PAR test of cree vs citi vs cutter

JorgeGonzales

JorgeGonzales

Well-Known Member
To be extra super duper clear, here is the 1818 @robincnn tested, with data according to Citizen, and my own digitized SPD charts for the efficiency numbers:

image.jpg

Personally, I run at 700ma on mine, but according to robin's data in this post https://www.rollitup.org/t/top-bin-cob-comparison-2.897765/page-5#post-12726618

And his chart here:



The 1818 is testing well above a 3590 CD, which means all those Citizen numbers are complete bunko, or conservative, to put it more politely. If these practical measurements are in the ballpark, at 700ma I'm somewhere north of 60% effficieny at 35W?

So yeah.

ttystikk said:
If you want to use current droop data, why wouldn't you want to use temperature droop data as well, for the same reason?
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For the same reason Supra normalized his data to 50C. You need to control for variables, and they are two separate things, so pick one and keep it static. The current droop curve applies equally at all temperatures, as far as I know. More current equals higher temperatures, but so does inadequate cooling, a hotter room, etc. One variable at a time.

And remember, all of this is indirectly measuring what we really want, which is straight up photon flux measurements. But until somebody buys a sphere or joins from a university with one, we have to approach things from oblique angles. We are lucky to get any useful data at all from cob to cob comparisons like people try to do here. It's tricky as hell.
 
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BOBBY_G

BOBBY_G

Well-Known Member
well... we are looking for reference data but real world comparison is useful too.

for example:
say i put a cxb3590 and a clu048-1218 and a clu058-1825 on the same heatsink/fan combo

at a given wattage and heat sink capacity, the clu058 should dissipate heat a lot more effectively than the clu048 due to more surface area on the larger chip size. the cxb is almost as big as the clu058 but is ceramic, so we would expect that its dissipation ability would fall somewhere in the middle of the two, etc.
 
JorgeGonzales

JorgeGonzales

Well-Known Member
BOBBY_G said:
well... we are looking for reference data but real world comparison is useful too.

for example:
say i put a cxb3590 and a clu048-1218 and a clu058-1825 on the same heatsink/fan combo

at a given wattage and heat sink capacity, the clu058 should dissipate heat a lot more effectively than the clu048 due to more surface area on the larger chip size. the cxb is almost as big as the clu058 but is ceramic, so we would expect that its dissipation ability would fall somewhere in the middle of the two, etc.
Click to expand...
These comparisons are more than useful, and are super exciting. But if you want a database of same-scenario data to compare like the Supra spreadsheets, that's an entirely different path.

The CXB is interesting. @guod claims it's got good thermal resistance, SupraSPL claims Tc=55C equals Tj=85C at 1900ma, so thats over 1.13 C/W at ~68W. Which is bloody terrible.
 
ttystikk

ttystikk

Well-Known Member
JorgeGonzales said:
To be extra super duper clear, here is the 1818 @robincnn tested, with data according to Citizen, and my own digitized SPD charts for the efficiency numbers:

View attachment 3718843

Personally, I run at 700ma on mine, but according to robin's data in this post https://www.rollitup.org/t/top-bin-cob-comparison-2.897765/page-5#post-12726618

And his chart here:



The 1818 is testing well above a 3590 CD, which means all those Citizen numbers are complete bunko, or conservative, to put it more politely. If these practical measurements are in the ballpark, at 700ma I'm somewhere north of 60% effficieny at 35W?

So yeah.



For the same reason Supra normalized his data to 50C. You need to control for variables, and they are two separate things, so pick one and keep it static. The current droop curve applies equally at all temperatures, as far as I know. More current equals higher temperatures, but so does inadequate cooling, a hotter room, etc. One variable at a time.

And remember, all of this is indirectly measuring what we really want, which is straight up photon flux measurements. But until somebody buys a sphere or joins from a university with one, we have to approach things from oblique angles. We are lucky to get any useful data at all from cob to cob comparisons like people try to do here. It's tricky as hell.
Click to expand...
Turns out you can find a testing laboratory and simply pay them to test your lights.
 
JorgeGonzales

JorgeGonzales

Well-Known Member
ttystikk said:
I'll be paying to test my own lights soon. It's gonna cost me a couple grand, but I believe it will be highly educational.
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You can get sphere testing done for a few hundred. Less comprehensive than Cree or I'm assuming Light Labs, but a damn sight better than nothing.
 
ttystikk

ttystikk

Well-Known Member
JorgeGonzales said:
You can get sphere testing done for a few hundred. Less comprehensive than Cree or I'm assuming Light Labs, but a damn sight better than nothing.
Click to expand...
Yes. That's included in the price, but I'd be doing a whole program. Just a sphere test would be 275.
 
CobKits

CobKits

Well-Known Member
info is ancient and not really worth discussing.

drblaze's links above are good places to find out info on a19 bulbs
 
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