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www.avantgarde-acoustic.de 1www.avantgarde-acoustic.de 1

META PICCOSPHERICAL HORN SYSTEM

The META PICCO is the second product in the META series of Avantgarde Acoustic™. The horn specialists from Lau-tertal managed to transform their eloborate spherical horn technology into a new product with significantly reduced di-mensions – the META PICCO is the smallest floor standing speaker Avantgarde Acoustic™ has ever produced. It is designed for all, to whom the shape and size of the classical hornsystems is too spacy. Now there is a hornsystem which combines the acoustical benefits of its bigger brothers with an intelligibly reduzed footprint, system height and depth.

The META PICCO is a spherical 2-way hornsystem with two active 300 mm bass drivers integrated in one single enclo-sure. For the first time Avantgarde Acoustic™ arranges the tweeter above the midrange horn. Here the reduced system size is taken into consideration to allow a controlled disper-sion on ear level heigth.

Despite its living room friendly dimensions, its sophisticated technologies position the META PICCO in the top class. Small but fine is the motto of the Lautertal company. Scaled down spherical horns and special drivers with the elabora-te OMEGA technology form the basis of this entirely new development. The midrange runs without any filter compo-nents in the signal path and the treble benefits from the pa-tented CPC technology. Bass drivers and power amplifiers correspond to the respective systems in the META PRIMO.

2 www.avantgarde-acoustic.de2 www.avantgarde-acoustic.de


SPHERICAL HORNS“We have a lot of friends who fancy the dynamics and sound quality of our horns, but who rather prefer a smaller speaker system. So when we started the PICCO project we first had to design new smaller horns” explains Holger Fromme, managing director of Avantgarde Acoustic™. The spherical horns SH5003 and SH1301 is a new developement for the compact arrangement in the en-closure of the META PICCO.

The horn curvature is based on the precise calculations of the physi-cal-mathematical requirements of spherical funnels. The typical pro-portions of the Avantgarde Acous-tic™ horn appearance have been preserved. Different to the well esta-blished 570 mm horn of the UNO, the hornmouth of the new midran-ge horn has been reduced to 500 mm diameter. At the same time the designers increased the horn throat dimensions to 75 mm.

This way Avantgarde Acoustic™ ma-naged to use bigger drivers which smoothly blend with the radiation characteristic of the META PICCO.

“Our main task with the PICCO was to achieve a perfect symbiosis bet-ween horn and driver. In order not to compromise the quality we had to compensate the smaller horn di-mensions by using a bigger and si-gnificantly stronger driver. Although the new horn is 45% smaller, we managed to get the same resolution as with our DUO system!” proudly explains Matthias Ruff the designer.

The horns are manufactured in an injection molding process using high precision steel molds.

THE MIDRANGE DRIVER“Mostly people focus on treble and bass and completely forget about the mids. But when we design a new speaker we always start with the mi-drange. The midrange is the core of any system. If you get this right you have practically done most of the job” explains Matthias Ruff, techni-cal designer of Avantgarde Acous-tic™. The META PICCO offers the same technology as Avantgarde´s flagship model TRIO. It features a sophisticated M1 omega driver with the OMEGA high impedance tech-

nology loading the new 500 mm spherical midrange horn.

“The M1 probably uses the stron-gest magnet ever being deployed in a 130 mm driver. We managed to further increase the effective ma-gnetic flow in the air-gap of the dri-ver by eliminating the usual copper inlay of the pole-piece. The roll-off at higher frequencies caused by the higher inductivity of the voice coil and a specially designed cellulose dome was set to the exact crossover point of the tweeter.” SH1301 TWEETER HORN


MIDRANGE 12 dB LOWPASS FILTER

TWEETER 12 dB HIGHPASS FILTER + LEVEL REDUCTION

4 O

HM

4 O

HM

R1

R2L1

C1

C1

L1

TYPICAL 12dB CROSSOVER

DAMPINGFACTORLOAD IMPEDANCE OF DRIVER

OUTPUT IMPEDANCE OF AMP

DAMPINGFACTORLOAD IMPEDANCE OF DRIVER

OUTPUT IMPEDANCE OF AMP + IMPEDANCE OF CABLE + IMPEDANCE OF COIL L1

��

DRIVER VOICE COIL

(4 or 18 Ω)SPEAKERCABLE

(0,36 Ω)COIL L1

(0,6 Ω)OUTPUT IMPEDANCE OF AMP

(0,04 Ω)

NORMAL SPEAKER4

(0,04 + 0,36 + 0,6) 4OMEGA SPEAKER

18

(0,04 + 0,36 + 0,6) 18 4,5 times better control !

VOICE COIL FORMER MAGNETMAGNET

CONVENTIONAL VOICE COIL

OMEGA HIGH IMPEDANCE VOICE COILwith up to 4 layers very thin wire and minimized voice coil gap

VOICE COIL GAP

POLE PIECE

POLE PIECE

OMEGA VOICE COILTo significantly improve the sound quality Avantgarde Acoustic™´s OMEGA ap-proach is based on two major concepts: simplification of the passive crossover de-sign and high impedance voice coils.

Different to conventional passive crosso-vers with six components (see graphic) the META PICCO crossover has only two components for the tweeter and no com-ponent for the midrange. Using no crosso-ver in the midrange is usually not easy due to the large overlapping of the frequency response. Using their “Controlled Dis-persion Characteristic” of the driver/horn configuration, Avantgarde Acoustic™ ef-fectively controls the output. This is how CDC works: The lower cut-off frequency of a horn loudspeaker is determined by the size of the horn. The larger the horn, the lower the response. Below the cut-off frequency of the horn, the response falls off steeply at 18 dB/octave. Avantgarde speakers thus operate only down to their cut-off frequency limit and require no high pass filters. The upper frequency response is determined by the driver. However, it can as well be influenced acoustically by the horn. For this purpose, Avantgar-de places a small chamber between the driver’s membrane and the horn throat. The driver does not emit directly but via a small air chamber into the horn throat opening. This air volume operates as a kind of band-pass filter and automatical-ly filters frequencies above the resonance volume of the chamber (at 6 dB/oct.). By choosing an adequate driver with a natu-ral roll-off at 6 dB in this frequency range, the manufactuerer obtains an acoustic at-tenuation of the frequency response of 12 dB without any passive frequency crosso-

ver. No further low pass filters are necessary! The CDC system thus causes the midrange to only operate within their operational band and steeply fall off at the transition points.

The attached graphics show the difference of conventional and the new OMEGA voice coils. To achieve very high resistance the voice coils of the OMEGA drivers are made with very long but very thin wires. Up to four windings are placed on the voice coil former. Elaborate production technology is required as the wire is so thin and easily breaks and the voice coil gap is so narrow. Now, why is the horn manufacturer taking so much ener-gy and effort to simplify the passive crosso-vers and enhancing the impedance of their voice coils?.

The key point is the damping factor. Dam-ping factor is the technical term for the abi-lity of an amplifier to control the movement of the membrane. E.g. simply speaking the force the amplifier applies to the voice coil to follow exactly the musical signal. According to common knowledge the damping factor is determined by the quotient of load impe-dance (driver) and output impedance of the amplifier.

An amplifier with an output impedance of 0,04 ohm will thus theoretically have a dam-ping factor of 100 when connected to an 4 ohm speaker. But this is a purely theoretical figure! In real life the signal has to pass a speaker cable and the passive crossover components till it reaches the voice coil. Using a typical 5m long speaker cable with an W-resistance of 0,36 ohm and a resis-

DAMPING FACTOR COMPARISON

THE OMEGA TECHNOLOGY

tance of the crossover coil of 0,6 ohm, the effective real damping factor will de-crease to a value of only 4! Connecting the same amplifier/cable configuration to the META PICCO will result in a real dam-ping factor of 18, which gives 4,5 times more control and presicion! E.g. the con-trol of the amp will increase by 450% and at the same time will reduce the negative effects of long speaker cables by 80%. As a result the OMEGA drivers have more authority, less distortions and an excellent detailled response characteristics.

The high impedance of the voice coil in OMEGA drivers can be best compa-red with the car tires. Big tires cause a higher rolling resistance but at the same time have a much better traction. Using low impedance drivers is thus like using thin tires. Adding resistance with cables and coils in the passive crossover, is in this case like using thin tires with pulled handbrake!.

Furthermore Avantgarde Acoustic™ added a powerful ALNICO magnet to this new M1 omega develop-ment. This precious magnet mate-rial generates a powerful magnetic field which homogeneously controls the movement of the voice coil.

The midrange cone of the META PRIMO is coated with trillions of tiny microfibres generating a “VELOURS DAMPING EFFECT”. According to the manufacturer, this incremental-ly small fur of the VDE technology cone effectively works in two ways. M1 ALNICO MAGNET

First it reduces partial resonances of the cone. “It is similar to a waterbed with only one chamber. Once you move it takes years till the movement of the water comes to a halt. Using multiple chambers in waterbeds will immediately calm any motion” exp-lains Matthias. “Same with our VDE drivers. Any movement of the cone itself is dampened by these micros-copic fibres”.

The second benefit of the VDE tech-nology is that it effectively absorbs high frequency distortions.


“If your listening room sounds hard you will probably use a carpet or hang up a curtain. That´s how simp-le VDE works. The irregular surface of the cone just eats up unwanted harmonic distortions.”

The generously dimensioned ALNI-CO magnetic structure of the 130 mm (5 in) cone, provides an exten-ded efficiency as well as offering very high power handling at long excursions. This way the M1 ome-ga has a very low cut-off frequency of 290 hz which allows for an inte-gration with the subwoofer without any passive crossovers. The design of the dome ensures the sound waves entering the midrange horn SH5003 are in phase and cover the required extended bandwidth.

The CDC system features a cont-rolled roll-off at 3,000 Hz and con-sequently allows the operation of the M1 omega in full range mode, without any degrading filter compo-nents in the signal path.

“When you connect your Avant-garde speaker the voice coil of the midrange driver is directly linked to your amp. No phase shifting com-ponents in between, only the spea-ker cable! You can´t get an any bet-ter direct connection.”

The M1 omega offers a neutral, silky and contoured sound reproduction across its entire frequency range. Vocals, instruments and complex signals are reproduced with speed and ease that will let you forget that you are listening to a recording.

THE TWEETERIn the treble of the META PICCO Avantgarde Acoustic™ uses a high impedance version of the H2 dri-ver of the DUO. This exceptional driver combines the smoothness of an electrostatic driver and the po-wer of a strong 1 inch horn driver. The H2omega features a voice coil former made of Kapton with a mini-mised air gap, a special geometrical shape of the 17 ohm voice coil and an ultra light diaphragm. The mere force of the 3 kg (6.5 lb) magnet on the voice coil guarantees 100% detail and precision even at low vo-lume levels, and provides the META PICCO compression-free sound reproduction at extreme sound pressure levels. With the spherical horn SH1301 the H2 omega offers an ultra wide bandwidth down to 900 Hz. Due to the passive cros-sover point being only at 3,000 Hz Avantgarde Acoustic™ achieves a seamingless smooth sound with in-credible dynamic headroom.

THE CPC CROSSOVERAlthough the M1 omega midrange driver is running full range without any crossover, the H2 omega re-quires a passive filter for thermal protection. “I would have loved to completely eliminate the crossover for the tweeter, but its physically not possible. The voice coil of the tweeter would simply melt having to cope with unfiltered bass signals” resumes the designer.

So the manufacturer was forced to research on components for passive crossovers. As with all their products Avantgarde Acoustic™ was taking a very puristic approach. Less is more is the design philosophy. H2 OMEGA TWEETER

CPC CROSSOVER BOARD

Filter output vs distortions photos of capacitorsin a high pass filter at various frequencies

CAPACITOR DISTORTIONS

“The spherical horns are so re-vealing that we had to restrict the number of parts to the absolute mi-nimum and use only highest grade components”.

A potential limitation of any passive crossover is the capacitor required to filter low frequencies. A capacitor consists of two plates or conductors. As both plates are separated by a dielectric or insulator, the conduc-tors have no direct contact but the signal is passed through a dielectric field. Every time the music signal is changing from the positive to the negative half-wave and vice versa the dielectric field gets inverted.

This permanent change of direction of the field in a capacitor - a phe-nomen called “dielectric memory effect”- causes distortions which get worse the closer the signal passes through the zero point and are at a max just when the electric field changes its direction.


MUSIC

100 VOLT LIMITER

UP CONVERTION STEPS

POLA

RISA

TIO

N V

OLT

AGE

MUSIC SIGNAL

100 VOLT

INPU

T OU

TPU

T

INPUT

OUTPUT

CPC MODULE

NORMAL CAPACITOR

CPC CAPACITOR

MUSIC

100 VOLT

Every time the music signal is changing from the positive to the negative half-wave and vice versa the dielectric field gets inverted

Non-linearity of the oszcillating electrical field caused by the dielectric memory effect

Linear modulation of the always positive electrical field due to the 100 V CPC biasof the dielectric separator

BIASED ELECTRICAL FIELD

THE CPC TECHNOLOGY

CPC UPCONVERTION OF MUSIC SIGNAL

The permanent change of direction of the field in a capacitor - a phenomen called “dielectric memory effect”- causes distor-tions which get worse the closer the signal passes through the zero point and are at a max just when the electric field changes its direction. The attached pictures show these distortions of capacitors at different frequencies.

To avoid these distortions Avantgarde Acoustic™ uses with the “Capacitor Pola-risation Circuit” an elaborate approach. Different to conventional capacitors the CPC–capacitor has multiple conduc-tor–foils connected with a special electric layout shown in the attached graphics. The CPC module up-converts the income mu-sic signal to the required voltage to bias the conductors. Only the inner conductor is biased with DC. In the CPC module a voltage cascade through a network of di-odes increases the voltage of the music signal to a multiple. This high direct cur-rent is than fed into the inner conductor. Furthermore is the diode circuit electrically decoupled through a very high impedance transformer to avoid any backlash to the music signal. Already a view moments after turning on the music the CPC module has generated the required direct current to bias the capacitor. As the CPC diode cas-cade can build-up voltages by far beyond allowable levels, Avantgarde Acoustic™ has included a protective circuit to avoid overloading the capacitor.

A solution according to Avantgarde Acoustic™ is to apply a strong force which holds the electric field in one specified direction no matter what the music signal is doing. Matthias Ruff tells about when he first got the idea of the so called “Capaci-tor Polarisation Circuit” to solve the problem:

“2004 in Athens I observed an Olympic flag. As it was only fixed on one side it was flattering in the wind. I could see the Olympic rings but they were distorted by the wave motion of the flag. If the cloth would have been stretched on both ends the rings would have been better vi-sible. The more the flag is stretched

the lesser the wind can distort the picture. You only have to make sure that the cloth is not torn apart”.

The solution was to find a way to prevent the electric field through the insulator to reverse its direction. By developing a new type of capacitor with an active polarisation circuit Avantgarde Acoustic™ claims to have solved the problem. “We de-veloped an unconventional type of capacitor with multiple conductors connected with a special electric layout. These where than used to induct a high voltage to polarize the capacitor” explains the designer. The function of the concept is fair-ly simple. The field in the dielectric

is biased with a direct current so it has a strong electric field strength in one direction. This force is far abo-ve the zero crossing point and much higher than the actual peak signal of the music. The electric field now remains in its orientation and can-not be modulated any more by the signal.

To get this theoretical principle to work, Avantgarde Acoustic™ had to overcome two problem areas. At first the designers had to make sure that the induced direct current does not reach the speaker. DC would heat up and likely destroy the voice coil. “Our capacitor is constructed in a special way. Instead of only two


plates we use multiple conductor foils. Only the inner conductor is bi-ased with DC. This way no current can leak”.

Having executed numerous test and listening sessions Avantgarde Acoustic™ verified that whenever the polarisation current was dupli-cated the distortions decreased and an audible improvement could be heard. This means that ideally the polarisation current should be as high as possible and is only limited by the load capacity of the capa-citor.

Now the task of the designers was to find a simple way of providing the required direct current. Using an external power supply would not have been practical and batteries were excluded as they did not pro-vide a high enough voltage. Instead Avantgarde Acoustic™ uses its pas-sive CPC board (Capacitor Pola-risation Circuit; patent pend.). As the music signal is providing the re-quired electrical energy to drive the CPC module no additional power supply is needed. The CPC module now automatically up-converts the income signal to the required volta-ge to bias the conductors.

A CPC biased capacitor has less distortions and can more precisely handle incremental signal variati-ons. “The effect of CPC is amazing. When executing our AB compari-sons, we could immediately hear the difference. There is much more detail and I thought the treble level has been increased. But at the same time the sound got much sweeter. Subtle nuances are totally detached to project lifelike aura of spaces and instruments” raves Armin Krauss, customer support manager of Avantgarde Acoustic™.

THE ACTIVE SUBWOOFERIn the bass of the META PICCO Avantgarde Acoustic™ melts the prooven technology of the SUB225 subwoofer with the drivers and po-wer amplifiers of the META PRIMO. As the META PICCO subwoofer does not have a horn flare, the AD-RIC compensation circuit has being replaced by an active REAL-TIME controller. This REAL-TIME control-ler compensates deviations of sig-

12X600 BASS DRIVER


nal and driver movement and line-arizes the low frequencies down to 18 Hz. Although the volume of the META PICCO enclosure is relatively small for two 12 inch drivers of this caliber, the Avantgarde Acoustic™ REAL-TIME controller ensures preci-sion and low frequency extension.

“Our active REAL-TIME controlled systems are superior to any pas-sive subwoofer on the market. Be-sides the linearity of its frequency response and the lower frequency extension, the major benefit is the compensation of all mass related deviations from the input signal throughout all volume levels.” ex-plains Matthias Ruff. According to the designer the inertia of the heavy bass membranes is the cause for problems all passive speakers are facing. When not beeing in motion inertia is the force which opposes the acceleration of the membrane. “Typically passive speakers have no bass when driven at low volumes! Only when turning up the volume the heavy membranes start moving and only than bass becomes au-dible”. Different to this, when be-eing in motion inertia is the force which opposes the deceleration of the membrane. “Passive speakers have a certain volume level they are confinient with. First they have no bass and when you play louder they become ok. But if you than further increase the volume level they will start sounding boomy. That´s phy-sics and there is nothing you can do against in a passive system.”

For these reasons Avantgarde Acoustic uses its REAL-TIME cont-roller to compensate the inertia of its bass membranes. The controller always compares the accelaration of the driver with the input signal. At low volumes the circuit detects that the driver is not start moving as it should and increases the inphase signal strength. At high volumes it detects that the membrane wants to continue moving although it should stop. The electronic increases the opposing electronic forces.

“Our REAL-TIME controller signifi-cantly increases the dynamic win-dow of our speakers. From very low volumes to very high volumes the speaker will not loose its tonal

AMPLIFIER BOARD REAR VIEW


balance. Turn the PICCO to back-ground volume, listen and you un-derstand what I mean” raves Holger Fromme.

The bass of the META PICCO is dri-ven by two 30 cm (12 inch) long-excursion 12X600 drivers with each 600 watt RMS power capacity. The paper membrane combines stiffness and acoustical neutrality with low mass. The 4 inch voice coil of the 12X600 provides a powerful drive with high thermal handling capabi-lities. The 230 mm magnet with a weight of 9 kg generates a BL factor of 20 N/A.

Each speaker is equipped with its own REAL TIME power module. The active modules are connected through line or speaker level con-nections. The input level attenua-tor adjusts the volume between the bass and the spherical midrange and tweeter horns. The crossover frequency range can be shifted to

12X600 BASS DRIVER

three zones and fine adjusted with a attentuator. The low frequency re-sponse can be set with a 3-position subsonic switch. The system can be remotely switched on/off using the 12V trigger signal of AV amps.

Each of the two powerful twin amps have 2 x 250 watts and are powered by a mechanical decoupled 540 VA toroidal transformer buffered with 80.000 uF capacitance. The ela-borate mechanical mounting with four buffers completely decouples the power transformer from the heat sink and thus inhibits induced vibrations. The total of 1.000 watt of integrated amplifier power in the META PICCO provides sufficient re-serves and headroom.

THE PRODUCT DESIGNAs with the META PRIMO zed., the renowned Swiss designstudio around designer Tobias Adami and Hannes Wettstein account for the product design of the META PIC-

MECHANICAL DECOUPLING OF THE 540 VA TRANSFORMER

AMPLIFIER BOARD

CO. The slightly recessed profile of the cabinet in exclusive wood finish with its tender rear section gives re-miniscence to the bigger META PRI-MO but at the same time continues the heritage of the characteristic tripod concept of the existing PRO-LINE series. The driver front panel is visually detached from the wooden cabinet by a subtle 6 mm shadow gap. “With this small gap the horns seem to float in a frame build by the cabinet. It puts the spherical horns elegantly in scene.”

“As a horn is something of everlas-ting value, we purposely refused to follow fashion and trends.” finalizes Hannes Wettstein his philospohy.

“In the design of the PICCO the lust of sounds and luxury explores a visual and content-related minima-lism. A lean style combined with a nearly exaggerated composition of small detail visualizes the quality of the technology inside.”


SYSTEM DATA

Frequency response – Bass 18 — 350 Hz

Power handling 70 Watt

Sensitivity (1W/1m) > 106 dB

Crossover frequencies 300 / 3.000 Hz

Nominal impedance 18 Ohm

Recommended amplification > 15 Watt

Recommended room size > 16 qm

CDC yes

HORN spherical Horn 180°

Diameter Midrange 500 mm

Tweeter 130 mm

Horn-length Midrange 280 mm

Tweeter 60 mm

Horn-area Midrange 0,196 qm

Tweeter 0,013 qm

Diameter driver Midrange 130 mm

Tweeter 1 Zoll

BASS DRIVER 2 drivers per channel

Power handling - RMS 600 Watt

Nominal diameter 300 mm

Voice coil diameter 100 mm

Magnet diameter 228 mm

Magnet weight 10 kg

VERSTÄRKERMODUL 1 modules per channel

Amplifier power output - RMS 2 x 250 Watt

Power supply 80.000 µF

High quality toroidal transformer 540 VA

Active crossover variable, 60 — 350 Hz

Subsonic filter, 3-position 20 — 30 — 40 Hz

Audio transformer yes

SoftStart circuit yes

REAL TIME control yes

ADRIC-compensation —Low and high level inputs selectable

12V remote ON/OFF integrated

DIMENSIONS / WEIGHT

Dimensions (per speaker) Width 500 mm

Depth 560 mm

Height 1.255 mm

Weight (per speaker) 85 kg

SPECIFICATIONS

HIGH ENDDESIGN AWARD

ACCADEMIA

dell´ AUDIO

Avantgarde Acoustic™ GmbHNibelungenstr. 349

D–64686 Lautertal / Germany

Tel: +49 (0) 6254/306-100Fax: +49 (0) 6254/306-109

email: [email protected]

spherical horn system - jazz-audiojazz-audio.com/pdf/equipos/picco_0_117.pdf · dance (driver) and...

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