Sylvania Hi-Spot ES50 - The First GU10 Product
Despite the phenomenal success of the MR16 display lamp for professional display lighting, its requirement for a low voltage step-down transformer proved to be an obstacle to its penetration into domestic and semi-professional applications. PAR and R lamps continued to hold court for many years, but were losing popularity on account of their large dimensions and the lack of sparkle from their flat optical surfaces. With groundbreaking fashion, Sylvania invented a major new format in 1996 to offer the best of both worlds. Dubbed ES50 (= Extra Short 50mm) it offers the size and aesthetic appeal of the sparkling MR16 product, while operating directly from the mains supply without the need for any transformer.

It was made possible thanks to the unique miniature W-shaped filament, in which a 230-240V coil measuring some 25mm long is folded into a tiny halogen capsule small enough to be focussed in the 50mm reflector. The capsule is made from aluminosilicate hard glass instead of the usual quartz, because this permits the glass-to-metal seals to be made with molybdenum wires instead of the usual flat foils. There is space to seal five support wires through the seal and this is a requirement to mount the W-shape filament. A parallel invention was the GU10 base, having a positive twist-and-lock action - a considerable improvement over the fragile 12V pins.

The ES50 has since grown to a position of dominance in retail markets, despite the fact that it is less efficient than the low volt MR16. Whereas a 12V 50W lamp operates at some 20lm/W, the first 50W GU10 capsules achieved only 10.5lm/W. On top of this the larger filament results in inferior beam control. Hence a 230V lamp typically delivers a peak intensity some 3 times less than a 12V lamp of the same beam angle.
Manufacturer: Sylvania Lighting International
Lamp Power: 50 Watts  
Lamp Voltage: 230 Volts  
Lamp Current: 0.217 Amperes  
Cap Type: GU10 Ni plated + Steatite
Bulb Type: MR-50 MR-16 in eighths/inch
Bulb Finish: Aluminised reflector Clear lens
Filament Type: CC-13 Coiled-Coil W-shape
Atmosphere: 25% Nitrogen in Krypton HBr-SiH4-PH3
Luminous Flux: 525 lm  
Luminous Efficacy: 10.5 lm/W  
Peak Intensity: 1,150 cd  
Beam Distribution: 25° to 50% peak
Colour Temperature & CRI: CCT: 2700K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.460 CCy: 0.411
Rated Lifetime: 2000 hours to 50% survival
Burning Position: Universal  
Max. Overall Length: 55 ± 2 mm 2¼"
Light Centre Length: N/A
Factory: Tienen Belgium
Date of Manufacture: December 1987 Date Code 24
Original / Present Value: EUR €7.20 (2004) GB £4.97 (2008)
 
References: 1) Sylvania Brochure - Hi-Spot ES50 - 1997
2) Sylvania Prijspocket Benelux - 2004
3) Lighting Equipment News - Hanover Fair Review - May 1996 p.10