Review: Acoustic Technologies Blackbird TLA1.4 Stick System
Acoustic Technologies’s Blackbird line array sings a sweet song that might just soothe your problems if you give it a listen.
By Mark Woods
24 August 2014
The first PA I was ever aware of was a column PA. A rectangular box, hung vertically on each side of the school hall’s proscenium arch. The cloth covers had imprints of four speakers, maybe 10 inches in diameter. They must have worked, because everything went through them… speeches, movies, the annual school theatrical production. If asked at the time, I would have guessed the four-speakers-in-each-box design was to make it louder, not realising it was an early application of line array theory and coverage was the real reason.
Books have been written about line array theory but put simply, it’s about sound projection. Mounting the speakers in a vertical array causes the speakers outputs to constructively and destructively interfere with each other. It sounds nasty but depending on the number of speakers, the size of the speakers and the spacing between their centres, a line array system can project sound in a tightly controlled vertical direction.
Pure line array theory describes some very large numbers of drivers and very long arrays that are impractical here in the real world, but even though the theory is compromised some benefits remain. In the case of the mid-range only old-style column PAs, any narrowing of the vertical coverage meant more sound energy could be directed at the audience, and less at the ceiling where it would bounce back to smear the sound. When I was mixing stadium shows in the ’80s and ’90s, the production companies were flying baskets of modular boxes or walls of full-range speakers. Walking away from the FOH position and moving around the venues usually revealed big differences in volume and frequency response, especially a long way from the stage. And once the speakers were flown there was little anyone could do about it.
Today’s big concerts have the scale for large arrays that deliver tight vertical coverage over a wide frequency range to focus the sound and reduce reflections. Current high-end line array systems extend the technology by using prediction programs combined with steerable elements to achieve even coverage for all seats.
LITTLE GUYS LINE UP
But what about line arrays for smaller shows? Early bands tried using column PAs, sometimes with a separate horn on top, but they lacked bass and weren’t efficient enough to provide the volume required for noisy bands, so they were replaced by horn-loaded, big black box systems. The big black box PAs are still widely used in venues today, and they’re certainly louder and bassier than those old columns, but their coverage is notoriously uneven, and they generally only deliver full-range sound to listeners who are right in front of the speakers.
Time for some new thinking. Australian company Acoustic Technologies makes a range of high-end speakers and over the last 10 years has gained considerable expertise in line array technology by supplying steerable line array systems to venues like courts, and houses of parliament and worship. Its Firebird and Blackbird speakers are modern line array systems designed for small- to medium-sized live productions. The entry point for these systems is the Blackbird TLA1.4 System.
BLACKBIRD’S SONG
The Blackbird TLA1.4 System starts with the TLA1164 mid-high line array. Custom made from extruded aluminium and finished with black powder coat paint, it’s a passive array with 16 x 3.5-inch full-range neodymium drivers stacked nearly 1.5m high. It’s tall but only 100mm deep and wide, that’s where the ‘stick’ nickname comes from, and weighs a mere 8kg — it can be carried in one hand.
The Blackbird system’s low-frequencies come from the TLA210A sub-cabinet and that’s where the line array theory gets compromised. According to the theory, to become directional a source needs to be bigger than the wavelength it’s producing… about four times bigger… so (without doing the maths) you need a very long array to be directional at low frequencies. Predictably, the TLA210 sub is omni-directional like others of its type. Made from birch ply and finished with Acoustic Technologies’s excellent AcoustiCoate finish, its dimensions of 370 x 650 x 520mm are normal enough for a sub housing two 10-inch speakers — in this case proprietary drivers made for Acoustic Technologies by B&C. Inside the 29kg cabinet lives a 2.5kW two-channel Class D amplifier. One side of the amp drives the stick, the other the sub.
The frequency response, internal delays and protection circuits are all controlled by the internal networkable DSP. The factory settings give you a tuned ready-to-go PA, but there is access to some DSP functions via Acoustic Technologies’s Podware software program. The optional TLA210 passive sub (that can be run from the TLA210A powered sub) completes the package. Systems can easily be scaled for different shows and Acoustic Technologies offers a number of ready-to-go turnkey systems.
Transporting them is interesting and even though the Blackbird Stick system is aimed at professional users, it’s not restricted to them. The sticks come in suitably long, custom road cases, the subs can be ordered with a road case built for two or individual padded bags. Production companies will get the subs in a road case and travel the system in a truck. Bands or acts that carry their own Blackbird system will choose the padded bags for the subs. Two sticks plus two subs in bags will fit in a large wagon, with room left for other gear. At the show the sticks are inserted into one of the two mounting sockets built into the top and side of the sub cabinet. The supplied Speakon lead connects the stick to the sub and away you go. Instant PA and it’s easier than putting speakers on stands.
NEED TO KNOW
Acoustic Technologies
Blackbird TLA1.4 Stick System
LINING THEM UP
Firing up the Blackbird system for the first time is quite exciting (if you like that sort of thing) and it takes a little bit of getting used to. The projection characteristics are very different to horn-loaded box designs and the first impression is the spacious, open sound these things produce. If you stand within a couple of metres of the sticks the sound is weird, you start to hear parts of individual drivers but the whole sound feels like it’s developing behind you. If you stand a few metres in front of them and give them a good roadie-strength ‘check, one, two’, they don’t bite like regular powered boxes and they’re not quite as loud, but they do have reasonable volume and they don’t want to feed back. If you move sideways across the front of the speakers the coverage is even and the sound seems on-axis over a much wider plane than horn-loaded speakers. If you play music through them and move back 50m they sound clear as a bell.
This long, wide, vertically-focused projection is the Blackbird’s main strength. By their nature line-array systems lose less energy over distance than point-source systems. And to provide the same horizontal coverage (120 degrees) with horn-loaded speakers you’d need more of them; they’d need to be splayed to get the horizontal coverage; and you’d need delays to get the same distance. The narrow vertical focus (15 degrees) also reduces distracting reflections, which in turn increases intelligibility at long distances.
HAIR OF THE BEARD
I took a pair of sticks/subs to the Theatre Royal for my new favourite band, The Beards’ recent show. I soon found out they weren’t direct enough for side-fill so I sat them beside the much bigger black box main PA and pointed them forward. At low to medium volume the Blackbird system was great and filled the room easily. At higher volumes it was noticeable that the system does have a volume limit… even though they sound much louder than they look. The DSP keeps them tidy but you can hear the limiting. For the show we ran them off auxiliary sends and fed them mainly vocals. Don’t know what it was like up the front during the show but they threw easily to the back of the room and seamlessly became part of the FOH system.
A better environment for them would be a jazz band in a park with about 500 people, or more, in the audience. It sounds like a lot of people for a system that’s quite hard to see outdoors, but the wide dispersion and long throw covers a large area with even, full-range, intelligible sound. The old problem of the level being too loud and too harsh near the speakers and too indistinct away from, or to the side of, the speakers is greatly diminished. If the band is bass heavy or there’s not enough bass outdoors, then more subs can be added. The Blackbirds also throw a fair amount of nearly full-range sound from the rear-sides of the sticks. They sound quite good back there, it’s stable with open mics, and small bands who play fairly close to them may find they don’t need separate monitors.
Acoustic Technologies reports the Blackbird has become its top-selling speaker system and I can see why. It doesn’t replace my old double four-way for really loud gigs but it would deliver more even, clearer sound to the audience than horn-loaded designs for many… maybe most… other types of audio productions. Typically, churches are cavernous yet require good intelligibility; the Blackbird system would be ideal. Town halls, school halls, sports grounds, back-of-a-truck-on-the-football-oval gigs are all candidates. Any sort of corporate event, whether spoken word or multi-media presentation, would benefit from the quick set-up, even coverage and modern, efficient look of the system.
The once ubiquitous old columns still adorn the walls of many country community halls… but I don’t think they get used much. The Acoustic Technologies Blackbird TLA1.4 system is the evolutionary replacement that leaves them about half a century behind.
