Did I over feed?

I'm growing in peat mix, similar to HP. I fed them at 1200ppm, pH= about 6.1
(A+B standard feed with recommended CalMag) leaves started to slowly discolour and eventually burn. The leaves also real Ridgid. Now new growth is turning more yellowish as well and slowing down. I'm on week two of veg.

480W LED Array, about 14 inches from top
Temp and humidity are 76F and 54%RH

Could you be cooking them being so close.

I’m still learning how to control the power of led.

It could be, but only two out of my four plants were really affected, but now the third plant is starting to show the same signs. I raised the lights even more to about 18-20 inches to see if that changed anything. I also PPM'd the run off and pH and both are in check (950 and 6.3)
Hoping this corrects thing. My grow was going so well up until this point.