Introducing Wavefront Line Array EASE DLL’s

Ambrose Thompson

November 15, 2004

1 Introduction

This article describes how to use our newly developed EASE DLL software components in conjunction with ViewPoint to design and simulate Wavefront line array products. A comparison between simulated output and measured data is also presented. It is assumed that the reader is familiar with EASE and its operation.

2 What is an EASE DLL?

DLL stands for ’Dynamically Linked Library.’ A DLL (.dll) file contains a library of functions and other information that can be accessed by a Windows program, in this instance EASE. From the users perspective an EASE DLL is just like any other speaker data file with the addition of setup dialog to control some array parameters. When using a DLL the responsibility for calculating the complex direct field sound pressure is transferred from EASE to the DLL. There are several reasons for wanting to do this.

Higher angular resolution of the output balloon is required and is achieved by combining measured data and advanced interpolation.
Sophisticated Band-Zoning drive techniques need to be employed for optimal performance of any practical line array. This requires the selection of correct settings from a very large list and is dealt with by the DLL automatically.
Allow the user to control and investigate the environmental correction EQ options of each array combination.

3 Starting point

Let’s consider a very simple implementation of a small line array system where we wish to cover a flat audience area directly in front of the array. ViewPoint is used to specify the venue details, restrictions of array placement and coverage limits. Splay angles are then determined for you (Fig 1). You can also check other important details regarding the array such as mechanical properties, which controller setting to use and how to patch your amp rack.

Figure 1:

ViewPoint Output

Armed with this information we can progress with the design in EASE. The array parameters we need to transfer are the splay angles, tilt angle and array height. To begin; insert a loudspeaker in the EASE room editor, enter the array height and tilt angle, browse to a Wavefront line array under ’Speaker Model’ and click ’Dll Setup’. A table will appear on the left, now click the ’...’ in the first row of the second column, a new window will appear. (Fig 2). Splay angles and optional EQ settings are specified here.

Figure 2:

MA EASE Dll dialog

Once this is done the array can be treated like any other EASE loudspeaker object. It is also possible to open the Dll in Speaker Base and view polars and balloons of arrays.

4 Results

Direct SPL output on the venue plane is shown at a selection of frequencies. Note the the last seat position is a distance of 27m from the array confirming that the coverage stop parameter has been achieved.

Figure 3:

800 Hz

Figure 4:

2000 Hz

Figure 5:

6300 Hz

Figure 6:

10000 Hz

5 Validation

Measurements of the above array were made to check the validity of the model used within the Dll. Microphones were placed in the seat positions shown in the results, the following figures show the measured (red) vs. predicted(blue) for these positions

Figure 7:

Position 1 - 2m from array

Figure 8:

Position 2 - 7m from array

Figure 9:

Position 3 - 12m from array

Figure 10:

Position 4 - 17m from array

Figure 11:

Position 5 - 22m from array

Figure 12:

Position 6 - 27m from array

The EASE DLL predictions show generally good agreement with measured data between the markers. The markers define the region of validity for the measurement, further away from the array a smaller anechoic time window is available thus the lowest measurable frequency is higher.

6 Conclusion

EASE users now have a simple way to predict the output of MA line arrays with a high degree of accuracy.