I have three Fotodiox LED 100WB-56, and I need some softbox modifiers. There are way too many options and I want to make sure I get something that will fit the lights I have. I like large light sources, so the bigger the better. Trying to figure out what the most affordable option is since we already dropped money on the lights, but now I need something to soften that light haha. Obviously I could start throwing white sheets up but I'd like something a little more controlled.
The challenge with LEDs is that they have a pretty narrow angle of spread.
Even arranged in arrays, they act more like rows of spotlights than a traditional broad source. Which means the larger the soft box you put on them - the farther it has to be away from the instrument order to fill up the diffusion and achieve the "softness" you are looking for.
I'd setup one of your lights in a darkish room. Move it a couple of feet back from a wall and look at the native beam spread. THAT is the max size of a soft box that instrument can properly fill.
You could, I suppose put in a secondary layer of diffusion like the old Westcott soft boxes that were designed for narrow beam hot lights - but typical LEDS just don't the the output to punch through multiple layers of diffusion very well.