Today I received a 9v battery, and I’m going to drill holes in 2mm and 3mm steel plates to test the battery and compare the sound. The first time I connected the 9v battery to the speaker through the relay module, I had the same problem as last time; no power to the speaker, only clicks in the relay module.

To solve this problem, I experimented from scratch, eliminating all the complicated stuff, and it turned out to be a bad circuit connection. I’m glad it wasn’t a big deal, but it might be going to have a lot more complicated when I have more speakers connected. However, this experience taught me how to troubleshoot complex situations, which is great for future troubleshooting.

I successfully connected the 9V battery, and it definitely sounded louder than when using 1.5V batteries (AA batteries), and because I used the battery connector, I was able to get a cleaner sound without the noise that I had previously heard from unstable connections when connecting by hand. I then tried connecting 2mm and 3mm steel plates to the speaker to compare the sound, and found that the sound was less resonant than when using the 0.8mm steel plates. This is presumably due to the thicker steel plates and less vibration of the steel plates themselves, but I suspect that it could also be due to the slightly different distance between the speaker and the steel plates. However, it would be difficult to experiment with this, as adjusting the distance between the steel plates is a very delicate task and would only be possible with the proper equipment (I don’t know what can be).

I tested the sound due to the difference in thickness of the plates, and later experimented with the sound changing depending on the object between the speaker and the plates, but the change in sound was not significant when using my wooden sauce bowl. I suspect that the shape of the base of the saucepan against the griddle might change the sound, but that’s something I’ll have to experiment with next.

I don’t have much time left. So tomorrow I’ll have to drill holes in all the other plates, connect them to the speakers and see if they can be controlled through Max/MSP, and think about how to position and sequence the speakers.