Mod: (w Beamshots!) UltraFire T90 (TF X6 Clone), Cree MT-G2 Emitter Swap

has the relative position of the base of the LED and the base of the reflector changed at all? Does the MT-G2 fill the hole at the bottom the same amount as the SST-90? Are the emitter angles the same? Are you able to vary the reflector height above the LED and measure the output? Might be worth trying to shim it out a bit and see if that makes a difference. Almost a 1/3 of the output lost is pretty high, what a bugger. Are there any other large reflectors that would fit? I remember Troutie tested a bunch with an MT-G2, although I think the one he like was 80mm in diameter!

thanks for the info

i suspect we’ll eventually figure out how to get the most out of the mt-g2

it has been tough at work for a bit but I hope to get back to my project soon

The position is very similar, which I think is not deep enough in the reflector. This MT-G2 seems to throw a lot of light sideways. It also has a thinner base so the reflector needs to go deeper into the head. The head design isn’t ideal for fine adjustments.
The dome size is similar, but the emitter surface area is larger. This is where part of the throw goes away I think.
I think the emitter angle is slightly wider, didn’t check the specs yet.
The output is droping a lot, I will do a bare emitter test on the SST-90 tonight to see if it suffered similar losses.

Do you mean that the driver is not able to regulate output very well? Or just that reflector is absorbing a lot of light?

hmm, from my minimal experience with changing XR-E lights to XP-E/ Nichia (plus an incorrect optic holder on an XM-L), you would expect more of a spot/ throw from having the reflector sit too high, at the expense total light output. When I machined the heads on my modded Romisens so that I could screw the reflector down further, I actually got more of a flood past a certain point. Correct focus seemed to be about 1/2 way between fully screwed in and the previous height. That depends on reflector of course, but it might help.

If the emitter surface is larger, most likely you’ll need a larger diameter reflector to get the same amount of throw. Not much help I’m afraid :frowning: Still, might be worth checking to see if there are MT-G2 specific reflectors in the diameter you can use - changes to the reflector profile might help mitigate some of the focusing issues.

the thing is, the emitting area isn’t as big as the dome makes it seems

mtg2, mtg2 badly dedomed, sst-90 (which has since been dedomed, well :stuck_out_tongue: )

If I were a betting man I’d put money that if dedomed you’d see a huge change in lux. I’m thinking that the cause for your issue is the dome on the MTG-2. You have two of them. Dedome one and see how it works in your torch.

that sounds suspiciously like an experiment :slight_smile:

Actually I have 5, and two have been destroyed by de-doming :Sp
the 2nd attempt was close to success, and it is highly likely I would succeed if I try a third. I haven’t decided yet, but curiosity usually gets the better of me.

I did a reflector position ceiling bounce test, and reflector position wasn’t a significant factor in overall output (unless much too far away). I didn’t test lux relative to position.

It will be interesting to see if relic gets reduced output when he tests the sst-90 bare and with reflector.

My power supply only goes up to about 6.5A, so I tested it at the max available.
Bare SST-90 at 6.5A: 1582 lm
SST-90 with T90 reflector/Lens: 1106 lm
OTF output is 70% of the bare emitter.

Bare MT-G2 at 5.0A: 2810
MT-G2 with T90 reflector/lens: 1900’ish
That puts OTF at 68% of bare emitter.
The losses are basically matching. Not looking good for this reflector/lens…

As a control, I took an XM-L at 3.0A and measured bare and then with a HD2010 reflector/lens:
Bare XM-L U2 at 3.0A: 1036 lm
XM-L U2 with HD2010 reflector/lens: 728lm
Again, OTF is about 70% of bare emitter.
I suspect some of this discrepancy is due to my integrating box not integrating perfectly. Another 8-10% is in the uncoated lenses. The numbers may be close to real. I may need a small ‘box’ factor to adjust for focused sources.
Mule/bare emitter sources appear to be somewhat accurate.
I hope to get more time for this on the weekend; the next day or two will be rather busy for me.

Posting up some info on the Luminus SBT-70:

http://kaidomain.com/product/details.S020860

German Video:

to be honest, the general rule of thumb is OTF lumens = 70-80% of theoretical lumens (bare LED, cooled well), so while 70% is at the lower range, I don’t think it’s completely out of line. I’m also fairly certain that reflector efficiency for a given effective emitter area increases with diameter (I think TIRs stay fairly constant). I don’t really know how big either of the reflectors you used are (not very familiar with torches), but it could be that you’re on the lower end of that efficiency curve.

You’re still getting almost 60% more OTF lumens with the MT-G2 though, which is not to be sniffed at!

I added a small update in the first comment
With my new light meter I measure a more expected OTF output of 2230 lumens. Throw measurement is about the same, since the faulty meter seems to be a problem on the 50k scale only (I measure throw at 3.65m usually).
More to come… contemplating my next move. :wink:

Well you have certainly given this mod a good shakedown. I think it was in one of troutie’s posts that he found that the MTG2 simply doesnt have the surface brightness to be a monster thrower in spite of the plethora of purpose built reflectors he had to play with. Placing 3 XML’s together via direct bond (so the emitters were about touching) produced some rather spectacular results in a large reflector. If you give up on that monster cree, maybe try 3 of the smaller ones all jammed up together. They seem to enjoy each others close company!:smiley:

I’m starting to like the floody nature of it. Plus, the NW tint gives it a real throw advantage; the air doesn’t seem to light up as much.
I may dedome one and see what happens… dunno for sure.

It sounds like youve struck a great useful combination. Range, flood and great tint… all in one. Id guess the SST90 that came stock would probably be low bin. I wonder if a nice new SBT-70 or SBT-90 would be a worthwhile investment? They arent exactly budget emitters though. If it were mine, Id live with the big fat cree for a while and see how that goes.

Nice mod relic38 complete with ongoing experiment. Any thoughts on some beam shots?

Beamshots are planned. At the least, brick wall shots from 40 yards or so. I think I have comparison shots from the SST90 resistor mod.

I’ve added some outdoor beamshots to the first comment, here
I think I’ll keep the MT-G2 in there. I see no need to go back to the SST-90. I have the BTU for reach and the UF-T90 is a searchlight with a giant NW spot.
Because of the tint, it reaches quite far without lighting up the air too much.
Am I done? For now… I may come back to this. I have another MT-G2 mod that I’m itching to start :wink:

Why do I miss so many threads?

I would think (having played with an MT-G2), that it would not be at all suitable for a "thrower", but great for a flood light. I think when you talk about the die size and surface brightness, the texture of the surface also has to be taken into account. It seems like that led was designed for use in flood lights, to cover a wide area. Maybe it would be worth a try with a very large aspheric (in the 100mm range). That might come out better.

Anyhow, it's an interesting test of the led.