Sylvania Hi-Spot ES50 - The First GU10 Lamp
Despite the phenomenal success of the MR16 display lamp for professional display lighting, the requirement for a low voltage transformer was 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 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 combined the size and aesthetic appeal of the sparkling MR16, while operating directly from the mains without need for any transformers.

It was made possible thanks to the 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, this permitting the glass-to-metal seals to be made with molybdenum wires instead of the usual flat foils. There is space to seal five wires through the seal, and this is what permitted the W-shape filament in such a short capsule. A parallel invention was the GU10 base, having a positive twist-and-lock action - a major improvement over the fragile 12V pins and based on the earlier GU7 base of GE-Thorn.

GU10 lamps quickly achieved dominance in retail markets, despite being much less efficient than 12V types. Whereas 12V 50W lamps operate at about 20lm/W, the first 50W GU10 capsules achieved only 10.5lm/W. The larger filament also leads to inferior beam control, with a luminous intensity typically 3 times less than an equivalent wattage 12V lamp.
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 1997 Date Code 24
Original / Present Value: EUR €7.20 (2004) GB £4.97 (2008)
References: 1) Sylvania Brochure - Hi-Spot ES50 - 1996 Switzerland
2) Sylvania Brochure - Hi-Spot ES50 - 1997 Switzerland
3) Sylvania Prijspocket Benelux - 2004
4) Lighting Equipment News - Hanover Fair Review - May 1996 p.10