Did you check run-out when they were fitted? Its likely to be disc thickness variation (DTV), usually caused by out of spec run-out which causes the pad to stike the disc during a normal revolution of the wheel. This causes the disc to wear down slightly in that area, which then when braking appears as judder as the pad conforms to thick and thin parts of the disc moving the pedal up and down. Unfortunately EBC discs seem to suffer with this more than others, why that happens is for you to decide
Usually curable by having the discs skimmed which means the surface is flat and true.