If you should ask an audio engineer what the main topic of debate within live sound has been for the past decade, the chances are you’ll walk away with a head full of opinions about digital and analogue mixing desks. However, as fierce as that debate has been, another long argument has been raging in the live sound sector for just as long, and it centres on this question: point source or line array?
To a casual observer, the debate may have seemed muted to the point of being inaudible. This is largely due to the overwhelming victory of line array technology over its older, more traditional cousin. However, it was not so long ago that industry magazines were filled with technical dissections of what line array could mean to the touring industry, of how it worked, and whether it really was the better alternative. Not long after the debate began, line array systems became the default choice for rental companies all over the world, and the question appeared to have been answered. Only a handful of manufacturers continued to argue the case against it, and line array dominated its field for years to come.
Now, however, the momentum is beginning to swing back to the naysayers. True, line array technology is as overwhelmingly popular as it has ever been and a wealth of new systems are released every year, flooding the market with products that are sometimes innovative and sometimes less so. But with great success sometimes comes stagnation – faced with such a huge volume of competing line arrays to choose from, and with little separating many of the systems that are available, rental companies and end-users are beginning to wonder what more can be done with the technology to make a particular system stand out from the crowded field. Beyond the comfort value of premium brands that offer premium quality, what else can be said about line array?
Montarbo, a loudspeaker manufacturer based in Italy, believes it has come up with an answer in the shape of its PalcoPlus line array system. Designed not as a me-too product, but as a new direction for the manufacturer, PalcoPlus is being introduced to the market, says Montarbo, ‘not as a loudspeaker enclosure but as a musical system’. The difference, it explains, is in the construction of the enclosure itself.
‘PalcoPlus is an instrument capable of reproducing faithfully every musical instrument without colouration,’ the manufacturer enthuses. ‘It is a system which minimises the use of heavy equalisation to which line arrays and their bass cabinets are customarily subject. Palcoplus has no equalisation that correct the acoustics of the enclosures because the enclosures have been conceived and accurately designed to sound as natural in their bandwidth as possible with no need for equalisation. The minimum-phase electronic filters employed are capable of extremely faithful impulse response. This design is then coupled with transducers that have been carefully selected over an entire year to optimise the system. It all makes Palcoplus “a musical instrument in an array”, not just a simple line array.’
The cabinet in question belongs to the RA16 two-way line source element, described by the manufacturer as the ‘heart’ of the PalcoPlus system. Moreover, the system has been designed to be scaleable to a level that brings line array technology to a far wider audience than many high-end systems, with only four RA16 enclosures required to form a basic array, thereby attracting the attention of Montarbo’s chosen market – medium-sized rental firms.
Explains the company: ‘The project of PalcoPlus was born from the idea of creating a system with a great efficiency in a small and lightweight package, that would be extremely simple to configure. We have given a great deal of attention to the flexibility of its use. Palcoplus fits with many different situations from fixed installations to touring, and from small to medium live events up to big concerts.
‘The design team has also done extensive work to simplify the use of the system, by creating all the necessary processing parameters for a variety of configurations, from the largest to the smallest. They have also provided an intuitive software control for customising further configurations.’ In other words: ‘The PalcoPlus has been created for the real life needs of mid-sized rental services.’
The PalcoPlus, says Montarbo, is intended to deliver: ‘A high pressure level of undistorted sound in a really little and lightweight package, plus precisely controlled dispersion and a neutral balanced response, from a small system right up to a 16-piece array. The design makes it easy to achieve great sound in every environment, from reproducing classical music to reinforcing jazz, rock or disco.’
As few as four RA16 line array elements can be combined to form the smallest configuration line array, with as many as 16 elements comprising the largest. The breadth of scalability that this offers end-users is key to what Montarbo believes will be the system’s great strength – flexibility of application. When the company claims that its line array can be employed for any event ranging from classical recitals to full-range rock concerts, it is referring as much to the musicality of the elements themselves as the components the enclosures contain. The combination of both is what Montarbo believes makes it different to competing systems.
‘PalcoPlus offers exceptional power to size ratio and produces excellent results even using a small number of enclosures,’ insists the manufacturer. ‘An array of only four elements weighs 80kg including flying hardware, and can handle 4kW of power.’
The RA16 is the reason why, offering 1kW of continuous power per unit in an enclosure no bigger than a 6U-high outboard rack case. Inside the box meanwhile, the manufacturer has rethought the generally accepted line array design.
‘Whereas most modern line array elements of the RA16’s dimensions use 6.5-inch woofers, the RA16 employs two 8-inch purpose-built woofers with 2.5-inch voice coils, using neodymium magnets,’ the company reveals. ‘The high frequency section consists of a single custom-built compression driver with a titanium diaphragm, a 3-inch voice coil and 1.4-inch throat. The driver is coupled to an aluminium planar waveguide, with its exit between the baffles of the two woofers, which are angled to accompany the natural dispersion of the waveguide. The entire forward section of the enclosure, in fact, behaves as a horn above a certain frequency.’
The external waveguide is precisely tooled from birch plywood, and serves to couple the outputs of adjacent elements into the cylindrical wavefronts characteristic to a line-source array. As a result, an array of just four RA16 elements ‘exhibits precise 120° horizontal dispersion with a frequency response of 70Hz to 20kHz (±3dB).’
The result could prove a blessing to small rental firms that desire the benefits of line array precision for events that are far too limited in size to accommodate the kind of full-scale array more usually seen in the live events sector. For particularly small applications, just two RA16 elements can be used in a cluster configuration, transforming the PalcoPlus system from a linear sources into a highly directive point source cluster. Says Montarbo: ‘Each unit can develop a maximum SPL of 130dB, thus providing ample power and coverage even in small numbers.’
Also furthering the system’s appeal to smaller applications is its ease of deployment. Each element’s cabinet is constructed of 15mm birch plywood, while the incorporated hardware is made of aircraft-grade, nickel-chromium-molybdenum steel. The splay angle from one element to another is adjustable from 0° to 12°, and this together with the enclosure’s weight means that just two riggers are required for assembly. The elements also include two customised bumpers that have been included to make it simpler to either stack or fly PalcoPlus arrays. The larger of the two, the B1, has been certified for the suspension of up to 16 elements, while the smaller version, the B2, can cope with up eight. Both flavours of bumper can be inverted for groundstacking, with the B1 supporting up to six elements and the B2 certified for up to four.
For power, the PLM6800 active digital controller can drive an array of four RA16s, while single enclosures can be driven by a power amplifier capable of delivering 800W minimum at 8 ohms for the woofers and 200W at 16 ohms for the driver. Another option is the LM24 loudspeaker management system, a two-input/four-output processor incorporating 56-bit DSP, a signal-to-noise ratio greater than 100dB, and a dynamic range of 113dB at the input and 112dB at the output. The processor delivers all of the functions of the PLM8600 without the integral four channel, class-D amplifier, and is another example of Montarbo attempting to simplify the use of the system, whatever configuration it might be used in, courtesy of a series of eight presets. These are intended for use in five different scenarios ranging from small systems using one sub and two RA16s, to long-throw and short-throw parameters for large arrays.
Completing the PalcoPlus range is the RAB1815 cardioid bass horn, which has been designed to extend the frequency range of the system down to 30Hz, facilitating the line array’s use in larger applications and providing a truly full-range system. According to Montarbo, the bass horn ‘offers a distinctive, dual-transducer configuration using one 18-inch woofer in a ported reflex configuration, and a second 15-inch woofer loaded by a folded horn. The precise interaction of these two transducers permits the RAB1815 to radiate in a cardioid pattern from a single enclosure, with 15dB attenuation at 180° from 40Hz to 100Hz, allowing much more bass reinforcement to be used for the public, even very close to the stage. Aside from creating a unidirectional polar characteristic, this design also provides the benefits of both bass reflex and folded horn systems: very deep bass, but with rapid response.’
Both transducers are purpose designed and built for use within RAB1815 enclosures, and are constructed with neodymium magnets and 4-inch voice coils. Both boast an excursion of ±23mm and can handle up to 1.6kW of continuous power, creating an overall bass horn that is capable of delivering 136dB SPL. More unusually, adds the manufacturer, the design of the horn ‘puts the actual cone movement of the two speakers in opposition on the same axis of the enclosure, assuring that the sub will not move’. Meanwhile, the cabinet of each RAB1815 is constructed of 18-21mm birch plywood and has been built to act as a base for stacked arrays of RA16 enclosures. A single PLM6800 can drive two RAB1815 boxes, or alternately each RAB1815 can be driven by a two-channel amplifier with a rated output of at least 1.6kW per channel at 4 ohms.
Forming the final piece of the system is Montarbo’s RAcon software, a remote monitoring and control system that works in tandem with the manufacturer’s LD24 USB interface to operate up to eight LM24 or PLM6800 processors (the two processors require different versions of the software). Again adding simplicity to the operation of PalcoPlus arrays, RAcon provides end-users with features including configuration presets that can be modified to suit the application, a 10-band parametric equaliser with ±12dB of boost/cut and variable Q on each filter, all of which can be set at any frequency from 10Hz to 18kHz, and delay control for each pair of output channels allowing alignment adjustment in 1ms steps up to 310ms.
As vital as the technical specification of the PalcoPlus system are however, it is the focus with which the system has been designed that it will ultimately distinguish it from the field. While it is by no means the only line array system of its kind to have been developed for small- to medium-sized applications, Montarbo has concentrated its efforts in developing a line array for sound technicians who might not otherwise have considered it. This design principle runs from the small arrays that PalcoPlus makes possible through to the care that it has lavished on the enclosures themselves, intending to minimise the need for overbearing equalisation in order to create what it believes is a truly musical line array. Whether or not the system succeeds in bringing something new to the crowded world of line array technologies will be decided by the market, but for now Montarbo is furthering the debate.