Antonio Paoluzi

L'arte Del Suono

The Z’Ester : The new way in testing loudspeakers

The Z-Ester

AST – Advanced Speaker Testing System

 

The Z-Ester is a device designed for verifying the correct operation of a loudspeaker,  a great aid for checking the efficiency of passive elements of a multi-way PA system. In particular is a one-piece tool that can be connected directly to the speaker without the need of external electronics and is designed especially for the on-site work.

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It appens so often to check a series of speakers before they are set up, or the need to test a system that is already hanged but no power supply to turn the amps on. Zester is the fastest and most accurate way to check speakers and power lines, and find out any failure in real time.

The only way to know if a speaker behaves the same way as another is to measure, and compare, the impedance curves. Until now, the normal field test is performed with almost Diy instruments such as improbable tone generators or, at the best, electrical resistance meters. Even in the case of a complete system check, we often rely on the ears: “you can hear pink, so it works” ….

But is not always the best way…

Operation is very easy: the instrument is connected to the speaker with a speakon cable, via bluetooth the device connects to the Android device running its App, and the test button is pressed on the touch screen. The instrument emits a sweep and records the impedance trend. The curve is displayed and can be stored for comparison with another speaker measurement.

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The Main Window

In the main window all the operating functions can be found, the windows of the impedance curves and all the needed buttons.

Let’s see the meaning of the functions in blocks.

 

Right hand section – Test and memories


TEST – Starts the test on the selected ways and stores the curves in the “LIVE” memory

Mem 1-6 – Memories where the curves are stored, to be compared with the LIVE

LIVE – The curve of the last test performed

STORE – Stores the curves in the selected memory. One of the Mems is chosen and Store is pressed. LIVE curve is now stored in the selected Mem

Reset ALL – Deletes all stored curves

 

Bottom left section – Graphics options

Zoom +/- – Allows to enlarge or reduce the vertical dimension of the curves

Smooth +/- – Adjusts the accuracy of the curve

Black / White – Background color of the impedance windows

Default view -Restores Zoom and Smooth values to default values

 

Bottom center section – Operating mode selection

4Way – 4 way mode, the test is executed on all four ways of the Speakon 8

2Way 1-2 – 2-way mode, the test is executed in sequence on ways 1 and 2. This mode is valid for Speakon 8 and Speakon 4 connections

2Way 3-4 – 2-way mode, the test is executed in sequence on ways 3 and 4. This mode is valid only for Speakon 8 connections

W1 – Test only on way 1, Valid for Speakon 8 and Speakon 4 connections

W2 – Test only on way 2, Valid for Speakon 8 and Speakon 4 connections

W3 -Test only on way 3, Valid only for Speakon 8 connections

W4 -Test only on way 4, Valid only for Speakon 8 connections

| Z | / Delta Z – Switches from the normal display mode of the impedance module to the display of its derivative. Useful to compare multiple speakers in parallel with similar characteristics

Utils – Go to the Utilities screen

 

Testing Operation

In the main window select the operating mode, in the example above 1Way mode on Way n1, and press TEST. The test runs and the LIVE curve is displayed. Choose a a Mem on the right and press STORE. Connect another speaker and TEST it. The two curves belonging to the selected memory and the LIVE, just obtained with the test, are displayed in the graph window. If the curves overlap, the test is positive and the speakers can be considered the same type with similar performances, withtin some tolerance, and the result in the lower right will show “GOOD”. However, if the curves are very different from each other, the test result will be “FAIL !!!” and we know that we face a problem.

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In the window can also be found some other useful information:

DC – indicates the electrical resistance in continuous, the same that we would measure with a normal multimeter

@ 1KHz – indicates the impedance at 1000 Hz, the value that is roughly referred to as the “nominal impedance”

Max Dev – is the maximum deviation measured at the frequency shown next to it

By swiping your finger on the graph you can read the impedance value at the various frequencies.

 

The UTILITIES Window

In the Utilities window there are some useful informations and some basic commands

QUIT – Exits the software

Conn BT – Set the connection with the device. When the software is started and the device is turned on, the connection is normally established automatically and the first window that appears is the main one. However, sometimes the response times of the Bluetooth are longer and the connection is not established correctly on time. In this case the first window that appears is Utilities, where Bluetooth can be connected manually.

Disc BT – Disconnects the Bluetooth connection.

Calib – Performs a calibration of the sensor reading parameters. Normally it is not necessary to manually calibrate, because the calibration is performed automatically before each reading.

SPK Check – Go to the main screen.

Batt – Battery charge value

The FILES Window

This window contains the commands to handle files, saving and loading.

On the left appears the list of files already saved in the Android device. The files are stored in a folder called “Zester Files”, in the documents folder of the Android archive.

On the right are shown the memories currently stored.

When a memory is selected, in this case the blue memory n.3, the preview of the curves contained in the memory appears immediately. Pressing the green button “Save mem” the keyboard pops up and allows to name the file.

If one of the files on the left is selected, a preview of the contents of the file appears and the load button changes to “LOAD”. Pressing the button loads the file into the selected memory location

Selecting a file and pressing DELETE the file is permanently deleted from the device.

With the “SETUP Save” button you go to the window where save and load the Setups, the set of all system settings and memories.

 

Quick Start Guide

First to do is download and install the Zester application on your Android device. Download it at this link

https://drive.google.com/file/d/18a0uqPCxMZIHAQClAO1Ellka6V38yZOc/view?usp=sharing

Your phone or tablet will ask you what to do with the file, click on install packages and then it will ask you if you want to install the application. Go ahead and the software will be installed.

Of course, you must give to the app the permission to use Bluetooth if asked.

Another critical step is to authorize the app to access the internal memory, otherwise saving the files will not work and the software will crash. To do this, go to Settings / Applications / Zester and check “memory” on the permissions page.

You are almost there.

The last step is to pair the bluetooth. You turn on the device, go to Settings / Bluetooth and scan. Something will appear with the name “H3” or “HC06”.

Perform pairing using the password “1234”.

That’s it. Have a good checking.

 

The Front Panel

zester pannello

 

Performing the TEST

In the main window select the operating mode, in the example above W1 mode on Way n1, and press TEST. The test runs and the LIVE curve is displayed. Choose a a Mem on the right and press STORE. Connect another speaker and TEST it. The two curves, the selected memory and the LIVE just obtained with the test, are displayed in the graph window. If the curves overlap, the test is positive and the speakers can be considered the same type with similar performances, withtin some tolerance, and the result in the lower right will show “GOOD”, while if the curves are very different from each other, the test result will turn on “FAIL !!!” and we know that we are facing a problem.

The picture shows one Speaker compared with two of the same model in parallel. The impedances look the same but the curves are shifted.

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In the window you can also find other useful information:

DC – the value of the electrical resistance in continuous, the same that we would measure with a normal multimeter

@ 1KHz – indicates the impedance at 1000 Hz, the value roughly called as the “nominal impedance”

Max Dev – is the maximum deviation measured at the frequency shown next to it

By swiping your finger on the graph you can read the impedance value at the various frequencies.

In this 2 way test the impedance match on both ways. The speakers look fairly similar. The test is good.

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In this test something goes wrong. The way 1 looks quite similar, but the way 2 is completely different. This speaker is failed on the driver section.

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