Seoul P4 initial Evaluation- Production LEDs

NewBie

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Well, I got home less than an hour ago, and just as I'd been hoping for, my first production Seoul P4 LEDs had arrived.

I know these are a hot item for many, so without any delays, lets get some photographs.


Photographing these was a real pain, as the very, very soft gummy bear surface acts like a powerful dust magnet. I'd clean it, get it set up for a photograph, and it would have new dust specks on it, so after three tries, I finally gave up. Unfortunately, I don't have a laminar flow bench to give me filtered air.

These LEDs are rather cloudy, so I had to play a few tricks with lighting, to get an okay image.

seoulp4.jpg


seoulp42.jpg



Focused up off the die at the top of the phosphor, notice the tint variation across the die area:
seoulp44.jpg


seoulp43.jpg



I fitted one of these to a SO27XA, which isn't the smoothest reflector (I'll get it in a more perfect reflector later) which hides a number of the tint issues since the surface is rather distorted, but it was something that I could quickly get pictures of. Due to the tint variation of the image, and AWB, the camera tint kept changing slightly between shots:

seoulp48.jpg


seoulp47.jpg


seoulp46.jpg


seoulp49.jpg



For the white wall crowd, I apologize, the camera doesn't render tint variations near as well as the human eye, but that is a common shortcomming of digital cameras. The distorted SO27XA did a decent job of mixing up the tint, so the distorted reflector actually helps. I'd *highly* recommend one of McGizmos textured reflectors. The "tintyness" of the beam is probably second only to the Nichia Jupiter and Nichia 5mm LEDs- but quite a bit better than the 5mm LEDs.


So, where does the tint variation within each beamshot come from? This image should help explain that, it is the bare emitter shinning on a piece of paper:
seoulp4a.jpg



For fun, I used a high end camera lens to image the LED on a wall, and took a photo of it:
seoulp4b.jpg



With some of the smooth reflectors, I could see artifacts of the bond wires on the wall, reminds me a little bit of the hotwires. I'll see if I can get a photo of it if I have time later. Again, I'd *highly* recommend one of McGizmos textured reflectors to help out with this!


Even though this LED uses the same CREE EZ1000 die as the CREE XR-E LED, the way the optics were done, it emits much more of it's light sideways, so you have a very substantial drop in flood brightness in a reflector. But, conversely, with so much more of the light going sideways, more of it is directed forward, so this will be great news for those folks who like burning bright hotspots which throw better. Unfortunately, if tint variations within your beam bother you, you'll need to use a textured reflector to hide them, which will cause the throw to suffer.

With an aspherical lens, with a much higher porportion of the light going sideways out of the P4, substantially less hits a given sized lens, so less will be directed forward, as compared to the CREE XR-E.

Another drawback of this LED is that the slug is shorted to the positive side, where nearly every flashlight has a negative body. If the heatsink spot isn't isolated with anodizing, you will need to come up with a method of isolating the slug (hurts thermal performance- unless you are clever), or risk blowing up your LED and also the flashlight converter.

Be careful with the dome lens on the Seoul P4, it is very easy to damage the very soft gummy dome.

I think we got *really majorly* spoiled with the Luxeons, which had very little if any tint variation at all within the LED. IMHO, the magic trick for the Seoul P4 is the rough textured McGizmo reflectors. With *plenty* of extra lumens as compared to the Luxeons, you can easily afford to use a rough reflector to blur the tints, IMHO- unless you need every single lumen possible in a tight spot. Personally, I prefer spots that fade, instead of sharply cutting off.

Anyhow, I've got more testing to go do...


Some tidbits from later points in the thread (plenty of other things to dig in the thread if you are interested):

1sp4set.jpg


sp4int2.png



The above graph has too much data on it to see clearly, so if you are interested, download the larger version:
http://www.molalla.net/~leeper/sp4int3.png
 
Last edited:

iNDiGLo

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Let me be the first to say thank you for this informative thread. I bet it took a long time to photograph and write everything up.

Once again another first rate job. :goodjob:
 

EngrPaul

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:clap: I hope this means the beauties I bought won't be long behind... :D
 

Nitroz

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Nice evaluation as always! I think I will stick with the Cree XR-E.
THanks!
 

SuperTorch

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Great to know that it is throwing a lot more to the sides and that its now verified. The tint shifts don't look bad at all to me and with anything but a white wall would be hard to see. Next up is how many lumens max can you get out of them. Very Cool, Once again your picture skills are top notch and thanks for the info, when you name is on a post like this it means 300+ reponses. Can't wait for your furter analysis. :)
 

CM

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Outstanding photos and write up. Any thoughts on brightness levels compared to the Cree's? In other words, did Seoul do the EZ1000 die any justice?
 

chimo

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Newbie, great photos and thanks for the quick review. Looking forward to the rest!

Paul
 

jtice

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Thanks alot for the photos and info newbie.

Im wonder the same as CM,
are they bright enough to warrant using over the Crees?
The Crees seem to have that odd halo effect in some reflectors,
but they at least seem to have a good overal tint, and smoothness.

~John
 

McGizmo

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Nice macro work and write up Newbie! :thumbsup:

In terms of flux, I know one guy I respect who claims that Seoul is doing a better job than Cree in releasing the photons from the die and out beyond the phosphor conversion. As I stated in another thread, I don't know how we could ever know one way or the other unless there was a blatant disparity which so far doesn't seem to be the case.

The only data point I can add at present is I did compare a XR27 (DBx2-917) Cree P4 against a S27 (DBx2-917) Seoul P4 U flux in my integrating sphere and measured 119 lumens with the Cree and 133 lumens with the Seoul. A tested (at 68 lumen) 27LT sporting U bin LuxIII measured 70 lumens at this testing time. All three lights "present" to the integrating sphere in the same manner. One sample of each LED is no basis for comparison really but I will go out on a limb and suggest that Seoul isn't butchering the EZ1000 from what I have seen so far.

I have noticed that the color of the phosphor varies from LED to LED in the reel I have been working with which I find a bit surprising. Some reflectors give a gold image and others a light yellow image. The gummy bear seems to vary in clarity as well. :shrug:

I agree that there is plenty room for improvement on tint with these; both within the distribution of the single LED as well as consistency from one LED to the next. The Seoul P4 does give you plenty of reasonable if not flawless light output to work with and in a lambertian distribution which is better suited for many of the optics we have become familiar with.

To my way of thinking, the XR-E and Seoul P4 have some marked differences and depending on the application and desired distribution of light, one or the other may have a distinct advantage. I think the ease of use and retro fitting with the Seoul P4 will steal some of the XR-E's thunder at least initially but the XR-E has its own strength and qualities which will keep it well in the picture, IMHO.
 

kogatana581

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I have seen a few comments such as those below that pique my curiosity.

"...consistency of jelly with too little water. It seems the glass was held on with this stuff."

"...the very, very soft gummy bear surface"


Will this characteristic impair this LEDs reliability?
 

McGizmo

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KT,

In an exposed environment, the Cree XR-E wins hands down, IMHO. Protected in the interior of a flashlight, the Seoul will do just fine. The first XR-E sample I had ended up loosing its lens from some rough bench treatment but Cree had caushioned that the lenses were not well retained. With the production parts, I would think that the shock required to make these LED's come apart would be of a level that would do significant damage to the host itself. :shrug:
 

SuperTorch

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Well for a quick toss in a none optimized reflector the hot spot and beam dispersion looks really good to me, I know tint shift is a issue(Small to me) but I like the looks of the throw in those shots even if it is early. If it only gets better then were really in a win/win situation. Cant wait for all my lights to be 150+ lumens.
 

SuperTorch

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LITEmania said:
Newbie : Thanks for review.

newbies ; FYI
emitter%20bros.jpg

So the diameter of the Seoul W42180 is not the same as the Lux 3? In the group buy thread there seems to be different Seouls version and a Data sheet there shows one of the Seoul's as very very close to a Luxeon.
 

NewBie

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Sorry, I was gone, went to dinner it was great.

Kogatana581,

I can tell you that when you don't abuse the XR-E's dome during assembly, that they in fact do stay intact after extreme vibration, HALT testing, and crash shock testing.


Yaesumofo-

This sample of 1 so far, measures 3.758V @ 1 Amp at the emitter leads.

Lumens looks to be similar, but I will need to do fairly precise comparisions as they are close. This one is consuming a good amount more power than my reference CREE P3 I tested, about 0.378 Watts more, or 10% more.

As far as tint variation comparisions, I'll offer the following:

CREE XR-E:
creeangd.jpg


Luxeon III (yes, it is actually on a curved surface, and the smooth tint output causes a lack of depth perception):
luxtint.jpg



Seoul Semiconductor P4:
seoulp4a.jpg



Don,

Your two parts you were comparing, your integrating sphere software (which also does spectral plots) indicates the CIE x and y co-ordinates, could you offer us the co-ordinates for the two you referenced for comparision?

Also, did you check the LED current during the test, I've noticed there is a decent amount of current set point variation in the GD converters.
 
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