# Another Cree XP-G mod .... Tower Module



## tx101 (Oct 24, 2009)

After a couple of posts from member *Justin Case*, I decided
to have a go at building a Tower Module with a Cree XP-G R5
Without his advice I never would have attempted this build
so kudos to *Justin* for spoon feeding me 

The R5s I received where purchased by member [email protected] from
Cutter. These are the R5s mounted on a 10mm board.
For the R5 to fit thru the Turbo head opening, the board had to
be reduced in size. I used pair of snips and to finish off, a file.







For size comparison, the emitter on the right is a SSCP4

Unfortunately, I did not have any spare empty Tower Modules
so I had to cannibalize a previously build Module






Here is the unfortunate donor






I used a very sharp blade and managed to remove the old emitter
intact.







The R5 has now been AAed to the Module






Now sitting inside a KT-4 head :devil:







Before and after whitewall beamshot ..... hmm they look more or less the 
same in the photo ?


From my own personal observations, I have build Tower Modules using
SSCP4s, Diamond Dragons and K2 TFFC they all have similar looking
beams. The R5 and P4 are almost identical, it is a shame I had to cannibalize 
the Module with the SSCP4, otherwise I could have taken
some outdoor beamshots comparing the two.
When compared to a Module with a K2 TFFC emitter, the R5 is brighter
and going from memory the K2 TFFC was brighter than the P4.


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## Nitroz (Oct 24, 2009)

tx101 said:


> From my own personal observations, I have build Tower Modules using
> SSCP4s, Diamond Dragons and K2 TFFC they all have similar looking
> beams. The R5 and P4 are almost identical, it is a shame I had to cannibalize
> the Module with the SSCP4, otherwise I could have taken
> ...



Wow if this is brighter then a K2 that is something! The K2 is quite a thrower in itself.


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## Justin Case (Oct 25, 2009)

Nice work. Good idea to use snips to speed up the trimming. Why did you choose to trim the MCPCB into the oblong shape, instead of a smaller diameter circle or even a less oblong shape?

See this XP-G tower build (not mine) for comparison. I like your approach of running the hookup wires straight up, without having to bend them around the emitter.

It seems that potentially a Lux focus AW tower might have a more optimum stem height than a Seoul focus tower. I've found that small focus height differences can result in small changes in hot spot lux, although the beam looks the same to the naked eye. Do you have a lux meter or a Canon P&S camera plus CHDK firmware to compare the hot spots for the XP-G vs P4?

At 1000mA drive current, the XP-G R5 should deliver about 100 emitter lumens more than a P4. Can you see a difference in a ceiling bounce test? Also, the XP-G should have lower Vf than a P4, resulting in a lower tail current draw. Do you measure a difference with a DMM?


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## tx101 (Oct 26, 2009)

Justin Case said:


> Nice work. Good idea to use snips to speed up the trimming. Why did you choose to trim the MCPCB into the oblong shape, instead of a smaller diameter circle or even a less oblong shape? oblong was the quickest and neatest. I did not want to use a
> file to make it nice and circular because I was concerned I might damage
> the dome.
> 
> ...


The problem is that the R5s I recieved have a very green tint (yuk!!!)
where as the P4, to my eyes has a very vanilla tint so will that effect the
way our eyes perceive how bright each beam is because they both look
about the same to me.
I should have taken some measurements before I swapped out the emitters 
Using a Fivemega 2 x C body with DX 25500 cells, I am getting 0.73A
at the tailcap


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## tx101 (Oct 26, 2009)

A beamshot comparing the XP-G R5 @ 1A against a K2 TFFC @ 1.5A


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## Justin Case (Oct 26, 2009)

tx101 said:


> The problem is that the R5s I recieved have a very green tint (yuk!!!)
> where as the P4, to my eyes has a very vanilla tint so will that effect the
> way our eyes perceive how bright each beam is because they both look
> about the same to me.
> ...



I hope the triple XP-G R5 I ordered will have a good tint.

0.73A at the tailcap is about 50% higher than what I've measured for multiple AW towers using Seoul P4 U2SWOH-bin LEDs and SOB1000s. For those, I consistently measure just under 0.5A at the tail for 2xLi-ion. Your result is very surprising considering the datasheet claim that the XP-G's Vf at 1000mA is 3.3V. Do you have a high contact resistance somewhere in the circuit path?


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## Nitroz (Oct 26, 2009)

tx101 said:


> A beamshot comparing the XP-G R5 @ 1A against a K2 TFFC @ 1.5A



Wow! That is a huge difference. The spot is larger and more intense and using less power than the K2.

It looks like the XP-G is a thrower after all in the correct reflector setup. Thanks for the testing. Now I want a tower!


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## maxspeeds (Oct 26, 2009)

Great outdoor shots! What is the color bins for the XP-G R5 and K2 TFFC?


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## tx101 (Oct 26, 2009)

maxspeeds said:


> Great outdoor shots! What is the color bins for the XP-G R5 and K2 TFFC?



Neither supplier of the emitters provided tint information


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## tx101 (Oct 26, 2009)

Justin Case said:


> I hope the triple XP-G R5 I ordered will have a good tint.
> 
> 0.73A at the tailcap is about 50% higher than what I've measured for multiple AW towers using Seoul P4 U2SWOH-bin LEDs and SOB1000s. For those, I consistently measure just under 0.5A at the tail for 2xLi-ion. Your result is very surprising considering the datasheet claim that the XP-G's Vf at 1000mA is 3.3V. Do you have a high contact resistance somewhere in the circuit path?



I got similar results measuring SSC P4 as you did (remember the PM I send you  )
With the same host and cells, with a K2 TFFC @ 1.5A, the tailcap is 
measuring 0.82A


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## Justin Case (Oct 26, 2009)

I remember now. :thinking:

So the question remains as to why the tail current seems much higher than expected. Can you put your DMM across the LED terminals to measure Vf?

BTW, what is the approx range to that bldg in the beam shots?


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## tx101 (Oct 27, 2009)

Justin Case said:


> I remember now. :thinking:
> 
> So the question remains as to why the tail current seems much higher than expected. Can you put your DMM across the LED terminals to measure Vf?
> 
> BTW, what is the approx range to that bldg in the beam shots?



Vf across the LED is 3.10V
The distance to the building is 50 meters (164 ft)


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## wquiles (Oct 27, 2009)

Awesome mod - very clever :thumbsup:


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## Justin Case (Oct 27, 2009)

tx101 said:


> Vf across the LED is 3.10V
> The distance to the building is 50 meters (164 ft)



Nice Vf and throw.

I just completed one AW Seoul focus tower with an XP-G R4 bin from nailbender. The XP-G came on a 10mm round MCPCB, so I had to grind it down to fit. I used the famous tx101 method of snipping away the MCPCB into an oblong shape. I had an SOB1227 available, so that's what I used. The SOB measured out to 1196mA drive current. I filed down the MCPCB by 0.4mm to match the XP-G die height with that of a Seoul P4.

Compared the tower to two other towers: 1) AW Seoul focus tower with an SOB1000 and a Seoul P4 U2SWOH-bin LED, and 2) AW Seoul focus tower with an SOB1000 and a 2S2P Cree MC-E K-bin (mounted on an 0.7mm shim to raise the MC-E die height).

Results:


```
Lux at 1 meter
Emitter/TH    SRTH   T-62   KT1/2   Itail (A)   Vf (V)
P4, U2SWOH   14000  11100   10800   0.49        3.40
MC-E K-bin    9500   7200    7800   0.82        6.22
XP-G R4      20300  15100   14200   0.58        3.28
```

The XP-G focuses to a very bright, tight hot spot. Also, the XP-G spill at the beam midpoint measured 145 lux in the SRTH, compared to 70 lux for the P4 tower.


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## tx101 (Oct 27, 2009)

Looking at your results, the XP-G is significant improvement over the 
P4 in terms of brightness.

Here comes a stupid question, comparing the XP-G to the P4, the current
for the XP-G is higher but the Vf is lower, so how does that effect the runtime
when compared to the P4 ?


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## Justin Case (Oct 27, 2009)

Remember, I'm using an SOB1227 driver (only because that's what I had available). If I had been using an SOB1000, the XP-G R4 Vf would probably be even lower -- let's say 3.1V like you found. Then, the LED power draw would be only about 3.1W and the tail current draw would certainly be less than the ~0.5A for the P4 tower (for which the LED draws about 3.4W). Clearly, run time for the XP-G would be better than for the P4.

For the SOB1227/XP-G case at hand, the tail current draw for the XP-G tower is 0.58A, so I would expect the run time to be a little less than that for the 1000/SOBP4 tower. But output is substantially increased.


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## Linger (Oct 28, 2009)

maxspeeds said:


> Great outdoor shots! What is the color bins for the XP-G R5 and K2 TFFC?


Here's an interesting little comparison between xp-g r5 and quark neutral / warm tint.


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## DaFABRICATA (Oct 28, 2009)

tx101,


That looks very promising!

I have an order for some drivers, and will be building a tower module very much like yours!

I can't wait to see how it does in a Surefire 3" Turbohead!:devil:

Thanks for posting your mod and sharing the info!:wave:


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## Justin Case (Oct 28, 2009)

tx101, it is interesting that you get a Vf of 3.10V at a nominal 1000mA drive current, but a tail current of 0.73A. Am I correct in understanding that this same tower, when it had a P4, drew about 0.5A at the tail? In my small sampling of SOB1000 drivers, I've typically measured a driver efficiency of 85% or better. So I would have expected your XP-G to draw about 0.45A at the tail.

My XP-G R4 tower, running at Vf=3.28V and 1196mA draws 0.58A at the tail using 2xIMR26500 in a FiveMega host.

Maybe your DX Li-ion cells are suspect?


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## tx101 (Oct 28, 2009)

I just tried the module with a different setup,
a Leef body with 2 x AW 18500 cells
The results are VF 3.10v across the emitter
and 0.8A at the tailcap

It is the same Module that originally had a SSCP4

Might be an idea to measure the current at the emitter ?
but I will not be able to get the soldering iron out until Saturday
evening (I have a rampaging 2 yr old son running around  )


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## Justin Case (Oct 28, 2009)

Interesting. I wouldn't think that there is any issue with the drive current to the emitter. The SOBs seem fairly consistent -- if you have an SOB1000, then the drive current is going to be within a few percent of 1000mA. Your Vf is also consistent with that magnitude of drive current. The XP-G datasheet says 3.3V at 1000mA, so if anything either you got a low Vf emitter (I've often found that emitters have a lower measured Vf than what's in the datasheet) or the drive current is lower than 1000mA. Either way, the tail current draw should be lower, not higher.

I just measured another P4/SOB1000 tower of mine and got 3.35V Vf at 969mA drive. Tail draw for 2xAW17670 in an SF 12ZM host was 0.47A. That tail draw corresponds to a voltage input of 8.0V on my bench supply, giving a driver efficiency of 86%.

For your XP-G tower, let's assume Vf=3.10V at 1000mA drive current and a driver efficiency of 85%. If your 2xLi-ion cells can hold 7.4V quasi-steady state, then the tail current could be around 0.49A. If the initial Vbatt is 8.0V, then the tail current could be about 0.46A. Either way, roughly 0.5A looks like a reasonable upper bound for the tail current draw for your XP-G tower.

0.7A-0.8A is baffling.

Since you tried two different hosts and got what seems to be a high Ibatt both times, I would think that there is some high resistance contact somewhere in your tower.


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## Justin Case (Oct 28, 2009)

I made some 1 meter lux measurements using a KT4. Host was a SureFire M900A weaponlight. Power source was 3xAW16340. Test towers were 1) P4 U2SWOH/SOB1000, 2) 2S2P MC-E K-bin/SOB1000, 3) 2S2P MC-E K-bin, SOB1227, and 4) XP-G R4/SOB1227.


```
Emitter         KT4 lux at 1 meter
P4              9900
MC-E SOB1000    8900
MC-E SOB1227    9900
XP-G            13400
```


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## Justin Case (Oct 29, 2009)

I just built another XP-G tower using the Netkidz kit this time instead of a AW Seoul focus tower kit. I didn't have a good 17mm buck driver handy (waiting for my KD1640 order), so I used a single-mode, 3xAMC7135 driver (1050mA nominal). Seems to work very nicely and the focus height looks good without having to file down the 2mm thick MCPCB. The XP-G was on a 10mm round MCPCB and I trimmed it as described previously by tx101.

Hot spot lux at 1 meter was 14400 for a T-62 TH, 13500 for a KT1, and 18600 for an SRTH. Host was a SureFire 6P running 1xAW17670. Tail current draw was 1.042A. For comparison, the numbers for the AW tower running at 1196mA were all slightly higher at 15100, 14200, and 20300, respectively.


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## Justin Case (Oct 29, 2009)

DaFABRICATA said:


> tx101,
> 
> 
> That looks very promising!
> ...



So I thought about this some more. I would suggest using an AW tower with Luxeon focus, not Seoul focus. Or if you have a Netkidz tower, use that.

I had previously measured a Netkidz tower stem height at 0.788", while an AW Seoul focus tower stem height was 0.806", a difference of 0.018" (0.46mm).

The LED dies for a Seoul P4 and XP-G both look to be right at the top face of the case. Thus, I estimate that the die height for a P4 is 2.38mm. For the XP-G on a 2mm thick MCPCB, I measured the height to the top of the XP-G case at 2.78mm, a difference of 0.40mm vs the P4. This can vary a little depending on the thickness of the reflow solder layer under the XP-G, but probably by not more than a couple hundredths of mm's.

So basically, it looks like the taller XP-G die height is almost exactly offset by the shorter Netkidz tower stem height. Technically, you lose about 0.46mm from the stem height and gain 0.40mm from the die height, so the XP-G die is still about 0.06mm low. But you have to glue the XP-G to the tower with thermal epoxy, and that will no doubt cover that slight shortfall in focus height (if not exceed it).

I don't know if the focus heights of the Netkidz tower or the AW tower account for thermal epoxy thickness, but in any case I get a nice beam with a good hot spot (basically the same hot spot size as what I get for a Seoul P4, but also noticeably brighter).

The advantage of using a Netkidz tower over an AW Seoul focus tower is that you don't have to file down the MCPCB by about 0.4mm to get the XP-G to the proper focus height. That was a hassle when building the AW tower. I would assume that the AW Luxeon focus towers have a stem height that is 0.03" (0.76mm) shorter. Using that tower focus, no filing of the XP-G MCPCB should be necessary. Instead, you probably need to use an ~0.3mm (~0.01") shim to raise up the XP-G. It just so happens that Amerimax Home Products 5"x7" Aluminum Step Flashing, #85-068, is 0.011" thick. How about that. You should be able to find the flashing at Home Depot or other similar hardware stores. I think 10 5"x7" sheets are around $5. That should last for a lifetime of XP-G tower builds.


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## Justin Case (Oct 31, 2009)

If you get an XP-G mounted on an 8mm round MCPCB from The Sandwich Shoppe, the board turns out to be 1mm thick vs 2mm thick for the 10mm round that tx101 and I both have used.

-------
Edit: I measured some XP-Gs on 8mm MCPCBs from The Shoppe and they measure less than 1mm thick (about 0.8mm). So the numbers in the table below have to be adjusted for whatever actual MCPCB thickness you have for your 8mm round. In my case, it turns out that I needed a shim of about 0.045" thick. I used Arctic Silver epoxy to glue a copper shim to the tower and the XP-G to the shim.

Additional edit: If you need a shim, you can order a sample pack of different thicknesses of aluminum or copper sheet from www.onlinemetals.com. For example, the copper sample pack contains five 4"x4" sheets with thicknesses of 0.0135", 0.216", 0.032", 0.048", and 0.0647". The aluminum pack contains six 4"x4" sheets with thicknesses of 0.025", 0.032", 0.040", 0.050", .0.063", and 0.080". If you want an ~0.01" thick aluminum shim, go to Home Depot and get Amerimax Home Products 5"x7" Aluminum Step Flashing (10 pieces), #85-068. I measure the flashing at 0.011" thick.

Some images:












-------------

That would put the estimated die height at about 1.58mm plus additional height from the reflow soldering. So let's say 1.78mm. This compares to 2.38mm for the die height in a Seoul P4, or a difference of 0.60mm (0.024"). So if you use an AW Seoul focus tower, then one of The Shoppe's 0.03" thick copper shims will probably work out, especially if you keep your thermal glue layer thin (and maybe file down the shim a little bit). Or you can use some of the Amerimax step flashing I mentioned in an earlier post (it measured 0.011" thick). Add the expected thickness of the thermal glue, and you are probably right were you want to me. Or don't use any shim at all. The single glue layer to attach the XP-G will probably get you close enough to the right height.

For a Netkidz tower (if and when he resumes selling them), that tower's stem height is 0.018" shorter than for an AW Seoul focus tower. Add that to the lower die height of the XP-G on the 8mm round, and you get a total of 0.043" lower die height for an XP-G on a Netkidz tower vs a Seoul P4 on an AW Seoul focus tower. My bet is that adding one 0.03" copper shim should be enough to raise up the XP-G to the right focus height (or at least close enough). The thermal glue will make up any height shortcoming.

It doesn't look like the tower focus needs the exact height to get good results. So for several of the XP-G/tower combinations, if finding a suitable shim is a hassle, then you probably can just ignore the small focus height differences and glue the XP-G and drive on.

I hope I got the following right. Summary (assuming a 2mm thick 10mm MCPCB and a 1mm thick 8mm MCPCB):


```
Tower          LED         Height Adjustment    Method
                           Needed
Netkidz  XP-G/10mm MCPCB     ~None               None
Netkidz  XP-G/8mm MCPCB       +0.043"            0.03" copper shim plus glue layers
AW Lux   XP-G/10mm MCPCB      +0.014"            None, or 0.011" aluminum step flashing plus glue layers
AW Lux   XP-G/8mm MCPCB       +0.054"            0.03" copper shim plus glue layers
AW Seoul XP-G/10mm MCPCB      -0.016"            None, or file down the MCPCB
AW Seoul XP-G/8mm MCPCB       +0.024"            None, or 0.011" aluminum step flashing plus glue layers
```


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## tx101 (Nov 1, 2009)

Justin, I was wondering, with the KT-1 or KT-4 head, how crucial 
is the height of the emitter. The reason I ask is that I have build
modules with Diamond Dragons and K2 TFFCs. To my eyes
all look very similar in beam shape and brightness but then again
I do not have the equipment to measure brightness.

BTW, I could not find the time to measure current at the emitter 
maybe later on


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## Justin Case (Nov 1, 2009)

I haven't made a comprehensive test of hot spot lux vs focus height, but the KT1 and KT4 don't seem to be super sensitive to focus height in the sense that you have to hit an exact focus height or beam quality suffers. It appears that there is a sweet spot range for the focus height.

Ideally, it might be nice to have an overlong tower and systematically insert a series of shims to steadily alter the focus height.

Well, until the XP-G I didn't have an overlong tower (the XP-G/10mm MCPCB combo with an AW Seoul tower). Unfortunately, I was more interested in building a tower than testing focus height, so I didn't run any before/after tests when I filed down the 10mm MCPCB by 0.4mm.

I've done only one formal before/after test of focus height. I took an assembled AW Seoul focus tower, with a Seoul P4 installed. Measured the 1 meter hot spot lux. Then I inserted an 0.03" thick shim between the wide flange of the AW Seoul tower and the bottom face of the SF TH (I forget which one now -- STH, T-62, KT1, or KT4) to simulate a shorter tower. To my eye, the beam quality was excellent and unchanged. To my lux meter, there was about a 15% drop in hot spot lux when I presumably defocused the beam by 0.03". 0.03" is 0.76mm. So it might be that anything less than ~0.03" off the exact focus (high or low) is no big deal. I don't know this for sure, and I don't know if it holds across the board for all emitters. But your beamshots of your XP-G on an AW Seoul focus tower sure seems to suggest that being high by an estimated 0.016" (0.4mm) is no big deal.

Actually, I did do one other test. I defocused an MC-E/AW Seoul tower by 0.03" using the same shim trick as above. In that case, the beam quality suffered. However, since the AW tower height wasn't designed specifically for the MC-E in the first place, I can't say for certain that my build had placed the MC-E at the optimum focus height (visually, the MC-E beam quality looks good, and 8900-9900 lux in a KT4 isn't bad). It is possible that maybe the focus was already around 0.01"-0.02" low, just to pick a number for example. By reducing the height by another 0.03", maybe I kicked the MC-E far enough away from the focus "sweet spot".


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## KDOG3 (Nov 7, 2009)

Whoa. That is just SICK. I didn't see what the output is though. Can anyone guess? I would LOVE to get a tower module that would fit in a M3-CB with one of these setups in it!


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## tx101 (Nov 8, 2009)

Nailbender builds D36 dropins for the M3 with any emitter you want :naughty:


See here

https://www.candlepowerforums.com/threads/234953


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## KDOG3 (Nov 8, 2009)

Thanks for the tip! I'm over there drooling now....


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## Justin Case (Nov 8, 2009)

KDOG3 said:


> Whoa. That is just SICK. I didn't see what the output is though. Can anyone guess? I would LOVE to get a tower module that would fit in a M3-CB with one of these setups in it!



As tx101 wrote, nailbender has drop-ins that should fit your M3 bezel (double-check, however, if you have to do any disassembly of some of the shock head components). No one makes a mini tower anymore to fit that head. Unless you find one for sale on the B/S/T forum or on the Marketplace, your best bet is to get a KT4 for the M3 (essentially an M3T). Then, one of the towers discussed in this thread will work.

As for output, see this post. Estimated emitter lumens is around 350-400 depending on drive current. The SOB1000 that tx101 used runs at a nominal 1000mA drive current. I used an SOB1227 that measured 1196mA.


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