Top bin COB comparison

[BuddyColas]

I just received a pair of Vero29s yesterday, thanks to @robincnn Here are the results of the first test, Vero29 V2 4000K 80 CRi

View attachment 3582635

I have a couple a questions for you (now keep in mind I am a “white belt” in the DIY COB arena). I want to see if I am understanding your chart and comparisons correctly.


So if I was comparing two COBs at say 27 watts (a power level I use). And I was comparing the CXB3590 3500. Would I say the CXB3590 3500 was putting out about 8.6 umols per watt as measured at 12” from the COB?


And if that is correct, then is the Vero 29 4000 putting out about 8.0 umols per watt at 12”? And if all that is correct, would I then say the CXB3590 is 7.5% more efficient than the Vero 29 at 27 watts? I got that by dividing 8.6 by 8. I realize that the K value of the COBs is not the same, but I want to see if I can use the chart correctly for comparisons.


I might be getting the hang of this…or I might have got off the rails somewhere. I need a little feedback. Thank you.

 

[SupraSPL]

Yes these graphs are based on photon count so technically the color difference is already taken into account for the most part (assuming the correction factors that I used for the Apogee SQ-120 were close).

You are correct about the 27W, that matches the power use of the COBs and was monitored carefully with a pair of fast multimeters.

The PPFD/W data represents how many photons the sensor received per dissipation W of the COB, rather than the photons emitted (PPF).

Theoretically, the math you worked out should be correct, except I would say in that example the CXB3590 makes 7.5% more photons/W than the Vero29, but with the caveat that I am not sure these curves can be used to make absolute comparisons as I originally hoped. The spreadsheets, CREE PDF and PCT suggest that the CXB3590 curves should be slightly more slanted and I have not figured that out yet.

A lot of careful work went into this test and I think it gets us in the ball park, but at the end of the day I used only $400 worth of gear while an integrating sphere with spectroradiometer could cost $10,000 or more. On top of that I am not sure if measuring from a constant distance may introduce distortions to the curves. So for now I am taking the data with a grain of salt but it is interesting to to see the shape of the curves and the fact that efficiency continues to increase even at 4 watts. Maybe I will try re-running the same tests but with the sensor closer to the light next time, and see if that affects the shape of the curves.

 

[BuddyColas]

Yes these graphs are based on photon count so technically the color difference is already taken into account for the most part (assuming the correction factors that I used for the Apogee SQ-120 were close).

You are correct about the 27W, that matches the power use of the COBs and was monitored carefully with a pair of fast multimeters.

The PPFD/W data represents how many photons the sensor received per dissipation W of the COB, rather than the photons emitted (PPF).

Theoretically, the math you worked out should be correct, except I would say in that example the CXB3590 makes 7.5% more photons/W than the Vero29, but with the caveat that I am not sure these curves can be used to make absolute comparisons as I originally hoped. The spreadsheets, CREE PDF and PCT suggest that the CXB3590 curves should be slightly more slanted and I have not figured that out yet.

A lot of careful work went into this test and I think it gets us in the ball park, but at the end of the day I used only $400 worth of gear while an integrating sphere with spectroradiometer could cost $10,000 or more. On top of that I am not sure if measuring from a constant distance may introduce distortions to the curves. So for now I am taking the data with a grain of salt but it is interesting to to see the shape of the curves and the fact that efficiency continues to increase even at 4 watts. Maybe I will try re-running the same tests but with the sensor closer to the light next time, and see if that affects the shape of the curves.

Awesome! I think after reading the threads the past few months my “inner COB” is beginning to turn on and get a little brighter!


I think your graph is a very useful way to compare emitters at various power levels. And I can sleep at night knowing you don’t have a spectroradiometer to make those “relative” comparisons. We don’t grow in a spectroradiometer. Most of us are just hobbyists (well some are operating a small business). And 12” below the emitter is a commonly used distance.


And even if you and I bought a Li-cor PAR meter to duplicate these “relative” tests, they are +/- 5% right from the factory. So when you hold the power, distance from emitter and PAR meter constant (and unless you work at the Bureau of Standards) it’s still a +/- 5% world at best. Just saying.


So also what I get from this is that Bridgelux way under reports the Vero 29’s performance. And with the Vero 29 4K being ABOUT 2% more efficient than the 3.5K (the one I use), I am extrapolating that the CXB3590 3.5K CD is (at about 27 watts) around a 9.5% better generator of PAR photons than the Vero 29 3.5K. And I can live with that kind of accuracy to make shopping decisions.


Thanks for getting right back to me.

 

[SupraSPL]

Yes Bridgelux has increased the specs for their low current figures and their lumen output several times recently, along with a price drop that is a big win for growers. I believe Kingbrite will or has reduced their Vero29 pricing as well.

 

[BuddyColas]

Yes Bridgelux has increased the specs for their low current figures and their lumen output several times recently, along with a price drop that is a big win for growers. I believe Kingbrite will or has reduced their Vero29 pricing as well.

I agree And for me anyway, contemplating my second COB build, I am not willing to pay twice the price for about a 9.5% performance gain. And I have not drilled a mounting hole yet. I use the Kapton tape, and the V29 gives sooooo much room to work with…shweeeet!


I like running my COBs naked and close to the canopy! It might be a while before I drill any holes in my heatsinks.


And better not change anything at your “lab.” You are turning into the defacto RIU DIY COB bureau of COB comparisons! It is appreciated.

 

[Abiqua]

I was the heatsink temp in this case. The Taylor thermometer is precise and accurate, but when measuring in between the fins the probe interferes with the airflow slightly, so I had to prewarm the thermometer probe until it was very close to the temp I was trying to measure and then get the measurement quickly. The idea was to use a "too small" heatsink to exaggerate the temp difference from one COB to another, in theory revealing the difference in efficiency and it does seem to work so far.

Measuring the case temp requires that photons are not hitting the thermocouple. That problem becomes trickier at high dissipation W. I have never been satisfied with the repeat-ability of my case temp measurements using any method including thermocouple, so instead I try to measure the actual temp droop which has been much more repeatable. Hopefully you will have more luck with Tc than I did.

If C/W is known of most of the componts, why can't we correlate Tc correctly? Even if we have disturbance, which should be apparent.....

 

[SupraSPL]

If C/W is known of most of the componts, why can't we correlate Tc correctly? Even if we have disturbance, which should be apparent.....

Yes if you know the heatsink temp, dissipation power, efficiency and thermal resistance of the TIM and COB, you should be able to estimate Tc and Tj. We can try to verify it by monitoring the hot and cold Vf while keeping the current steady. We can also try to measure temp droop to further verify it.

CREE does not give us the CXB3590 thermal resistance from junction to case/solder point, and I suspect it is variable depending on the application. Bridgelux lists thermal resistance from junction to case/solder point for the 3000K 80CRi Vero29 as .06C/W at 2.1A and .07C/W at 4.2A but that is based on dissipation W rather than heat W. So at 2.1A (80W) the Vero29 junction temp should only be 5 degrees C above the case/solder point temp.

 

[bassman999]

I agree And for me anyway, contemplating my second COB build, I am not willing to pay twice the price for about a 9.5% performance gain. And I have not drilled a mounting hole yet. I use the Kapton tape, and the V29 gives sooooo much room to work with…shweeeet!


I like running my COBs naked and close to the canopy! It might be a while before I drill any holes in my heatsinks.


And better not change anything at your “lab.” You are turning into the defacto RIU DIY COB bureau of COB comparisons! It is appreciated.

I run naked with kapton for now as well. I feel like I will be making lots of changes. I have extra heatsinks available to practice with o when real mounting comes (when I decide to use optics) I will be able to hopefully get it right.

 

[BuddyColas]

I run naked with kapton for now as well. I feel like I will be making lots of changes. I have extra heatsinks available to practice with o when real mounting comes (when I decide to use optics) I will be able to hopefully get it right.

I am about 2 weeks out from finishing my first run with COBs, and I wanted to keep it real simple this first time. I have changed the configuration of my cobs 4 times now…and will LIKELY keep them in the spots they are now. I have 4 cobs per bar at 9” apart. 2 bars in a 2x4’ box. The canopy measurements are fairly consistent…waaaaay more consistent than using HPS for sure. But I am not ready to commit and fire up my drill and tap some holes just yet.


And I am still on the sidelines on the whole reflector, lens, degree of lens debate.


I do know running them 6-8” above the canopy, the cola tops are neither bleached or burned and the lions share of the photons from the “Typical Polar Radiation Pattern” hit the canopy straight out of the cob and don’t reflect at all. And many of the reflected ones find their way to the canopy. And add to that some of the old hands with many runs under their belt still run bare!


My only regret in my first build is I should have read the “how to power cobs” section first. I have 6 Meanwell supplies and only 2 of them are in use! Ahem…


I can build a few more bars without buying another supply now...I have a good assortment.

 

[SupraSPL]

No worries either way, the Mean Wells have a good resale value. You can probably ship an HLG-185 in a flat rate padded envelope for $5.75.

 

[bassman999]

I am about 2 weeks out from finishing my first run with COBs, and I wanted to keep it real simple this first time. I have changed the configuration of my cobs 4 times now…and will LIKELY keep them in the spots they are now. I have 4 cobs per bar at 9” apart. 2 bars in a 2x4’ box. The canopy measurements are fairly consistent…waaaaay more consistent than using HPS for sure. But I am not ready to commit and fire up my drill and tap some holes just yet.


And I am still on the sidelines on the whole reflector, lens, degree of lens debate.


I do know running them 6-8” above the canopy, the cola tops are neither bleached or burned and the lions share of the photons from the “Typical Polar Radiation Pattern” hit the canopy straight out of the cob and don’t reflect at all. And many of the reflected ones find their way to the canopy. And add to that some of the old hands with many runs under their belt still run bare!


My only regret in my first build is I should have read the “how to power cobs” section first. I have 6 Meanwell supplies and only 2 of them are in use! Ahem…


I can build a few more bars without buying another supply now...I have a good assortment.

I went crazy buying different shit everytime I saw a price drop on a different cob. I wish I would have waited and just bought 8 xb3590s at once and been done with it.
I will find a use for them all though, even if its lighting the garage or bathroom.
Buddy PM me if you wanna sell a driver

 

[BuddyColas]

I went crazy buying different shit everytime I saw a price drop on a different cob. I wish I would have waited and just bought 8 xb3590s at once and been done with it.
I will find a use for them all though, even if its lighting the garage or bathroom.
Buddy PM me if you wanna sell a driver

Thank you. I appreciate that. Having "paid my dues" for the class Sizing COB Drivers 101, I am taking it as a sign to fire up a second grow box and upgrade some veg space and take all the T-5s and HIDs out and put them in retirement. I am going to build more!

 

[bassman999]

Thank you. I appreciate that. Having "paid my dues" for the class Sizing COB Drivers 101, I am taking it as a sign to fire up a second grow box and upgrade some veg space and take all the T-5s and HIDs out and put them in retirement. I am going to build more!

My plan is to maybe get a 700mA driver and run the cxa cobs on that and use them (even though they are 3000K) for veg

EDIT
I can add the CXB3070 3500K BB pair I have with the CXAs all on an HLG-185H-C700 and run it close to max efficiency

That would average out to approx 52% effieiency

 

[BuddyColas]

No worries either way, the Mean Wells have a good resale value. You can probably ship an HLG-185 in a flat rate padded envelope for $5.75.

Thanks for the information.

 

[alesh]

Nah used my handy dandy PAR meter from Apogee. What would you guess the difference in results would be if one were to take, say, two samples and test with both approaches, those approaches being the use of a PAR meter, which is what most growers and grow light manufactures utilize to get an idea of light output, and the use of an IS through a third party? Obviously a few parameters distinguish one approach from another but would results, more or less, share the same answer in regards to the question of which sample discharges the most light?



Do you cover the Vero thermo point with anything, such as kapton tape?

Well, the differences would be large because a PAR meter and an IS each measure different quality.

 

[AquariusPanta]

@AquariusPanta
I use vero 29 clamp , which is used to mount the ledil reflector.
It gives some isolation between veros Tc point and LES
The Tc point is close to LES in vero so I do not compare Tc of Veros with Cxb. It is not apples to apples IMO

I'm curious as to how you managed to fit even a 26AWG wire through the already tight crevice between a Vero and the clamp that attaches to the ledil reflector. Not saying it can't be done but I looked at my leftover clamps, presumably the same series of clamps you are using, and mounted them to both a Vero 18 and 29 and see no likely possible way to attach a thermocouple to the Vero Tc measuring point from the outside w/ mount, as the mount was designed to be screwed down, thereby clamping down the Vero. Furthermore, from my observations, there is an opening to the Tc point from the inside area, where the LES presides, leading me to believe that you could test the Tc if a wire came from the LES section inwards onto the measuring point but again, that would surely interfere with accurate Tc measuring, as dissipation would leak in at some degree.

I can only think that you had the wire attached first and then had the mount and/or reflector attached afterwards but with those latter components shifted at an off-balance angle from the x-axis of the heatsink or mounting surface due to that wire coming in and offsetting the designed levelness.

I will note that where the Vero typically conveniences the consumer/user with on-board perks, such as an EZ-mate connection, it fails royally when it comes to providing an approachable and workable Tc measuring point. In comparison, the Tc measuring point for the CXB3590 is by far more engageable although not ideal, as the point itself is fairly tiny, making thermocouple mounting accuracy a tedious job.

 

[AquariusPanta]

Well, the differences would be large because a PAR meter and an IS each measure different quality.

When you mention quality, you're referring to various wavelengths correct? That seems to be the only argument against PAR meters, regardless of the fact that most of us have correction factors for those missing wavelengths. If there's something you or someone else knows about those corrections factors that obsoletes them, please share.

Don't you think that if the correction factors for the PAR meter's wavelength imperfections were indeed legit and that the argument against PAR meters was benched, that the results from the PAR meter between the two samples would correlate/match the same answer, more or less, with the answers/results of pushing those same two samples through an IS test? I'm not at all proposing that the values of the results between both tests from both samples will be the same or even close, but that the simple question of which sample performs better would be clearly obvious and shared between either of the proposed testing methods.

 

[PurpleBuz]

When you mention quality, you're referring to various wavelengths correct? That seems to be the only argument against PAR meters, regardless of the fact that most of us have correction factors for those missing wavelengths. If there's something you or someone else knows about those corrections factors that obsoletes them, please share.

Don't you think that if the correction factors for the PAR meter's wavelength imperfections were indeed legit and that the argument against PAR meters was benched, that the results from the PAR meter between the two samples would correlate/match the same answer, more or less, with the answers/results of pushing those same two samples through an IS test? I'm not at all proposing that the values of the results between both tests from both samples will be the same or even close, but that the simple question of which sample performs better would be clearly obvious and shared between either of the proposed testing methods.

wow dude you are really dumb. what is it about wavelengths that are NOT being measured that you do not understand ? when I use a par meter I want to measure what I get in my controlled conditions. NOT what somebody else got in some other conditions.

 

[AquariusPanta]

wow dude you are really dumb. what is it about wavelengths that are NOT being measured that you do not understand ? when I use a par meter I want to measure what I get in my controlled conditions. NOT what somebody else got in some other conditions.

Lol it is YOU who are being dumb, as you have repeatedly refused to LISTEN to and ACCEPT the SOLUTION to the PAR meter's wavelength imperfection. I don't know how else to spell it out for you - can someone help this poor individual with basic comprehension, please??

 

[PurpleBuz]

Lol it is YOU who are being dumb, as you have repeatedly refused to LISTEN to the SOLUTION to the PAR meter's wavelength imperfection. I don't know how else to spell it out for you - can someone help this poor individual with basic comprehension, please??

THAT is not a solution to measuring what the plant actually receives. its an approximation, because the data from 655 to 700 nm is an approximation and not representative of the system that you are trying to measure.