What happens to Spectrum when we dim our lights?

waynejohn

waynejohn

Active Member
I think i read something a while ago also about the spectrum shifting from 32 to 36v...it was something about 3500k shifting it's spectrum to green the higher the voltage of the chip...basically the result was that the chip lost around 20% red photons when switched from 32v to 36v which doesn't sound small at all
 
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VegasWinner

Well-Known Member
Evil-Mobo said:
This is what I want to know because I believe the same and that the shift to blue caused me non desirable tighter node spacing and shorter plants. So at least now if I'm looney tooney on this the looney bin isn't empty :dunce:
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What is happening here is not spectrum shift but higher micromoles allowing the plant to absorb more energy and grow tighter nodes due to efficiency of energy.
I achieve the same result by mixing 5000k and 3000k at 200w in a 2x2 50wpsf and get great tight nodal growth similar to when I ran my cobs softer than 50wpsf more like 25wpsf.
I use the mixed spectrum to get bushier plants that stretch nicely first two weeks of flower.
I never dim my fixtures as they are designed to operate at the range established unless emergency occurs, otherwise full speed ahead.
 
freemanjack

freemanjack

Well-Known Member
Evil-Mobo said:
As for me myself I am not interested in the heat debate. So how would what you state affect (or not) spectrum of the source of light? That's what I want to know............. :bigjoint:
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Sorry, my point was it should affect other 'heater' type light sources but leds should be more or less unaffected, tho as pointed out by someone here, temp of the phosphor might have some slight impact but I'd guess its nominal between say 50% drive current and 100% tho that is me guessing.
 
Evil-Mobo

Evil-Mobo

Well-Known Member
VegasWinner said:
What is happening here is not spectrum shift but higher micromoles allowing the plant to absorb more energy and grow tighter nodes due to efficiency of energy.
I achieve the same result by mixing 5000k and 3000k at 200w in a 2x2 50wpsf and get great tight nodal growth similar to when I ran my cobs softer than 50wpsf more like 25wpsf.
I use the mixed spectrum to get bushier plants that stretch nicely first two weeks of flower.
I never dim my fixtures as they are designed to operate at the range established unless emergency occurs, otherwise full speed ahead.
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The issues I had occurred with less light?

Thanks for your input brother good to see you around. :hump:
 
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VegasWinner

Well-Known Member
Evil-Mobo said:
The issues I had occurred with less light?

Thanks for your input brother good to see you around. :hump:
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Yes. exactly. At lower wattage or amps your fixture emits more energy for the plants to absorb more readily and they do not have to work as hard so they stretch less and bush out more.

SupraSPL talked about this. I did this by accident. I hooked up a light 36v cobs with a 700B driver driving cobs at 25w max 13w min. Plants vegged out with lots of bushiness. I figured it out six months later, when I took an inventory of my cobs and realized I was using 36v cobs with 700mA driver. I have both 72v and 36v cobs and of course 700mA and 1400mA drivers.

Since then I also mixed Spectrum 3500k and 500k first adn later 3000k and 5000k ad got the same result as lower wattage with higher wattage now and faster bushiness, but still the same bushiness.

Interesting. The experiment continues. Keep an eye out for something new and interesting. Been busier than usual.
nice to be around.bongsmilie
 
Evil-Mobo

Evil-Mobo

Well-Known Member
VegasWinner said:
Yes. exactly. At lower wattage or amps your fixture emits more energy for the plants to absorb more readily and they do not have to work as hard so they stretch less and bush out more.

SupraSPL talked about this. I did this by accident. I hooked up a light 36v cobs with a 700B driver driving cobs at 25w max 13w min. Plants vegged out with lots of bushiness. I figured it out six months later, when I took an inventory of my cobs and realized I was using 36v cobs with 700mA driver. I have both 72v and 36v cobs and of course 700mA and 1400mA drivers.

Since then I also mixed Spectrum 3500k and 500k first adn later 3000k and 5000k ad got the same result as lower wattage with higher wattage now and faster bushiness, but still the same bushiness.

Interesting. The experiment continues. Keep an eye out for something new and interesting. Been busier than usual.
nice to be around.bongsmilie
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Thanks for this explanation and this makes perfect sense. If it's ok I'd like to PM you a question on something?

Also to note, the reason I found this interesting is I had previously used a different LED source with higher K rating (more blue) and not experienced these issues with growth.............
 
Abiqua

Abiqua

Well-Known Member
Binning denotes the spectrum shift, depending on the method....some don't use binning.....Vero cough cough.

4 step is more precise etc etc
 
waynejohn

waynejohn

Active Member
Do you think for different spectrums it could change a bit more?Altough i don't see it making that big of a change anyways, even if it would be a 5% change it should still be pretty much the same and shouldn't cause visibly bushier plants
 
wietefras

wietefras

Well-Known Member
Malocan took some measurements of a few COBs at different watts (CXB359 and 1825 IIRC). His spectral charts didn't show any real difference.

Perhaps if you go really overboard like when it just lights up or when it's pushed really hard, but in the watts range that we use them it doesn't seem to matter for spectrum.
 
jonsnow399

jonsnow399

Well-Known Member
everyone is interested in cobs, but i was wondering about gavita's 750 watt de bulb dimming. The website says it can be dimmed to 400 watts. I emailed the rep and asked him how did it affect spectrum, efficiency and lamp life. I will let you know what he or she says when they reply.
 
ttystikk

ttystikk

Well-Known Member
jonsnow399 said:
everyone is interested in cobs, but i was wondering about gavita's 750 watt de bulb dimming. The website says it can be dimmed to 400 watts. I emailed the rep and asked him how did it affect spectrum, efficiency and lamp life. I will let you know what he or she says when they reply.
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Having read the white papers years ago, I can tell you that dimming HPS results in both reduced efficiency and an altered spectrum. DE might be different than SE in terms of exactly how it alters the spectrum, so I'm interested to hear what the rep comes back with.
 
jonsnow399

jonsnow399

Well-Known Member
ttystikk said:
Having read the white papers years ago, I can tell you that dimming HPS results in both reduced efficiency and an altered spectrum. DE might be different than SE in terms of exactly how it alters the spectrum, so I'm interested to hear what the rep comes back with.
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Yeh, well i can tell you part of what he will say, Gavita's advertising says "We named it 6/750 DE FLEX because it is as efficient running on 600W as it is on 750W" So he isn't gonna deviate much from the company line. I'm curious if they make the same claim at 400 watts too. My other question for him was, does it affect lamp life? and if so how much.
I would like to run a 400 watt de in the summer but I can't see this being practical. Gavita would have to be using some special tech on their bulbs to do this and nobody else has it. If that were true why wouldn't they be shouting it from the rooftops?
 
ttystikk

ttystikk

Well-Known Member
jonsnow399 said:
Yeh, well i can tell you part of what he will say, Gavita's advertising says "We named it 6/750 DE FLEX because it is as efficient running on 600W as it is on 750W" So he isn't gonna deviate much from the company line. I'm curious if they make the same claim at 400 watts too. My other question for him was, does it affect lamp life? and if so how much.
I would like to run a 400 watt de in the summer but I can't see this being practical. Gavita would have to be using some special tech on their bulbs to do this and nobody else has it. If that were true why wouldn't they be shouting it from the rooftops?
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Shortens lamp life somewhat.

If you want one fixture to be efficient across a wide variety of output settings and not to produce much heat, the answer is LED.
 
Rocket Soul

Rocket Soul

Well-Known Member
ttystikk said:
Having read the white papers years ago, I can tell you that dimming HPS results in both reduced efficiency and an altered spectrum. DE might be different than SE in terms of exactly how it alters the spectrum, so I'm interested to hear what the rep comes back with.
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Hey Ttystikk
Do you still have that paper or a link? Im looking at leds for a friends grow, trying to figure out some kind of hybrid hps led setup. His problem is that wintertime is so cold that any watts saved by led gets eaten up by having to put loads of extra heating, and summer is too hot (no aircon, only ventilation). Looking into a setup where he could use as much dimmed hps he needs for heating the cannopy and Qbs to fill in the the missing light. But if the HPS gets dodgy when dimmed down it might be a bad idea. Would really like to get my hands on that paper.
 
Evil-Mobo

Evil-Mobo

Well-Known Member
Rocket Soul said:
Hey Ttystikk
Do you still have that paper or a link? Im looking at leds for a friends grow, trying to figure out some kind of hybrid hps led setup. His problem is that wintertime is so cold that any watts saved by led gets eaten up by having to put loads of extra heating, and summer is too hot (no aircon, only ventilation). Looking into a setup where he could use as much dimmed hps he needs for heating the cannopy and Qbs to fill in the the missing light. But if the HPS gets dodgy when dimmed down it might be a bad idea. Would really like to get my hands on that paper.
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Mix COB's with 315 CMH if that's what youre after IMHO.

I know @GroErr has done this in the past and I think @ttystikk as well.
 
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