cabin led lights

In the light (!) of jfm's post I mailed prebit for a few more technical details on the white part of their red/white switchable lights. The core of the reply, received promptly (always a good sign) is as follows:
the CRI from all our LEDs are ~85. Basically also a CRI >90 is possible, but then the light output is reduced clearly.
By default we use 3.000K LEDs from Lumileds or Osram. It's also possible to produce the lights in 2.700K.
We use LEDs in 3-step MacAdam binning, so you will not see any color difference in the white light.
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jfm said:
Chris I think the problem there is CRI not K. After all, daylight is 5000k+

Cheap LEDs including the cold white ones make a spike of R, G and B light, and when those 3 wavelengths land on human retina a signal goes to our brain saying "white". But if you plot the wavelengths on a graph, you see a spike of R, G and B, but no light at all in say orange or purple. In contrast, the light from the sun (and a halogen) contains no wavelength spikes - it contains a roughly equal amount of every light wavelength, so when you plot it as a graph it is roughly straight line with no spikes of R, G and B.

High CRI of an LED means it makes a flat line not 3 peaks. The brain still gets the "white" signal, but when you see the light reflected in a real room or off say human skin the look is completely different and more like daylight, bringing out all the colours and textures without the flatness and ugliness of low-CRI light that is trying to reflect off the colour of human skin when all it has to [play with is spikes of R G and B with nothing in between. I'd suggest it is this factor that made the white lights you refer to look horrible, not their colour.

You can get lucky and find high CRI leds at low prices, but (and I'll get shot now...) you really need to be in the zone of £50 per light fixture, and then you get LED light that truly feels as good as halogen. Say 85-90% CRI. The choice of 2700 vs 3200 is then a secondary matter (personal choice as you say) but when you get the richness of colour and texture that high CRI lighting gives many people prefer 3000-3200
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Brilliant! - I think that explains why my cool whites in the engine room blind me to look at them but provide no light to see anything!!!!

I shall look at the CRI factor - never heard of it before and didn't realise its significance. Now to check the CRI of the lights I have bought already :nonchalance:
 
laika said:
In the light (!) of jfm's post I mailed prebit for a few more technical details on the white part of their red/white switchable lights. The core of the reply, received promptly (always a good sign) is as follows:
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That's a very good reply and would give me much confidence. ~85 is a decent number. Lumileds (phillips owned though currently for sale, far east manufacture, California technology) and Osram (I don't know them as well) are at the top end of the quality spectrum here. (As also are Cree, btw). The fact they have been binned is excellent as a lot of the ebay stuff is pretty random - unbinned product is cheaper

(I don't want to tell anyone how to suck eggs but binning is sorting out. LEDs are made in sort of large sheets/arrays and the exotic materials are applied across the sheet/array. The exotics cannot be applied perfectly consistently - imagine spraying a 1m sq panel with paint using a process that inevitably leads to heaped thicker paint in the centre and thinned out paint at the edges, and then afterwards chopping the 1m sq sheet into zillions of 5mm square little pieces - the bits that came from the middle of the sheet have thicker paint. Binning is all about separating them at this stage so you have bins of thick painted little pieces and other bins of thin painted little pieces. With LEDs it isn't about paint thickness of course but the concept is the same. If you separate and bin at the early part of the production you get bins each full of very consistent product. This is premium priced product compared with unbinned or coarsely binned product)
 
Chris_Robb said:
Brilliant! - I think that explains why my cool whites in the engine room blind me to look at them but provide no light to see anything!!!!

I shall look at the CRI factor - never heard of it before and didn't realise its significance. Now to check the CRI of the lights I have bought already :nonchalance:
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Yup. It is hard to describe light quality in words on a forum of course. If anyone is ever in Antibes I'd be delighted to show you an ultra high CRI set up on my boat. My boat is all LED from new build, zero incandescent, and the interior downlights are high CRI cantalupi. At night time when there is no sunlight to help, they really do feel better than halogens and no-one thinks they are LED, such is the quality of the light. Though I say so myself it is truly remarkable light quality. The spectrum is the full set of ROYGBIV in more or less a flat line ( a few humps don't matter, but you need to avoid the RGB spikes with nothing in between that cheap white LEDs give) and when you fill a room with that, plus fixtures/reflectors to direct it nicely so avoiding flatness and evenness of light distribution, the result can be outstanding. The colour also remains the same as you dim the lights.

But you kinda have to see it. It is hard to make the case convincingly in just words so I'll stop!
 
Chris_Robb said:
Now to check the CRI of the lights I have bought already :nonchalance:
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BTW, CRI as a measure is the subject of some debate in the industry and some folks don't like it. Alternatives have been suggested. But for now it is all we have on a reasonably widespread basis to rate the flatness and completeness of the spectrum output so I suggest stick with it for now
 
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