There was an ancient era (1960s and 1970s) when column loudspeakers were all the rage in church installations. After that was a long period when, as Rodney Dangerfield would have said, “They didn't get no respect.” Perhaps for good reason.
Today, however, sleek and slender column loudspeakers are making a comeback. Thanks to improved transducer technology and computer-aided design, newer column loudspeakers offer improved performance across the board. Beyond that, when you give each little driver its own amplifier and put everything under advanced DSP control, the column can do tricks never dreamt of in the age of the Shure Vocalmaster.
First, regarding nomenclature, the industry shows little agreement. These devices are variously called “column arrays,” “line source arrays,” “architectural columns” and combinations thereof. For the sake of uniformity, we'll call them “column arrays.”
A Matter of Principles
Next in order is a review of relevant acoustical principles. Loudspeakers are placed in a vertical column in order to provide a wide horizontal dis- persion pattern (typically 120 degrees or more) in combination with a far more restricted vertical pattern—usually between 10 and 30 degrees. That spreads the sound power across a wide seating area, yet also throws it effectively toward the rear of the room without splattering useless sound on the ceiling. That's a good thing, if you can do it uniformly across the whole audio spectrum—something not easily done.
Two basic physical characteristics determine the upper and lower limits, as well as the uniformity, of a column array's vertical control pattern:
The driver (loudspeaker cone) diameter defines the upper frequency limit, assuming all drivers are adjacent to each other. The smaller the loud- speakers, the higher the frequencies you can reproduce without losing your desired vertical pattern and generating unwanted discontinuities (“lobing”). A column with six-inch cones will couple smoothly to nearly 1,200 Hz, while one with three-inch cones won't start serious lobing until about 2,400 Hz. Obviously, having smaller drivers will extend your high frequency performance, which is why many new columns are far skinnier than older models. Two-way column arrays, usually with cone drivers four-inch or larger, will add either small dome tweeters or a magnetic planar (“ribbon”) driver to extend the highs.
The total length of the column defines the low-frequency limit of pattern control. A column four feet long will hold its pattern below 300 Hz, generally considered the bottom of the vocal range. For meaningful bass control, however, you'll need a column at least double that length.
But will the skinnier columns still deliver? Amazingly, with proper powering and processing, new high-excursion two-inch and three-inch drivers produce solid low-frequency response. With enough of them lined up—24 little three-inch drivers have about the same cone area as a 15-inch woofer. So you can push some serious air with small drivers.
Classic Designs, Updated
The column arrays in this group require external amplifiers and contain no internal signal processing. Frequency response and vertical beam-width (the -6 dB points of vertical response) are determined by the driver size(s) and type(s) along with driver spacing, column length, and column shape (curved or straight). Prices are reasonable, dipping under $500 per unit and topping out at around $5,000 for a top-end, 32-plus driver system. Frequency response figures are not given, as meaningful comparisons are virtually impossible. Some will manage significant low frequency response to 80 Hz, or high frequency response to 19 kHz. But be mindful that everything above about 4 kHz will be subject to lobing in the response pattern.
The Bosch LA-1-UW36 is a lightweight (13 pounds), cost-effective column comprising four 5-inch cone drivers. Coverage pattern is given as 90-degree horizontal by 30-degree vertical, and a multi-tap transformer is included.
The MA-12 from Bose incorporates an even dozen 2.25-inch drivers and claims a maximum output power of 113 dB (@1 m) across a nominal 145-degree horizontal by 20-degree vertical coverage pattern.
The EAW CLA-37—packing a total of seven 3-inch drivers—spans a coverage area of 120-degree horizontal by 30-degree vertical. It employs special “frequency shading” EQ to maintain a uniform 30-degree vertical response below 1 kHz while maintaining the nominal 120-degree horizontal at higher frequencies.
Innovox manufactures several families of column arrays in various lengths and with several driver types and sizes. Typical is the ULA-12-8, with 12 four-inch cone drivers alongside eight ribbon HF devices. Coverage is given as 120-degree horizontal by 8-degree vertical, with peak output of 129 dB (@ 1m).
The slender, fully modular K-Array Kobra is based on eight 2-inch, long-excursion drivers (with neodymium magnets) mounted in a metal cabinet with built in stacking/arraying hardware. Multiple units can be linked for long arrays with well-defined low-frequency control.
The SSE-LA16 in Peavey's Sanctuary Series is a compound-radius, curved line array with 16 two-inch drivers. The dual curves provide a tight 20-degree vertical cover- age for the primary long-throw pattern and a 40-degree pattern for the near field.
TOA's Type H Series comprises four models. The larger models have sixteen 2.8-inch cone drivers, while the shorter have nine of the same driver. Both are available with either straight- or curved-front cabinets to provide, respectively, tighter or more open vertical coverage.
Tannoy's i9 is a two-way system with four 5-inch drivers plus three 1-inch tweeters for extended high frequency response. Vertical coverage is a relatively open 60 degrees.
Neither Fish nor Fowl
The next three loudspeaker types defy categorization. They don't have digital beam steering, but they offer extras that those above don't.
A-Line Acoustics makes a number of standard and custom column arrays, with a twist that they use the B&O ICEpower modules for internal self- powering—but without digital beam steering. The ELI is typical, with 15 three-inch drivers in a still lightweight 23-pound package.
The Entasys from Community occupies a cat- egory of its own. It's a novel three-way system (6 x 3.5-inch, 18 x 2.35-inch plus 42 x one-inch in patent-pending planar devices) that comes as factory default with a curved front for 12-degree vertical dispersion. But in a few minutes, the user can change it to a straight front for, presto- magico, a 6-degree nominal pattern.
BL employs patent-pending analog electronic circuits to offer vertical coverage options with four models in its CBT (Constant Beamwidth Technology) Series. With the flip of a switch, the vertical coverage pattern can be changed from broad mode (for mid-throw) to narrow mode (for long-throw). Another useful feature is a built-in variable voicing switch for choice of music or speech optimization.
Amazing Science: Digital Beam Steering
All the models in this group offer beam steering capabilities, an impossible feat before the ad- vent of miniature class D amplifiers and sophisticated yet affordable digital processing. In order to accomplish this feat, every driver (single or coaxial) must have its very own amplifier, usually built into the cabinet. That means every driver in the column can be individually equalized and delayed as needed to manipulate the vertical coverage pattern as desired. You can steer the whole beam upward or, as is more often the case, downward. You can make the beam broader to cover a steeply raked auditorium, or narrower for a deep, flat seating area. With some models you can even split the beam to cover two distinct seating levels. Amazing tricks, but costs are high, starting above $5,000 and steering upward from there.
All systems below use the same underlying principle, as variable delay and EQ of speakers in a column is (apparently) non-patentable. They differ significantly in the sophistication of DSP algorithms applied to the task, the number and types of drivers, and the user interfaces for setup and control. Many makers offer modular systems, allowing two or more column units to be stacked and linked for increased power output (for longer throw) and better low frequency control.
The Bosch Vari-Directional Array is a modular system that combines a 1.2-meter base unit with one or more extension units to form arrays of 1.2, 2.4 or 3.6 meters long, the latter unit claiming a maximum throw distance of 50 meters. Other features include a network interface for control and monitoring, as well as optional support for the CobraNet digital audio network.
The Netherland's Duran Audio was a pioneer in beam steering, and its line of Intellivox columns now includes 18 modular options based on four- or six-inch cone drivers. Some also incorporate small coaxial tweeters for high-frequency exten- sion. Though pricey, Intellivox systems come complete with network control, built in ambient noise sensing for auto volume control, and pro- prietary software for set-up of beam steering.
The DSA-250z from EAW is a fixed two-way system with eight 4-inch cone drivers and eight 1-inch dome tweeters. Asymmetrical pattern configuration disperses equal sound levels to near and far listeners. Two inputs are provided, each with adjustable EQ, delay and compression.
Meyer Sound's CAL (Column Array Loudspeaker) series allows beam steering of plus or minus 60 degrees, along with vertical beamwidths ranging from 5 degrees to 60 degrees. Inputs are analog, AES3 digital, and AVB- (Audio Video Bridging) enabled Ethernet. Three column lengths are available, with the mid-sized CAL 48 containing 16 four-inch cone drivers and 48 3⁄4-inch tweeters.
The fixed VSA (Vertical Steerable Array) 2050 from RCF incorporates 20 full-range, three-inch drivers, each powered by its own 50W class D amplifier. A handy IR remote unit allows control of beamwidth, beam tilt and EQ without connecting to a computer. An auto off option turns power off when no signal is applied for a defined period.
The extensive Iconyx line of modular columns from Renkus-Heinz offers a wide range of op- tions for different room sizes and acoustical environments. Typical is the IC16-R, with 16 dual coaxial tweeters (two 1-inch tweeters inside each four-inch woofer). Inputs can be analog, AES3 or CobraNet. Multiple presets can be stored in the unit, allowing selection from the unit or a remote wall switch.
Tannoy fields another extensive range of modular systems in its QFlex series. Six different variants are offered (QFlex 8 through QFlex 48), with combinations of four-inch and three-inch cone drivers and one-inch dome tweeters. The BeamEngine software enables vertical dispersion from 10 to 100 degrees, and aiming angles across a 70-degree arc. New “second generation” control and monitoring features are compliant with international voice alarm regulations.
That's all, folks, except for one final disclaimer: The focus here was on installation systems. A number of nifty, self-powered portable columns are now on the market, and we hope to look at these in a future issue.
