how keyboards get velocity values...

[skynare]

Hi.

I searched the web to know how keyboard controllers transmit velocity values but I could not find good answer.

My question is "Does keyboard use drum-pad-like method or optical measurments?"

I found some yamaha keybeds measure velocity by their optical sensor. But what about others?

I just guess all hammer-action keys have small trigger pad so they can transform my finger's strenth to velocity value; is it right?

Also, can I adjust keyboard's weight? (I heard that keyboard gets lighter as it gets old.)

Thank you.

[Krakit]

I want to preface this by saying that I do not know the answer, but I postulate that a measurement of time between the keys start position and the end of it's arc determines the volume (and in better keyboards, the timbre) of the note struck.

 

Just a guess though.

 

[Frosty_dup1]

I believe that there are two sets of contacts on each key, one near the top and one near the bottom. When a key is struck the top contacts are connected, and a short time later the bottom contacts are connected. The microprocessor measures the interval between these signals and calculates the velocity. The Yamaha keyboards I have seen have all used this method - it's cheap and works.

 

Frosty

[Krakit]

So then Frosty, you are confirming my hypothesis?

[The T Dot]

Your hypothesis is confirmed, but it's not necessarily the top and bottom key positions that are measured. At least it isn't on my Triton, which uses a Yamaha keybed. On this particular keybed the contact points make up a very short range within the entire key movement.