I used to prep every roast the same way. Same grind, same temperature, same everything. Then I kept getting sour light roasts and bitter dark ones and couldn't figure out why.

Turns out, roast level changes everything. Light roasts need hotter water and a finer grind. Dark roasts require cooler water and a coarser grind. Medium sits between both.

If your shots taste off and you haven't adjusted your prep by roast, that's likely the problem.

What roast are you working with right now?