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Polar Plot (MDT-4000 Turntable) Sequence

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This sequence measures the polar response of a loudspeaker in both the vertical and horizontal dimensions. It is designed to work with the Portland Tool & Die MDT-4000 turntable, and has all the necessary commands to automatically rotate it via RS-232. The sequence uses a log sweep stimulus with the Time Selective Response algorithm so that the measurements can be run in a non-anechoic environment. Note that the time window needs to be adapted to the user’s measurement space.

The sequence plays the stimulus and measures at 10 degree increments from 0 to 180 degrees. This process is repeated with the speaker positioned horizontally. The two results are mirrored to display full 360 degree polar plots for each axis. A directivity index curve is also calculated for each axis and is displayed at the end of the test.

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Loose Particles Sequence

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This sequence demonstrates how to use SoundCheck to detect loose particle defects in loudspeakers. Loose particles typically reveal themselves as randomly spaced impulses, so they may not be detected when performing frequency based measurements such as THD, even though they can be clearly heard as undesirable artifacts. The loose particle algorithm, which is an available function in all analysis algorithms, analyzes a time waveform to detect these impulses. The user sets a customized threshold level for detection.

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Complete Test Sequence

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The purpose of this sequence is to perform a full suite of basic measurements for a loudspeaker. A 500 mV stepped sine sweep from 20 kHz to 50 Hz is played through the speaker and measured via two channels of the audio interface. A calibrated reference microphone is connected to one of the channels, and an impedance reference is connected to the other.

A HarmonicTrak™ analysis step analyzes the recorded waveform from the reference microphone, and outputs frequency response, THD, Rub & Buzz, and various harmonic curves. A second analysis step analyzes the waveform from the impedance reference and outputs a curve of impedance versus frequency. A post processing step is used to estimate the characteristics of the impedance curve and calculates the max impedance, resonance frequency, and the Q of the resonance peak.

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Measuring Loudspeaker Maximum Linear Sound Levels Using Noise to the AES75-2022 Standard

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The AES75-2022 standard details a procedure for measuring maximum linear sound levels of a loudspeaker system or driver using a test signal called M-Noise. This is a complex procedure with many repetitive steps, which makes it time consuming to implement manually. This sequence automates the entire process, accelerating test time, minimizing operator intervention, and ensuring accurate and objective test results.

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Polar Plot (Linear X Turntable) Loudspeaker Sequence

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This sequence measures the polar response of a loudspeaker in both the vertical and horizontal dimensions. It is designed to work with the Linear X turntable, and has all the necessary commands to automatically rotate it via RS-232. The sequence uses a log sweep stimulus with the Time Selective Response algorithm so that the measurements can be run in a non-anechoic environment. Note that the time window needs to be adapted to the user’s measurement space. The sequence plays the stimulus and measures at 10 degree increments from 0 to 180 degrees. This process is repeated with the speaker positioned horizontally. The two results are mirrored to display full 360 degree polar plots for each axis. A directivity index curve is also calculated for each axis and is displayed at the end of the test.

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Complete End-of-Line Speaker Test (includes ePRB and eLP)

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This sequence is an example of the many types of tests that can be performed quickly and simultaneously on a loudspeaker production line. A stepped sine sweep (StweepTM) from 20 kHz to 50 Hz is played through the speaker under test and measured via two channels of the audio interface. A calibrated reference microphone is connected to one of the channels and an impedance reference built into the SC Amp or AmpConnect is connected to the other. A HarmonicTrak™ Analysis step analyzes the recorded waveform from the reference microphone and outputs Frequency Response, THD, Normalized Rub & Buzz, Perceptual Rub & Buzz (ePRB), Loose Particle Prominence and Threshold (eLP) and Polarity. A Post-Processing step calculates the Average Sensitivity from 100 – 10kHz. A second Analysis step analyzes the recorded waveform from the impedance reference and outputs a curve of impedance versus frequency. A Post Processing step performs a curve fit of the impedance curve and calculates the max impedance (Zmax), precise resonance frequency (f0), and the quality factor (Q) of the resonance peak. All measurements and parameters are tested against limits in Limit steps. All these limits can be adjusted to suit your own DUT.

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Production Testing Seminar

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March 10th, 2022. 9.00am and 2.00pm Eastern US time (6.00am and 11.00am West Coast time)

In this short seminar, Les Quindipan explores the use of SoundCheck for end-of-line production testing. He discusses typical test configurations and the type of measurements that can be made, how to set pass/fail limits and how to optimize tests for high throughput.

He will also explain how SoundCheck is easily scaled for high volume production testing, with such features as external control via another program and auto-saving data to databases, and how SoundCheck’s capabilities are easily expanded through the use of custom steps to control all types of devices and test fixtures.

This seminar will be of interest to anyone considering a production line implementation of SoundCheck, or curious as to how to transition R&D measurements to fast and effective end-of-line test.

This event has passed. Watch the recording.

Basic Loudspeaker Measurement Seminar (China) / 扬声器测试基础篇

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Oct 13th, 2021. 10.00am China Time / 2021 年 10 月 13 日上午 10 点（中国时间）

Join Les Quindipan and Anastassia Tolpygo on Oct 13th for a seminar on basic loudspeaker testing. This introductory seminar is aimed at anyone new to audio measurement, specifically loudspeaker testing. It will begin with an introduction to the basic design of a loudspeaker, including how a typical loudspeaker works. Various loudspeaker measurements will be explained, such as frequency response, distortion, sensitivity, phase/polarity and impedance, and how they might offer indications as to potential defects in a speaker. Typical test configurations for both R&D and end-of-line production test will be shown. A complete speaker test will be demonstrated, using SoundCheck and our free Loudspeaker complete test sequence. This will include setting up software and hardware, calibrating and configuring the test (e.g. setting pass/fail limits) and a discussion of the results. There is no charge for this seminar, but registration is required.

于10 月 13 日加入Les Quindipan 和 Anastassia Tolpygo主持的有关基础扬声器测试的研讨会吧。

此研讨会目的是向任何不熟悉音频测量的人介绍一下音频测量, 特别是扬声器测试。在研讨会中,首先会介绍扬声器的基本设计, 包括典型扬声器的工作原理。并将解释各种扬声器测量，例如频率响应、失真、灵敏度、相位/极性和阻抗, 以及扬声器测试如何提供有关扬声器潜在缺陷的指示。研讨会将展示用于研发和下线生产测试的典型测试配置。

在研讨会中将演示完整的扬声器测试。使用 SoundCheck 和我们免费的扬声器完整测试程序。这将包括设置软件和硬件、校准和配置测试（例如设置通过/失败限制）以及对结果的讨论。本次研讨会不收取任何费用，但需要预先报名。

This event has already taken place. Check out our Youtube Channel for the recording.

 

How to Measure Free Field Speaker Response without an Anechoic Chamber

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Did you knowSimulated Free field measurement you can make free-field measurements without an anechoic chamber? In the March 2021 issue of VoiceCoil, Steve Temme explains his unique method for achieving this. The article explains how the ‘splice’ method results in a full range frequency response from a combination of near-field and windowed far-field measurement, and compares the results with anechoic chamber measurements and the manufacturer’s published response curve.

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