The Alcons LR24 has been a long time coming but it is finally here (by “here’ I
mean, “officially launched’, not as in “here in South Africa’; not just yet, anyway)
and given the hype that’s been circulating not only among ourselves here at Pro
Systems but in the industry at large, I’m sure we’re all waiting with bated breath for
the system to hit our shores so we can hear it in action once and for all.

The Alcons LR24 (a three-way larger format line source loudspeaker used as a
vertical array) system has been in development for quite some time and was only
launched this year at Prolight + Sound 2014 while here locally we only got a taste
of it at Mediatech 2013. Of course, at that point it was still in development.

Alcons is different in that they opt to use ribbon drivers – a natural line source – in
their line arrays that they call the Pro-Ribbon driver that by nature produces an
isophasic, cylindrical wave front that compression driver loaded systems struggle to
produce without the use of sophisticated wave guides. This, they claim, delivers up
to 90 per cent less distortion than traditional compression driver HF systems and a
precise pattern control without any horn-induced distortion.

The LR24 is a dual 12-inch, reflex-loaded enclosure with four 6.5-inch mid-
frequency drivers and a 3000W (peak) 14-inch long Pro-Ribbon driver. The rigging
system is certified for 24 elements per side at a 10:1 safety ratio.

Pro Systems deputy editor Greg Bester caught up with Tom Back, Alcons co-
founder, for more information on the development and challenges therein of the
LR24, more information about the product and where Alcons sees itself in the
future.

Give us some background to the development of the LR24
The initial idea for a larger format line-array started with the Phitom design study
from 2007. That study was based on the RBN1801, our most-powerful Pro-Ribbon
driver at the time with an 18-inch voice coil and a 3000W power handling. The
concept showed a three-way, symmetrical design with horn-loaded eight-inch mids
and double 15-inch for LF. The Phitom LFE section was an additional LF module,
placed left and right of the main line-array, to complement the bass and sub-
performance, while at the same time bring the 90 degree horizontal control down to
125Hz.

That LFE section was cardioid-loaded with an 18-inch woofer on front and a 15-inch
woofer on the rear for rearward LF cancellation. Despite being ahead of the market,
we decided the time wasn’t right for a production-ready product because we had
larger ambitions for the HF section (proving that our Pro-Ribbon technology would
be capable of higher SPL performance than currently available on the market), but
also as the brand recognition of Alcons would not bring a sufficient attention level
for such a game-changer. Also, our amplification and DSP processing platforms
were not up-to-speed with requirements for such a demanding market segment.
At the same time, with the economic situation uncertain, we decided to spend our
R&D efforts on smaller (array) systems that would fit our existing markets very
well and would see the quicker return-on-investment. For example: the resulting
LR7 micro line-array has sold thousands of units and has become a very important
part of our turnover.

Also, our RR12 point-source array is a direct result of the extended R&D we did on
the acoustical set-up of the LR24.

Why did we not see an official launch of the LR24 for so long, despite
seeing it pop
up in individual festivals and events?

Alcons as a brand doesn’t have a background in the touring market and would thus
have some deadline for replacing an existing product. We decided to take our time;
build a fairly large rig and do gigs with that to gather experience information. Also,
as Alcons’ philosophy is to offer the complete sound experience, the package of
LR24 development was just much more than “just’ a loudspeaker cabinet. [It is also
about] array extension, subwoofer solutions, logistics, and also a completely new
amplification and processing platform.

Where other manufacturers would go the OEM-route and just rebrand an OEM amp
platform, we have developed our proprietary amp and DSP solution, which we call
the “Sentinel Amplified Loudspeaker Controller’ as the control functions are much
more prominent than just the amplification function. The Sentinel plays a crucial
role in the future feature development of the LR24 system as well.

In the first quarter of 2013 we launched the Launch Partner Program, with which we
got in touch with the most interested rental partners (“early-adopters, if you wish)
to get more precise feedback and co-development in the last stage of the
development.

What have been the challenges, if any, in designing and developing the LR24?
Ha, there were plenty! Of course, our primary challenge was to get our Pro-Ribbon
technology suitable (read: loud enough) for the ’Formula One circus’ (as we call the
touring market). We felt it would not be suitable to come up with a transducer in
the LR24 line array that would produce “just-enough’ SPL for the job as the LR24 is
more than just a new market segment for Alcons. More than that, it’s “proof-of-
concept’ to show that the Pro-Ribbon technology is the real-world alternative for the
(almost) 100-year old compression driver technology.

Besides the HF challenge, to develop a system according to the Alcons “engineering-
integrity’, it should perform acoustically superbly, primarily, with a secondary role
for DSP. Instead of the other way around as we see too often nowadays. A system
with symmetrical transducer arrangement and a stable horizontal dispersion
behaviour is a pain-staking process of trial-and-error with prototypes, simulations,
measurements and listening sessions. Due to the all-natural cylindrical behaviour of
the Pro-Ribbon technology, we had an easier job to obtain a side-lobe free
projection in the vertical plane.

The flying system is a task in itself: minimal hardware, simple but reliable set-up
with on-the-ground curve angle pre-setting, all under the highest safety ratios
(10:1). We have worked with the University of Delft in this development. At the end
of the process, we had a very sophisticated flying system with a very high degree
of “automation’ but we decided not to continue this design in the production version
due to the higher risk of component failure (due to lot of parts) and the significantly
reduced involvement of the operator; especially since this last item was something
we thought to be an important finding in our research, ie. automated spring-loaded
connecting parts create a false sense of security as they enhance the neglect of
check, re-check, double-check. So, in the development process we had two
development teams working side-by-side, separately, to choose the best solution in
the end.

Last, but certainly not least, the Sentinel amplified loudspeaker controller has taken
us close to four years to develop (to many in the industry, this is a record time!
But, it has been the delaying factor in the LR24 launch to some extent). To bring our
drive platform at least to the current state-of-art, we needed to go the Class-D
amplifier route (coming from a more bulky, heavy Class-G design). In our research,
we found during calibrated listening tests that practically all Class-D designs on the
market were limiting the performance of our Pro-Ribbon transducer technology,
hence the task of starting development ourselves. We have taken amplification to
the next level with custom-designed sample-rate converters with utmost high-end
hi-fi response as our goal combined with sound-reinforcement output power
capability and a state of the art control and user-interface.

What do you feel the LR24 does differently or offers over other line source
systems
in its class?
It’s the first time ever in the professional audio industry history that sound can be
amplified to the highest SPL’s in such a high quality resolution: lowest distortion
combined with full 1:16 dynamics, a flat frequency response up to 20 000Hz,
perfect stereo-imaging and depth/width in audio staging. It is a linear responding
system with fully predictable performance without any coloration; the perfect tool
to amplify sounds as the artist meant it to be. Instead of wrestling with the system,
the engineer can fully focus on the artist’s performance without any compromise.
The engineer can make a “rock “n roll system’ out of it, a “classical system’ or a flat-
response system. It gives the creativity back to the engineer.

Is the Pro-RBN driver in the LR24 a completely new design?

Yes, what we call the “02-platform’ is a completely new Pro-Ribbon platform,
developed by Philip ’Dr Phil” de Haan, my partner in the company and initiator of
numerous patents in the field of Pro-Ribbon transducer technology since 1986. It
sets a new benchmark in terms of efficiency and output capabilities. The
RBN1402rsr is a 14-inch Pro-Ribbon transducer with a 14-inch voice-coil, a power
handling of 3000W plus an efficiency of 112dB 1W/1m and flat to 20 000Hz. In
output performance, this surpasses even the most powerful compression drivers
(even in multiples).

Have there been any patents applied for in the design of the LR24? If so,
how many
and for what components?
Yes, there have been. Two new patents on the RBN1402 based on optimising
efficiency, a patent on the amplifier technology and a patent on the flying system.
In total the RBN1402rsr in the LR24 contains four global patents and pending patents
alone. One thing is to have a patent, but the more challenging is to maintain it
against the “copy-cats’ in this industry!

What do you see as the primary application for the LR24?
Well, looking at the output capabilities, the system can be used in even the largest
applications (touring, concerts, in / outdoor). But if you look at the sonic qualities,
the LR24 could even be used as a studio monitor! If you look at the impulse-
response of the LR24 compared to our VR8 compact reference monitor, the LR24 is
even better / cleaner!

As the system is perfectly linear throughout the SPL range as well as the frequency
response and also does not colour [the sound], it is not a typical rock “n roll system,
or a classical system. As such, it can be used for any type of event; pop / rock /
classic / jazz / speech, from low to high SPL applications.

What can we expect from Alcons in the future?
The structure of our R&D team enables us to undertake more progressive-focused
developments, whereas we stayed more main stream until now – new technology in
market-proven concepts. Our pay-off is “evolutionary audio solutions’. It may be
time to focus on “revolutionary audio advancements’. But, for now the LR24 will be
further developed; not in terms of hardware, but in terms of software where we can
utilise more control options in the DSP processing (ie. beam steering additions).