Please see lightening of the negativity in this review, in this subsequent blog post:
Please read on knowing I am unhappy with this light, for inefficient use of state-of-the-art >100 lumens per watt LEDs, netting only 52 lumens per watt. These lights also buzz on dimmers, just like T67 and T47. How could that be allowed?
New LED disk light products were brought to my attention by a commenter at post Review, Sylvania 70732 LED Disk Light . Here is the commenter conversation, shared this way so I can edit my response and activate links.
I had not known of the Cooper SLD4 and SLD6 lights. They are not marketed to consumers, but seem to have been around for several years, where they are only 52 lumens/watt technology. In Portland, Oregon, I find one commercial lighting representative, and I will call on them. I see no gasket, and would not need such feature, where I seal the junction box or can annulus with my easy flexible grout.
The 6" and 4" SLD both have nearly the 750 lumens brightness of a 6" Glimpse light. I think I like lesser brightness in a 4" LED downlight.
Where do you buy the Cooper lights?
Wanting to know what's inside, I removed three assembly screws and forced the aluminum back pan out from under the foam gasket. Within there are nine bright diodes, three each at spaced points on an acrylic disk periphery. Black and red DC leads become yellow series connectors.
Here I note two issues of unhappiness with the SLD6. The DC wires are outside the bounds of a junction box, somehow exposed. The AC quick-connect is only in the way, with junction box mounting. I wish the quick connector were eliminated, as in Sylvania 70732, Mod 2 .
Note the now-gone foam gasket. It had to be peeled off in shreds, to reassemble the light.
The quick connector and some leadwire length will not be mannerly, as the luminaire is blindly raised against the ceiling. I am doing this installation turned 90°, on my test stand.
Further examination was prompted by realizing that Cooper WaveStream™ technology with light beaming into an acrylic edge may illuminate both sides of the plate. The matte surface of the “dark” side is a white paper liner. Beneath, the hidden face is glossy, unlike the matte bright surface.
Please watch for growing presentation here. Researching parent technology, edge-lit phenomenon, TruEdge™ LED Coupling, licensed to Cooper by Rambus .
Edge-lighting is also used in GE Lighting Lumination™ LED Luminaire. It seems an edge-lit downlight may produce about 70 lumens per watt with an appropriate reflector. This with >100 lumens per watt diodes that would give more light where simply beaming down.
Big luminaires may make sense in commercial lighting, but starry-sky residential lighting will consist of dispersed dots perhaps 1.5" to 6" diameter. Lights will be wired in low-voltage DC circuits. Each dot will be inserted push-in as in sound jacks, simply plucked to rearrange size distribution or to paint a ceiling. They will be set artistically, beautifully, and as elements of architectural art. Soon they will be OLED. Point-source and tube lighting or even LED troffers as above, will disappear from our homes. We must declare a vision in this. Vision will include knowledge all new fixtures must be forward-compatible with OLED elements.
Continue now to address the Cooper SLD6, light as a 5 inch dot, bigger than an SLD4 3.5 inch same-brightness dot, only to cover the crime of a big can light hacking.
The glossy hidden surface is not much brightened by the nine diodes.
The white paper liner improves appearance, and adds some efficiency. The acrylic is transparent, and the aluminum pan would be visible without the liner.
Here is Cooper information for one offered luminaire, light beaming from both light guide faces, at about 100 lumens per watt.
Divide Surface LED
Here light at both light guide faces gives 100 lumens per watt.
See more lighting like this beyond minute two in this video:
I wonder if it is more effective to beam light downward always, than to aim sideways. Isn't this a step backward toward point-lighting?
It is evident to me that Cooper has sacrificed half of the available light, to present a disk light in challenge of the T67 and T47, with little advantage over those panned products. This is going too far in the quest to curve light through an acrylic sheet, as means of illumination. The nine diodes here could just beam down directly, more efficiently by times-two.
Are there other concerns with SLD4 or SLD6 dimming?
Video is this cluster of all available LED surface-mount disk lights, and an LED spot light set in a can, observing function in a dimmer circuit.
Clockwise from upper left: Cooper SLD6, 4" Glimpse, Sylvania 70732, Cree T67, 6" Glimpse. At right in can, Philips 15° spot. All 3000°K except T67 is 2700°K. All served by a Cooper DAL06P dimmer. Here all are at full power. Photo is a frame of Flip video.
Full power at start. Slide dimmer to 25% preset. Power off fifteen seconds, power on, in the video.
The DAL06P dimmer is a new offering from Cooper.
This replaces CWD 106P on Lowe's shelves , simplifying stock, with three choices of faceplate color in the package. Two adjustment wheels are added to right of the dimming slider. Black is power setting at fully dimmed. White is described this way:
features an adjustable Rapid-Start setting which provides additional power for a brief time period to ensure lamp start-up at low dim settings.
At full up the white wheel causes a current spike in starting that is a bothersome flash. I find the boost doesn't help LEDs to fire, and will leave the setting full down.
The gem in a dimming picture is the 4" Glimpse. It dims nicely to 10%, about a watt, and reliably restarts if turned off, giving really nice night light in a bathroom or hallway. An SLD4 dimmable to 25% will be much bigger and brighter, drawing three watts.
The SLD6 in a dimmer circuit hums at the same sound level as T67. The Glimpse lights buzz at half the noise level of T67 and SLD6. The Sylvania 70732 is silent on a dimmer, but this one does a dimmed start only above 50% power. The Sylvania also has a delayed start always, that isn't noticed here, or in a circuit of only Sylvania 70732. The Philips 15° spot is a dimbulb outside the 15° cone.
The Home Depot/ Cooper SLD6 and SLD4 products will compete against Lowe’s/ Sylvania 70732. Here note equal color temperature, and the greater brightness of Sylvania for nearly-equal wattage.
The Sylvania 70732 is again brighter vs.the 4” Cooper light, as expected.
The Sylvania review commenter was excited about a foam gasket in SLD4 and SLD6 luminaires. I am not. It is thin vs. much heavy ceiling texture. If you don't want air leakage past a luminaire, seal its junction box, as I do with flexible grout .