What the compass diagnoses
Espresso has two independent levers. Grind controls extraction — how much flavor the water pulls out. Yield controls strength — how much of that flavor ends up in how much liquid. Confusing the two is the most common mistake:
| What you taste | Likely issue | First move |
|---|---|---|
| Sour, sharp | Under-extracted | Grind finer |
| Bitter, hollow, drying | Over-extracted | Grind coarser |
| Balanced but overpowering | Too concentrated | Pull it longer |
| Balanced but watery | Too dilute | Stop it earlier |
| Bitter and watery together | Ran too long | Stop it earlier — not the grind |
| Sour and bitter together | Channeling | Fix the puck, not the recipe |
Why it asks about your basket
A pressurized (dual-wall) basket builds its own back-pressure, so grinding finer or coarser barely moves the shot the way it does with a standard basket. A pod machine fixes the grind and dose before you touch anything. The compass changes which lever it recommends based on what you actually have — see dialing in on a pressurized basket.
What it cannot fix
Sour and bitter in the same sip, or a shot that sprayed or blonded early, is channeling — water cutting a shortcut through the puck. No grind change fixes that; better puck prep does. The compass will say so instead of recommending a recipe change that will not work. The full espresso dialing-in guide covers the mechanics behind every recommendation here.
Brewing filter coffee instead? Grind is filter coffee's only real lever, and it behaves differently than it does under pressure. Use the Brew Compass for AeroPress, drip, pourover, French press, Moka Pot, or cold brew.