Hello everyone!
I've been checking this forum and trawling the internet for resources for a while and am finally ready to build myself a light.
Many thanks to everyone who has provided experimental data and design resources.
I don't know if it's been mentioned but for anyone looking for tip top deep reds to supplement, led-tech in germany have (or at least claim) to have a preproduction batch of osrams next generation
GH CSSPM1.24 horticultural 660nm ssl120 for those interested, which boasts a min 400mw @ 350ma drive current. The voltage range on their website looks suspcious, quoted at 1.6v - 2.3v. They differentiate between min and max values, so really the min voltage should match up to the min current that they state, but I doubt this as that would give an efficiency of just over 57%. Here's the link to the release note:
http://www.osram.com.cn/media/resource/HIRES/546291/538626/15-gb.pdf From what I understand though osrams red chips do perform better at lower drive currents.
So my build is for a micro cab that will be 45cm x 60cm x 1m (Depth-Width-Height) and I very luckily came across 4 62v (0.3-1A) 50w philips xitanium DALI drivers on ebay for cheap. I'm going for a super efficient set up, with full control of spectrum and high efficiency, so I can make it stealthy quiet on the extraction side. I'll be using a 6" phresh hyper fan on low @ 8w for the extraction
So far I'll be using
2 x cree cxb3590 @ 13w - 35w approx. each (max 70w total)
(10 x osram
Oslon SSL 80 LHCP7P-2T3T @645nm) maybe
24 x osram
GH CSSPM1.24 SSL 120 (Horticulture) @660 nm (approx 17w - 40w)
6 x osram
CS8PM1.24-3S4S-1 @730nm
as of yet unknown quantity of either cree XTE or XP-E2 royal blue
1 or maybe 2 x 11w arcadia D3 7% UVB lamp
I might need more drives to control it all how I'd like, but I also plan to integrate this into a fully automated system, with data logging of all sensory info, communicating over wifi or GSM, with a control application running on a raspberry PI.
So I'm really posting to get opinions about colour temp. From what I understand 3500k has been hailed as the optimal colour temp for a single led solution, however my build is going to use the cree cob as a base and then supplement both red and blue. In my opinion they all need extra deep re 660nm which is unavoidably inefficient. Now from what I understand a COB led is basically something like an XTE blue array without the lenses with a phosphour LES, which in my mind makes me think that every photon is penalised by the phosphour, including the blue spectrum.
The drop in efficiency compared to the distribution of blue to red between 4000k,3500k and 3000k makes me think that using the 3000k CB bin and supplimenting with blue LEDS, which are much more efficient than the reds is the way forward. If I run the royal blues at 100ma in flowering the efficiency gain will cancel out or better the efficiency gain of the CXB efficiency gain from using a higher bin in a higher colour temp. At the same time I gain the benefit of the fact that the CXB 3000k does a really good job at providing red in the 620 - 630 nm, as well as green and yellow and having a string of royal blue, I can dim the COBs and crank up the blues for veg.
I'm yet to do proper calculations, which are part science part voodoo anyway, but I thought I'd ask the opinions and knowledge of those with more experience first. I'd really appreciate any input.