PR-T-DB917 vs Aleph3-DB917

[luxlover]

I am so lucky that Don "likes me enough" to have sold me two of his handy dandy bezels, a PR-T-DB917 w/TY0J Luxeon III emitter and an Aleph3-DB917 w/TW0K Luxeon III emitter. About a week ago, my buddy Joe (aka jtr1962) tested these bezels with his newly acquired handheld digital luxmeter. The readings using an L4 body and a Z57 tailcap, at exactly one meter, were:
PR-T = 4,600 lux
Aleph3 = 5,430 lux

Per a conversation I had with Don at the time I bought the PR-T, he said that I can expect near 3,000 lux from it. The Aleph3 is pretty much according to what has been posted in an Aleph3 thread somewhere (5,410 lux). What will make me very happy about my Aleph3 purchase, is that the Aleph3 will have much more throw than the PR-T, which is why I bought it in the first place. I wanted massive throw. Regarding the PR-T's output, it is a giant leap above what it has been rated by Don. Good show, Don!

For those who question the method of luxmeter use, here is how Joe managed the readings. He set the meter's pickup and digital display against a wall. We measured 39.37 inches away (one meter), and made a pencil mark on the table. He aimed each light toward the pickup, from that mark, moving it in all directions until he detected a maximum reading, meaning that the centerline of the light was aligned with the center of the pickup. When he saw that one light position lead to the highest reading, he held it rock steady for about thirty seconds until the display stabilized. Since the numbers on the display wavered a little, we averaged the highest and lowest numbers that we both saw.

For comparison, we measured my two KL4 bezels since these use two 123s as do the other two bezels. The yellow tinted KL4 bezel that came with my L4 put out 1,050 lux, and my white KL4 replacement put out 900 lux. I was happily surprised, when using my McE2S-60 ohm tailcap switch instead of the Z57 gave the same output figures on high level with all bezels. This calls for another pat on the back for Don. I was so sure that the many components that make up the switch, would introduce circuit resistance, reducing the flow of juice to the regulation board, and reducing each light's output.

A very happy Luxlover, over and out!

 

[cue003]

Congratulations on two very nice pieces of work. You got some good ones.

Curtis

 

[Miciobigio]

And congrats also for your KL4 and L4 , 900Lux and 1000Lux are very high score !!
You are a lucky-boy. /ubbthreads/images/graemlins/wink2.gif

 

[McGizmo]

Luxlover,

It would appear that your PR-T is quite an over achiever! /ubbthreads/images/graemlins/icon15.gif It does have the new McR-27 reflector which helps but the lux reading is still well above typical!! In a number of tests I have done using the same LED and driver, going from the McR-27 to the McR-38 doubles the lux measured. If you double 4600 lux you are getting into a realm I have never seen with these drivers and reflectors, plain and simple!!

I have noticed that the latest revision of DownBoys seem to fall short of the target current output based on the resistor selection; that is to say that couple 917's I measured were at 900mA. I recall when I first went to the 917, I could get measured outputs around 960 and in fact on a DB1000 I would see 1050 mA and this was one reason I chose the 917. However, this possible diference in output is not enough to explain 4600 lux! If someone were to tell me they were getting a legitimate 4600 lux from a 27 mm reflector, my immediate response would be to guess that the LED is being driven at close to 1.5 amps! This was certainly not the case when I sent the PR-T 917 to you so either the driver is now for some reason in major Overdrive or you got one bright and tight LED/reflector package there!! /ubbthreads/images/graemlins/icon3.gif

EDIT: an interesting data point worth mention is the relative readings of your two KL4's. As I have noticed and your measurements concurr, the warmer 5W's are quite often brighter than the cooler tinted ones. If one can live with the tint of the warm LED, one can probably assume a brighter LED as well as one that seems better at return of reflected light from objects in the red spectrum. This seems to be the case with some Lux III's I have seen that have a yellow tint in their beam as well /ubbthreads/images/graemlins/thinking.gif

 

[bajaiman]

4600 lux from McR27 with DB917/TYOJ is an outstanding result!! /ubbthreads/images/graemlins/eek.gif ... I believe the avg lux reading are about 2800 - 3000 lux with this configuration. The highest reading I've got with my Aleph 1/DB917/TWOL is 3450 lux. I reckon your 4600 lux is the highest I've known so far from a PRT head. Congrats /ubbthreads/images/graemlins/wink.gif

 

[Chop]

Don,

I agree with you on the warmer luxeons. I tend to try to stay with the TX1 luxes in lights that are going outdoors. They really perform and I think that they give better color rendition.