Si tengo un dimmer en 4 led cob con un Driver de 1...

I would use the lowest setting on the seedlings and use the maximum distance recommended by the manufacturer. With out using a PAR meter to know how intense the lights are your just guessing and risk burning them. As the plants grow you can slowly lower your lights a few inches at a time especially if they look like they are reaching for the like by stretching too much. Typically maximum light is used during mid to late bloom then the last 3 weeks before harvest lower the light intensity. I would keep an eye out for signs of light stress in the leaves like the leaf blades curl up or they look like they are folding up like a canoe. Also the leaves closest to the light will begin to get pale in color. Hope this helps.

Your question isn't clear. You want to know the output weight you can expect with that setup ? Which watts for your LEDs?