Does 3 sensor keyboard matter?

There are other less expensive 3 sensor models on the market, like the Casio PX-350:
http://www.casiomusicgear.com/products/.../PX-350MWE
Does it happen to you that some fast repeated notes don't sound? If yes you will enjoy a 3 sensor model. I would love to have one...

I completely concur with Beto-Music's logic, that you need to try several keyboards in a store before you buy anything.  One needs to feel how a given keyboard works with your own fingers and sense of touch.  Manufacturers are completely aware that many people buy a given product, sight unseen, based on specifications alone.  As a result, they sometimes trump up specifications that look good on paper, but have no real musical value to the user.

Some of my favorite trumped up specifications include the use of "ivorite" and "ebonite" or some similar name to imply the feel of ivory in a keyboard.  The irony of this is that ivory has been essentially discontinued and replaced by plastic key coverings, even in the finest real grand pianos manufactured since the early 1950s.

My own preference for keyboards include those made with wooden keys with plastic key covers, instead of purely plastic keys.  The latter have a tendency to deflect sideways, and have a "cheap" feel to them.  I also get the feeling that purely plastic black note keys have the capacity of being sheared off, if one were to perform a hard black key glissando on them.

* * * * * *

In the end, my suggestion is for you to buy the best quality keyboard you can afford, even if that means spending more money than you had initially intended.  If you buy a cheap keyboard, you will be unsatisfied with it in very short order.  Conversely, if you buy a more expensive, but substantial keyboard, you will be happy with it for years to come.

I happen to own an ancient Roland A-80 mother controller keyboard, purchased new in 1990.  Other keyboards have come and gone from the market place, but I have never felt the need to "trade up", despite advertisements for graded hammer action, various escapement emulations, ivorite keyboards, etc., etc.

Cheers,

Joe

3 sensor tech hasn't anything to do with aftertouch. During Chopin's time, grand pianos picked up an improvement to rapid repeated-note-response, known as 'repetition'.

Digital pianos are now trying to incorporate a similar improvement, and I'll post here a PDF I've clipped from some CASIO brochure (which since it's infoblurb shouldn't matter) as PRIVIA ACTION.

The graph is interesting, seems to imply that on the (uncircled) return-crosses of the Sensor 2 level, a note-off will be sent, to match the previous (circled) note-on message. But also implied is that until full key-release is achieved (blue circle) the damper will not be fully-dropped and all sustained sound cease. Further implied is that this action provides for repeated presses to start from different key-depths, allowing for greater velocities to be achieved, as well as lesser ones, on the re-strike. Overall could be a problem for fast staccato (and real grands may have this too), plus may be different from other systems (in particular KAWAI's, where the sensors are hidden from inspection, so who can know).

I don't know what zooming particular PDF readers provide (I use NITRO), but at worst, open it in Adobe Reader and there'll be zooming. Switch attention to the Action diagram - 400% and a bit of thought taking count of the graph will show how the action works.

In particular note how very close are the actuating positions of sensors 2 and 3, compared to the relatively enormous gap to key-release (damper ON). Close = fast!

No idea how aftertouch is implemented, and it's too new to have any settled industry approach, but polyphonic aftertouch is almost bound to be expensive.

ADDED: PDF isn't a file type that can be posted here, so I'll stick PRIVIA ACTION.PDF in my DropBox, and here's the LINK.