I'm already use 18v adapter but still has a little bit noise, specially when i'm twaeking the knobs.
the flanger sweep should be calibrated to work between 69.6 KHz and 2.6 MHz.
You could try to lower it to 2.4 or 2.2 MHz if the noise appears at the top of the sweep. You can try to increase the lowest end up to 80 or 90 KHz, if the noise appears at the lowest point of the sweep.
I remember reading something about parts locations on the pcb : It could get noisy if some of its components are too close. One section of the circuit might be picking noises from an other part of the circuit. Power section near the clock section, for exemple, but I can't say anything for sure.