Wednesday, July 12, 2006

How to Aim Loudspeakers

Cheat Sheet: How to Aim Loudspeakers (from Pro AV web site for AV Professionals)

High-quality professional loudspeakers can provide excellent pattern control, and modern software tools can accurately predict coverage based on specific hanging and aiming details. Here’s what you need to know to implement loudspeaker aiming in the field.

Loudspeakers aren’t like flashlights, and sound doesn’t behave like light.

New technology on the horizon will create practical aiming methods that require less guesswork and no actual physical aiming. Using columns of multiple DSP controlled drivers and software, users can vary the vertical coverage pattern from 15 to 120 degrees, as well as aim the pattern ±30 degrees.

The coverage pattern is a rough approximation of the geometry of the area of expected coverage. Because loudspeakers have varying degrees of pattern control, there can be significant energy “outside” the pattern. This problem is further complicated by erratic polar response; all frequencies aren’t necessarily produced with equal energy within the pattern. The best way to aim an individual loudspeaker is to align a laser aiming device on-axis, and aim it at the center of your listening area.

When more than one loudspeaker is used near another one, you can expand coverage, but there will be interaction effects. Most loudspeaker manufacturers now provide proprietary calculators to model arrays to minimize interaction effects and maximize coverage. Once optimal parameters are determined, the physical data (array height, angles between cabinets, and angles of the entire array) is given to the installers to implement in the venue, using various tools.

Using Array Calculators
The typical process for using an array calculator is:
1. Determine the rigging points for the array.
2. Determine where the vertical coverage starts and ends (the front rows to the rear of the venue).
3. Take physical venue measurements using a laser range finder and a clinometer.
4. Plug this data into the calculator software.
5. Adjust the software parameters (array height, array angle, inter-box angles, and number of loudspeakers) until a desirable solution is found for both SPL and coverage.

Line Array Calculators
Adamson,, Adamson SHOOTER

Alcons Audio,, Alcons Ribbon Calculator (ARC)

d&b audiotechnik,, Q-Calc

Duran Audio,, DDA

Eastern Acoustic Works,, KF730 Wizard, KF760 Wizard

Electro-Voice,, Line Array Prediction Software

JBL Professional,, Line Array Calculator

L-Acoustics,, Soundvision and Array 2004

Martin Audio,, Viewpoint

McCauley,, McCauley Line Array Calculator

Meyer Sound,, MD3 Placement Calculator, Array Calculator

Nexo,, GeoSoft

Renkus-Heinz,, Aimware

SLS,, Line Array Software Simulator (LASS)

Worx Audio,, EASE Focus

Integral Angles — Most professional loudspeakers intended for arrays have built-in angle indicators in the hanging hardware for cabinet-to-cabinet spacing.

Laser Level — Align the device on-axis and attach it to the loudspeaker to show where its coverage hits the audience. (Lists for approximately $70,

Pitch and Slope Locator — This device measures angles and altitude. (It lists for about $8.50,

Clinometer — This tool measures altitude. (It lists for approximately $189,

Range Finder — This device measures distance. (It lists for about $270,

Laser Vertex Hypsometer — This tool measures distance, height, or angles. (It lists for about $2,395,

Digital Inclinometer with Remote Readout — This device remotely provides angle information. (Prices start at $436,

Sources: dB Sound, EAW, Electro-Voice, Renkus-Heinz, Rieker Inc.

Thursday, March 23, 2006

Updated Remote Angle Display (RAD2)

The Remote Angle Display (RAD or RAS) was specially designed for speaker positioning. Most of our customers have a number of speakers that they need to level but typically only want one display box. We can supply the display as a single line display reading one sensor at a time (RAS) or a dual line display to measure two sensors at the same time (RAD). For example, most V-Dosc users are purchasing the RAD2 dual line display with the REL feature being programmed to read Top - Bottom, please let us know what system you are using.

A RAD or RAS system includes the display box along with a number of matched sensors; typically 1, 2, or 4 sensors. Both the sensor unit and the display box use standard type audio XLR cord plug connectors for easy connection. We normally do not supply the interface cables, most customers make their own cables to meet their required length. We can supply cables if necessary, however, we have found that customers who are in the speaker and lighting industry already have an abundance of XLR cable and can get it much cheaper than we can. In most cases, the sensors are permanently mounted on the speakers with cables running down to the floor. The cable connector is then plugged into the display box as needed.

We have two choices on sensor ranges - either ±30° (60° total range) or ±70° (140° total range). The display can be calibrated to anywhere within the total range of the sensors specified. For example, we have a number of customers selecting the ±70° sensor and having them scaled to read +50° to -90°. (Typical V-Dosc application.)

The RAD2 Remote Angle Display with dual line LCD allowing 2 remote sensors to be read at the same time.

The RAS2 Remote Angle Display with single line LCD allowing 1 remote sensor to be read at a time.

Sensor option A: an inclinometer sensor is mounted into Nema 4 box for extra protection, cable strain relief, and easier, more flexible mounting. Includes male XLR built into box. Can be configured to lay flat on top of the speaker box or on a flat vertical surface. It can be mounted with screws for a permanent installation or with gaff tape or heavy Velcro for easy removal for transportation and storage – please specify mounting position. Mounting feet are available.

Sensor option B: CS9. Solid Zinc housing, small footprint, sturdy and extra rugged for a more permanently mounted position. Very nice if you are using multiple line arrays and a RAD system together, not necessary to recalibrate each setup - once screwed into proper position, hang the speakers, plug in to display – mounts on a flat vertical surface.

Relative Zero (REL) Button:
Standard on all display models: The REL button allows the user to set a new zero position after the RDI is mounted. Press the REL button and release and the display will read REL ON * for 1 sec then 0.00° *. The ( * ) indicates the measurement is not referenced to the true calibrated 0, but a referenced zero. The MIN/MAX angles are now referenced to the new referenced zero. Press the REL button again and the display will read REL OFF for 1 second then return to the true calibrated zero. The MIN/MAX angles are now again referenced to the true calibrated zero.

Relative Diff (REL) Button: (available on RAD displays only)
This is programmed to give the difference between the TOP and BOTTOM sensors. The RAD2 with ±70º sensors scaled to -50/+90º, is a typical VDOSC configuration but the REL button is reprogrammed for SENSOR 1/SENSOR 2: SENSOR 1 would be placed on top of the speaker array = TOP LINE OF DISPLAY = TOP CONNECTOR on side of box; SENSOR 2 will be placed on the bottom of the speaker array = BOTTOM LINE OF DISPLAY = BOTTOM CONNECTOR on side of box.