L'Acoustics K1 (left) and Martin Audio MLA (right) in position on the test site

As a top audio rental company that now encompasses Wigwam and Canegreen, SSE Audio Group knows it is vital to have the best systems available to provide to its clients.

In recent years, SSE Hire has focused its investment in L’Acoustics K1 and K2 systems - the latest line array technology from the French manufacturer that pioneered the field of modern line source array loudspeakers with their V-DOSC system over 20 years ago.

The addition of Wigwam hire means the company also offers d&b and (through Canegreen), MeyerSound.



A data recorder deployed by Vanguardia at 150m measuring position.









“We are committed to providing our clients with what they want and in the large outdoor festival market, that usually means what the client needs to please audiences while keeping within the local authority licences for off site noise limits”, stresses SSE Senior Project Manager, Miles Hlllyard.

“Each year we reinvest considerable sums into systems and all the other bits and pieces, so it’s important we make the right decisions”, Hillyard continues. “We believe in loyalty to our key suppliers, but it is also important that we remain independent from the main manufacturers and are not afraid to consider alternatives.”

At the start of 2014, the new Martin Audio MLA system provoked considerable debate within SSE. As SSE MD John Penn notes: “Here was a new system that was receiving considerable publicity and Martin Audio were positioning it as something of a ‘magic bullet’ for challenging outdoor environments - so as we regard ourselves as the UK’s leading festival PA provider, we have a duty to make sure we are using the best tools available.”

SSE provided systems to more than 25 festivals over the summer of 2014, many of which are potentially challenging with regard to off-site noise restrictions, so it was probably no surprise that SSE’s hire team decided to explore the possibility of purchasing the MLA system.

Investment in yet another system could not be taken lightly, so SSE resolved to try and obtain empirical evidence of the MLA’s efficacy. There was no shortage of rumours.

SSE Project Manager Dan Bennett explains: “We were made aware of a comparison test between MLA and (L’Acoustics) K1 that was being cited in a number of publications as evidence of the MLA's capability. The test, undertaken in 2013 sought to replicate the PA format for Hyde Park. But the more we looked into this, we felt it was by no means a ‘head to head’ test. In fact each system was tested on different days and with different weather conditions.”

“We quickly concluded the only way to obtain the information we needed was to carry out our own test", Miles Hillyard adds. "However this had to be done as independently as possible.”

To create a completely fair and valuable comparison, SSE realised the following parameters would be vital:

the full cooperation and involvement of the respective manufacturers, enabling them to set up their own systems to produce the best results

the respective products to be set up in an outdoor environment, side by side and set up mechanically and electronically as closely as possible

measurements to be taken at defined points on-axis, off-axis (30º and 60º) and behind the PA at various distances using pink noise and music.

all measurements taken and processed by respected independent acoustic consultants.

the tests to be fully paid for by SSE Audio Group, enabling the company to fully utilise the test results.



Representatives from SSE, Martin Audio and L'Acoustics listening at 50m.





Off-Axis measurement position at Hatfield (click to enlarge)





Diagram showing the planned positions for on-axis and off-axis measurements at Hatfield Park (click to enlarge).



Hillyard explains: “We approached both L’Acoustics and Martin Audio, and both were extremely cooperative and keen to participate in our test. I drew up a detailed test plan to enable us to evaluate the two systems on a head to head basis and we submitted our proposals for the test to both manufacturers to ensure they were confident that each system would have a ‘fair crack’. We appointed Vanguardia Consulting to take the measurements and collate the results, as they are respected by all concerned.”

So it was, on a cool spring day last March that two line arrays were erected in Hatfield Park in the Hertfordshire countryside for a sequence of tests managed by Vanguardia and with the active participation of representatives from L’Acoustics, Martin Audio and SSE.

"On the day we were really pleased with the co-operation we received from the two brand's teams", says Dan Bennett. "Both L'Acoustics and Martin wanted to ensure their own system was set up properly and everyone involved was just really positive."

A single hang of each system was positioned as close to each other as possible using the same length of line array. All parties agreed this would comprise 12 x K1 and 14 x MLA respectively.

The objective was to mirror the mechanics of the systems as closely as possible, while accepting that some differences were inevitable due to the nature of the two products. Each system was set up to cover an area from 10m to 100m. The two arrays were then set to a dB(A) target of -6dB over distance before the eq of the arrays was normalised using SMAART, with six proving microphone locations inside the listening area. The two arrays were then tested, with a series of measurements taken outside the listening area. Both pink noise and music tests were carried out, alternating between the ‘A’ and ‘B’ system. A total of 114,750 measurements were recorded in all.

Once the results were collated and verified by Vanguardia Consulting, a report was submitted to SSE, who shared this with both L'Acoustics and Martin Audio. A link to this report, which includes a detailed description of the test methodology, can be found at the bottom of this page.

Basic Interpretation of the Test Results

On-Axis

Levels were set and equalised to deliver matched SPL from front to back, recording 105dB(A) at 50m from the line arrays on-axis (ie notional centre line from the two arrays at 90 degrees to the loudspeaker front). The 50m position was deemed to be the typical front of house position. Measurements were taken at 150m with further points ‘off site’ at 200m 300m, 500m, 600m, 700m and 820m.

Hillyard noted: "We would expect each system to deliver the optimally high SPLs to the audience area and would then drop off rapidly outside the chosen coverage area.".

The most striking result was the similarity in measurements of both systems. The MLA system achieved marginally better results than the K1 system on-axis beyond 550 meters, although both sets of measurements would be acceptable in terms of typical off-site maximum levels.

These results were not what Dan Bennett and the SSE team were lead to believe: "Having heard the various rumours and read the claims in the industry press before these tests, it was the On-Axis measurements where we expected a significant difference between the two systems - so we were surprised just how similar the readings were."

Off-Axis

Measurements were taken at both 30 degrees and 60 degrees off axis, at distances ranging from 50m to 600m. Levels of 105 dB(A) were set up for measurement at 50m - both at 30 and 60 degrees off-axis. Further recording points were set up at 150m, 200m, 400m, 500m and 600m.

Again, the results for both MLA and K1 were quite similar, although in this instance the K1 had the edge over the MLA in terms of reduced level at the furthest recording points.

Rear of Stage

Measurements were also made at positions directly behind the PA systems at 50m, 100m and 150m from the source. While measurements for pink noise from the two systems were very similar, the most marked differences between the two systems were noted when music measurements were taken. The MLA system was recorded at about 2.8 dB(A) louder at 150m than the K1 system.

The relevance of this to ‘real world’ scenarios was pointed out by SSE’s Senior Project Manager, Miles Hillyard:

“When you are working on outdoor concerts in parks or on green fields with sensitive off-site areas, the stage is set to avoid pointing the PA in that direction. Often, the stage is positioned with its back to a sensitive or densely populated area."

SSE Audio Group’s Conclusions

The hire team at SSE believe that both L’Acoustics K1 and Martin Audio’s MLA systems are ‘fit for purpose’, performing well as PA systems for outdoor events. The SSE ethos is that it is so much more than the technology that is significant - it's the people behind the system that makes the difference.

Key People at the Tests 25-03-14

Florent Bernard - L'Acoustics



Dan Orton - L'Acoustics



Andy Davies - Martin Audio



Jason Baird - Martin Audio



Mark Pantlin - SSE Freelance Engineer



Simon Gladstone - SSE Technical Manager



Dan Bennett - SSE Project Manager



Miles Hillyard - SSE Project Manager



Mark Muphy - Vanguardia Consulting



Jim Griffiths - Vanguardia Consulting







Hillyard concludes: “The artist's production and front of house engineer may well judge one system preferable to the other in terms of audio quality, but that’s a fairly subjective matter. Generally we've found the K1 is more rider friendly when dealing with international acts with world class engineers. But what we were interested in was creating, as far as possible, an objective assessment of system directivity. In those terms our conclusion is that there is very little to choose between the results of each system apart from a slight disappointment with the MLA’s measurements behind the stage. As a design tool, this test supports our view that the K1 is more directive and therefore a better choice of system for minimising noise pollution."

John Penn adds: “The similarity in performance of both systems leaves us confident that L’Acoustics will remain our system of choice for the most challenging of outdoor environments. We are convinced that the most important factor is the specific system design for an individual event and the optimum distribution of sources across the site. We believe that the K system as a whole, in the hands of our experienced audio designers and engineers, can deliver what the market demands in all respects. Therefore we will continue to expand our L’Acoustics inventory and see no need to invest in an alternative system at this time.”

“We have decided to make the findings of our tests available to the industry to counter some of the rumours and claims that have been swirling around for the last 12 months."