They’re my favourite lightbulb ever; had to look up the name from my Amazon order history, and they appear to be in the Philips WarmGlow series, though that Philips link has nothing like the bulbs I bought, and nothing in a UK-standard B22 bayonet fixing. The one I bought is here - am undecided whether to stock up on my favourites that now seem to be obsolete, or check out the latest model. The old model claims 60 W standard incandescent equivalence (about 40 W halogen) for an 8.5 W power draw. Anyhoo, it’s great to have an efficient, long-life bulb that colour-shifts red-wards as it dims, just like the setting sun. Good colour rendering too (CRI >80), which is a must. I hung onto incandescent halogens during the era of CFL fluorescents as the latter had appalling colour rendering and messed with my FM radio signal, but now that decent LED bulbs are available I am a total convert.
The people over at Clear Lighting have a great page on the spectral and efficiency differences between warm and cool white LEDs. It’s the universal law that states You Can’t Have Everything, so a high-CRI warm white (red-ish) LED will chuck out fewer lumens per watt than a low-CRI cool white (blue-ish) LED.
There was always a clear distinction in the quality of light between incandescent and fluorescent lights. The thing about kelvins just replicates that distinction, as far as I can tell. Didn’t like fluorescents, don’t like “daylight” LEDs.
There are three parameters, and I think you’re mixing up two of them.
First is brightness. Most people who grew up with incandescents think of this (incorrectly) as measured in watts, as incandescents have a pretty linear relation between watts and brightness. Since flourescents and LED each produce more light per watt, thinking of brightness in watts becomes unhelpful even with the “x watts equivalent” labeling on LED bulbs. As mentioned upthread, brightness is properly measured in lumens.
Second is colour temperature.This is measured in Kelvins, and is the colour emitted by a blackbody radiator at that temperature. Think of this as scaling up through the visible spectrum of light from red through the rainbow of colours all the way to blue. The important numbers to remember are ~3000K for a warm yellowish light like ye incandescents of yore, and ~5500K for a hard white “daylight” light more suitable for workbenches or the like. No colour is any higher quality than any other. They’re just light peaking at different frequencies.
Third is Colour Rendition Index (CRI) which is a measure of quality - specifically relating to the accuracy of our perception of colour when lit by the light in question. Incandescent lights glow at all frequencies. While peaking at that yellowish frequency, they shine in a broadband fashion because they are, after all, blackbody radiators themselves. This lights objects of all colours roughly equally, and leads to near perfect CRI. LEDs operate in a fundamentally different fashion. They produce light at a single frequency, or at just a few frequencies, and then various tricks are used to convert some of the light to some other frequencies. But the resulting output is not the smooth curve of frequencies of a blackbody radiator, but a bunch of spikes at a few specific frequencies, kind of like how the white produced by an LCD monitor is a whole bunch of red, green, and blue pixels lit at the same time. But if you shine a bunch of red, green, and blue light at a brown object, it will look kinda much reddish gray, not brown. So CRI is measuring how well the LED is modulated to put out enough light at enough different frequencies to allow us to see things in reasonably true colour. Sadly, CRI ratings are not displayed much on bulb packaging, and aren’t even easy to find looking at more detailed specifications.
Flourescents have absolutely atrocious CRI, which is one of the primary reasons most people don’t like flourescent lighting. Lots of ‘daylight’ LEDs have pretty bad CRI too, but there are some high CRI daylight bulbs which produce pretty much noontime sunlight lighting. It still isn’t really pleasant in most residential settings where most of us prefer a redder cast to our light, but for work spaces and the like they’re excellent.
Since this factor isn’t given on any of the lightbulb boxes I’ve been looking at, it’s irrelevant to me. I’m just interested in brightness and colour.
I think they’re terrible in the workplace. The building maintenance people swapped out the fluorescents in my office for LEDs. They gave me a migraine within 20 minutes. I had them all taken out and outfitted my office with incandescents (old) and 2700 k lamps. I’m not the only one to do so. Lots of discussion that management should provide us with green eyeshades:
Since 2020 California has had somewhat more stringent requirements for light bulb efficiency & quality than the rest of the country has. You can read all about them here:
Importantly, the requirements are not just on light emitted per power used, but also involve color rendering (so not entirely off-topic after all!) and spatial distribution of light. Some crappier LED bulbs might not meet these requirements. What’s more, any bulbs sold in CA have to be certified as meeting the requirements by a state board; I could totally believe that manufacturers & vendors are choosing to sell down their old stock outside of CA rather than going through the process of getting them certified, even if they might be compliant.
Look up Big Clive’s YouTube video about “Dubai Lamps.” They use more LED elements/filaments driven at lower power. They cost a little bit more to manufacture but they use half as much power as typical LEDs (3W for a 60W equivalent) and last twice as long as their counterparts which drive fewer elements harder. They’re not sold outside of Dubai and good luck finding any other manufacturers of something similar because, you know, there’s profit to be had. California could force these companies to offer up the better technology too.
It’s also standard photography terminology, so if you do any color photography, it’ll be useful to understand as well. (Back in the film days, transparency/slide film would be sold either tungsten balanced (3200-3400K) or daylight balanced (~5500K), so if you wanted a neutral white in a scene lit by incandescent bulbs, you’d shoot with the tungsten balanced film (or use blue filters). So, with 5500K in the middle, anything higher is bluer light, anything lower is more amber light. I do have some daylight-balanced bulbs with high CRIs in my house where I want to review prints and stuff where a daylight white balance is important, but in living areas, I find daylight bulbs clinical and psychologically maddening and opt for something “warm” around 2700K-3000K. On the other hand, my brother likes much cleaner whites, so he goes for 4000K-5000K. I do find those color temps more appropriate for something like a workshop or home gym. Even a kitchen I might step up to 4000K, though right now I have 2700K. Bedrooms definitely 2700K-3000K for me, dining room can go a little cooler, 3000-4000K. Living room I like warmer (2700-3000K), too. But it’s a bit of personal preference. I would try out a number of color temperatures and try them in different rooms and see what you like.
Lumens are a better guide to getting the brightness you want, than Watts. But they still usually grow in proportion to each other. So between a 6W LED bulb and a 8W LED bulb, the 8W bulb should be brighter. Compare the respective lumens, too.
Back when bulbs were measured in Watts only, they were measuring power input, which made it easy to calculate e.g. your electricity bill based on how long you had the bulb on. But incandescents are really inefficient; they produce mostly (invisible) heat, which means, to me anyway, they’re more like glass bulb heaters. Remember those toy ovens for kids (Easy Bake, Holly Hobby, etc.)? They use a light bulb as a heat source.
Some light results from these bulbs, a small fraction of the input power. What you want is bright light without all that unnecessary, wasteful heat. The modern LED bulbs are moving us closer to that ideal, so much so that it’s better to use Lumens and not Watts to measure light output.
I just bought 4 of those, and put two in my bedroom fixture. And they hum. It drove me nuts and I had to replace them. You’re the third or fourth person who has recommended them to me, so I don’t know if it’s just my fixture, or I got bad bulbs, or something else.
They did look nice.
One thing to be aware of is that if you buy LEDs that let you select their color (kelvins) they often look better in the middle choices than the extreme choices – my guess is they are used multiple, um, lighting thingies, and have a higher CRI as a result.
I’m very sensitive to CRI, and I’ve liked the CREE bulbs, although they tend to fail sooner than some other brands.
I have dozens of all shapes and sizes and no hum that I have ever noticed. Is there a dimmer? I’ve had issues with bulbs humming on older dimmers that seem to have issues with the low current.
Pretty sure the Philips bulbs have two color temperature LEDs and basically dim them at different rates. I had some in outside fixtures here in the desert and after the summer all of the high color temp diodes died so the bulbs have warm light all the time.
Yes, of course they are on a dimmer. I don’t understand why anyone would buy a bulb that changes color as you dim it if they didn’t intend to use it with a dimmer.
(sorry to sound cranky, but this is the third time I’ve been asked that about this story.)
I, too, have dozens of LEDs in several shapes, sizes, and colors around the house, and this is the first time I’ve noticed a hum. I’ve had issues with some flickering, but not with sound.
I meant to say that I have dozens of Philips Warm-Glo bulbs in use, none of them hum. I have heard that some dimmer/bulb combinations can cause hum (I had a hum issue with a different brand years ago).
Trailing edge dimmers are good with Dimmable LEDS.
Older Leading edge dimmers flicker and hum with Dimmable LEDs. So maybe change the dimmer.
Then there is the electronics within the dimmable LEDs themselves. Some struggle to produce a smooth dimming effect with a temperature change similar to a tungsten filament.
Finding the right combination of dimmable LED bulbs and a compatible dimmer……it is a challenge. But there are some manufacturers that are better than others, but they cost more. Especially if you have a lot of decorative bulbs in your light fitting.
This retrofit corner of the LED market tends to develop quite slowly.
Various sources I’m finding online indicate that LED bulbs actually work well in cold temperatures, unlike compact fluorescent bulbs, which often struggle in the cold.
D’oh…