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Well done PianoManChuck! Great explanation. ( OT: Check out all his stuff on YouTube if you have a chance. Everything he does is so entertaining and thoroughly informative)

Great explanation !!

THX PianoManChuck !! Looking forward to the next in this series




Great find Marko

EDIT: Typo

After 10 minutes of explanation, I still don't get what the third sensor adds - why not just put the first sensor lower down, where the second sensor is in the triple sensor arrangement? Maybe the first sensor is required to sense when the key is lifted far enough to apply the dampers?

Yep, nicely done.

James
x

May I refer you to the explanation (and audio clips) on this page:

http://www.kawaimp.com/mp11/detail/touch/

Cheers,
James
x

You may, but that still doesn't tell me what Sensor 1 is bringing to the party in the diagram. If you only need sensors 2 and 3 to sense velocity for your repetitions, what's Sensor 1 for?



edit: it says "allows the sound of a single note to be gradually ‘layered’ without the previous tone being lost.". I guess this means it's so that the damper isn't applied, like I mentioned above, and is not mentioned in Chuck's video.

The first sensor lifts the damper. if you trill only between sensors 2 and 3 without lifting high enough to reach sensor 1, you have the notes overlapping each other, which is a smoother sound. On a 2 sensor action, a trill cuts off each note each time it's released. I actually believe Pianomanchuck doesn't understand this - he was referring only to the fact that you can trill faster with a 3 sensor action, but it's also about the fact that notes don't get cut off on a shallow trill.

Having 3 sensors also makes for a more accurate judgement of the travel of the hammer too. The velocity may be slightly decreasing or increasing through the keystroke. 3 sensors can somewhat allow for this. 2 sensors can't do it at all.

To detect when the key is released.

James
x

I'm not sure I understand it completely, but PianoManChuck said the third sensor was needed for fast repeats, like trills. If you have only two sensors, you have to lift your finger(s) high enough to trigger the first sensor, so it can measure the speed, by computing the distance between the two sensors.

If you have three sensors, the second one is triggered somewhere between the first and third, that is triggered just before you release the key. Thus, the speed can be calculated without lifting your finger completely up from the key, because the distance between sensors two and three is known.

By playing repeatedly the same key without releasing the key (all the way up) you never trigger the first sensor, when you have only two. That way the piano can't measure the speed, as it has no starting point to build on, for measuring a distance in a fixed time period, between some ( or not defined) point to the place where the latter sensor is triggered.

Let me emphasize these reflections are more of a guess, than a thorough understanding of the subject.

I am only guessing as well, but I think the higher sensor is kept to avoid loosing resolution in the calculation of velocity. The longer the distance between the two sensors, the longer it takes for the key to travel, the more acurate the velocity calculation (velocity = distance / time), which translates in increased sensitivity to the pianist touch.

I doubt the development will stop with three sensor. I can see potential use for up to 5 sensors (or possibly more). The fourth sensor you could use for half damper (rather than using the pedal). You could also have one more sensor very close to the top sensor to accurately calculate the key-off velocity.

Technology already exists to measure distances such as key travel with practically infinite resolution, e.g. http://en.wikipedia.org/wiki/Lidar Software can then actuate an arbitrary high number of events to happen as the key travels.

Will somebody explain how a single sensor DP can still reproduce different tonal quality when hitting notes at different speeds? Because it has been mentioned that the Yamaha CP1 had only one sensor; is that true?

Indeed Doremi, if we talk about advancing technology with more sensors, why not use optics ??
Then you can calculate and measure a much higher resolution.

These rubber contacts are being used for ages now. And can wear and get dirty.

So time for a new and better method I think.

If it measured how hard the key or hammer came thumping down, then that would be sufficient to sense velocity - and therefore timbre etc.

Or a single sensor with a timing circuit - that could do it too. The longer the contact, the lower the velocity.

It puzzles me why they are still using these old rubber sensors !!

Simple: It's because they're inexpensive.

What should they be using instead?

Something like PNOscan. With optical sensors.

What would be the advantage, what would be the cost difference, and how do they compare in terms of service life, calibration and longevity?