LED downlight with dim to warm starting at 4000k?

ManOnMission

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Hi All-

New to the forums, found you all because I'm on a quest for a residential downlight that appears to be a unicorn of sorts. I'm trying to find a flangeless (trimless) LED downlight that warms the color temperature when dimming, but that starts at 4000k with no dim - NOT 3000k.

The other features of the light are pretty pedestrian; round, white, fixed (not adjustable) with flood beam. It's the trimless and warm dim starting at 4000k that seem to be combo that I can't find.

I've looked at WAC, Tech and Alcon and only found starting temps of 3000k. For the Zaneen Bioniq line I can't find documentation of where their warm dim color temperature starts at.

What's frustrating is that I've found press releases / marketing material for the makers of the LED PCBs intended to be integrated into luminaries that list warm dim specs of 4000k to 2700k - which is perfect! But I'm striking out on finding products suitable for a residential install that actually use those boards.

Any leads would be much appreciated, I've done the rounds with my local specialty lighting supply companies and big online vendors.
 

Dave_H

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I am not sure this is what you are looking for closely enough but will throw it in.

I picked up a couple of A19/E26 60W equivalent (9W) dim-tint-changing bulbs which start at 5000K (but not 4000K) at full brightness, going down as low as 2000K. It's called Globe Duo Bright 33229, available in Canada and elsewhere I presume.

For this you'd probably need a pot light with E26 socket, sufficiently deep, no experience with these.

Dave



I notice they have flush mount and recessed versions as well:



 
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idleprocess

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4000K is a color temperature that major OEMs experimented with several years ago and the market largely rejected, settling into the present 5000/3000/2700 slots - much to my disappointment since I find 4000K easier on the eyes than 5000K without the penalty to concentration and visual focus that 3000K and especially 2700K extract.
 

Dave_H

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I did some dimmer tests on this bulb starting with inline slide dimmer. 5000k to 3000K transition occurs in the top 10% of dimmer range which allows tint selection with minimal effect on brightness, though it is somewhat touchy; and it restricts tint/brightness control range.

Not sure how this compares to other bulbs or fixtures of this type.

I also tried a 3-stage touch dimmer module (got a bunch of these cheap) with pleasant results. High/Medium gave 5000K and something appearing close to 4000K at high brightness, and Low gave a dull soft orange which is great for night-light. It just worked out this way.


Dave
 

Dave_H

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Another A19 bulb option which might work is a product like the Feit "intellibulb" ColorChoice 60W equivalent. On the collar is a 4-position slide switch which allows manual selection of 2700K, 4000K, and 5000K, and is dimmable.

The 4th position allows you to toggle through the tints with a fast off/on of the power switch. This gives three tint selections plus full brightness control. A rotary dimmer with push on/off should work great for this. Note that if power on/off is not done too quickly, the bulb "remembers" the tint setting; no need to cycle through every time (like some flashlights).

Dave
 

ManOnMission

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Thanks for the suggestions all, I'm sure some of the suggestions could be useful to others looking for similar functionality.

For me, I was looking for a very specific downlight for a bathroom: 4000k because I like the "medical grade" color temp at full intensity, and much warmer (at least 2700k) for using the bathroom in the middle of the night, or just for my wife who like warmer color temps.

These lights are going to be used in a full gut-to-the-studs reno, so I also wanted flangeless (trimless) - because if you're looking for a unicorn, why not shoot for an albino one as well right? And it should be 90+ CRI, offered in shower trim, etc. I'm making it hard.

The residential lighting market doesn't have a solution that fits this bill, "CCT" type lights sold by commercial electric have a switch to set color temp, sure, but that's not "dim to warm". Dim to warm itself appears to be a marketing term that specifically refers to lights starting at 3000k at 100% intensity, and dimming to (usually) the low 2000s. But the starting point of 3000k is baked into any light that offers "dim to warm" as far as I found.

Separately, in the commercial downlight sector, I stumbled upon "tunable white". This is a feature of LED downlights that can be generally described as variable starting and ending color temperatures, and two-channel control such that intensity (lumen output) is driven on channel A and color temperature driven on channel B. Two independent controls, but this is getting closer to what I need because one of the configurations I found starts at 4000k and goes down to 1800k. Perfect!

But - this is a bathroom in a residential building that I'm sharing with my family. I don't really *want* the complexity of two dimmers, or even worse (in my opinion) a fancy touchscreen control. That dim to warm functionality, one slider controlling both intensity and color temperature in tandem, is still the goal.

So I found two ways to make this happen, and I'd like to share both with the community.

Option 1
Tech Lighting's Element series offers tunable white (TW) flangeless shower-trim high lumen output downlights with a TW range of 4000k to 1800k. Critically, they offer several different drivers, one of which is a "dumb" 0-10V driver wherein both intensity and color temp channels use the same type of 0-10V electrical control signal, able to driven by a simple lutron-type 0-10V ELV dimmer.

driver.png

Because the electrical specifications for the intensity and color temp (CCT in the above picture) channels are exactly the same, I can drive this fixture as a "dim to warm" can by joining the positive intensity and CCT channels on one post of a single 0-10V dimmer, the negative channels on another. Since the same dimmer part numbers are used for both channels, there is no risk of incompatible control signals here.

This is ultimately what I went with, because it it's less finicky. The cans are ordered, and I'm going to test one on my bench when it arrives. If, for some reason, this doesn't work the way I expect it to, I've resigned myself to the gamble that I'm taking and we will end up with two "dumb" 0-10V dimmers in a two-gang in our wall.

This is the E4R-L-LH-TW41-60-D-I-ELT0 housing with E4R-L-B-H-W trim, should anyone care.

Someone who wants more options or less hardcoding of the light behavior would prefer option 2 below.

Option 2
Alphabet Lighting's NU series, specifically the NU4RD configured as tunable white (TW). This light's TW board goes from 6500k to 2700k, which is the principal reason I did not go with it. This is both a broader range than I need, while being too cold on the high end and not warm enough on the low end.

But, if I did go with this light and was OK with dimming across its entire color temp spectrum I could have also ordered it with a dual channel 0-10V driver (DIM10Z order code) and, in principal, wired it to a single dimmer switch as for Option 1. Separately, I think I could have also achieved 4000k to 2700k dimming on a single switch if I ordered it with the Casambi bluetooth driver. This driver has a mobile companion app that you can connect to the fixture with, and set a custom color temp map. Such that at 100% intensity T_color = 4000k and at 1% intensity (or whatever) T_color = 2700k, with linear or log interpolation between the two. The downside of this is several fold tho, (1) if power goes out you need to reprogram the lightS, plural, which sounds like a PITA, and (2) I never got far enough down this path to determine if that bluetooth driver still let me wire the cans to a switch, or if I would need a bluetooth enabled control panel in my wall.

*****************************************

Anyway - maybe that'll be useful to one of you in the future. These aren't cheap FYI - if you want 4" version, you're looking at almost $500 a pop. For the Elements series, I know they get cheaper as you go down in size, but the driver has to be external and I didn't want to deal with junction plates in our ceiling or hidden in a cabinet somewhere.

Thanks again for the suggestions!
 
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ManOnMission

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4000K is a color temperature that major OEMs experimented with several years ago and the market largely rejected, settling into the present 5000/3000/2700 slots - much to my disappointment since I find 4000K easier on the eyes than 5000K without the penalty to concentration and visual focus that 3000K and especially 2700K extract.
Preaching to the choir. I like delineating areas in my home with different color temperatures, and of course I found 3500k the best for the kitchen.

Just curious - where do you use 4000k? My bathrooms are 4000k, closets are 5000k, living spaces 3000k and kitchen 3500k. That's all overhead, for lamps I tend to stick with 2700k or even lower, depending on where and how the lamp is used.
 

idleprocess

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Preaching to the choir. I like delineating areas in my home with different color temperatures, and of course I found 3500k the best for the kitchen.

Just curious - where do you use 4000k? My bathrooms are 4000k, closets are 5000k, living spaces 3000k and kitchen 3500k. That's all overhead, for lamps I tend to stick with 2700k or even lower, depending on where and how the lamp is used.
Used to have an oddball 3500K circline floro fixture in my dining room that was fantastic. Only retired it because the ballast seemingly went out and spare ballasts/tubes were pricey/hard to locate. I would use 3500K everywhere if it were available as LED in common bulb formfactors.

Otherwise, I've got a couple 4000K flushmount fixtures (dining room, hallway) and 4000K LED tubes in the kitchen. I use 5000K (office) and mix 2700K / 5000K in multi-bulb fixtures most everywhere else that I can: 1:1 5000K:2700K nets ~3850K while 1:2 nets ~3467K. Master bedroom has 3000K LED bulbs and a homebrew linear ceiling-bounce fixture with commodity 4000K LEDs that satisfies nonetheless.

I miss the Cree 4flow bulbs, which made in-bulb color mixing easy. Swap the center PCB between 2700K and 5000K bulbs: instant pair of ~3850K bulbs.
 

Dave_H

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Because the electrical specifications for the intensity and color temp (CCT in the above picture) channels are exactly the same, I can drive this fixture as a "dim to warm" can by joining the positive intensity and CCT channels on one post of a single 0-10V dimmer, the negative channels on another. Since the same dimmer part numbers are used for both channels, there is no risk of incompatible control signals here.

This is ultimately what I went with, because it it's less finicky. The cans are ordered, and I'm going to test one on my bench when it arrives. If, for some reason, this doesn't work the way I expect it to, I've resigned myself to the gamble that I'm taking and we will end up with two "dumb" 0-10V dimmers in a two-gang in our wall.
What strikes me is that by connecting a common dimmer channel to both CCT and brightness channels of the fixture, you'll get 100% brightness at 4000K but maybe only 50% or less by the time you get to 3000K/2700K; if the controls for both are (somewhat) linear. The Globe DuoBright seems to do much of its tint control at the top end of brightness; probably also true of similar products like it.

Still wondering if toggling between fixed tints, with full brightness control, would be acceptable. Unfortunately it means the bulb goes off when toggling, could be bothersome compared to a smooth dimmer change. Or at least with slide dimmer having switch at the low end, dimming fully down, off, then up again. At least there is independence with a single control. I tried this with the Feit bulb, seems to work well. Minor issue is the order of tint change, and getting one in sequence you may not want. Bulb sequence was 5000K-2700K-4000K. A fixture which does this (to your liking) might exist.


Dave
 

ManOnMission

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@Dave_H I hear you, it actually uses log dimming rather than linear, due to perceived brightness vs actual lumenous flux. This was a new piece of information for me, and I'm trying to find the graph on Tech's website but comming up empty, but in short: perceived brightness is always greater than true lumen output. The graph demonstrates that, at say 50% lumen output, you perceive it to be 80% as bright as when the intensity was at 100%. At 10% lumen output, it's about 25% perceivable brightness. That is why log is more common than linear, at least for well engineered lights, so that you can access a greater dynamic range of perceived brightness. without it all being at the bottom 5-10% of the dimmer switch.

But also, I went with nice and bright lights. Due to the cost of the lamps, and the small size of the bathroom, I'm only using 3. But each one will put out ~1200 lumens each, so at 3000k or ~50% real intensity, that's going to be 600 lumens each and a perceived brightness of around 80%. 2000k is down at 10% intensity, and it will look more dim with a perceived brightness of around 25%.

I'm pretty happy with that, and I get it all with a single dimmer in a nice trimless recessed that is shower rated.
 

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