Post 19: I got to build a monochord first to do some testing on scales and tunings

    I was again yesterday reading about scales and intervals,  the seven pitches of the major scale, frequency ratios relative to the tonic,  just intonation with unequal frequency intervals:

                                 1:1 ,  9:8 ,  5:4 ,  4:3 ,  3:2 ,  5:3 ,  15:8 ,  2:1  

the 12-equal intervals of the tempered scale, the key multiplication ratio of 1.05946 from one frequency to the next, and the compromises involved. 

    I was also reading about the other equal temperaments that had frequencies approximating the just intervals, namely 19, 24, 31, and 53. That got me intrigued, and I got into some more research, which led me to the idea of making a monochord to do my own experiments, and to try to find what are the sound combinations I like best. It's a very simple instrument to build, so I looked through my stuff, and found part of a reinforced 3"x 1/4" aluminum rail from long ago video experiments, that could be modified and turned into an Aluminum Monochord. 

      The monochord actually has 2 strings exactly one meter long from one end bridge to the other, with a built-in metric scale so the ratios can be measured easily and accurately. It has a moveable bridge that needs to be exactly the same height as the other two (so there is no stretching of the strings raising the pitch), so it has to both pinch the string and be tied down. 

      It didn't take long to assemble. I stuck 3 piezo pickups to the underside of the soundboard. I didn't even have to use a preamp, it was pretty loud. But the sound is very metallic, so I also tested it with a regular magnetic pickup set at an angle across the two strings, and it sounds better .

         I then tested the unfinished monochord with a little wooden bridge and marked the seven ratios for just intonation, plus other simple ratios to test such as  6:5, 7:5, 7:3, 8:7, 8:5, 8:3, 9:7, 9:5, 9:4, 15:11,  15:5, 16:7, 16:9,  16:11. The bridge raises the strings slightly and causes a  small increase in pitch.

        I want to cut a long slot in the base on which I can slide and clamp down in place a metal pinch bridge made of brass and aluminum along those lines: