Lumintop GT4

It’s direct drive, so there is no 100%. The driver does not have an upper power limit (in theory). So yes, it will run full power on 4 cells.

Of course, 8 cells will make full power a bit brighter.

12 cells, brighter still. It’s direct drive, so feed it more voltage and the brighter it will get. With 4 xhp70.2 it might do 25,000 lumen.

The leds forward voltage will influence the output.

With the MT09R, it had 3 x 70.2 and 4 x 18650. Output varied from 15,000 lumen to 20,000 lumen depending on the leds used. The GT4 will use 4 x 70.2, so output will be higher. Then add 4 more cells and output should go up higher still.

Thanks for the excellent explanation!

So I guess this light is similar to the Acebeam X45, with bigger reflectors?

With its bigger reflectors the GT4 will throw twice as far as the X45, with its bigger size and way bigger surface area the GT4 hardly needs to step down while I expect the X45 to need a stepdown fairly soon.

Based on the reviews I’ve seen the X45 can sustain approximately 4000 lumens (basically it’s highest non-turbo power setting) until the batteries run out, with turbo lasting a minute or so. Which is pretty good. Most (all?) lights beating or equalling this are larger and/or actively cooled.

Earlier in this thread somebody working on the GT4 said it might run on turbo until the batteries ran out - which probably isn’t that long as this beast will drain batteries fast! From a full battery turbo should start out somewhere well over 20,000 lumens, but being direct drive will drop off as the battery drains. I don’t think anybody has determined the GT4’s maximum thermally sustainable output; however, it should beat any other passively cooled light on the market.

I’m hoping for a maximum regulated output of 4000+ lumens that can be sustained for as long as the batteries hold out.

Any updates? Checking back every few hours for more info haha.

Haha you and me both.

Roger that :wink:

I am also eagerly waiting for news...

Any predicted estimates for throw? We talkin 1500 meters? 1750 meters? 2000 meters? 2300 meters?

What does this head size, reflector shape, LED choice, and drive suggest it should be capable of in terms of throw?

Probably around 1500 meters like the GT70. Remember that the 70.2 is a big emitter and they are in 4 little C8 sized reflectors. The hot spot size will be larger than the GT70 which means less throw, but the fact that there are 4 emitters total makes for massive lumens which helps to extend the distance.

It would only theoretically extend the distance if it was able to supply more output to a single emitter than the GT70. However, it will surely make a much larger hotspot and much more lumens but that alone does not add or supplement throw.

I’m going to have to disagree with you. Light is cumulative. Increasing the brightness always increases throw.

EDIT: I may not understand what your saying.

Probably 3.5x the lumens and 70% the throw of GT70. 20,000 lumens and 500k lux?

Now I’m kinda interested in this host with 4 SBT90 gen 2.

This discussion is incredibly interesting, please continue with scientific evidence, beamshots and other comparisons to support each theory!

Regardless, I am a bit disappointed as I was highly anticipating 1800m throw at minimum, to match the R90TS. I figured 4 large reflectors should throw better than 18 small ones…

Perhaps the R90TS which has 1800m throw at 36k lumens according to Vinh Nguyen’s measurements may shed some scientific light on this debate?

So by this logic a C8F will out throw a single C8 of the same LED type?

I think we just need 4 C8’s being held side by side/taped together, next to a single C8, pointed at the same white wall at the outer limits of the single C8. Then just see if there is any noticeable increase in the throw of the 4 C8’s taped together.

Yes, 4 C8s taped together will outthrow a single C8. Lux is nearly linear with output increase, but actual throw is not linear with lux.

If this wasn’t true, then people wouldn’t be making multi-reflector lights like the R90TS or this GT4.

It’s the ratio of the reflector to die size that is important. The R90TS uses really small xhp35-HI leds which are about 1/5 the size of the xhp70.2 with it’s dome on.

The GT4 reflectors are bigger than the R90TS reflectors, but are not 5 times bigger. So the 70.2 emitter is just too big for throw as good as the R90TS. A sliced dome 70.2 would be better to maximize throw, but that requires slicing the dome by hand which is difficult.

See post 694 and 695.

When you have a 70.2 making 5000 lumen in a C8 reflector it’s throw distance is way lower than the same emitter in a big GT reflector (maybe 500 meters?). If you add a 2nd 5000 lumen 70.2 with a C8 reflector and overlap the hot spots the throw distance increases. Add a 3rd and the distance increases more. Add a 4th and the throw distance increases again. I hope that 4 leds and reflectors will add up to about 1500 meters. I don’t really know. We will have to wait and see the actual measurements.

EDIT: I think we would need 750 meters from a single 70.2 and small reflector to get 1500 meters from 4 of them.

I know 4 C8 reflectors can fit in the bezel of the GT, but the actual reflector design in the GT4 is a bigger diameter than the C8 with 2 sides sliced partially off. Can one of those reflectors and a 70.2 do 750 meters? IDK.

Of course throw increases. Your math shows the candela increases 4 times. That is equivalent to double the throw in meters. It’s not 4 x the distance, but just double the distance.