RGBW not sending white parameter

I have a generic RGB and a generic RGBW fixture in Beam linked to a RGB / RGBW bulb respectively in the Capture visualizer. When I choose generic instrument in ableton I can indeed control red, green and blue on these lights but on the rgbw the ‘white’ parameter does nothing. As the RGB works on paramater 1, 2 and 3, I would assume parameter 4 would automatically be linked to the fourth channel on the fixture. What am I doing wrong? It feels like Beam is not sending the white information?

Hi Tessa,

With fixture profiles such as the Generic RGBW (which uses the RGBW colorspace macro, such as the one you can add in the Fixture Editor), the white channel intensity is derived from the luminance of the color specified by the red+green+blue combination.
As the perceived brightness of a color increases and its saturation decreases, you will see the W channel intensity increasing and the R/G/B channel intensities decreasing. This allows for working in the RGB/HSL color spaces (e.g. using the colorpicker) and ensures the white LEDs are used for representing white and desaturated colors as much as possible (something that RGB LEDs are not capable of accurately representing on their own).
Here is a small demo, see channels 1-4 as the R/G/B amount changes (you can see the channel 4 go up once the color starts to go towards white):

However, with such a profile it is indeed not possible to manually adjust the white modulation, e.g. by selecting and modulating it in the Generic* Instrument or using the LFO or Scale effects.
This is something that would be possible with a fixture profile like this following one, where the White channel is decoupled from RGB and you can control it yourself: Generic RGB+W.sbf.
Depending on what your goal is, there might also be some other solutions.

To begin with, check if you can reproduce the same behavior as in the video above.
Afterwards, please let us know if there is still something around this you might be trying to achieve but are unable to.

EDIT: *Maybe that’s something you already discovered yourself, but just in case - Generic Instrument’s colorpicker is already mapped to control red, green and blue modulations, so no need to select those additionally in the section to the right:

Hi luka, a game changer indeed! Immediately changing all my instruments haha. So far so good, except the midi note doesn’t trigger the lamp any more as the test button in Beam stopped working. But I can make rgb+w faders in automation just like you described!

Hey Tessa,

  • The Test button at the moment doesn’t have any effect on fixture profiles that do not contain a dimmer channel, such as Generic RGB and Generic RGBW, so it was likely never working :slight_smile:
    An update (1.5.2) that will make this work will be out in the coming weeks though!

  • As far as “the midi note doesn’t trigger the lamp” - could you check if the modulation selector of your Generic instrument has the dim selected?


Hi, that makes sense about the rgb. At the moment set up to test through ableton so no worries. Also found a lamp in the free student capture that responds to your rgb+w fixture. Most of them only have rgb or have 6+ channels (which dont respond to rgb). The COLORdash in the free edition has options for 10/6/4 channels and the 4 channel one gives a rgb + yellow (white ish) one so for my specific purpose I have found a lamp that works and that I can save!

MIDI notes was just my fuckup. Had a look with my partner - Darius, who is also in the project - and he figured out a way to neatly group all lamps and midi notes together so that works now! And yes, dim had to be selected on the AR envelope.

Thanks for reporting back - good to know the MIDI-triggered envelopes are now behaving as expected & you found a way to make things work with Capture Student edition!

Update: after discussing this once again, we came to the conclusion that - if the creative goal is to be able to “morph” between a “given color” and “white” using a single parameter - it is (instead of using the above attached Generic RGB+W) better to stick with using a fixture like Generic RGBW and instead of controlling the white modulation directly, choosing the HSL color mode in a Beam device, finding the desired Hue and controlling Luminosity between 0.5 and 1.0 to transition between the chosen color and white.
This way we can keep using Beam’s RGB → RGBW conversion, which ensures the white LEDs are correctly used for representing whites.

So far so good, except the midi note doesn’t trigger the lamp any more as the test button in Beam stopped working.

Beam 1.5.2 is now out, and as promised above, the Test button should now also work with fixtures like Generic RGB and Generic RGBW.