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Re: Kawai Novus NV10 - Hands On
JoBert #3019587 08/30/20 10:36 PM
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It seems that I can only reproduce the issue if I play an extremely fast repeating note. While my repertoire does not involve such kinds of repeated notes so I don't find it annoying. Wondering what kind of repertoire are you practicing?

Re: Kawai Novus NV10 - Hands On
Axl86 #3019603 08/31/20 12:28 AM
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Hello Axl86, welcome to the forum.

I've watched the video a few times, but am unable to fully understand the nature of the problem - partly due to the low audio.

Can you upload another version with audible sound, please?
Moreover, would you be willing to set this video and the new video as "unlisted", please?

Kind regards,
James
x


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Re: Kawai Novus NV10 - Hands On
Kawai James #3019607 08/31/20 12:41 AM
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I do see what he is talking about now. Rapid double note repetition and the key does not go all the way to the keybed. Interesting also seen on the N3X above. I'll have to try this on my RX-5 in the morning. Peculiar to a grand action itself perhaps?


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Re: Kawai Novus NV10 - Hands On
JoBert #3019615 08/31/20 01:26 AM
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I could just reproduce it on both my N1X and Cybrid (an old grand piano action that I’ve recently meticulously regulated for days). And since it is open, I analyzed it. All is normal smile

During a normal single strike the hammer is detached from the jack because of the escapement 1mm before the string (and 1mm before the key bottoms out). So, the hammer needs to hit the string and rebound and check in the backcheck. During this the key has already bottomed out.

When doing repeated strikes though, you apply a jerking motion to the downward moving key so that you can repeat it. Jerking meaning that you accelerate the key but then slow it down and release it slightly before bottom so that you can repeat the already bounced off hammer. If you happen to do that fast enough and close to the escapement point, the jack wouldn’t have returned back to its position although the key is above escapement position. And at the same time a hammer is bouncing off with a high velocity and will check because there’s no jack under its knuckle. When that happens, you won’t be able to move the key further although it’s above escapement.

I could also artificially reproduce it by tipping the jack with my finger directly while the key is only slightly pressed, which in turn will “break” the hammer and allow for it to be pushed against the backcheck and thus block/jam the entire system.

I believe this is all a result of jack springs not strong enough. But if they were strong, it would make escapement too hard to overcome.

Last edited by CyberGene; 08/31/20 01:29 AM.

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Re: Kawai Novus NV10 - Hands On
JoBert #3019620 08/31/20 01:42 AM
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My N1X does the same thing. I'll try a real acoustic this week and see if I can duplicate the "stuck key" issue on it.

God Bless,
David


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Re: Kawai Novus NV10 - Hands On
JoBert #3019631 08/31/20 03:00 AM
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Wow. I need to try this again, I couldn't repro it earlier and couldn't tell if I was just playing too slow (likely the case). I assume regulation affects how likely it is to happen on a given action?


Yamaha P-85, P-105, CP50, Kawai MP11 || Kawai NV-10
Re: Kawai Novus NV10 - Hands On
JoBert #3019638 08/31/20 03:29 AM
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I don't think it's related to regulation. It's rather related to the strength of the jack spring. It's a very fine balance. The weaker that spring is, the less resistance it will make when pressing the key, so it's desirable that the spring is not strong, otherwise the feel will be unacceptable. However a weak spring will also make the jack return slower and in this particular situation with repeated fast notes it can happen that there's a bouncing hammer that manages to sneak and check before the jack has returned. BTW this is also the reason why there is a hammer rest rail. Most of the time it's not possible for the hammers to go uncontrollably down because they should ideally be above the knuckles (i.e. stopped by the key-whippen-jack system). However in rare cases of fast repetition and jack spring not quick enough, they can escape the jack even in the key rest position and then nothing can stop the hammer to go down until it hits the whippen and possibly snap... And so the key rest rail is there as a precaution only. Which is why it stays a few mm below the hammer since it doesn't stop the hammers in the regular case.

Last edited by CyberGene; 08/31/20 03:31 AM.

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Re: Kawai Novus NV10 - Hands On
JoBert #3019657 08/31/20 05:49 AM
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I did a few more experiments and comparisons and this is much easier to reproduce on the N1X, especially on the left half of the keyboard where I can consistently reproduce it with more than 80% probability. On the Cybrid it's much more difficult and happens in 10-20% of my deliberate attempts.

I am convinced this is due to the counterweights. They make the keys having higher inertia which contributes to more sluggish and slower key travel (ignoring the rest of the action: whippen, jack, etc.) and so that increases the chance of occurrence for parts of the action not being reset.

It's a bit of an offtopic for the NV10 thread but I'm growing more and more convinced I don't like counterweights. On the Cybrid there are no counterweights and all the keys and hammers are extremely lightweight (the highest keys have downweight of 36g for instance, whereas the lower ones reach 50g on its own, without the need for counterweights). The counterweights are indeed making the keyboard feel a bit more consistent across the ranges and especially when playing quietly but other than that the naturally lightweight action of the older (and smaller) grands is so much easier to play... We've discussed that on the piano technician forums and there's one particular technician Ed McMorrow who is an opponent of this seemingly dead spiral that started around the end of the 19th century to make pianos louder, hence having heavier hammers and then compensating with deeper keydip, heavy counterweights, etc. It's known that, for instance, Chopin's piano had a shallower keydip at 7-8mm (compared to modern standard of 10mm), very lightweight and nimble action and the piano was rather quiet with much emphasis given to the soft dynamics at the price of overall sound volume. He preferred the salon environment and listeners have confirmed he used to play so quiet that one should put his ear above the piano to hear the softest pianissimos. And then came Liszt and the need for a piano to be loud and powerful in a big concert hall... I'm not saying one is better than the other. Apparently modern pianos are what they are for a reason. But I would personally prefer a quiet piano with lightweight and nimble action that's easy to play quiet (and fast). To a certain degree the Cybrid is serving that purpose and although it's already an old action with all the inherent age problems (despite my best attempts at restoring it regulating it), I prefer it to the N1X in certain aspects of playing. Of course, the N1X feels much more consistent, smoother, and "better" overall.

All that being said, I'm interested in the NV10 action and whether it's lighter-feeling than the N1X or not. Many people that compare them have said the NV10 feels heavier but who knows, it's all so subjective.


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Re: Kawai Novus NV10 - Hands On
CyberGene #3019667 08/31/20 06:57 AM
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Originally Posted by CyberGene
....to make pianos louder, hence having heavier hammers and then compensating with deeper keydip, heavy counterweights, etc. It's known that, for instance, Chopin's piano had a shallower keydip at 7-8mm (compared to modern standard of 10mm), very lightweight and nimble action and the piano was rather quiet with much emphasis given to the soft dynamics at the price of overall sound volume. He preferred the salon environment and listeners have confirmed he used to play so quiet that one should put his ear above the piano to hear the softest pianissimos. And then came Liszt and the need for a piano to be loud and powerful in a big concert hall... I'm not saying one is better than the other. Apparently modern pianos are what they are for a reason.....

From a layman’s perspective, I wonder why manufacturers do not build acoustic pianos for the ‘home’; in other words, a piano not having to be excessively loud; therefore, not needing all the excesses; like deeper keydip, counterweights, heavy hammers, etc....

Most people, even seasoned musicians, find acoustic grands to be too loud for moderately sized living rooms, and they’re right; because these instruments were not conceived for the home but rather for medium-sized halls to huge concert halls.

Nowadays things are even worse; with people living in ever smaller dwellings in cramped up buildings where neighbors can hear everything; so why not make ‘quieter’ pianos that are also easier to play (shallow keydip, lighter hammers, etc...)

Perhaps it’s just not practical for manufacturers to do this with acoustics in the same way they don’t offer different key sizes (width-wise), but there’s no excuse to build ‘hybrids’ to these so-called ‘modern’ standards for obvious reasons (no strings to strike, etc..)

So why not make hybrids easier on the fingers by avoiding counterweights, deep keydip, and heavy hammers if these things are simply not needed for a digital piano?

Re: Kawai Novus NV10 - Hands On
JoBert #3019674 08/31/20 07:14 AM
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^ Pete14, exactly my thoughts I’ve been having for some time 👍🏻


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Re: Kawai Novus NV10 - Hands On
JoBert #3019678 08/31/20 07:28 AM
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CG has dealt with this in detail. I can't reproduce this on my grand. I have the springs set so they're just strong enough to do what they have to do. When springs are weak the hammer can collapse below their rest height. When they're too strong, notes can "bobble", and strike the string a couple of times in soft playing. The happy medium allows really fast repeated notes without too much effort.

Last edited by johnstaf; 08/31/20 07:31 AM.
Re: Kawai Novus NV10 - Hands On
johnstaf #3019689 08/31/20 07:59 AM
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Originally Posted by johnstaf
CG has dealt with this in detail. I can't reproduce this on my grand. I have the springs set so they're just strong enough to do what they have to do. When springs are weak the hammer can collapse below their rest height. When they're too strong, notes can "bobble", and strike the string a couple of times in soft playing. The happy medium allows really fast repeated notes without too much effort.

John, you're thinking of the double-repetition lever spring while I mean the jack spring. They are usually one and the same spring though, although it's angled, so regulating it for the double-repetition (which is the only regulation available for that spring) might also affect the jack part tension, I don't know. Also, I'm not very sure if the effect I'm describing is really caused by the spring, it's just a conjecture. Maybe it's some combination of many factors including the mass of the key, the hammers, the friction of the parts, chance, coincidence of mechanical subsystem timings... However the problem is IMO not related to the double-repetition mechanism since the jam occurs with the key above the escapement point (hence the jack should be beneath the knuckle but it isn't) and so the hammer checks deeper within the backcheck because the backcheck hasn't risen high enough and all the leads to a jam of the key at a level above bottom.

In order to reproduce it you have to execute a repeating note (i can do it on middle C on both keyboards) with a single jerking push to the key around the middle and find a proper speed/frequency. I was able to reproduce it rarely on the Cybrid in the morning, but now it's much more difficult and I can reproduce one out of 50 times. But on the N1X it's an easy way. Maybe it's still some regulation. You may be right it's the double-repetition spring but I need to think a bit more to imagine why that is.


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Re: Kawai Novus NV10 - Hands On
JoBert #3019690 08/31/20 08:00 AM
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OK, I got it how it is but I have to go to lunch smile Will describe it later.


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Re: Kawai Novus NV10 - Hands On
CyberGene #3019693 08/31/20 08:10 AM
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Originally Posted by CyberGene
All that being said, I'm interested in the NV10 action and whether it's lighter-feeling than the N1X or not. Many people that compare them have said the NV10 feels heavier but who knows, it's all so subjective.

When I tried both the N1X and NV10, I felt that the N1X had the heavier action. At the time I actually preferred that more because it resembled in feel the two Kawai acoustic grands that I was playing on a regular basis.

I noticed that after a few weeks of playing the N1X my finger strength was increasing. Prior the the N1X I found it difficult to transition between my MP11SE and the Kawai acoustic grands at church. After playing the N1X for a few months the transition became effortless. However, after owning the N1X for over a year now, I noticed that my fingers get fatigued after playing for a few hours (ever if I take breaks). Ironically, now I think I might prefer a lighter action. That way my fingers might not feel like they are getting such a workout all the time. Maybe this feeling has to do with not playing acoustic pianos much over the past five months (California has shutdown our churches because of COVID) and therefore no need to transition.

God Bless,
David


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Re: Kawai Novus NV10 - Hands On
JoBert #3019695 08/31/20 08:13 AM
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CG, I don't think you can separate the two. The jack spring isn't strong enough to work unless the repetition lever is supporting the hammer. The repetition lever has to lift the hammer so the jack can slide back under the knuckle.

This issue can be caused if the wippen and jack screws aren't set properly. If you trip the jack with your finger, does the hammer move? It should only be a tiny bump. Techs refer to it as winking.

Yes. Lunch sounds like a good idea. 😀

Last edited by johnstaf; 08/31/20 08:22 AM.
Re: Kawai Novus NV10 - Hands On
Pete14 #3019697 08/31/20 08:21 AM
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Originally Posted by Pete14
So why not make hybrids easier on the fingers by avoiding counterweights, deep keydip, and heavy hammers if these things are simply not needed for a digital piano?

Unless someone wants a piano that feels like an acoustic, why would they buy a hybrid?

Last edited by johnstaf; 08/31/20 08:26 AM.
Re: Kawai Novus NV10 - Hands On
JoBert #3019708 08/31/20 09:02 AM
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So, here's how and why this jam happens.

Let's first look at a regular piano strike: you press down the key in its front part, the rear part of the key with the backcheck raises, the capstan pushes the whippen, the jack pushes the hammer knuckle. The jack is tripped at escapement point and from this point on the hammer has high velocity with only 1mm before hitting the string. The key also has about 1mm before hitting the bottom but since key to hammer travel ratio is 1:5, the hammer is already rebounding and moving in the opposite direction against the backcheck (the rear part of the key) which is still moving upwards with your finger pressing on the key. This opposite movement makes the hammer tail to get caught (checked) in the backcheck while at the same time also pushing the double repetition lever (with jack even higher up but to one side of the knuckle). This happens because you keep pressing the key while it bottoms out hence providing support for the backcheck to hold the hammer. Once everything is still, the slightest release of the key will make the backcheck go downward and away from the hammer tail, hence unblock it, then the double repetition lever spring will move the hammer up from the jack, so that the jack can reengage under the knuckle again, ready to be repeated.

Now let's look at a staccato strike. When the hammer rebounds and starts moving opposite to the raising backcheck, the jack will be tripped, the hammer will just have started compressing the double repetition lever and so the jack will be on the side of the knuckle. The hammer tail will be just getting caught by the backcheck but then you abruptly release your finger. So, there's no opposing force that holds the key, hence no support for the backcheck to catch and hold the hammer. Instead, the hammer will touch the backcheck and just start getting checked but the force is removed from the key, so the key will start moving back because the hammer has momentum and is hard to stop and it will push the double repetition lever which will then in turn push through the double-repetition spring towards the whippen and ultimately returning the key to its rest position. If the key is light enough, the spring will be able to throw the key back fast enough so that the jack reengages under the knuckle midway during that release. And now, this is important: if the key is heavy (full with lead counterweights), the double-repetition spring will be pushing against the key but the key will be sluggish. The hammer, because of the rebound, is still moving down with high velocity hence it's also hard for the double-repetition spring to slow it down fast enough and so the jack can't be reengaged under the knuckle. As a result, all the following parts move together in the same downward direction: hammer (due to inertia), double-repetition lever compressed against the whippen, rear part of the key slowly being pushed down.

And now if you don't release fully but at that very moment try to repeat again, you will stop the key midway but the hammer will still be moving down and will check (get caught) in the backcheck but at an unusual deep position where the backcheck is still not high enough, hence the front part of the key is not deep enough. This blocks the entire system suddenly and to unblock it you need to release the key. Or in other words it's an extraordinary circumstance where the hammer is checked at an incomplete key position.

With all that in mind, I think the root cause is when the keysticks are too heavy, e.g. from counterweights, and they have high inertia to react swiftly to the rapidly changing forces.

Not sure how many people followed that and my non-native English probably makes it harder to understand frown

Last edited by CyberGene; 08/31/20 09:11 AM.

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Re: Kawai Novus NV10 - Hands On
JoBert #3019710 08/31/20 09:13 AM
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Impressive Gene.



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Re: Kawai Novus NV10 - Hands On
JoBert #3019711 08/31/20 09:14 AM
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Since I can't edit my post anymore, to add another clarification: It's blocked because the jack is still tripped, so nothing is pushing the hammer. Quite on the contrary: the further you try to press the key, the more you press the backcheck against the hammer and that leads to a total jam.


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Re: Kawai Novus NV10 - Hands On
JoBert #3019713 08/31/20 09:22 AM
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Your explanation is great, and your English is clearer than mine on a screen... I still think repetition problems (including this one) can be improved through regulation-- I have experienced this problem before on a previous piano and after a tech regulated my piano it was gone. We know repertoire where this kind of attack is used, and when I'm watching competitions and concerts, action malfunctions are not common.


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