Armytek Prime C2 Pro v3 Warm review (XHP35 HD, 18650)

The color temperature from the LED varies by angle. If some angles aren’t getting out, the result is different. Also, different optics and reflectors blend the angles differently. Just like adding a diffusing material in front of the lens might make the beam look very different in color.

I’m not expert in this field but I’ll share you my observations. Perhaps Maukka can chime in too
The CCT and tint are highly affected by the primary (LED’s dome if any) and the secondary optic used (reflector or TIR optics). Ideally the LED will have a tiny spot - point source and a perfect sphere dome centered at the exact die center. This will make the LED emits light with perfect 180° light distribution with no diffraction at all. Each light ray will exit the dome at 0° relative to the entry point out off the die. But this is not possible because there’s no such thing as a point source, the die requires a dimension.
Because of this, each light rays closer to the outer dome radius will be diffracted more than those in the center. This means the light rays from the outer die will exit the dome at angle, farther from the center light ray. This what makes the lambertian light distribution in most single die LEDS. Thus, the center ray will have different CCT from the outer ray, depending heavily on the dome’s index of refraction.
Usually, the high angle emissions will have warmer CCT than the low angle emission. The dome - die size ratio gets worse as the die gets larger (same dome diameter).

And flip chip technology makes things worse as the outer light rays produced tend to be even lower in CCT because it has to pass through thicker phosphors layer.
Good optics is mandatory in this flip chip era. The primary optic just can’t handle the job unless it’s made overly large to keep the ideal proportion. In my opinion, XPG has the optimum ratio between die - dome size.
In this Armytek Prime case, most of the light says from the high angle emissions are dumped unused, upsetting the designed tint and CCT
Anyone with more valid expertise in this field are welcome to
Add/correct me.

- Clemence

clemence, maukka,
thank you for explanation :slight_smile:

Is this an issue with the XP-L emitter as well, or just the XHP35 model? I have a Prime C2 Pro with the XP-L emitter, and I’m wondering if this is worth looking into.

Also, which angle is generally recommended for an EDC light?

+1 and Bob

What great info in short thread!

BLF at its finest.

AFAIK, all current Prime models use the same optics. Just open the bezel and take a look inside, it’s very easy to open. If it’s too hard to open, you can make your own wrench from an M12 Hex bolt.



Check your Prime Pro C2 special modes (4x clicks) if it still has the voltage reading then it’s the older Prime with good TIR optic. Older Prime optic creates very clean and well defined hotspot, while Yajiamei is tighter and has good transition from hot spot to spill.

How to check:
4 fast clicks to enter special modes. Hold and release to select: strobe - fast beacon - and voltage reading like this: (long) Blink………(fast) blink blink blink blink.
The last four fast blinks will follow your battery voltage, four blinks for fully charged, three blinks 75, two blinks 50, and one short blink 25% to near depletion.

- Clemence

Ok, thanks. I’ll check to see if I have the battery check later tonight. If not, I’ll try to open it up and see what the TIR looks like.

I’m interested in one of those Yajiamei reflectors if someone wants to get rid of one or knows how to order a single reflector… i only saw an option to buy them in lots of 20 on the AliExpress link.

OK, want to see something even more ridiculous? I replaced the optic with a dimpled Yajiamei (45 degree I think) which is installed without glass. The output is now 967 lumens from 635 lumens with the stock optic. It handles heat so much better the runtime is shortened by over 5 minutes because the driver can maintain higher output in addition to the improved optical efficiency. This light is in a different class with a simple drop-in mod.

How do you measure output? How do you know the accuracy of your method?

I’m using ceilingbounce calibrated with lights of known outputs. It’s not that accurate, but the difference between optics is readily apparent, and the numbers should be approximately correct. You can even see the better thermal management in the driver behaviour.

I’m interested. Can I get an English link to these optics?

EDIT. I remember some time ago a company selling AT lights with reflectors. Any know them?

I bought a bunch of Prime A1 Pro and A2 Pro. I wonder if the Yajiamei optics fit in those. I searched and found a bunch of them but don’t know which ones fit? Does the dimensions (e.g. 20mm) refer to the outer diameter of the ring?

Sure would like to get my hands on a couple of those optics.

Edit, OK the link is working now in English. Now I gonna try and find place to order less than 20

Check this out:

- Clemence

Got my order of Yajiamei optics today.

By far the best one to replace the Prime C2 Pro (XHP35 HD) optic is the YJM-XP-20mm-30° with beads . Just remove the original centering ring first and the beam is very smooth.

Suddenly the hotspot is nice and neutral duv near zero instead of strong pink. I might still put in a minus green filter, since the lower modes are a bit on the green side.

All the other ones I tested produced some artifacts or discoloration.

Yes, there are still artifacts but still so much better than the stock one with pink circle hahaha. Also the beam transition is way better
Did you get the same increased output?

- Clemence

With the beaded Yajiamei
0 sec: 1344 lm
30 sec: 1284 lm
1 min: 1245 lm
2 min: 992 lm

Measured again with the stock optics since the original test was done with a DIY sphere
0 sec: 1135 lm (old measurement 1090 lm)
30 sec: 1082 lm (old measurement 1045 lm)
1 min: 1051 lm

So an 18% increase. Would probably get more with a clear optic, but I’m not going to use them.

Correct, the plain tight TIR produces the most OTF lumens 30ish% in my case.
With Prime max angle for max OTF output is < 20°
With Wizard ax angle for max output is < 60°
The reason is the unusually deep recession in Prime’s lens. It’s not too severe in Wizard because the bezel isn’t as tall as Prime and it’s countersunk.
I use 5° because it’s my sidekick for occasional medium thrower, 90% of the time I use my Tiara Pro for hiking/EDC.

- Clemence

I’ll be trying the 5 degree and XHP35 HI for mine. I’m hoping to get 250m+ FL1 throw with nice tint and 80 CRI.