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What is the difference between the following? I am mainly interested in the difference in terms of how they feel when you press a note.

"Tri-Sensor Scaled Hammer Action"

And

"Fully Weighted keys (Graded Hammer Standard), Hard/Medium/Soft/Fixed sensitivity"

Sebastian Nielsen
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  • The question arose while browsing for a new piano: (1) piano 1 with tri-sense sclaed (2) piano 2 with graded hammer standard – Sebastian Nielsen May 11 '20 at 18:24
  • They sound like marketing terms. ;) I've never understood the terminology, and just like real acoustic pianos are different and I don't like many of them, digital pianos are different and I don't like many of them. Some digital pianos are nicer to play than some acoustic pianos, but I have yet to find a digital piano that feels like an acoustic. Even my Yamaha Silent upright - activating the silent mechanism shortens the key action a little bit, and then it doesn't feel the same anymore. Every instrument can be fun in its own way, and acoustic pianos can be bad. Try before you buy... – piiperi Reinstate Monica May 11 '20 at 18:28
  • As piiperi says, there's action, then there's action. Even some 'real' pianos won't suit individuals. Whatever the jargon, the proper proof of the pudding is in the eating - try it out for yourself. Whatever it's called, it may or may not be right for you. – Tim May 11 '20 at 19:33
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    One important thing in an acoustic piano - or an acoustic guitar for that matter - is that it physically vibrates in the same room as you are as a physical person, and that in itself adds an important dimension. When you virtualize the room and put on headphones, something important disappears. Some digital pianos try to mimic this aspect by having lots of individual speakers pointing to various directions and maybe trying to make the piano's wooden body vibrate as well. I think this physicality adds something to the instrument's impact and impressiveness that helps motivation and learning. – piiperi Reinstate Monica May 11 '20 at 19:40
  • Thanks for the input guys. The way you put it, my question wasn't really answerable, so I just edited it. – Sebastian Nielsen May 11 '20 at 20:03
  • @piiperiReinstateMonica - it's an interesting concept, but the action of any piano like this won't be affected by any of this, will it? – Tim May 12 '20 at 06:18
  • @Tim I meant to point out that there are other important factors to how an acoustic piano behaves besides the key action. – piiperi Reinstate Monica May 12 '20 at 06:22
  • @piiperiReinstateMonica - no, that's fine. Interesting about the speakers, etc. But it would all need to have several reincarnations to be successful, like reverb can be hall, stadium, studio, etc...Maybe it can be really clever : Bosendorfer, Carnegie Hall, stage right, please... – Tim May 12 '20 at 06:26
  • @Tim If I understood correctly, the point with the speaker thingies is specifically not to try and create a different room, but to make the piano sound like an acoustic piano in the actual physical room where the piano is. No reverbs and stadiums. It's always a bit problematic if you have virtual room coming through loudspeakers - then you have TWO rooms on top of each other for that instrument - the virtual one and the real one. Which makes it feel less real and more like listening to a record. But if you have a real acoustic instrument, its sound only has the real room. – piiperi Reinstate Monica May 12 '20 at 06:33
  • @piiperiReinstateMonica - fraught with too many problems! Headphones might save some of the idea - but even then, you'd need ones with at least two speakers on each ear! – Tim May 12 '20 at 06:42

2 Answers2

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Those terms do have specific meanings, although there is a bit of variation (for example, "progressive weighting" is used by some manufacturers, but it's identical to "graded hammer"). In the order presented:

Tri sensor means each key has three sensors. You need at least one sensor just to tell if a key is being played, and you need at least two to deliver a dynamic range. The dynamics produced by a piano depend on key velocity. When you have two sensors the key will strike them in sequence, starting with the sensor closest to the hinge. The smaller the time between the sensors being triggered, the faster the key must be moving, and the software will respond by delivering a higher dynamic level. Adding a third sensor can allow you to do other stuff in addition, like the next item.

Scaled hammer means a note can be re-triggered without completely releasing the key. This is the purpose of that third sensor - the one farthest from the hinge. When the front of the key starts to rise, this sensor will release first, and as soon as it does, the key can be re-struck. On pianos with just two sensors the key must return to the full-up position before you can re-trigger the key.

Fully weighted keys refers to the resistance of the key. Keys can be either weighted or unweighted; weighted keys provide resistance by literally using a weight to simulate the resistance provided by the action of an acoustic piano. The simplest weighted keys just add a weight to the back of the key mechanism, but most will lift a weight using levers or cams in the key mechanism. "Fully weighted" means the resistance is completely provided by the weight, and that weight will also serve to return the key to its "home" position. The other weighted option is "semi-weighted", which uses a spring in conjunction with a weight. Fully weighted keys will typically have more resistance and a faster action.

Graded hammer means the lowest notes have more weight resistance than the highest notes. Some folks will say that this makes them different from weighted keys - that's based on the belief that "weighted key" means the same weight, but that's not actually the case. Weighting refers to the method of achieving the sense of touch, and grading is a difference in degree across the range.

Hard/medium/soft/fixed sensitivity doesn't actually change the "feel" of the keyboard, since that's set by the weights. Instead, it puts limits on the dynamic range. The lower the sensitivity, the louder the lower end of the dynamic range (the upper end is set by the volume knob or slider). So a high sensitivity lets you get more shades of dynamic variation. But if you don't have much touch control, high sensitivity can sound pretty awful, so the lower sensitivity grades are a better choice for less skilled pianists.

Tom Serb
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Honestly, based on these two terms I'd say they'd feel exactly the same. Hammer action will simulate acoustic pianos' feel of a hammer when pressing keys. However, even though both products descriptions say they use hammer action, the feel could be completely different based on the quality of that hammer action mechanism and the overall quality of the keys. But from what I can tell, these pianos are both hammer action.

Luke Abram
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