Monday, January 02, 2012

Making some bass finger piano samples

I took the time last week to make a new set of bass finger piano samples from some spring steel inside a plumber's snake. The material is about 1/4" wide, and somewhere around 0.40" thick. One of the least known things about thumb piano tongues is that they have a prominent overtone that is just under an octave above the fundamental. If you add solder to the ends, you can lower the fundamental, without changing the prominent overtone as much. For example, if a 3" long tongue has a fundamental around C 1, but an overtone around Bb 3, the tongue will sound out of tune. But if you add some rosen core solder to the tip, it will lower the fundamental to around A 1, while the overtone drops only a half step to A 3. If you do it just right, you can end up with the overtone exactly two octaves above the fundamental. Add more solder, or file off the excess until the two notes converge. This sample library has about two dozen notes from G 0 to D 5. Each is a bit out of tune to the 12 TET scale, but by calibrating the cents from 12, Csound is able to tune them back up. These are the samples used in the last complete piece, Drums in 12/8 from last week. Here's the G 0 four cents sharp from 12 TET.

A picture of the rig. Low notes need more solder than high ones. Once I made the first low note in tune, it was mostly shaving off solder with the file, about three strokes per cent flat for the fundamental.

Play it here

or download this link

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Here's another sample, F# 2 17 cents sharp:

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