Cree XP-G VS. XR-E

[Thumbster]

Just curious if anyone has compared PAR readings between these two LED's and if there is much difference between the two of them. I know the XP-G is supposed to put out more light but i have not heard anything on here yet.

I am looking into getting 48 LED's for my 75 gallon tank (half blue, half white) and placing them in two rows about 6 inches above the tank in my canopy. My concern is getting as much light as I can without having spotlighting. I was thinking about using the XP-G's without optics (They don't have them do they?) or the XR-E's with 80 degree optics.

I have a ton more questions about LED's even after reading through all of the other posts, but I'll start here i guess.

Thanks

[serpentman]

Honestly, I wasn't impressed with the PAR results on the XP-G. First, the spread from the lense is much wider than the XR-E so without optics, they tested lower. However, I've read that measuring PAR on "white" LED's can be misleading as the meter may not recognize the spectrum/bandwidth. Perhaps someone on here may be able to elaborate.

[AngelAddict]

I would use optics on the XP, I run 60°. With optics, they will be approximately 40% more powerful then the XR-E and while I believe producing less heat and consuming slightly less energy. I'd run XP-G (only come in white, no blue yet) and you'll need a 40/60 ratio with the XR-E to obtain a 14k color since the XP-G are more powerful.

[Thumbster]

I did not think the XP-G's had optics available for them. Do you have the 60° optics on your XP-G's or are they on XR-E's?

I saw on Cree's site that the XR-E's without optics are 90° compared to the XP-G's that are at 125°. I was wondering if the XP-G's would have more par drop off due to the wider angle. Thanks Serpentman!

Due to the short distance that i will be hanging these i have to try to avoid spotlighting while getting the most out of the LED's at the same time.

I will probably have 2 18"heatsinks (one on both sides) with two rows of 12 LED's spaced evenly 1 1/2 inches or so apart, with the rows 3 or 4 inches apart. It's hard to guess though because i have never seen a setup like this in person.

Are you saying to run the XR-E's in a 40 white/60 blue ratio or the XP-G's to get a 14K look?

[TheFishMan65]

XP-G have optics at 60 degree. ETG sent me the wrong ones by mistake. i don't know what other angles are available.

[Soundwave]

I am using the XP-G and XP-E LEDs. The XP-E royal blues are the same small size as the XP-G whites. Works wonderfully and is stupid bright. Brighter than the XR-E LED fixture I built.

[westmoorenerd]

So just wondering why has everyone been on the XR-E bandwagon if XP-E's work better?

[tahiriqbal]

Originally Posted by westmoorenerd

So just wondering why has everyone been on the XR-E bandwagon if XP-E's work better?

I think it would be simply due to limited availability on optics for these LEDs. Cree's XP-E in royal blue are excellent and few of us are already using these LED DIES (soundwave is your prime example for his latest project).

[westmoorenerd]

Hmm iono, I don't think I've seen a fixture using XP-G and XP-E besides Soundwave's...but it makes me want to build mine that way. Man are LEDs a pain in the (Y) to make your mind up about....I was dead set on XP-G/XR-Es, now XP-G/XP-E, new Orphek light fixtures...

[tahiriqbal]

Well, you have to wait to see my new setup then I have built a tile containing 30 LEDs (50/50) XP-G (R5) for white and XP-E for the royal blues. Everything is in testing mode and once I am happy with everything I be more than happy to post my results.

[westmoorenerd]

Please PM me when you post it up then...I'm quite anxious to get LEDs over my tank already... Any projections on PAR numbers with your pendant

[tahiriqbal]

I will post my results on the mian thread. Have a look at my thread on touch screen controller which I built a while ago for testing. I bought myself Apogee quantum meter and sensor which I am using to collect the data (goshhhh this hobby is very expensive) lol.

[mtcs]

correct me if I am wrong, but as far as I researched prices, http://www.cutter.com.au/proddetail.php?prod=cut937 is the best price for XPG leds ( U$ 7,08 for more then 10 units).

XR-E sells anywhere, DealExtreme sells them at 5,10 for more than 10 units

ps.: I think XRE lens would fit XPG leds, someone in this thread said that: http://www.reefcentral.com/forums/sh....php?t=1867014

[TheFishMan65]

MTCS, are you in a different country? I got mine from DX for $4.34 (IIRC) and that is still the listed price.

[Thumbster]

Well crap, i had not even looked into the XP-E's. They look slightly brighter (122 lm vs. 107 lm) on paper than the XR-E's. Although they have a 115° viewing angle w/out optics where the XR-E's have 90°.

Question on the color temps though for the cool whites. On the Cree site the range for both LED's is ranged from 5k to 10k. Is that dependant upon the amount of milliamps supplied to the LED, or some other factor? would a dimmer change the color temp?

[TheFishMan65]

According to a seminar I just watched yes dimming will change temperature. But I can not tell you how much or what way. Heat of the junction temperature will also change the color.

[TheFishMan65]

The seminar is supposed to be available online in a week or so. But from 5% to 100% dimming and current vs pwm for controlling dimming.
RED leds (don't know whose) both go from aroung 632 (5%) to 639 (100%)
Green CC 535 (5%) to 525
Green PWM 521 to 525
Blue CC 468 to 465
Blue PWM 463 to 465
Black (I guess white) CC 459 to 458
Black PWM 455 to 458
And of course they are not linear . But this gives you some idea. I guess the good news is that for Blue and White(maybe) there is not much shift.

[der_wille_zur_macht]

Originally Posted by mtcs

ps.: I think XRE lens would fit XPG leds, someone in this thread said that: http://www.reefcentral.com/forums/sh....php?t=1867014

This is NOT TRUE. Some XP-E optics will work OK on XP-G LEDs, but XP-E and XP-G are not (by default) interchangeable with XR-E. When in doubt, find out the manufacturer of the optic and ask them directly, or worst case, ask the vendor you're buying from.

XP-E and XP-G are very close to the same physical dimensions and viewing angle, hence optics are more readily swappable. XR-E is a much bigger physical device, and the viewing angle is much different, so optics aren't typically swappable.

Regarding other specifications, in general, XR-E and XP-E are the same with respect to comparing numbers on the same bins (i.e. a Q5 XR-E is more or less the same as a Q5 XP-E). The difference is the viewing angle (wider on the "P") and optic selection.

Some vendors and some versions of Cree's own documents list XP-E in bins higher than the XR-E is available in, but these might be very hard to get and/or vaporware (similar to the R2 XR-E discussed 6 or 8 months ago).

Originally Posted by Thumbster

Question on the color temps though for the cool whites. On the Cree site the range for both LED's is ranged from 5k to 10k. Is that dependant upon the amount of milliamps supplied to the LED, or some other factor? would a dimmer change the color temp?

The color temp range you are quoting is for the WHOLE PRODUCTION range of that model of LED. You need to look up the specifications for the bin you're actually talking about. Each bin covers a much smaller range. The binning is done at a typical drive current and temperature. Running at different specs will change the color temp, but not in a significant manner for our purposes (IME and by looking at the small amount of actual published data). The only time when the current-dependent color shift would be an issue would be if you're using the LEDs to backlight a computer monitor, or some other application where color temperature control is extremely critical.

It's also important to note that the cool white LEDs are binned on a 2-D color space (CIE 1931), whereas us reef keepers are used to talking about color in one dimension (kelvin scale). If you're really curious, do some searching on this forum for "CIE1931" and I'm sure you'll dig up some of the discussions we've had in the past.

[mtcs]

Originally Posted by TheFishMan65

MTCS, are you in a different country? I got mine from DX for $4.34 (IIRC) and that is still the listed price.

yes I'm from brasil
I just rated the R2 cree emitter there for 10+ bulk...

strange...

[mtcs]

And there is another advantage from the XPG. Its heat dissipation is better (according to CREE obviously). So they rate it to 1.5 A and the XR-E is rate to only 700ma. So you can squeeze more light from it... hehehehe

some time before I was eve considering using those 50W leds that you can find in the market, but they are just not so efficient.

Originally Posted by der_wille_zur_macht

This is NOT TRUE. Some XP-E optics will work OK on XP-G LEDs, but XP-E and XP-G are not (by default) interchangeable with XR-E. When in doubt, find out the manufacturer of the optic and ask them directly, or worst case, ask the vendor you're buying from.

XP-E and XP-G are very close to the same physical dimensions and viewing angle, hence optics are more readily swappable. XR-E is a much bigger physical device, and the viewing angle is much different, so optics aren't typically swappable.

But the adaptation capability is what make us humans so resilient and effective...

some glue here... some scraping there... and voilà, there is our Frankenstein.

Originally Posted by der_wille_zur_macht

...
It's also important to note that the cool white LEDs are binned on a 2-D color space (CIE 1931), whereas us reef keepers are used to talking about color in one dimension (kelvin scale). If you're really curious, do some searching on this forum for "CIE1931" and I'm sure you'll dig up some of the discussions we've had in the past.

I always thought that eternal color discussion from 14.000k was a little off... color specter is definitely not just linear... it would be at least bi-dimensional. Some would say tri-dimensional even... Of course that interpretation of color is only how our cerebra interprets visible electromagnet waves... or it would be particles...

[mtcs]

ops me again

If I used those 50W leds, a watercooling solution would be niiice....

take all the heat from the lights to outside of the room... you know, Brasil is veery hot. Here people chills at 23 C...

[TheFishMan65]

mtcs the XR-E can run at 1000ma except for the green ones.

[tahiriqbal]

Originally Posted by mtcs

ops me again

If I used those 50W leds, a watercooling solution would be niiice....

take all the heat from the lights to outside of the room... you know, Brasil is veery hot. Here people chills at 23 C...

to do this you would require a very long copper pipe leading from your light fixture to the outside world

only joking

[wld1783]

Originally Posted by westmoorenerd

So just wondering why has everyone been on the XR-E bandwagon if XP-E's work better?

Personally I prefer the XR-E based on Colour. The XP-G is more efficient but it is harder to find the cooler temp bins. With enough XR-E Royal Blue this is not a worry as the growth spectrum is good.

I find the only problem with LEDs is spread. For my 36" wide tanks they are great. For my 440 gal tub a single 400 watt MH works great.

Overall for our application I see a limited return using anything over a XR-E Q5 based on light distribution and colour. Once Cree has a more cooler temp XP-G readily available that would be great.

Bill

[mtcs]

Originally Posted by TheFishMan65

mtcs the XR-E can run at 1000ma except for the green ones.

yes, its 1000ma manufacturer rated. But you could increase the current if you have a good heat dissipation. I saw some guy in a forum in DealExtreme that used 2.4A on a XRE R2...

I think we should never forget that as we increase the current passing through, the LED its efficiency decreases...
that link that I posted before shows it grately for the XPG : http://www.candlepowerforums.com/vb/...&postcount=354