Assuming you're PRINTing from Archicad, use the same HP settings and Save As PDF from the Print dialog.
If that doesn't work, try Save PDF As Postscript from the same dialog, then run the .ps file through Distiller.
Check both by Printing the resulting PDFs from Adobe Reader (or Acrobat).
If just the looks on-screen is the problem, turn on Contour smoothing in Adobe's Preferences.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1