline.it
                                                                      - page 16
                                                                               Tha t s a ll!

                                                                               I hope I ve m anaged t o give a sum m ary t hat suit ably
                                                                               reflect s and rewards t he recent years hard work
                                                                               carried out wit h great ent husiasm and det erm inat ion
                                                                               by Out line s R&D t eam .

                                                                               January 2003, BRESCIA, ITALY

                                                                               This docum ent s cont ent s are subj ect t o copyright
                                                                               law. Reproduct ion, even part ial, is forbidden wit hout
                                                                               the explicit authorization of the author.
                                                                               All t he brands and product s m ent ioned as exam ples
                                                                               of t he st at e of t he art are t he propert y of t heir
                                                                               respective owners.
                                                                               The charact erist ics of t he product s m ent ioned and
                                                                               t he perform ance report ed in t he t ext were t aken
Keying in dim ension param et ers of t he m iddle                              from t he original docum ent at ion published by t he
sect ion of t he surface at which each individual                              manufacturers.
element of an array or several arrays installed has to                         Information on people m ent ioned was t aken from
be aimed.                                                                      sources available for consultation by the public.

                                                                               Re fe r e nce s a nd t e chnica l bibliogr a phy quot e d
                                                                               in the text

                                                                               1)         Dr. Christian Heil CEO of L- ACOUSTICS
                                                                                          Parc de la Fontaine de Jouvence
                                                                                          91462 MARCOUSSIS
                                                                               2)         Duran Audio, Koxkampseweg 10, 5301 KK
                                                                                          Zaltbommel, The Netherlands.
                                                                               3)         James F. Novak, A Column Loudspeaker
                                                                                          with Controlled Coverage Angle. Preprint
                                                                                          260; Convention 14; October 1962
                                                                               4)         Sound Fields Radiated by Multiple Sound
A graph is enclosed with each Array supplied, with all
                                                                                          Sources Arrays
t he param et ers for flying according t o t he lim it s set
                                                                                          Heil, Christian; Urban, Marcel
by international norms on suspended load safety.
                                                                                          AES Preprint 3269; Convention 92; March
                                                                               5)         Wavefront Sculpture Technology, MARCEL
                                                                                          URBAN, CHRISTIAN HEIL, PAUL BAUMAN
                                                                                          AES Convention Paper 5488, 111th
                                                                                          Convention, New York, 2001.
                                                                               6)         Acoustical Engineering, Harry F. Olson
                                                                                          D. Van Nostrand Company, Inc., 1957.
                                                                               7)         Acoustics, Leo L. Beranek, McGraw- Hill Book
                                                                                          Company, Inc. 1954.
                                                                                          Heil Christian, US Patent N° 5,163,167
                                                                                           Sound Wave Guide
                                                                               8)         Eric Vincenot is CEO and designer with
                                                                                          NEXO SA
                                                                                          154 allée des Erables
                                                                                          ZAC de Paris Nord II
                                                                                          B.P. 50107
                                                                                          F- 95950 Roissy Cedex
                                                                                          Francois Deffarges is a collaborator and co-
                                                                                          invent or of t he Sound reproducing device
                                                                                          wit h acoust ic wave guide described in t he
Am ong m any acoust ic param et ers represent ed in                                       patent application mentioned.
report s of various t ypes, it s int erest ing t o see t he                    9)         Design of a Loudspeaker Syst em wit h a
display, in all t he posit ions of t he plane int ercept ed                               Low- Frequency       Cardiodlike    Radiat ion
by t he aim ing axis of an Array elem ent , of t he spl                                   Pattern, Boone, Marinus M., Ouwelt j es,
wit h an oct ave bargraph t aking int o considerat ion                                    Okke,     JAES Volum e 45        Num ber     9,
t he cont ribut ion of all t he array elem ent s at t hat                                 September 1997

Outline - via Leonardo da Vinci, 56 - 25020 Flero (Brescia) - Italy - tel. +39-030.358.1351 fax +39-030.358.0431 - www.outline.it - info@outline.it
                                                                      - page 17
                                                                               January 2003, Brescia, Italy

                                                                               IMPORTANT: Outline Butterfly
                                                                               m a y t h e r e for e diffe r fr om t h e
                                                                               de scr ipt ion s foun d in t h e se
                                                                               pa ge s, bu t spe cifica t ion s a n d
                                                                               features w ill a lw a ys be better
                                                                               than those indicated here.

                                                                               Please visit www.outline.it

Outline - via Leonardo da Vinci, 56 - 25020 Flero (Brescia) - Italy - tel. +39-030.358.1351 fax +39-030.358.0431 - www.outline.it - info@outline.it
                                                                      - page 18

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