Measurements and GLL / CLF Files: Overview

Excelsior Audio features a lab specifically for loudspeaker measurements. Our focus is on performing directivity balloon, sensitivity, maximum input voltage, and other measurements to characterize loudspeaker system performance. These measurements are the primary data required for use in building loudspeaker modeling files (e.g. GLL and CLF). We will continue our work to author GLL file for our clients based on these of measurements.

The Excelsior Audio lab is positioned to fulfill almost any of your loudspeaker measurement and modeling needs. Charlie Hughes has over 25 years of loudspeaker design and measurement experience. He was one of the first to adopt and work with the GLL format for modeling loudspeaker performance. Charlie's close work with AFMG (makers of EASE, EASE Focus, EASERA, SysTune, and other electro-acoustic simulation and measurement software) over the years allows him to help you to make sure your loudspeakers are modeled in the best way possible via the right type of GLL (yes, there is more than one type). As one of the main authors of the user's manual for AFMG's SpeakerLab program, Charlie helped to literally write the book on the software used to create GLL files.

We are pleased to be one of only a handful of independent labs world-wide providing measurement and GLL/CLF authoring services.

If you are a loudspeaker manufacturer, sound system design consultant, design-build firm, or someone that needs objective measurement data for your loudspeakers please contact us.

Frequency Response / Impulse Response
The impulse response (IR) measurement is one of the most often measured characteristics of a loudspeaker. The IR is the time domain equivalent of the transfer function (TF) in the frequency domain. The transfer function is often called the frequency response. It contains both magnitude and phase information (complex data). The on-axis IR can be used to determine the sensitivity of the loudspeaker. IR measurements at off-axis positions can be assembled to form the directivity balloon for a loudspeaker.
Frequency Response Frequency Response (Magnitude and Phase)
Impulse Response Impulse Response
Directivity Response (Directivity Balloon)
The directivity balloon is the 3D equivalent of a polar graph. It shows the radiation characteristics of the loudspeaker in three dimensional space. It contains both magnitude and phase information (complex data). The directivity balloon is very useful in acoustical modeling programs, such as EASE, to map the SPL (sound pressure level) on the various surfaces of the room, as well as the audience areas. Directivity Balloon
Impedance Measurements
Impedance measurements are used to determine the rated impedance of your loudspeaker per industry standards. Our impedance measurements are also complex data, containing both magnitude and phase angle information.
Maximum Input Voltage Measurements
The maximum input voltage of your loudspeaker is determined according to industry standards. This helps to assure maximum SPL calculations in modeling programs that correlate well with real world measurements.
GLL and CLF Format Loudspeaker Modeling Files
EASE, EASE Evac, EASE Focus, and AFMG FIRmaker all require accurate, complex directivity data for the loudspeakers used in these modeling and optimization programs. We supply GLL files with the required data to meet your needs and those of your customers.

Other modeling programs (CATT-A, Odeon, etc.) use CLF data files. These are magnitude only files (i.e. they contain no phase information). We we can also supply these CLF files for your loudspeaker that be used in these modeling programs.

Custom Measurements and Analysis
We can perform other loudspeaker measurements not usually performed to generate GLL or other loudspeaker modeling files. Contact us to discuss your needs.
Crossover Design and Optimization
We offer a crossover optimization service. If the directivity balloons of each individual pass band (e.g. LF, MF, and HF) are measured separately they can be used to help optimize the crossover design and investigate the directivity of the loudspeaker system through the crossover region(s) without having to re-measure the loudspeaker.

The graphs below show a comparison of the response, before and after the optimization process, for a two-way loudspeaker comprised of a 15 inch woofer and a high frequency horn. The result of the optimization is much more consistent vertical directivity through the crossover region from 1 kHz to 2 kHz. The on-axis response remains virtually unchanged.

Frequency Response On-Axis Frequency Response
Before Optimization (red)
After Optimization (blue)
Vertical Beamwidth Vertical Beamwidth
Before Optimization (red)
After Optimization (blue)
Vertical Directivity Map Vertical Directivity Map
Before Optimization
Vertical Directivity Map Vertical Directivity Map
After Optimization
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