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Outline System “E.T.”Electronically controlled dispersion measurement turntable

System componentsSystem propertiesNew featuresMake-up of the basic system InstallationManual controlControl via the “ET Commander”Examples of system useExample 1: Polar measurements - 1 axisExample 2: Polar measurements - 2 axesExample 3: Polar measurements of MicrophonesExample 4: Listening testsSome referencesTechnical specifications

Outline “E.T.” system components

The system comprises:

• ET 2Electronic Controller

• ST 2Turntable

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Outline ET2-ST2: Electronically controlleddispersion measurement turntable

Properties of the Outline “E.T.” system

Outline “E.T.” is a manual or automatic rotation system for carrying out dispersion measurements.

Outline “E.T.” can be interfaced with all analog measurement systems, in both manual mode and automatic mode, using the sophisticated Outline ET Commander software, which controls all its movements.

Since it emits and receives TTL sync pulses, Outline “E.T.” can be directly interfaced with computerized measurement systems which recognise or generate this TTL pulse (LinearX LMS®, DRA MLSSA®, GoldLine TEF 20®, Audiomatica Clio®, etc.), as well as with others, by means of the ET Commander software in a Windows® (95, 98, NT) multitasking system.

These possibilities make the Outline “E.T.” system unique for use in research labs in which several sound reproduction or measurement systems have to be moved simultaneously.


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An Outline “E.T.” system allows to control the rotation of one or more turntables. It's thus possible to carry out acoustic measurements on loudspeaker systems and obtain dispersion graphs.


The 2D polar diagram shown alongside was drawn using an LMS® system: it shows the SPL response values of a speaker enclosure measured at 500, 800,1K, 2K e 4K,10K Hz, while carrying out four complete rotations in 5° steps.


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This 3D diagram was drawn using an MLSSA® system: it shows the SPL response curves of a speaker enclosure (freq. between 200 and 20kHz) +/- 180° as a function of the angle of rotation referred to the measurement “Z” axis (0°).

Properties of the Outline “E.T.” systemOutline ET2-ST2: Electronically controlled

dispersion measurement turntable

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This diagram shows the polar response of a microphone plotted in an anechoic chamber using a calibrated wide-band source and rotating the microphone as indicated in the example alongside.


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New features introduced

“ET 2” is completely controllable via Personal Computer by means of the Outline “ET Commander” program.

“ET 2” can control TWO “ST 2” (*) turntables: the first (Master) rotates clockwise, whereas the second (Slave) rotates counterclockwise.

The Outline “ET Commander” program can control up to TWO ET 2 units, driving two ST 2 (*) turntables, which can therefore rotate separately and freely (plus other two “slave” turntables).

With “ET Commander”, the turntable can be rotated in both directions (clockwise or counterclockwise), in either automatic or manual mode.

“ST2” now can rotate also a suspended load up to 100 Kg. with 30 Kg. of twisting moment, thanks to a 20% more powerful motor with stamped steel gear.

(*) The second ST 2 unit is optional

After the success of the first version of the ET1-ST1 turntables, Outline modified the ET 1 control unit, now called “ET 2”, with the following upgrades, in between ST1 was improved mechanically and named ST2:


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The basic system of Outline “E.T.” comprises:

10m. cable (DB9 – Micro) for connecting the ET 2 and ST 2

Make-up of the basic system

The equipment is completed by:

1 220V power cord for ET 2 10 - 10MA hexagon socket screws

for fixing the ST 2 to the dedicated hardware or optional “STAND-ST2” stand.

1 - 8mm hexagon key.

1 “ET 2” electronic controller

1 “ST 2” turntable

1 “ET Commander” software for controlling the system via PC with Microsoft Windows®.

1.8m. cable (DB9M – DB25M) for connecting the ET 2 to the PC LPT

0.5m. cable with one DB9F (for connection to the measurement cards' TTL output).


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The DB9/F connector of the 10 m. multipole cable (supplied as standard) must be connected to the “Turntable” DB9/M connector on the rear of the ET 2.

The other end of the cable must be connected to the connector on the ST2

Installation – Connecting the ET 2 to the ST 2

First turntable

Rear of the ET 2


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Installation – Connecting a SECOND ST2 UNIT

With ET 2, two ST 2 units can be controlled:

The DB9/F connector of the 10m. multipole cable (supplied as standard) of the SECOND ST2 unit must be connected to the “Turntable (Reverse Slave)” DB9/M connector on the front panel of the ET 2.

The other end of the cable must be connected to the connector on the ST 2.

The second ST2 unit will be in sync with the first, but will rotate in the opposite direction (slave conditions).

“ET Commander” can control two ST2 units independently (plus two slaves more), but in this case, two ET 2 units must be used.

Second turntable

Front of the ET 2


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Installation - Connecting the ET 2 to a P.C.with “ET Commander”

Connect the DB9/DB25 cable (supplied as standard) to the parallel port of the Personal Computer and the “Computer Parallel Port” DB9F connector on the front panel of the ET 2 unit:

When initiated, “ET Commander” runs a test of the ST2 turntable's status, returning it to the 0° (zero degrees) position.

The new ET 2 control unit is fully controllable via Personal Computer thanks to Outline's “ET Commander” software: Personal Computer

LPT


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Installation - Connecting the ET 2 to the Measurement Card

To synchronize the movement of the ST 2 unit, using the TTL output of the measurement card used, connect the DB9M connector of the 0.5m. cable supplied as standard to the “Computer” connector on the rear panel of the ET2. The cable's conductors (centre and ground) must be connected to the TTL output signal PIN and the earth of the measurement card respectively.

a second ST 2 turntable is connected, it will also be synchronised with the first by means of the TTL pulse generated by the audio card, but will rotate counterclockwise.

Once the required angular movement is finished, the ET 2 unit generates another TTL pulse (with the required delay setted by the user) to communicate the audio card that it can begin a new measurement.

Rear of the ET 2

The cable supplied with just one DB9 is for permanent connection to the measurement system. For example, with LinearX LMS, it will be soldered directly to the DB15 connector. For DRA MLSSA on the other hand, an (optional) normal DB9-DB9 cable must be used.


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Manual control – ET 2 controls:“Switch on”, “Reset” and “TTL Output Delay”

The “RESET” button on the ET 2's front panel returns the ST 2 to a position of zero degrees (0°).

The “TTL OUTPUT TIME ADJ” trimmer on the ET 2's front panel is used to adjust the running time of the measurement cycles by introducing a delay in sending the TTL pulse, which can be set between 3 and 25 seconds. It can be used where the measuring program (for example MLSSA®), provides for the continuation of measurement after a pulse is received from the ET 2 control unit.

This switch switches on the ET 2 and powers the ST 2


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Manual control – ET 2 controls:“Deg Step”, LED and “Manual” buttons

The “DEG STEP” selector on ET 2's front panel is used to select the step (in degrees) of the movement which ST 2 will carry out for each pulse received via automatic command from a measurement card. This selector is only used for the automatic control of the turntable by a measurement card (connected to the “COMPUTER” connector on the rear panel). If ET Commander is used, the position of this selector is unimportant.

The two buttons under “MANUAL” are used to manually turn the ST 2 counterclockwise (COUNTER/ CW) or clockwise (CLOCK WISE)

The two LEDs under the “AUTO” printing indicate the direction of rotation of the ST 2 (COUNTER/CW - CLOCKWISE) in both Manual and Automatic mode. This is useful when ST 2 can't be seen directly from the measurement position.


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Manual movement is carried out using the control buttons on the ET 2's panel or the Outline “ET Commander” software's “virtual" buttons.

Manual control – Rotation

ST 2 turntable rotation can be controlled either manually or automatically.

Automatic movement is carried out with the custom “macro” controls available using Outline “ET Commander” software.

Automatic movement is also carried out with “macro” controls created “ad hoc” or already available in the measurement software controlling TTL pulses on input and/or output, such as LMS, MLSSA, TEF 20 or Clio.


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The ”ET Commander” control panel gives a complete display of all the functions available on ET 2.

This is the screen seen by a user with just one ET 2 unit connected.

Control with “ET Commander”


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Selection of Manual or Automatic controlwith “ET Commander”

This button shows the selection enabled: “Manual”, “Timer”, “External” or “Internal”. Clicking on it, the “Start Control Mode” screen appears to enable the required option to be selected.

Manual: manual mode

Timer: rotation according to the interval of time set between the ST2's movements.

External: the turntable rotates when an external TTL pulse is received on the “Computer Parallel Port” connector on the ET 2's front panel.

Internal: the turntable is rotated by a TTL pulse received on the PC's parallel port.


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The ”ET Commander” control panel give a complete display of all the functions available on ET 2.

Manual control with “ET Commander”

A Manual movement is set here: pressing “Start”, the turntable carries out a movement equal to the degrees selected.

This part displays ST2's position (in degrees) and the two LEDs indicate the direction of movement.

This button runs a turntable status test.

Pressing this button returns the turntable to the Zero (0°) position.


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Automatic control via “ET Commander”

The Macros are set here by keying in the (negative or positive) "step" for rotation in automatic mode.

One of the 10 letters available (from A to J) is selected, the required angle is set with the arrows and confirmed by clicking the “Insert” button.

Pressing “Start” starts the macro sequence run from “A” to the last letter set: the ST 2 turntable carries out a movement equal to the angular step set.

For example, it's possible to set a 10° step on A, 340° on B: in this case, ST 2 moves in a clockwise direction from 0° to 10°, then goes back to the 340° position (-10°).

The command varies according to what has been set with the “Start Mode” button.

The “step” for the complete rotation in Automatic mode is set here: when “Start” is pressed, the turntable rotates through 360° with the selected steps.


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Control of 2 ET 2 units via “ET Commander”

This is the screen seen by users with two ET 2 units connected to an ET Commander.

The On/Off buttons for units A and B are used to enable or disable them.

The Outline “ET Commander” program can control up to TWO ET 2 units, driving two ST2 (*) turntables, which can therefore rotate separately and freely (plus other two “slave” turntables).

When the button is clicked, the writing on it changes from “On” to “Off” and vice versa.


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Examples of use of the Outline “E.T.” systemThe “E.T.” system has been designed and built to carry out polar response measurements on loudspeaker systems, but can also be efficiently used for all applications requiring a sophisticated computer-controlled turntable system.


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Example 1: Polar measurements - 1 axis – 2D

Other Polar Plots with different appearances but the same results can be obtained with the following measurement systems (among the best known):

DRA MLSSA®

Techron TEF 20®

Audiomatica Clio®

Example of 2D Polar Plot obtained with LinearX LMS4®

This system allows to obtain 2D Polar plots(just one axis per set of measurements)


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Setup for Polar measurements - 1 axis: example of hardware

One stand with adjustable height regolabile

One adjustable microphone stand

ST 2

Adjustable stand

Microphone

Adjustable stand

As well as the Outline “ET 2 – ST 2” set, the following are required:

System under measurement


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In this way, the polar response of the speaker enclosure on the horizontal plane is obtained:

Position the speaker enclosure's acoustic emission centre on the axis of rotation of the ST 2 and the measurement microphone perpendicular to the speaker enclosure's acoustic centre.

Carry out a set of SPL response measurements until the required rotation is achieved.

Polar measurements:1 axis – Horizontal plane of the speaker enclosure


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In this way, the polar response of the speaker enclosure on the vertical plane is obtained:

Carry out the same procedure as for “1 horizontal axis” measurement, with the speaker enclosure turned through 90° on its emission axis.

Polar Measurements:1 axis – Vertical plane of the speaker enclosure


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Using two ST 2 turntables (one rotating the speaker enclosure and the other the microphone), it's possible to obtain measurements for drawing up 3D Polar Plots.

With “n” rotations of 360° of the speaker enclosure equal to “n” movements of the microphone from 0° to 90°, a 3D polar plot relative to a hemisphere (2 steradians) can be obtained.

Example 2: Polar Measurements – 2 axes – 3D This system enables 3D polar plots to be obtained (two axes per set of

measurements) in the shortest possible time and taking the smallest number of measurements.


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By means of dedicated simple hardware (built “ad hoc”), such as that shown in this example, any type of speaker enclosure can be positioned, maintaining the emission axis perpendicular to the centre of rotation.

Setup for Polar M. – 2 axes – 3D: Hardware example for speaker enclosure

The arms shown here, which can be freely moved, are bolted to the top holes of the ST 2

The lower circular section, which serves as a rotation support for the arms, is bolted to the bottom of the ST 2 and will in turn be fixed (for example) to the walkway grating of an anechoic chamber, or simply place on an absorbent floor for the measurements in 2 str.

The components shown can be built using normal steel tubing, easily found anywhere.


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Example of dedicated hardware for the second ST 2 base for rotating a microphone.

Setup for Polar M. – 2 axes – 3D: Hardware example for microphone.


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Example of a set-up in an anechoic chamber for a system with two ET 2 and two ST 2 turntables: to carry out this type of measurement, the speaker enclosure must be positioned with its horizontal emission axis turned through 90°, i.e. laid on its side.

Setup for Polar M. – 2 axes – 3D: Example of set-up in an anechoic

chamber

The component being measured in this case is the top horn of the speaker enclosure, whose emission axis is perpendicular to the axis of rotation and coincides with that of the microphone.

All supports will be covered with soundproofing material to avoid reflections

Anechoic conesSecond ST 2

First ST 2Microphone

Grilled flooring

If a measurement in 2 ster. has to be carried out, it's obviously possible to repeat the same “sketch” in a free field with the system laid on the floor.

Grilled flooring


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First measurement on the chosen emission axis:speaker enclosure and microphone both positioned at 0°

Polar Measurements – 2 axes – 3D: Step 1

The microphone remains positioned at 0° while the speaker enclosure carries out a complete rotation (355°) with 5° steps (or multiples thereof).


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Polar Measurements – 2 axes – 3D: Step 2The speaker enclosure carries out a complete rotation for each microphone

angulation: here it has already carried out a rotation of 330° with 5° steps, whereas the microphone remains positioned at 0°.

The last measurement at 0° on the Horizontal axis finishes with the speaker enclosure positioned at 355° (if a 5° step is selected).

When the speaker enclosure returns to position 0°, the microphone turns through 5° (clockwise) and the measurement sequence starts again with a second complete rotation.


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In this example, the speaker enclosure has already carried out two complete rotations (in 5° steps) and is in position 330°, whereas the microphone has moved 5° three times.

Measurements Polar – 2 axes – 3D: Step 3

The last measurement for preparing a 3D polar plot is taken when the microphone is in the vertical position (90°) and the speaker enclosure has reached position 355°.


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The polar plot of the complete sphere can be prepared by using the measurement system software to calculate a “Mirror” of the hemisphere obtained.

Polar measurements – 2 axes – 3D: result

Mirror

Every computerized measurement system generally has its own programming language. The routine for carrying out the necessary calculation will be prepared using this language.

It is however possible to create a simple data conversion program, no matter what the measurement system.


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Example 3: Polar measurements of microphones This system can be used to prepare a 2D polar plot of a microphone.

According to the type of microphone being measured, its acoustic centre (the capsule) will be perpendicular to or coincident with the ST2 turntable's rotation axis.

With additional equipment (to rotate the microphone on the other plane) and suitable interpolation software, a 3D plot can be prepared.

Anechoic cones

Grilled flooring

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Example 4: Using ET 2 with two ST 2 for listening to musicTaking advantage of the possibility of controlling two ST 2 (one of which is

counter-rotating), tests can be run to find the best stereo image.

For example, Hi-Fi stores continually carrying out demos of various types of loudspeakers enclosures can experiment directly from the comfort of a demo room chair, and hear (in real time) the change that take place in the stereo image when the loudspeaker enclosures' reciprocal angle is changed.


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Example 4 - Enclosures in position 0° The emission axes of the two enclosures are perpendicular to the plane of

the listening point.


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Example 4 - Enclosures in position X1 The emission axis of speaker “L” is rotated by –(X°) in relation to the

listening point. The emission axis of speaker “R” is rotated by +(X°) in relation to the

listening point.


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Example 4 - Enclosures in position X2 Loudspeaker enclosure's “L”'s emission axis is now rotated by –(X1°+X°). Loudspeaker enclosure “R”'s emission axis is now rotated by +(X1°+X°).

With ET Commander, the movement of the two turntables can be freely inverted (however, one of them is always a “slave”).


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Outline “E.T.” SystemOutline ET2-ST2: Electronically controlled

dispersion measurement turntable

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AKG Acoustics - Austria

AUDIOMATICA – Italy

AURA Systems – USA

BOSE Corporation – USA

CARVER Corporation – USA

CELESTION – England

CHALMERS University of Technology – Sweden

COMMUNITY Professional – USA

CROWN International – USA

DRA Labs – USA

EVI Audio – Germany

GENELEC – Finland

HARMAN Motive – USA

HELSINKY University of Technology- Finland

KEF – England

INFINITY Systems – USA

KLIPSCH Professional

KRELL Industries – USA

LinearX Systems – USA

LUCASFILM THX – USA

MACKIE Designs – USA

MILLER & KREISEL – USA

MUNRO Associates – England

NEXO – France

NOKIA Research Center

PEAVEY Electronics – USA

PIONEER Electronics – USA

RCF - Italy

ROCKFORD Acoustic – USA

SAN JOSE’ State University - USA

SIEMENS Hearing Instruments – USA

STAGE ACCOMPANY - Holland

Synergetic Audio Concepts – USA

TURBOSOUND – England

USA Distributor:Old Colony Sound Laboratories (Audio Amateur Group)

Some references:

Technical specifications of the Outline “E.T.” System

Power requirements: 110/220 VCA 50/60Hz mains socket with fuse and voltage changer.

12/20 VCC XLR connectors; internal short-circuit and inverted polarity protection circuit

Max rotation speed: 200 msec/degree

Precision: ± 0.25°

Control system: optical position sensor

Input/output connectors: 9-pole sockets (DB9)

Input pulse: TTL (from 5 to 12 VCC) imp. 680 Ohms

Output pulse: TTL with delay variable from 3 to 25sec.

Pulse length 0.5 sec.

Rotation angle: variable from 2.5° to 22.5° in minimum 2.5° steps

Automatic reset button

ST 2 maximum load admitted: stacked 300kg., appended 100 Kg., twisting moment 30 Kg.

ET 2 dimensions: 1 x 19” E.I.A. unit standard Rack x 125mm. depth

ST 2 dimensions: diameter 35 cm. - height 10 cm.


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presents: outline system “e.t.” electronically controlled dispersion measurement turntable ...

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