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I'm not into Physics, but if there could be some micro-variations in the fundamental frequency, I think these would be gone after a few milliseconds from the hammer strike, being that sometimes I enjoy analyzing (in Audacity) the waveform of a piano note from pianissimo to fortissimo and I've never seen such a behaviour.
Or maybe it's so trascurable that is not relevant in considering a piano note fundamental frequency and so I think it's not important for the matter of how to interpolate two velocity layers.

Looking at the referenced article by Harrison in 1948, where the first page is available without a paid subscription:

https://asa.scitation.org/doi/10.1121/1.1906452

the point seems to be that the equation for vibrating strings (where the solution for resonance frequency is independent of amplitude) is a model derived using the assumption that the string is vibrating in a (2-dimensional) plane.

Per the referenced article, for sufficiently large amplitudes (that is, for sufficiently loud dynamic levels of a played note) the string will vibrate in a circular manner along a 3-dimensional surface similar to the path of a jump rope in motion, and this will lead to a change in the fundamental resonance frequency, which is then dependent on amplitude/dynamic level.

However, they also give an example with a string having a fundamental resonance frequency of 400Hz, which lives between the fundamental frequency of G4 and Ab4 in A440 equal temperament. In their example, measurable deviation from the string vibrating in a plane was detected for amplitudes around 3/16 of an inch and greater.

Would there be that much displacement even in a fortissimo strike of Ab4 or G4? Of course their example is for a string of different length, mass, and tension.

The frequency varies depending on the hammer blow, before settling down to a final frequency. This can take a couple of seconds. You can see this using a high-precision tuner.

What made you think that CP88 reminded you of MP11? Its key action? Or its piano sound?

That's cool to know. But it is getting too technical! I'd just focus on the general term timber which covers the whole idea. Since this formula is in the time domain, it will play two samples at two different velocities. What really expected though is just one sample which shares some characteristics of both timbers which can be adjusted based on the velocity. The superposition quickly kills the polyphony this way... every extra note you interpolate with this method will reduce the polyphony at least by 2 (samples are stereo).

That's exactly what the interpolation does: it makes the sample transition from a layer to another in a smooth way, so you'll have the impression of having tens and tens of velocity layers, when you really have just 3 or 4 of them.This is partially true. To make this method work, the hardware has to play 2 samples for a single note. But all the other post-processing effects you apply on that single note are applied just one time on the sample that results from that formula. I think this is the only way to achieve good dynamic when you have so few layers for each note.

Big VST libraries that have 20 or more velocity layers per note, don't have this problem, because they don't have to interpolate. They just play the layer with the velocity closest to the one required, and most of the players will not perceive the passage from a layer to the next, being that they are very close to each other.

Its operation/design. They share a somewhat sparse sound selection, addressed through three independent sections labeled PIANO, E PIANO, and SUB, from which you select up to three total sounds to mix and match across the keyboard. Each of those three sections is presented with its own on/off, volume, effects assignment, and key range selection. Each then adds 4 zone MIDI control, 8 patch recall buttons, pitch/mod controls. Biggest panel operational difference is Yamaha uses dedicated knobs for effects parameters, whereas Kawai uses 4 assignable knobs.

+1

From what I've picked up reading this thread. The CP88 has a fairly lowly action in the range of actions that Yamaha has to choose from. Whereas the MP11SE has a relatively high level Kawai action?

Is that just a specific thing, or does it represent a difference in mindset between Kawai and Yamaha as to what these models (MS11SE, CP88) intended purpose is? For example I get the impression the CP88 is a gigging piano to be played with other instruments, whereas the MP11SE is also aimed at piano players who want a quality keyboard which can be played without other instruments to disguise its weaknesses.

I don't see any similarities. The action is different, the voice in CP88 is not even similar to its predecessors... I don't see how having 3 sections is going to make a keyboard superior? Have you ever used the effect in CP88 "Damper Resonance"?

And have you ever used those 4 nobs in MP series in conjunction with the SUB keys to see how intuitive and quick you can modify your voice? In a live performance having 1000 buttons is useless. I just need presets.

The MIDI implementation in CP88 is not complete. In MP7 I can set up user micro-tuning in CP88 there are useless micro-tuning presets. Drawbar organ in MP7 and none in CP88.

The problem with CP88 is that it's not a genuin instrument. It's a copycat. It did not address the problems CP4 had. It still has the same 30-year-old DSPs and just new samples.

And I don't think MP11 is direct competitor here. You should compare CP88 with MP7SE. MP7SE beats CP88 in every department.

CP88 has one of the higher end Yamaha hammer actions (NW-GH). In current portable models, I think only one is presented as higher end (NWX) while all the rest are roughly the same or lesser (BHE, BHS, GH, GHS).


CP88 has portability as a key goal, MP11SE does not.


Did you read that whole paragraph of similarities? The features and operation are nearly identical!


Of course the action and sound of a Yamaha and a Kawai are going to be different, always. So? (And yes, this Yamaha's action and sound combination is different from previous Yamahas as well).


I never said it did. But it depends what you're comparing it to, and what you're looking for the keyboard to do. For example, there are numerous stage pianos that max out at only one or two sounds at a time (i.e. Korg SV1, Grandstage, Nord Pianos...)


No. What's your point? That it's bad? I don't see how that qualifies something as a stage piano or not.


Not every live player works the same way. Some create presets for all the splits/layers they want, others like to be able to split/layer their choice of sounds on the fly. Similarly, some want to pre-program their effects and leave them that way, others may want to manipulate them as they play. Regardless, CP88, MP11, and MP7 have similar abilities for calling up presets (though MP7 is stronger here, with more buttons for directly selecting sounds/banks).


The post I replied to talked didn't specify MP7, but MP7 is a great board, with different design philosophy from the MP11 or CP88.

In the U.S., the number of live players who need micro-tuning is probably tiny. Regardless, user micro-tuning scales would be an odd criteria for whether something is a stage piano or not, even if it might be something some players need. Nor do I see how whether a piano has a drawbar organ function qualifies it as to whether it is a stage piano or not. Or even necessarily differences in MIDI implementation, though I do think, for example, that any board designed for the stage should have true MIDI connectivity (not just USB). BTW, what essential MIDI functionality is missing from the CP88? That's not something I've really looked at. Anyway, I'm still left with the original question of why Kawai MP -- whether MP7 OR MP11 -- qualifies in your mind as a stage piano while a CP88 does not.

Getting back to presets vs. lots of hands on control, while MP7, MP11, and CP88 all have banks of buttons for calling up presets, the advantage of the additional front panel controls on boards that have them is not just for those players who don't work as much from presets, but also even for players who DO mostly just want to call up presets... because the procedure for creating your split/layer/effects presets in the first place goes more quickly with direct access to many key controls rather than menu diving.


You don't like the CP88, I get it. Fine, not every board is for everyone. It's not for me either. All I asked is what makes it not a stage piano. ;-)

Let's say I'm not religious about Yamaha ;-) When I opened up the user manual of CP88, everything is identical to MOTIF series (and s90XS).

There is not much difference between S90XS and CP88. The existence of 3 sections is not going to candidate CP88 as an MP11 competitor. Toyota Corolla and Lexus both have steering wheels and similar dash design. Can we say they're in the same trims?

At this level, the action becomes somewhat a matter of preference and I like KAWAI MP7SE more. Sound-generation wise, CP88 is not in the same league as Kawai, Nord, Korg, Roland and almost everyone else. Sample quality though is top notch but alas we don't get any simulations.

Some key CP88 advantages over S90XS:

Lighter weight (41 lbs vs. 49.6)
Updated action (NW-GH vs. BHE)
Seamless sound switching
More/larger piano sample sets - 4 grands (CFX, S700, C7, Bösendorfer Imperial 290) plus two uprights (also new/updated EPs)

although S90SX had its advantages too, like aftertouch, bigger sound library, zone sliders.

Though one of the biggest differences ie the whole "dedicated control" aspect of the CP. It's not for everyone (not for you), but as Nord has shown, a lot of people like that way of working.

I have to admit, at first I couldn't fathom how the two had any notable similarities. But yes, what you describe is a very MP11-esque control scheme. Personally, I think it suits the sparse (focused?) sound selection quite well, though on occasion I wished there was a way to layer two acoustic piano sounds together on the MP11!

I consider the MP11SE to have the best action (for me) of any instrument I’ve ever played that claims to be a portable piano or stage piano, but at 72 lbs, it is pushing the boundaries of such a classification at best.

The desirability of a piano action is far too personal and subjective to be evaluated by considering design parameters and technical specs. You have to play the instrument and see how it responds to your playing.

Actually it’s 75 lbs. . . . the Kawai US site has trouble with kilogram to pound conversions.
That’s about 25 lbs. more than what I personally would consider portable.
May as well get a Novus.