The one point I will not bend on

About almost everything in buying an instrument I am relaxed. Brand, colour, speakers, Bluetooth — that is taste and budget. About one thing I am not: an instrument without true hammer action teaches your hand something you will later have to unlearn, laboriously. That is not an aesthetic argument. It is a physical one.

What happens inside a real piano

When you press a piano key, you are not triggering a sound. You are throwing a hammer. The key is a lever. Through a mechanism it accelerates a felt-covered wooden hammer toward the string. Just before it arrives, the hammer disengages and flies the last stretch freely — otherwise it would rest against the string and choke the sound instantly. It strikes, rebounds, the string rings, and a damper waits for you to release the key. The crucial part: loudness in this process is a question of speed, not force. How fast the hammer meets the string decides everything — soft, loud, gentle, hard. And the mass of that hammer is precisely what your fingers feel while they accelerate it. That resistance is not a side effect. It is the feedback system through which you learn to control dynamics at all.

What a keyboard without an action does instead

In an instrument without hammer action there is a spring or a rubber dome under the key. It pushes the key back up. A sensor measures how fast you pressed, and the electronics play back a correspondingly loud sample. The result can sound dynamic. But the route there is completely different, because you are accelerating nothing — you are pressing against a spring, and a spring behaves differently from a mass. A spring's resistance grows with distance: the further you push it, the harder it gets. A hammer resists not distance but acceleration — what you feel is its inertia. And just before the string it escapes the mechanism, so the resistance gives way at exactly that point. Your hand learns within weeks to work with whatever it finds. That is the root of the problem.

Why that teaches the hand wrongly

On a spring you learn to press. On a hammer you learn to weigh and throw. Students who have practised on springs typically do three things I then have to correct: Too much downward force. Because a spring answers pressure with more pressure, you get used to pushing into the key. On a piano that is useless after the strike — the hammer is long gone — and it builds tension in the forearm and shoulder. No sense of where the note happens. On a real action you feel where the tone is created, and that is well before the bottom of the key. On a spring that point does not exist, so you drive every key all the way down. It costs time and makes fast passages heavy. No real gradation in the quiet range. The hardest thing on a piano is the very soft: the hammer has to only just reach the string. That control only develops when there is a mass to meter out. These habits are correctable. But it takes months, and it is thoroughly demoralising — because you are unlearning something you worked hard to acquire.

The vocabulary, and what it really means

This is where the fog is deliberate. "Touch-sensitive" means only that a sensor measures velocity. It says nothing whatsoever about the action. A €90 keyboard is touch-sensitive. "Semi-weighted" usually means springs plus a little added mass so it feels heavier. No hammers. "Weighted" is vague and gets used for both. Be careful here. "Hammer action" is the term that matters. Manufacturer names for it include Yamaha's GHS and GHC, and Roland's PHA-4. "Graded" additionally means the keys run heavier in the bass than the treble — as on an acoustic piano, where the bass hammers are simply larger. Nice to have, but secondary to whether there are hammers at all.

The sixty-second test in a shop

You need no prior knowledge for this.

1. Press a single key down very slowly. With a real action you feel the hammer's inertia first, then a distinct give just before the bottom — that is the escapement. With springs there is no such point: light first, then steadily firmer.
2. Compare the lowest C with the highest. Does the bass feel heavier? Then the action is graded.
3. Release a held key slowly and listen. A real action has a soft, wooden settling. Springs make a click.
4. Play one key as quietly as you possibly can. Do you get a note that is genuinely delicate — or does it jump from "nothing" straight to "audible"? That threshold is the most honest criterion there is.

The ladder

It is not "hammer action, yes or no", but a set of steps — and you do not have to start at the top. At the entry point sits Yamaha's GHS, fitted for example in the AdYamaha P-45 ↗. Real hammers, somewhat lighter than an acoustic piano, entirely sufficient for the first years. A step up is Roland's PHA-4 in the AdRoland FP-30X ↗. The difference is clearest in the quiet range: there are more gradations between "barely audible" and "normal". That is where the musically interesting things happen, which is why it is my most frequent upgrade recommendation. At the top sit hybrid instruments that stop simulating altogether and fit a genuine piano action with real hammers, replacing only the string with sensors. Yamaha's AvantGrand range and the NU1X belong here; Casio's Grand Hybrid models use wooden keys and a hammer action Casio developed in collaboration with C. Bechstein. They cost several times as much and make sense for very few beginners — but they show what the whole scale is aiming at. I do not list these, because they really must be played before buying. The digital pianos I recommend regularly, with current prices, are on my recommended instruments page.

What this means for your practice

If your instrument has a real action, every minute of practice works for you. Your hand builds strength, control and feel in the form it can call up again on any other piano — in a lesson, at a friend's house, on a stage. That is exactly the point: you are not practising toward your instrument. You are practising toward playing the piano. If you are facing the buying decision right now, your first piano is the practical guide to it. And if you are unsure about a specific model, send me the link — I will look at the action and tell you honestly what I think of it.