piano midi controller diy

PASHKULI
qre1113 - an infrared LED shines on an object(hammer), a phototransistor captures the reflected light and changes the current through the collector-emitter. It operates from 1 to ~ 10-12 mm. No touching is required. The minimum speed is taken from the moment the hammer begins to reach the second actuation point (string contact). The maximum is at the limit of the instrument's integrity. There is a maximum speed limit, where increasing force on the key no longer results in faster hammer movement—the system springs and bends, deforms, and flight speed is not increased. However, the risk of damaging the keyboard increases. This speed range is determined by several thousand gradations.

scherbakov.​al

Aha, got it. So, technically for lower dynamics the hammer does not need to travel all the way "up" (as would usually touch the real strings) but close enough of at least 12mm from the sensor. Correct?

This is very different from real acoustic\mech. play, where the hammer will have to always touch the string. Infra red are "long" wave lengths (up to about 1mm). Interesting how those can bounce off of a felt.

Wouldn't it be possible to mount it at the shank, above its base near the point of rotation (or maybe just pass where the knuckle is on an Erard's action) where the length of he arc (vertical secant) will be in the 12mm range?

• typically the shank is horizontal when the top of the hammer's felt hits the string
• maybe the sensor hanging from about 15mm so it can possibly capture a acceleration too

Lower (quiet) dynamics happen when the hammer is decelerating, louder when accelerating even pass the horizontal line (then bouncing off of the string). Wouldn't such construction be more accurate? Technically, the sensor (gray rect. with three dark legs on the illustration above) should be able to capture even small bouncing of the hammer (before it reaches horizontal position). By adjusting the sensor's position horizontally such behaviour could be regulated or in combination with software "accel.\vel. curve".

Only the hammer's passage through points at a distance of ~ 3 mm and 1 mm from the sensor is measured (plus or minus, adjustable). Tracking the entire hammer range is not required. Technically, it is possible to monitor the entire range of hammer motion, but why bother? (You could use this information to model damper behavior, but I prefer separate damper sensors.) Speeds lower than those at which the hammer reaches the string can be recorded. But why bother? I don't see the point. Pianists don't play silently (usually). Perhaps only to use unconventional playing techniques. You can install sensors anywhere on the hammer—whatever you prefer. A quiet sound is produced when the hammer slows down at a slow speed, and a loud sound is produced when the hammer slows down at a fast speed. When approaching the string, the hammer is in free flight for the last couple of millimeters and is only slowed by air friction, friction at the pivot point, and gravity.

scherbakov.​al

For loud sounds the hammer does not need to decelerate at all. A quiet sound with a hammer mechanics is only possible when it already has been decelerating due to gravity (mainly + the tiny friction within the construction elements).

In a experimental setup lets say the pianist only makes a slight impulse to the knuckle. The hammer accelerates to overcome its own weight + additional acceleration for some louder dynamic. But if that additional acceleration is such that the hammer's felt barely touches the string → then we have a very quiet sound. Such technique is very difficult on piano (almost none can pull it off probably) especially in fast tempo (short notes in a row).

I assume with your setup and what I suggested above such playing (very piano) should be possible. The problem then though will be that there are no sample libraries with such gentle (piano) samples. They probably use just volume + EQ adjusted louder ones (as recorded).

And therefore, that is why I also do not like the available sample libraries. On the other end of the range the overly louder samples typically cause nasty self resonances (shown in the other threads of the forum).