noob about to make a final decision. Please help.

All you really need is one point of reference, TotalPAR or PPFD to make an informed comparison and your spreadsheet looks all good in that respect. If you solve for the 2530 at .7 amps I think you will find 10 will fit on a 250w driver. T2 bin won't be as efficient but they have a nice price and 10 at .7 amps would probably be around 1200 PPFD. If you don't want that kind of intensity or wattage, I think the 3070s at 1.05A or 3590s at 1.4A would be great 150w choices still putting serious light in your space.

Thanks everyone, especially Rahz, for your patience and understanding as I went through the exercise of figuring all this this out. I now understand the meaning of all the data within the spreadsheet and have a much better appreciation of the suggestions you have all been proposing. Your language is no longer foreign to me.

I'm going to go back over the thread and re-read everything that you guys have had to say, and then I'll be in a position to take it all in and make a decision. I'm now seeing and understanding the pro's & con's of going one way over another. Not really as simple as buy a COB and away you go.

Once again. Thankyou very much.

You could run 14 2530s on a 185h-c700 split into 2 strings @ 350mA / chip giving you about 52% efficiency and 28000 lumens.

I need some additional information in order to continue my decision process.

My original design was to limit the flowering chamber to a height of 4 feet. After having a few people mention that 4 feet was quite restrictive, I changed the design of the cabinet so I would end up with 5 feet of height, and it is this 5 feet that the discussion has been based on since.

If I was to utilise the entire cabinet to flowering I would end up with a base dimension measuring 860 * 500 mm (33.8 x 19.6 inches) given me an area of 0.43m² (4.62852 Feet²) and the height of the chamber would increase from 1500mm (4.92 feet) to 2200mm (7.22 feet).

Given the new height limit, does this open up the possibility of better utilising the space I now have?

This is my latest spreadsheet. I've added 2 lines in the CXB2530 grouping labelled 0.7T2 & 0.7 witch mathematically calculates the 0.7 values & 0.7T2 values based on the average difference between the T2 & U2 Bins for the CXB2530. My mathematical calculations assume a linear relationship, which obviously isn't the case in the real world, but it gives you the ability to quickly and easily compare figures at a glance.



Also, in opening up the cabinet to purely flowering, I have made some savings as I no longer need to build an internal cabinet to segregate the chambers as originally planned, so there's a bit more cash available for lighting.

I'd also like to know what the ramifications would be if I were to bump up the amperage of the 3 x 3590 to 2.1A in this area. Would the higher cabinet allow for it, and would it be beneficial or detrimental?

Also, my initial plan was to go SCROG due to my 5 foot height limit. Having almost 8 feet of height now available, would I have enough space to eliminate SCROG and do a normal grow, or would I be better of sticking with SCROG?

Thanks.

I think moving from 4 feet to 5 feet opened up your options. Without a filter in the way 5 feet is not bad and you could run the larger cobs near their nominal current. Probably still better to scrog but it depends on how many plants and how long you veg them. More plants and short veg and scrog wouldn't be necessary.

With 7 feet to work with you have even more room to do whatever grow style you like.

Nice to see you've converted the numbers to reflect the T2 bin, just keep in mind the wattage will be the same (250 watts at .7 amps). For the price they're a good deal, just depends whether you want to spend the extra to reduce the wattage (4 3070 at 1.4 amps = 200w). PPFD with the 3070 combo would be a little lower but I think you would be happy either way. The 3590s at 2.1 amps would boost the PPFD back up with efficiency similar to the 3070 at 1.4 but would require a 250 watt driver.

With 5 day veg and 3000k 3070's I end up with 3-4' plants, so plan accordingly......also 30watts sf.

Is there a point of diminishing returns with PPFD values?

If I recall correctly, 1200 PPFD seems to be the target we aim for. Less isn't as good, but what happens with more?

Rahz, you said earlier "Ideally, in a 6 foot area, 8 3590s ran on a HLG-185H-C700B. (killing it with 200 watts)" This would create a total of 1230 PPFD. If I'm correct, a HLG-240H-C700 could run 10 x CXB3590 @ 0.7A pumping out 1537 PPFD in the 4.6 Feet² I have. Does this end up being wasted light due to the limited size of the cabinet base, or is it a case of more is better, as long as we can manage the heat?

Thanks.

More is better up to about 1500, but there's a law of diminishing returns. There's not going to be a lot of difference between 1230 and 1500.

There are two basic rules of light intensity but many people find themselves falling in-between.

1- if you have limited space run the PPFD high.
2- if you have unlimited space run the PPFD around 650.

At some point below 650 the flowers will begin to get fluffy, but it's hasn't been determined exactly where that point is. I've seen good results at 500, but even with unlimited space there's not a lot of justification in going much lower than 600. A lot of people find the sweet spot to be around 800-900. The chart is for vegetative growth but flower production is probably similar.

Airwalker16 said:

The driver is dependant on the amperage. Your forward voltage of the cobs is between 33-36% dependent on the current itself (how hard you're driving them). It's a simple equation
(Fv)X anperage = wattage.
So 36 X 1.050= 36watts
36X 1.400= 56watts

Each driver has a maximum output of current, getting less and less as the amperage goes up (500,700,1050,1400,1750,2100)
So to answer your question, you can fit the 5 cobs on a 1050 & NOT a 1400, because it's exceeds the max output. You see?
36x5= 180. Okay
56x5= 280. Not okay
The (185) in the driver name relates to the wattage max.

Click to expand...

Actually the 185s are all around 200 watts. The 185 1050a is 199.5 watts I think. And the b is 200 even.


Sent from my iPhone using Tapatalk

Rahz said:

More is better up to about 1500, but there's a law of diminishing returns. There's not going to be a lot of difference between 1230 and 1500.

There are two basic rules of light intensity but many people find themselves falling in-between.

1- if you have limited space run the PPFD high.
2- if you have unlimited space run the PPFD around 650.

At some point below 650 the flowers will begin to get fluffy, but it's hasn't been determined exactly where that point is. I've seen good results at 500, but even with unlimited space there's not a lot of justification in going much lower than 600. A lot of people find the sweet spot to be around 800-900. The chart is for vegetative growth but flower production is probably similar.

View attachment 3619620

Click to expand...

In my experience 600-1000 is the sweet spot.
You can run a limited amount of bud per sq ft.....It is really self apparent when you grow sog like me.

HLG-240H-C1400 driving 14 x CXB2530 @ 0.7A for $204.12 (excluding driver)




That's a lot of grunt for just over $200.

Overkill?

Honestly I don't have any experience at that light level, but in theory it would be fine. Potentiometers are cheap and getting the A or B driver version costs the same.

Chuff420 said:

HLG-240H-C1400 driving 14 x CXB2530 @ 0.7A for $204.12 (excluding driver)

View attachment 3619637


That's a lot of grunt for just over $200.

Overkill?

Click to expand...

14 holders, reflectors/lenses. After you spend more to hook all those up you still have the added risk of one or more being a dud. You're also running a way higher voltage which also increases risk. I think there's something to be said about simplicity. Four 3070's would be a great choice or 3590's.

Danielson999 said:

14 holders, reflectors/lenses. After you spend more to hook all those up you still have the added risk of one or more being a dud. You're also running a way higher voltage which also increases risk. I think there's something to be said about simplicity. Four 3070's would be a great choice or 3590's.

Click to expand...

I hadn't planned on using reflectors/lenses. Are they required?

I'm investigating heatsinks at present and being in Australia really limits my choices, and what's available is really pricey compared to what you guy in the US get from HeatsinkUSA.

At this stage less COBS will be better.

Still thinking.

Thanks everyone.

With that amount of light, id say reflectors are not necessary. You could cut pieces of 3/4 inch plywood just large enough to give you about an inch around the outside of your COB, angled @ 45% on the inside and paint it white, it would reflect a good amount of the light going out horizontally down to the plants. This would be relatively cheap and you could probably just glue it to the heatsinks using a high temp adhesive, to save you from drilling your heatsinks any more than you already are. Also if you have access to a computer repair place, or even a local dump, you can scavange some pretty wicked heatsinks from old PCs and use them individually, hanging alone or built into a wooden frame of some sort. These would have to be actively cooled, but any decent sized CPU heatsink will have more than enough cooling ability to cool even the most powerful cobs.

I'm currently looking at cooling requirements.

Cooling them, be it actively or passively, is proving to be quite costly if you live in Australia. Our range is limited, and what is available generally costs about 3 times as much as in the USA. And if I purchase from anywhere OS, then shipping costs blow the final figure right out of the water.

This Sunday I think there's a PC Swap Meet down the road. I plan on going and seeing what CPU heatsinks are available. Ideally, I would have much preferred to go with a passive sink, by again, range and cost in Australia makes it difficult when you can buy some cheap CPU heat sinks.

This brings up a question I have regarding cooling. Does it matter where I place the COBS on the heat sink?



Are both acceptable?

Thanks.

Bottom one. Leave a little space on the end if Ya can.

@Chuff420

If you're cooling passively, bottom choice is the way to go. If you take actively cooled route, with fan, then either or will more than likely work for you. Lots of factors that could sway the final decision though, so second one is most likely suitable, although the first gives you a possibly better spread potential depending on cob output; gotta make sure middle ground is covered before advancing outwards.

^^^Exactly^^^