Best Extraction time for 15 Bars machine?

Hi everyone,

I would like to know what is the best extraction time for a 15 Bars Coffee Machine ?

I tried 25 seconds but even with the finest grain my grinder produces, I can’t get a 1:2 ratio, it’s more like 1:6…

Thanks for your help.

Just out of interest why is your machine 15 bar? Is it not adjustable?

My machine is a delonghi 685, 15 bars is the standard pressure for this machine.

I could’nt find in the manual a way to adjust the pressure…