These lamps have a round ‘bulb’ and are designed to retrofit anywhere you would use a normal tungsten filament lamp. They are LED versions of what are often called GLS or A-line lamps. Some of the bulbs are frosted or opal and some have visible LED ‘filaments’. All the lamps claim to be dimmable.
It is worth remembering that a 60W tungsten filament lamp produced about 700 lumens. This much light from a bare filament was usually considered to be too glaring and so people fitted lamp shades over them. Alternatively, the bulb was made with an opal or frosted finish to soften the effect.
Of course, the difference is found in the better efficacy. The average of the LEDs we tested was 95 lumens/W, compared with 10 lm – 12 lm/W for a standard tungsten lamp. That’s an 85 percent saving in energy.
We tried the lamps on two different dimmers. One was a traditional resistive load type of dimmer used for tungsten filament lamps. The other was a more sophisticated unit designed for retrofit LED lamps. The purpose of the test was simply to highlight whether there were likely to be any problems or, conversely, lamps which performed particularly well. We could not test every combination because there is such a wide range of dimmers on the market.
All the LED lamps worked well on both dimmers but this may be because we also had a 70W incandescent lamp in the circuit in order to make a fair visual comparison when dimmed.
None of these lamps became warmer as you dimmed them. Most of the lamps were 2,700K, which is similar to a tungsten lamp.
We only tested lamps from reputable suppliers. You can find thousands of horror stories on the internet concerning lesser known brands.
Data is as quoted by the manufacturers
Crompton LED filament GLS
Crompton has been manufacturing since 1878 and it is good to see a trusted name revived. The lamp was above average in efficacy but had a lower quoted life.
It doesn’t appear to dim as low as some but maybe that is due to the higher output at 100 percent.
The diffusing works well on this lamp and so you get a uniform glow over the 220° beam. Efficacy is mid-range but you get a longer life than most. Subjectively, it doesn’t appear to dim as low as some; again, this may be due to the higher output at 100 percent.
This is an interesting lamp as Factorylux deliberately reduced the light output and wattage in order to reduce the glare from a bare bulb. The pear-shaped lamp we tested is often used in coffee shops and places that have a retro or ‘industrial’ interior design. The reduced output gives much more comfortable viewing and it dimmed to a much lower level than some. It is also Warmer in appearance at 2,200K.
You can see that this lamp is slightly flatter in appearance and the base is larger than most. Other similar shapes are available for the same type of lamp. It benefits from a longer life than most we tested. Subjectively, it doesn’t appear to dim as low as some; again that may be due to the higher output at 100 percent.
Unlike many suppliers, I can’t remember ever having a poor lamp from Integral. This filament style lamp is another good example. It dimmed to a lower level than most and it is also in the top group for efficiency.
Ledvance is the new name for the Osram lamps business. You can see that this is one of the most efficient lamps we tested and it is also a trusted brand name. The diffusing is less than on some lamps and you can just see the brighter filaments inside; just like an opal tungsten lamp.
On our dedicated LED dimmer, this worked very well and dimmed to a very low level. It has a lower efficacy than most we tested but it has a small bulb and would be useful where you want low levels of illumination.
We tested the warm white version with a clear bulb. It has above average efficacy and dims to a low level. They also make a similar lamp described as Flame. This has a slight gold tint on the glass and is a bit warmer. They do not quote the colour temperature of the Flame, but my guess is that it is around 2,200K.
Sylvania is another company that, in my own personal experience, makes consistently reliable lamps. This one dims smoothly and is in the top group for efficiency. You can see that it has a clear bulb and, like other lamps with a clear bulb, you might prefer to use it with a shade.
The diffusing works well here, so you get a uniform glow over the 240° beam. Like many of the lamps, it emits over 800 lm at full output, so you get a lot of light from a small item. The efficacy is a bit lower than average.