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In my view, I think the weakest aspect of my digital piano is the short pivot length of the keys. This is the Casio AP-470 but the 270 and the equivalent Privia models will all suffer the same problem.

I try not to but I end up playing near the fallboard regularly. The short pivot length means it is really quite difficult to regulate the force/speed at which a key is pressed when playing near the fallboard. I can't afford a new DP soon, but when I do this will be an important consideration.

I don't see for many models the pivot length of the keys given. All I know for my piano is that when the key is fully pressed the distance is about 2.5 mm, about a quarter then near the end of the key.

Has anyone looked into this, and worked out a useful way to evaluate different models other than buying a pair of callipers and measuring the amount of movement at the end of each key and at the fallboard? Is this even the best approach to thinking about this problem?

I assume grands are mostly better than uprights in respect to this issue as well, but without experience I could be wrong.

Very few DPs have long key sticks. I think the 22 cm PHA50 is ok for me. I wouldn't upgrade just for a longer key, but I don't think I'd go any shorter.

Here's a list of actions. This is what I remember, so someone correct me if I'm wrong about any of them.

Kawai RM3 around 18-19 cm ???
Casio Celviano Hybrid 20-21cm.
Roland PHA50 22cm
AvantGrand N1 etc. 23cm. I've come across conflicting measurements. Some have it about 1cm longer.
Kawai Grand Feel/II 24cm
Yamaha GrandTouch >24cm
Kawai Novus around 26cm
Roland Grand Hybrid around 26cm

Few grands have a shorter pivot than the low 20s. Large grands are usually mid 20s to around 30.

Modern uprights tend to have fairly decent length.

I find the pivot length on my Yamaha P-515 to be entirely acceptable. I never feel a lack of dynamic control when playing near the fallboard.

Or any(?)

Except indirectly, when manufacturers release photos or drawings and we can estimate it.

Sometimes people also post photos here (or on other sites) if they open up their piano.

If we consider a loose (debatable) categorization like "short", "medium" and "long", then some examples could be:

Short:
- Casio CDP, Privia and Celviano apart from the "hybrids"
- Yamaha GHS
- Fatar TP/100
- Medeli K6

Medium:
- Roland PHA4 family ("Standard" is shorter than "Premium" and "Concert", but still better than e.g. Casio)
- Roland PHA-50
- Korg RH3
- Korg NH
- Fatar TP/40
- Fatar TP/400
- Most Yamaha's actions above GHS (some belong to the "long" category)
- All Kawai's actions with plastic keys
- Some Kawai actions with wooden keys (some belong to the "long" category)
- Medeli K8(?)

Long:
- Roland Hybrid Grand
- Yamaha GrandTouch
- Some of the Kawai actions with wooden keys
- The "hybrids" from Yamaha and Kawai with real grand piano actions

Thanks John, that is useful information. I could calculate very roughly what the pivot length on my keyboard is from the length of the exposed key and the ratio of movement at the key end and at the fallboard. But the errors will be large. My rough calculation is 20cm.

The exposed length of the white key is 15cm, the key travel reduces from 1cm to 2.5mm near the fallboard. But that 2.5mm could as easily be 2 or 3 mm since I don't have callipers to measure accurately.

Lets say I wanted to double the key-travel at the fallboard to 5mm, keeping the exposed length of the white key constant that would mean a pivot length of 30cm.

That is too long for anything sensible.

4mm of key-travel is a pivot length of 25cm.

A 4mm of key-travel compared to 2.5mm reduces the difference in required force at the front of the key to the back from 4 times to 2.5 times. That seems like a good improvement. The improvement in the ability to regulate by the player should be discernible. Excellent players should be able to compensate but that isn't me which is probably why I am noticing this as an issue. Too many ghost notes or overloud notes.

There's a large difference between 20 and 22 for me, 22 to 24 not as much, and 24 to 26, not really an awful lot at all. On a concert grand, with a pivot length of 30 cm, the back of the playable key has roughly 5mm of key travel, so once you get much over 20 cm you have quickly diminishing returns. I have an old Kawai MP10 that I'm thinking of operating on...

While this is currently an academic issue for me, I did manage to locate Tony's (of Bonners) video on key actions while I was researching models. Tony says what really matters in the end is the length/size of the key.



If I am reading it correctly, you have three main options:

• "Real" piano actions offered by Yamaha and Kawai hybrids.
• Casio Natural Grand Hammer, Yamaha GrandTouch, Kawai GrandFeel
• Rest of the pint-sized plastic and wooden actions, some being better than others.

My back of the envelope calculations would seem to agree with this. Anything over 25cm is pointless. I don’t think I would like to go below 24cm though. The the 24 to 25 cm range feels to me like the point of inflection, where gains are easily achieved up to that point but diminish quickly afterwards.

Here's the Casio key full view:



It's centimeters, obviously.

He talked about key length but not pivot length. No details given and so little practical information given out in so much time.

Watching closely I found it interesting the Yamaha AvantGrand action has long keys (the longest by the looks of it) but the pivot point looks about halfway along the key, whereas the Kawai and Casio's were closer to the end furthest from the exposed part of the key probably making the pivot distance similar.

Now that is wow. 18 cm in total to the pivot point with 15cm of visible key. That is at the absolute worst end of the range of possibilities of my measurement giving just under 2mm of key-travel at the fallboard. So much extra force is required when playing near the fallboard and when it happens the speed of movement of the action will be fast. Almost impossible to give any practical regulation.

What model is that exactly. I assume it will be exactly the same for mine?

Thanks so much for doing the measurements and taking the photo.

So do I. About 30 years ago I did serious damage to my right thumb with a table saw. It’s got a funky shape and somewhat limited mobility which I’ve overcome to the best of my ability, but I’m forced to play closer to the fallboard than I would like. The new Privia was never going to happen for me, which was a shame - I otherwise liked it. But I’m good with my new 515, and my old KX88, which I still play regularly.

Would it have mattered if he had given measurements of the keys and the position of the pivot? I think not. Fact of the matter is, long keys allow for better positioning of the pivot, and only a certain number of actions are known to have long keys.

There is another video where he displays the Kawai GF action again and claims that while the Yamaha GrandTouch and Roland Hybrid Grand actions have longer keys, based on diagrams/photos he has seen online, the pivot is positioned further to the back.



There are a lot of photographs online of various keyboard actions. Based on the exposed part of the key being about 14cm, you should be able to easily calculate the length of the key as well as positioning of the pivot.

Roland PHA-4 Standard:


Roland PHA-50:


(Possibly) Roland Hybrid Grand:




This is probably because the AvantGrand action is a real piano action, while the Kawai and Casio ones (from the video) are not.

This is the Roland PHA 50 and the Hybrid Grand.

This seems to be the correct one.

My third image looks like a version of the PHA-50.

Also, Tony is right in saying that the keys may be long but the pivot is at the end.

I was suffering from this with my newly purchased Casio AP460. I kept it about 6 weeks before trading it in for a Kawai CA67 - and by far the strongest reason was the pivot length.

There is a post somewhere on this forum which lists all the key lengths.

Just been hunting for it without luck.

Interesting that was your reason to return. I find the speaker system and opening lid of the AP-470 works well in my room where I practise and it is far superior to that of any similarly priced DP. That is enough reason for me to stay with this model until I can afford I real proper upgrade. But I do find the pivot length is a real issue for me.

I find it interesting to note that people just talk about the force required to move the key so it is harder to make a sound, but there is a second side to that as well, when you do press the key hard enough near the fallboard to make a sound it is much harder to regulate and the sound of the note is often way too loud. That is a result of the high amount of leverage near the fallboard.

The inevitable result is poor regulation. I suppose a super skilled pianist with really good control could mitigate the worst of this. But well, that aint me.

Perhaps by sticking with it, I'm forcing myself to learn to have greater control and when I upgrade just imagine the sensitivity I can give to each piece of music I play then.

My photo was from a PX-800, contemporary of some x20 series models and my understanding is that it's part of the same continuum as the action in the x70 series. Casio has changed it gradually by adding a third sensor, adding a key surface texture and apparently the feel has also changed. But not the dimensions, I believe.

The Yamaha NU1 has a short pivot length, and it's regarded as an excellent action, along with that on the Kawai VPC-1. The GHS keyboard on cheaper Yamahas aren't highly regarded here, but I can say it made no difference to the playing volume when inevitably, one finds one's fingers near the fallboard. Maybe Yamaha looked into this, but I played my best stuff on that keyboard. I didn't necessarily like it though; it didn't fit my fingers!