Flexible-Array – A New Training Aid For SynAudCon Seminars

SynAudCon introduces new training aid for the “Sound System Design” and “OptEQ – Equalization De-mystified” seminars.

by Pat Brown

I love demos. There’s just something about seeing and hearing in real time that trumps learning concepts from a text book. It’s fun to watch people’s “light come on” when a demo really hits home. For many years, Jon Taylor of d&b audiotechnik has used a flexible array as a teaching tool. He described it to me a few years back, and several individuals had very favorable reviews. While he offered to build one for me at the time, it was a project that I was sure I could tackle, and it went on the “Do This” list for seminar demos. With our Sound System Design and OptEQ seminars looming on the horizon, I finally got around to doing it.

The “Flexible-Array” is a 12-element array that can instantly change shape between straight, curved, and half-curved. The elements are sealed-back mid-high frequency drivers – each mounted on a 5-in. by 8-in. baffle. The baffles are hinged to allow bending, and the base provides stops to assure the proper array shape. It is at home on a ground plane or in free space. For classroom demos it will usually be positioned horizontally, allowing the class to hear the vertical coverage pattern for a deployed array.

I intentionally used a device spacing that is excessive in the 8 kHz octave band. It is important to hear how an array behaves when it “breaks up” due to phase interference.

In Sound System Design, I will use it to explain concepts such as

  • Near-field vs. Far-field
  • Coherent vs. Incoherent Summation
  • Polar Response
  • Effects of element spacing and baffle size
  • Measured vs. predicted performance

and a host of other concepts. We’ll use CATT-Acoustic to examine the predicted behavior of the array, and compare it to the actual behavior. It’s a great lesson on what can be modeled with accuracy on a PC.

In the OptEQ seminar I will add a few more investigations, including

  • Near vs. Far-field equalization
  • Spatial Averaging
  • Data Smoothing
  • FIR and IIR Filter Generation

In both seminars, we will not only investigate the benefits of each array type, but also the detriments. In engineering you never get something for nothing, and by learning the strengths and weaknesses of each array type, system designers will be able to better deploy each to solve sound system problems. pb

Flex-Array - Straight Position Flex-Array - J shaped Flex-Array - Curved Position Flex-Array - Curved Position

Above: The Flex-Straight, Flex-Curved, and Flex-J on a ground plane. The battery-powered drill is added for scale.

Below: The predicted horizontal polars for the Flex-Curve configuration. These are front lobe-only and at 1/1-octave centers. Many other resolutions are possible, depending on what is being investigated (courtesy CATT-Acoustic).

Flex-Array - CATT AcousticFlex-Array - Polars of the Curved Position