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Soraa AR111 range

Issue 82 December / January 2014 / 2015

Aiming to turn the world of LED lighting on its head with its GaN on GaN technology, Soraa introduced its range of AR111 lamps earlier this year. David Morgan takes a look at the benefits of the range and how they truly compare to that of a halogen lamp.

The general view at the outset of the solid state lighting revolution in the early 2000’s was that only dedicated LED luminaires could provide the full reliability, light quality and efficiency possibilities inherent in LED technology. Retrofit LED lamps that could be used with existing luminaires were considered to be suitable only for low-end applications where short life and light quality were not important.

Soraa has turned this idea on its head over the past couple of years by incorporating its proprietary Gallium Nitride on Gallium Nitride (GaN on GaN ) technology into a range of retrofit lamps where the light quality and lit appearance is so close to halogen that in many situations it is hard to tell the difference.

Soraa was formed in 2007 by a team of pioneering professors from the worlds of engineering and semiconductors - Nobel Prize winner Dr Shuji Nakamura, inventor of the blue laser and LED; Dr Steven DenBaars, founder of Nitres; and Dr James Speck of U.C. Santa Barbara’s College of Engineering. They came together with funding from Vinod Khosla to develop and commercialise GaN on GaN technology for LED lighting.

It is understood that the nearly flawless crystal structure of Soraa’s GaN on GaN LED allows it to operate at currents that are more than five times higher than LEDs built on non-GaN substrates such as sapphire or silicon carbide. As a result, Soraa’s LED emits five times more light from a given LED area than any other LED. The advantage of the smaller light-emitting surface area is, when used in conjunction with an advanced prismatic lens narrow beam angles down to nine degrees can be achieved. Using a single emitter also results in a single sharp shadow that is very similar to halogen.

The GaN on GaN structure also results in a higher overall efficiency that Soraa employs to produce light in the purple area of the light spectrum rather than blue used by most other LED manufacturers. The purple light is used in conjunction with a tri phosphor coating to produce white light in a continuous spectrum with a deep red R9 >90. The spectrum follows the black body curve more closely than blue-based LEDs and without the potential for the circadian rhythm disturbance that blue light can induce.

Unlike blue LEDs - whose emission starts at 430nm - Soraa’s spectral emission begins at 400nm, which provides fluorescent excitation needed to discriminate clearly between shades of white giving much more natural looking whites.

The initial Soraa product range, introduced over the last two years, was based on an MR16 size lens and heat sink and a GU5.3 pin base for use with a 12V power supply, as well as a GU10 base version for use direct from 230V AC.

In addition to the ground-breaking advances in LED emitter design, Soraa also developed an ingenious magnetically connected SNAP range of beam shape, glare control and colour temperature control accessories. This is a simple design idea that transforms a retrofit MR16 lamp into a lighting designer’s adaptable tool kit.

Earlier this year, Soraa launched its new AR111 range at Euroshop. This lamp incorporates all the advantages of the MR 16 sized lamps outlined above but with much greater light output. The AR111 range is available in 4 beam angles, 9º, 25º, 36º and 60º with colour temperatures from 2,700K up to 5,000K. The AR111 is rated at 18.5W and gives an output of up to 1,200 lumens for the Brilliant 80 CRI version and up to 1,050 lumens for the Vivid 95 CRI version. The lamp life is rated at 35,000 hours.

These lamps provide over 30,000 Candelas for the nine degree 3,000K Brilliant and over 24,000 Candelas for the nine degree 3,000 K Vivid. According to Soraa these peak intensities are twice as high as other LED AR111 lamps.

To complete the range Soraa has developed a larger size set of the magnetic SNAP control accessories for use with the nine degree versions of their AR111 lamps.

I tested the nine degree Soraa AR111 Vivid lamp against an eight degree halogen lamp and the light appearance and quality of the Soraa lamp was remarkably similar to that from the halogen lamp, although the beam angle was noticeably wider and the edge of the central beam, was a bit sharper. The SNAP accessories all connected strongly to the lamp using the central magnet. The honeycomb louvre controlled glare effectively and gives the lamp a high tech appearance.

The Soraa AR111 heat sinks do run at quite a high temperature in free air which, for a conventional retrofit LED lamp, would cause me concern particularly if the lamp was going to be used in an enclosed luminaire or in a high ambient situation. However, according to the Soraa literature, the lamp has been designed to run at elevated temperatures so I assume the lamp will perform for the full 35,000 hour life without colour shift problems or reduced efficiency.

At the moment the Soraa AR111 lamps are only available as constant voltage lamps with integral drivers, to be run at 12V AC or DC.
One of the issues often mentioned by lighting designers and users about Soraa lamps is dimming. In order to get good dimming with the integral driver CV Soraa lamps the right combination of power supplies and trailing edge dimmers need to be used. Soraa now publishes a list of the recommended combinations of power supply and dimmer that will dim down to a low level. Attempting to use Soraa lamps with halogen transformers and dimmers is likely to cause problems.

For applications where 1 - 10V or DALI dimming is required the UK-based company Trulux has recently launched a range of dimming drivers that will dim 12V CV Soraa lamps down to 1% with these dimming inputs.

It would appear that Soraa has changed the rules of the LED game and that very good lighting results can now be achieved using retrofit lamps in existing luminaires if adequate air flow and volume are available. Soraa has also hedged its bets on how the market will develop in the future and will introduce a series of light engines based on its technology early next year for incorporation into dedicated luminaires. This opens up some exciting luminaire design opportunities and we have already started work on a number of developments to incorporate these light engines.


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