Feurich High Speed KAMM Upright action

Here’s the website of the inventor describing how it works (in German, so I used a translator):
https://klavieratelier-kamm.de/High-Speed-KAMM-Action

To my understanding this is very clever because the spring actually acts as a double repetition lever because it’s attached to the hammer and gets stretched when you are holding the key (hence the jack) up and the hammer has rebounded and is caught by the check. Usually on an upright when you release the key after that point, the hammer will fall back to its rest position which is why you have to completely release the key-jack to reengage it under the butt. However with this spring the hammer stretches it and thus the spring tends to to move the hammer forward (towards the string) in a similar manner to a double-repetition lever. Watch carefully the video in the first post where they show models of upright actions. This is so clever! I’m amazed. It’s much better than using magnets IMO because the springs have a double purpose: they act as a double repetition lever that prevents the hammer from falling backwards and then also facilitate the jack to slide under the butt. Awesome! And so simple at the same time.

Very interesting, it seems to work very good. It's a bit strange that there isn't more upright manufacturers that think of these things. Feurich isn't the first one though. Sauter have a similar solution in their uprights with an extra spring for double repetition and to get performance similar to a grand, they call it the R2 mechanism and it works very well.

https://twohundredyearssauterpianos.de/en/milestones

@ delvento: I don't see how gravity plays no part in an upright. The keys return because of gravity. And only because of gravity.

And so do the hammers. They don't move horizontally as is often claimed. They pivot, just as do those on a grand piano. The difference is that the hammers on a grand spend more of their time nearly horizontal, while those on an upright more nearly vertical.

As for springs: A grand rep depends on at least two springs for the hammer action ... one on the repetition lever and another under the jack. An upright has only the jack spring. It also has a damper spring, not found on the grand.

So it's mostly gravity for both, with judicious use of springs.

I, too, am surprised that this innovation has not previously come to market. I wonder why.

My first speculation is that in the past, before grand piano sales started to decline, the introduction of this technology into uprights would have put uprights into more direct competition with home and studio grand pianos, an undesired effect.

But, now that grand piano sales are down, seemingly for the foreseeable future, the manufacturer's priority now is on winning the battle between competing upright brands, and between the uprights and the high quality digitals and hybrids that have grand piano actions. This technology now allows the upright to compete with high quality digitals of similar footprint size without doing much harm to their already reduced grand piano sales.

Hello,

Some time ago I saw this:

Where also a new repetition (spring) system for uprights is presented.

Perhaps, in essence, similar?

Cheers and happy innovations,

HZ

HZPiano
Yes, there are a few similar systems already. Which is why I wonder why that is not a standard already. I tend to agree with Ralphiano it could be to not cannibalize the grand piano sales.

HZPiano I actually contacted Fujii Piano Service last year for a quote to install this Granfeel spring upgrade.

At the time I was going to turn an NV5 into an NV10 upright 🙂

Their contact details are:

Fujii Piano Service CO.LTD

15-11 Nishimukoda-cho, Satsumasendai-city, Kagoshima, Japan 895-0027

TEL +81-996-25-3320 URL　http://granfeel.jp http://fujiipianoservice.jp

It would probably make the NU1X playable as well - although it isn't much more expensive just to purchase the N1X.

Hello,

burkey At the time I was going to turn an NV5 into an NV10 upright 🙂

So did you?!

Cheers and happy DIY modding,

HZ

HZPiano So did you?!

Cheers and happy DIY modding,

They usually send out a trained/certified professional technician to install it. I think it takes them a few hours.

Although for me they said:

'Fujii, the developer of Granfeel himself, could visit Singapore for retrofitting, after the situation calms down…'

However due to COVID shutting down our airport for 5 months we couldn't return home (Melbourne), so the piano purchase was postponed.

Hello,

burkey However due to COVID shutting down our airport for 5 months we couldn't return home (Melbourne), so the piano purchase was postponed.

What an adventure.

Are you still planning of having him "upgrade" your NV5? That would be a very interesting and somewhat groundbreaking case. (Or didn't you even get an NV5(S) as of yet?)

Cheers and happy innovations,

HZ

I have contacted KAMM and asked if they had any Yamaha U3 or U1 pictures with their system installed, but no luck. But they say it should work just fine.

I know the U3 is not what limits my playing, though 😅

Jose

Do they sell it to anyone or just technicians? Did they quoted a price for the springs?

Surely (Shirley 😆 ) it changes the touch weight? Maybe it's insignificant.

spanishbuddha Surely (Shirley 😆 ) it changes the touch weight? Maybe it's insignificant.

Maybe not the touch weight (particularly at the beginning of the key press) because the spring is not being forced, but it should increase a bit the upweight because it seems that the spring is forcing the key return...

According to the KAMM website it doesn't change the touch because the spring is not pressing against the jack while you are pushing the key. It's only when you've thrown the hammer and it rebounded that the spring gets stretched by pressing on the jack (and of course conversely) pushing the hammer forward, not backwards, so that the jack can slide under the butt again.

If you think about that, it's almost the same principle as the double-repetition lever of the grand piano. Very clever. BTW, I think the magnet solution is similar, since the magnets have non-linear force.

I believe all these systems basically do this thing: they prevent the hammer from going backwards (towards rest position) when you start releasing the key and so the jack can slide under it. Whether they use magnets or springs with different shape and location is a matter of patents I guess 🙂

And thinking even more about that, on theory this seems like making the upright action very similar to a grand piano action in terms of repetition capabilities and being able to repeat without releasing it fully. Kamm even states that his device allows for the key to be repeated even when you have released the key only 1mm which is not true for grand pianos where you need to release the keys a few mm more.

CyberGene Very clever. BTW, I think the magnet solution is similar, since the magnets have non-linear force.

Exactly... As far as I (don't) remember, Steingraeber uses attracting magnets but there is another company that uses opposite polarity magnets between the jack and the catcher to facilitate the repositioning of the jack. The problem with magnets is that they need to be small (otherwise the effect is too strong), and small magnets depend a lot on their relative distance. An error in tenths of millimeter causes large differences from key to key. I expect a return spring to be much more forgiving.

Simple and clever. Possibly game changing? If the action was the only limit in an upright, now upright builders have no more excuses, they need to build them as good as any grand, with the same wood, same strings, same cast iron, same everything.

Hello,

Pianissimo need to build them as good as any grand, with the same wood, same strings, same cast iron, same everything.

Happy days, interesting times to come!

Cheers and jolly anticipation,

HZ

vagfilm Do they sell it to anyone or just technicians? Did they quoted a price for the springs?

This is my next step, asking for a price. I will let you know.

Jose