Setting color via RGB vs color temperature

Is what I'm experiencing with a Sengled RGBW bulb true for many/most/all brands of RGBW bulbs?

When I set the color of the bulb using RGB values (in this case, 255/230/130) versus setting the color temperature to 2400K, the bulb isn't as bright, even though in both cases, the level is 100%. My guess is the bulb is only about 75% as bright as when setting the color temperature. It's very noticeable at night when there are no other lights on in the room.

I realize 255/230/130 is not as warm/yellowish as 2400K, but it seems like that would make the RGB setting brighter than the color temperature setting.

The reason I want to use the RGB method is because if the bulb is in color mode "CT", it shines red for maybe 1/4 second when it is turned on instead of starting at 2400K. Not sure if this is a Sengled issue or common among RGBW bulbs because the Sengled bulb is the only one I have.

This is not unique to Sengled and common across all bulbs that have a dedicated white pixel. White color temperatures will always be brighter when the dedicated pixel is used.


Thanks for the explanation. I hadn't thought about it that way.

I accidentally found a way to eliminate the initial red color.

I'm now controlling the bulb with a ZEN37 remote and the Button Controllers app. Whenever one of the buttons is pressed that triggers a rule to toggle the bulb, the rule checks to see if the bulb is currently off. If it is, it sets the color temperature (CT) before toggling the bulb to "on". None of the button rules sets the color via RGB.

Initially, the rule was setting the CT to 2400, and that's when the bulb would initially flash red when it was turned on. I changed the rules to set the CT to 2700, and the red flash went away. I don't see any initial color now.

No idea why this works.

Do you have prestaging turned on? This kind of thing should only work if that is the case (and it can cause problems with a lot of apps that don't expect this non-standard behavior, but if you're using something like Button Controller where you can define your own actions, you can, of course, make it work).

Otherwise, a "Set Color Temperature" normally also turns the device on, so you wouldn't need an explicit "On" command. If you do, that's the difference and the only reason it would work, which it may not for all devices.

Just some extra info if it's helpful!

I'm not using pre-stage. The button rules are pretty simple...

Button 1 does Toggle: Kitchen Light

Button 2 is unused

Button 3 does Dim: Kitchen Light: 20 --> fade: 2

Button 4 does Dim: Kitchen Light: 95 --> fade: 2

I'm setting the initial color temp to 2700K via the bulb's device details page, and don't change it via any rules.

I think my initial issue (bulb turning red for 1/4 second when turned on) is somehow related to the current color temperature. When I used 2400K, it would be red briefly. When I used 2700K, I couldn't see any initial color different from a "warm white", That doesn't mean there wasn't an initial color. Maybe there was but it was indistinguishable from the final 2700K color. For grins, I tried 3100K. That caused a noticeable brief blue color before the final color.