Ah I see.
I find 3 x separate pots provides perfect control. I can set each colour to an exact value.
With 3 x pots controlled simultaneously, RED may be sitting on 400 Ohms resistance, GREEN 410 ohms and BLUE 394 Ohms. Turning them all at the same time lowers or increases the resistance but the difference shifts up and down as well. No two pots are identical, one may sit at a particular value at a given position, while another will sit at a slightly different value at that same position.
I have also noticed that in the case of composite / s-video, equal values doesn't always work well for colour balance. I.e. you may need less red and more blue.
I find 3 x separate pots provides perfect control. I can set each colour to an exact value.
With 3 x pots controlled simultaneously, RED may be sitting on 400 Ohms resistance, GREEN 410 ohms and BLUE 394 Ohms. Turning them all at the same time lowers or increases the resistance but the difference shifts up and down as well. No two pots are identical, one may sit at a particular value at a given position, while another will sit at a slightly different value at that same position.
I have also noticed that in the case of composite / s-video, equal values doesn't always work well for colour balance. I.e. you may need less red and more blue.