[jyt]

Hi I'm building 4 of those and two of them are giving me 33vdc instead of 45-48vdc, what could be the problem? I was able to calibrate it no problem only when it come to adjusting the VU to 6db I can't do it properly.

[JPK]

Check that you have the correct resistor in R37, and that C18 is not reversed.
Same thing with R8 and C5.
Check the value of R9, R10.
What are the DC voltageson TP1, TP2, both sides of R8 and both sides of R37 (against 0V)?