LED test / review Osram SYNIOS P2720 DMLQ31.SG white - Small chip, but big in luminance - at low current!

Very cool led, thanks for the test! I think I will get me both versions now and see how I can make them work in a flashlight.

In the past the phosphor layer of most Osram is more like a paste and not really solid as we know from other LEDs (Cree XP-G2, XM-L2). If it is dedomed in chemical way the phosphor came off the die too. I didn’t try a dedoming of the SYNIOS myself.
Since the SYNIOS is dedomed already, I don’t think that a higher throw performance (or luminance) can be obtained. But as I said, I didn’t test this, and my samples available are needed for a SYNIOS compilation test with comparison of all types.

Interesting on the other hand is the light color. If I mix the light of my DMLN31.SG sample up (in ceiling bounce or wirh diffusor) the color changes from white with some blue to a really nice cool white with a little bit rosy or red in it.

Has anybody told luminarium iaculator about this?

Ooh, i want to try this too.

I forgot:
Welcome to BLF, Koef3. :slight_smile:

Great news, thanks for another comprehensive test! :slight_smile:

I just did a test on my DMLQs and found them to top out at around 155cd
155/.503 = 308cd/mm^2
This is slightly worse than my DMLN LEDs did, those got up to 327cd/mm^2
Of course my tests are a lot less scientific than yours so i’ll probably try reflowing a few more another day and testing them again directly against the DMLN.

I wouldn’t be surprised though if the smaller LED gets higher intensity because of less heat.
That would make more sense, since other than the die size they’re the exact same LED type and manufacturing.

I am stuck with old XP-G2 S4 2B but who knows what future brings.

Thanks for beautiful review :+1:

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A couple mods with this LED have been done and the measured in-flashlight candela values were slightly below the dedomed XPG2.

The picture above of the lit LED and of djozz’s aspheric lens beamshot show that there is significant light coming from the areas to the side of the die. This extra light could artificially inflate the calculated luminance value (315cd/mm^2). Maybe this is not the intensity king after all.

I haven’t done any lux readings but experienced a similar thing myself in the build I am working on.
A small spot (the die projection) surrounded by a lot of extra light, coming from the white area around the LED.
It did not look any more intense (when in the light) than a black flat, although I haven’t had the chance to compare them side by side.

Please redo the test with the white area blacked out, using some electrical tape or paint (or even better, some blackout paper)

I covered the white areas with aluminium foil (I tested black paper and tape but that melting away directly on the die). I checked very carefully if the foil covers precisely the white area and not the die itself.

I placed the luxmeter 1 m away from the LED, like my earlier tests. For the so modified SYNIOS I got 216.7 cd/mm² at 2,500 mA (101.4 cd/mm² at 700 mA). Much less than I measured in the test, but still not bad for such a low current and therefore battery drain.

Enderman, thanks a lot for this very important hint and for everyone who did some real-life tests with this LED to explain what I may have wrong in this test. I always learning a bit more, especially in doing such LED reviews. :)

It’s very unfortunate that you started doing these luminance measurements just as these new LEDs started appearing.

This LEDs are on sale at least for over two and a half years (begin mass prod. Apr 15). I don't know if these emitters were already mentioned in flashlight forums.

Maybe it is better that other members doing these luminance measurements. In most cases my values seems to be wrong. I am not sure to take newly this risk for updating the luminance values because they could also be wrong for any reason.

Well yes, but we didn’t know about them.

I think you should continue ;).

As the frontier of luminance testing you stumble upon problems. That’s expected. Please don’t give up, luminance is just as important as total output.

Both me and koef made the same mistake when measuring the synios.
I only found out that we had a flaw in our testing method after three people used synios LEDs and got bad results in their flashlights.

Fortunately this is just for the synios LEDs, all other LEDs are fine and the results are still correct :slight_smile:

Actually many LEDs will have a problem with this method of calculating luminance. Any light that you see not coming from the die itself will inflate the calculated luminance. To name a few: XPG3, XPL2, luxeon V, nichia 219C, XHP50.2, XHP70.2.

That being said I find koef3’s detailed pictures and measurements to be very useful. But for the luminance measurement I think a careful in-flashlight test will give a more accurate result.

Yes,

Koef3 tests are very very good.

Final word about the certain led should be given in practical use. It can have all numbers in a world but when I “throw it” to light meter that is truly real state of matter.

Are you sure about the 219C?