Cheapest High Quality/Efficiency COB build?

skoomd said:

You'll be rocking it without the need for the blurple. You're already at 36 watts a sq foot with the COBs which is good. The blurples would be too much on top of that.

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I was thinking I would run the COBs all the time, and then only run the "veg" switch on the blurple for veg, and only the "bloom" switch for flowering. That would only be an extra 100 (real) watts coming from the blurple, and it would be much more diffused light than the COBs. I'll have to mull it over. Perhaps just best to sell the blurple... I dunno.

The only way to really diffuse an LED (without adding more LEDs) is with some kind of optic/cover over the light. A lense will diffuse the light, but no where near as good as a frosted acrylic cover would. The lense eats 5-10% of the photons, frosted acrylic/glass would be like 15-20% loss. If the loss was worth the diffusion gains in a reflective mylar tent using already fairly diffused light by having multiple light sources (it isnt) then everyone would be using diffusers on their LEDs. But say you have a parallel strip build: if you want more diffusion you simply slap another strip on the light. Strip costs $14 and heatsink $5.

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Point taken. I do have some ideas on how to diffuse the light with minimal loss, but I want to test it before I let the cat out of the bag. Hint; the solution sh

This article explains the benefits of diffused light. And diffused light makes a biiiig difference in terms of photosynthetic efficiency and canopy penetration. I saw a photo of a guy that had 2 cobs @ 100w each in a small closest (maybe 2x4) and it was his veg room. Literally was completely shaded only a few inches below the canopy.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4559655/

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Thanks! I'll give that a read shortly.

skoomd said:

COBs cause hotspots/bleaching, have worse penetration, cost way more, are hard to cool, and are just lame.

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skoomd said:

I dont use cobs. Just an obervation ive made over the last couple years

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So youve never used cobs, but your observations (of other peoples grows presumably) tell you they are fraught with these critical problems?

not sure if i would put a lot of weight into observations of somebody who has never used a product, especially when it runs contrary to so many others experiences

There are some really good growers on this site who got fantastic results with cobs. Then they tried the mid power diodes in either strip or board form, and they also got fantastic results. Nothing night and day or definitive about it. Both techs have their advantages, in reality the cost/efficiency ratio is on the order of single digit percentages in most cases. At the end of the day both are white phosphor, and any decently sized cob array (say 4 or more cobs) is already an order of magnitude more diffuse than a single source like an HID. midpowers are only margianally more diffuse in most applications. (strips moreso than boards. boards can be worse coverage than cobs think a board at 150W vs 4 cheap cobs in like a 2x2 space. same efficiency, 4 cobs spread out are more even and diffuse than diodes all the emitters in a 10x 6 square)

Honestly now I am questioning the need for more than this blurple. I mean, I'm still going to build the COB unit because I love electronics/electrical and building stuff, but I have had absolutely amazing (to me) growth in my plants over the past 8 days with this blurple. I'll post some progress photos later.

OK, so here is the growth of a couple of my plants. Please forgive the off colours in some of the photos. Their natural colours are all pretty-much like this first one:

CB Dream - May 3rd:


CB Dream - May 11th:


White Widow - May 3rd:


White Widow - May 11th:

For you experienced growers, this probably looks "meh".

To me, it is pretty amazing.

man, i went with 4 Luminus cobs from cobkits, awesome service i must say.
used the heatsink fans, which are awesome also.

I use around 250-200 watts,

these are at day 53 from seed, 12/12 from seed.

tallest is 39inches tall,

cogitech said:

Are the savings worth it?

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if your grow room is close to the place where you live - try it with light-heat-cogeneration.
as heat production of led chips is still 60-80% of the inverted electric. energy -
you can harvest this energy with a heatexchanger and triple ***energy-efficiency***
The extra cost of the heat exchanger in my case was compensed after less than 1 year
by my hot water bill.

https://www.rollitup.org/t/water-cooled-cobs.963565/page-2#post-14240157

once the square tube is closed, you can choice "your" led-chips and driver


direct contact of the platines with water guaranties lowest chip temps.
no wires between the chips, cooling the driver(s) as well.