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Loudspeaker Measurement: An Overview Of EASERA SysTune

An inside look at some of the more common functions and uses for this program

By Charlie Hughes March 30, 2011

A frequency vs. magnitude graph, showing frequency placed on the horizontal axis. (Larger view of this image included in article below)

EASERA SysTune is an audio measurement program from the Ahnert Feistel Media Group (AFMG), designed for real-time analysis of acoustic signals and aimed at those doing system alignment, tuning and live sound applications.

SysTune is not a replacement or upgrade for the EASERA measurement program, but rather, it has its own unique features that allow it to perform measurement tasks not currently available in other measurement programs. More in-depth acoustical analysis of the measurements made with SysTune can be done with EASERA.

SysTune runs under Windows 2000, XP and Vista operating systems. It’s a multi-threaded application that is capable of taking advantage of multiple processors within a computer.

SysTune supports up to eight input channels simultaneously at up to 192 kHz sample rate, and it can operate in a dual-channel FFT mode, meaning that one input channel receives a reference signal (mixing console output for example) to which the other input channels are compared.

SysTune can also output its own signal (sweeps, pink noise or user selected files) and use this as the reference. Switching between each of the input channels is accomplished easily by clicking on its channel button. These are located just above the mini-meter for each channel.

The mini-meters are very convenient to tell at a glance which channels are receiving good signal level. If an overload (clip) of the A/D converter occurs the meter turns red. After the overload passes the outline of the mini-meter stays red until it is reset.

There is a multi-channel mode which allows two or more inputs to be averaged in real-time and the result displayed. This feature can be very useful to spatially average the sound system response using multiple microphones in different locations.

There is a very important process at work under the hood of SysTune. This is the Real-Time Deconvolution (RTD) engine. This newly developed algorithm allows for the calculation and display of impulse response (IR) data of up to 10 seconds in real-time and with fast on-screen display refresh rates.

To accomplish this, SysTune performs an FFT on the signals from the input channel and the reference channel. The transfer function (TF) of the input channel is then calculated in the frequency domain by complex division of these spectra. Finally, an inverse FFT is performed on the transfer function to yield the IR.

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About Charlie

Charlie Hughes
Charlie Hughes

Managing Director, Excelsior Audio Design & Services
Charlie Hughes has worked at Peavey Electronics and Altec Lansing, and currently heads up Excelsior Audio Design & Services, a consultation, design and measurement services company based near Charlotte, NC. He’s also a member of the AES, ASA, CEA and NSCA.


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