Cool White?

A couple of years ago I decided to buy a headlamp for reading in bed and purchased a Spark ST5-220CW. The high parasitic drain of the electronic switch should have disqualified this iteration of the headlamp from sale to the public, but that's a quality control and ethics issue (apparently improved in subsequent runs). What I want to mention is the "CW" in the model number, which stands for "Cool White". In fact there's very little white, cool or otherwise, about it: it's quite green, not just greenish in the corona like my Clicky 170, but green throughout the beam pattern. Fine, if you like green LED lights. Not so fine if you don't. Green possibly has a better CRI than the bluish-white I favor, but CRI isn't everything.

I take night walks six or seven times a week, lots of hills and trees and deer and racoons and owls around here, and I thought I'd like to experience what it's like with a headlamp. The ST5 is okay for closeup work but it's not bright enough for distant viewing and you won't get all that much run time from an AA alkaline. So I bought an ST6-500CW using an XM-L2 U2 and the redoubtable 18650 primary. This one looked mostly white in the video. And I have flashlights using the XM-L U2, XM-L U3 and XM-L2 U2. They all have some green in the beam pattern, but at any reasonable distance really appear cool white. The ST6 arrived yesterday and, you guessed it, once again "Cool White" turns out to be a euphemism for "Saturated Green". Much greener, in fact, than my ST5. Color in YouTube videos can be deceptive, but I had three XM-L lights that didn't have the green problem. What gives?

I called the dealer and he said the green has to do with the shallowness of the reflector. This doesn't explain why a greenish light is called cool white, of course. I'm don't know how LEDs are manufactured, how the phosphor is applied, but I can kind of get how the reflector angle might play a role in beam pattern color. I invite comments, and suggestions for a high quality headlamp that is actually cool white, takes an 18650 and has decent throw.

Most headlamps are designed for flood, not throw.

How far, say in meters, did you want the light to show you what's out there?

Cool white has become the "standard" since the introduction of LEDs along side incandescents. Now, the term is still around and a total marketing gimmick IMO. Someone walking thru Home Depot or whereever will pick up a cheap light becuase it says "COOL WHITE" in large font and a big lumens number.

Most people don't care. They're just impressed by the brightness.

I'm so sick of "COOL WHITES" in general. The color sucks. It's blue. End of story. We argue on CPF often about tint, CCT, and CRI but in the end most lights labeled cool white are fairly blue so I don't care what the CRI or lumens may be. I used to love neutrals, but now more and more I'm finding them to be green as well. It comes down to the "tint lottery". I happened to get lucky with tints on my Fenix PD32UE, and Zebralight H51w and H600w.

I really like the Zebralight H600w, so you may want to try it in a cool white if that's your desire.

Must be the luck of the draw...I have a Spark SL6-800CW XML-T6 whose color is closer to neutral than white. When I ordered my Spark SD6 headlamp I went with the -460NW instead...very happy with both my Sparks.

I unscrew the battery tube a half turn when not using either light to reduce the effects of parasitic drain.

Only complaint I have with the Sparks is that protected cells are a little long for either battery tube.

LowFlux said:

Must be the luck of the draw...I have a Spark SL6-800CW XML-T6 whose color is closer to neutral than white. When I ordered my Spark SD6 headlamp I went with the -460NW instead...very happy with both my Sparks.

I unscrew the battery tube a half turn when not using either light to reduce the effects of parasitic drain.

Only complaint I have with the Sparks is that protected cells are a little long for either battery tube.

Click to expand...

The Eagletacs fit OK, they're smaller than some other 18650.

TEEJ said:

The Eagletacs fit OK, they're smaller than some other 18650.

Click to expand...

I put a minor crimp the button on the head of a Readilast 2900 on the SD6 when I first got the light so instead I am using an AW 2200 in the SD6. That damaged Readilast 2900 is in the SL6 but even then I have to position the internal battery sleeve on the battery just right else the tail switch will not work - and it is tough to screw shut with the taught springs on both the head and the tail cap. IIRC the original sale thread Xyber said he did his testing with unprotected cells only.

Mind you both of the lights were first production run from CPFM too so no idea if they've changed the interior dimensions since. Other then those minor issues, I still like these Spark lights and kept both when I downsized the rest of my collection...

Cool white generally means a color temperature over 5500k, if you look at the cree LED color bin charts you'll see there's a region above the blackbody line most likely to be perceived as pure white, and regions above and below it. At low color temperatures like 2800-4000k, that usually means you get yellow above the black body line, or pink/red below it. At 5500+ those regions above and below are now green and magenta. The reason that green is more common than blue is that the human eye is most sensitive to green light, and that means the easiest way to boost lumens is to make an LED that throws more green out. ( lumens are based on our eye's sensitivity to light and dependent on color)

Cool white is mostly a holdover coined back in the day when bluish white 5mm LEDs and blue tinted "daylight" CFL bulbs were most common. The push to maximize lumens per watt on the phosphor level comes at the expense of the more psychologically pleasing blue color at that end of the color spectrum. Thankfully there have been big advances made in neutral and warm LEDs and more accurate color binning all around, so if you know what you want light modders and builders can usually accommodate without much fuss.

I only purchase lights that are sold as neutral white. I had the same experiences as the poster and decided that cool white just had to large a margin in terms of color temp. The neutral white LED's vary slightly but not enough that I am bothered by any of them. My standard way of looking for a new light is to just search neutral white on a suppliers website and only purchase lights listed in that search. Knock on wood, I have not been disappointed "with the tint" of a light since I started purchasing that way.

The Zebralight H600w is the bees' knees, in my opinion. I use it for mountain biking at night. Great throw and great tint.

+1 on the H600w. I have one and I quite like it. Very versatile output range, very efficient driver, and has battery lockout.

In Spark products, it is very easy to change the LED to whatever makes you happy, even I managed this task in few minutes. They are not glued, open the head, order the XM-L2 in tint you like on 16mm pcb, swap it and done, problem solved. And when maybe XM-L3 comes to market? Swap it again, new power for a few money, no need for new headlamp.

And one more thing - I found out that the reflector in my SX5 actually changes the tint of the LED, so I had to use 3A tint instead of my standard 3C to compesate for this. So this may be the case also in ST6.

Stanley_BA said:

In Spark products, it is very easy to change the LED to whatever makes you happy, even I managed this task in few minutes. They are not glued, open the head, order the XM-L2 in tint you like on 16mm pcb, swap it and done, problem solved. And when maybe XM-L3 comes to market? Swap it again, new power for a few money, no need for new headlamp.

And one more thing - I found out that the reflector in my SX5 actually changes the tint of the LED, so I had to use 3A tint instead of my standard 3C to compesate for this. So this may be the case also in ST6.

Click to expand...

Interesting info re: the ease of swapping emitters in Spark lights Stanley. I've never owned a Spark light but are you saying no soldering/desoldering is necessary and the existing 16mm star w/emitter merely falls out after removing the bezel and a new one drops back in? If so...do you know if this is the same feature on Spark's newest headlamps?

cyclesport said:

Interesting info re: the ease of swapping emitters in Spark lights Stanley. I've never owned a Spark light but are you saying no soldering/desoldering is necessary and the existing 16mm star w/emitter merely falls out after removing the bezel and a new one drops back in? If so...do you know if this is the same feature on Spark's newest headlamps?

Click to expand...

Well, of course you need to desolder the original PCB, pull it out and then solder the new one, but that is so easy that it really can do a child. There is nothing glued, easy access to everything, really no problem to do this. I have done this on my SX5 and now on the new SG5, I previously owned once ST6, did it there as well. This is my solution to the tint-lottery.

Stanley_BA said:

Well, of course you need to desolder the original PCB, pull it out and then solder the new one, but that is so easy that it really can do a child. There is nothing glued, easy access to everything, really no problem to do this. I have done this on my SX5 and now on the new SG5, I previously owned once ST6, did it there as well. This is my solution to the tint-lottery.

Click to expand...

Ahhh...I see...thanks. I'm a modding noob. I somehow envisioned self aligning contact pads on the bottom of the star interfacing w/similar contact points in the light's head, lol. Still sounds relatively easy though.

I have a couple of Sparks ST6 and the tints are fine in my units. Whenever you buy a light CW, there will always be a tint lottery in what you will receive.

I too would recommend modding to a XM-L2 U2 for flood or XP-E2 R3 for throw.