Armin's Weblog

2-Note Analog Synthesizers
Adam Parrish and Armin Cooper

Concept

Roughly a month before the end of the semester, Adam and I got together to discuss a final project for Physical Computing. We both wanted to do something that involved sound but at first we weren’t sure exactly what to do. After a couple of meetings, we agreed to do a project that involved constructing simple instruments that would produce tones. Adam began ordering some of the electronic components that we would need while we continued to think about what the next step would be. How many instruments would we build and once built, what would we do with them?

Ultimately, Adam came up with the idea of building one instrument for everyone in our Physical Computing Class. We would then direct the entire class in a performance with the instruments. As construction began, the details of the performance were still not set in stone, but as our deadline for the Final was approaching, we moved ahead anyway to begin constructing the instruments.

The final design was dependent on our last decision regarding how the instruments should be activated. At first, we wanted to use photocells to either change the note or the volume. However, after experimenting on a breadboard, we realized that photocells weren’t sensitive enough. They were greatly affected by the ambient light in a room and unless we used very bright lights, the instruments would be difficult to control. In the end, we settled on using two switches, one to turn on the instrument and the other to change its pitch. In addition, each instrument would pulse with a different rhythm that was dependent on the functionality of the instrument’s capacitors.

Construction

Each instrument is constructed using the following electronic components:

1 Perforated Board
1 556 Timer Chip
1 Chip Socket
1 Speaker, 2 inches in diameter
1 Battery connector
1 9-volt Battery
2 Trim Potentiometers
2 Capacitors
2 Button Switches
2 Matchboxes (2.5” by 4.5” by 1” each)
5 Resistors (various ohms)
7 Wires

Adam designed the circuit, and we used several breadboards as prototypes. However, we had problems finding a container to hold the instrument. The device wasn’t very large as we planned to use the smallest perforated boards available. Nevertheless, when we searched the Internet for a box that was the right size, we came up empty. Finally, my wife suggested using matchboxes that I had at home. When I brought one in, I saw right away that it was the perfect size. Adam then came up with the idea of using two boxes to fit around the device’s components and we were set with our construction design.

Once construction began, Adam did most of the work on the perforated boards while I soldered wires to most of the switches and speakers. It took several days to finish work on all of the devices. In the end, we had completed twenty-four working perforated boards. We then used the trim potentiometers to tune the devices. In the end, we had four groups of four to five each that were tuned to the same notes. Each group received a small sticker on its cover that identified which group it belonged to: red, green, blue or yellow.

Composition

Before construction began, Adam and I discussed the nature of the composition we would have our class perform. Adam was looking for something that sounded very modern, perhaps even atmospheric. He gave me a CD with a dozen examples. From that, I began to form some ideas in my mind. By then, we had already decided to tune the instruments to the notes of a whole tone scale that began with C.

Red Group: F# and C
Green Group: C and F#
Blue Group: D and G#
Yellow Group: E and A#

These pairs emphasized one of the most distinctive elements of a whole tone scale: the interval of the Augmented 4th. What’s more the instruments covered all the notes of the scale, with an additional two notes doubled an octave apart.

Adam thought it was best if I composed the piece for my class to play as I had a background in composition and performance. However, I had never composed a piece using a whole tone scale. My first thought was to simply improvise, following a general structure. I would make sure to use all of the intervals of each instrument group and follow my ears and instincts. The one thing that I could not anticipate was the sound of twenty-two instruments playing at the same time, particularly since each instrument had its own unique rhythm.

Interestingly enough, though, as the day of the performance got closer, I decided to actually compose a specific piece just so I could be sure I wouldn’t forget any of the intervals. However, I opted not to use my music composition program but instead to just type a series of notes on a page. Adam called this style “John Cagish.” Indeed, the composition on paper looked like an essay-outline-composition hybrid, with groups of notes being marked off into sections. For me, I felt it was the simplest way to conduct the performance, which was essentially what I was going to do.

CLICK HERE for Composition Outline

Performance

As our concept for the instruments developed, Adam came up with a clever idea for the manner in which we would conduct our classmates in the performance. He postulated that he could use programs in Processing and Max to display simple representations of the instruments on the screen, broken down by colors for each group. Within those representations there would be two circles that corresponded to the two buttons on the instruments. The illumination of the circles would tell our classmates which buttons to press. Thus, if we wanted Red Group to play a C, the left circle in the red display would light up and if we wanted Yellow Group to play an A#, both buttons in the yellow display would light up.

The final piece of this puzzle was to tie in the circles on the screen to actual keys on a MIDI keyboard that we would take out of the Equipment Room. I would sit at the keyboard and whenever I played a note, the corresponding circle would light up and my classmates would press the appropriate button. In many ways, this plan was simple and elegant. It also emphasized the straightforwardness of our analog instruments. All one needed to know was which button to press.

On the day of the performance, Adam and I were able to get twenty out of the twenty-two instruments to work. A couple devices needed some last-minute repairs but they functioned. As we learned, the one problem with the boxes we were using was that although they were the perfect size, they weren’t very sturdy. After all, they had been designed to hold 250 matches, not electronic equipment.

All the same, the performance went off almost flawlessly. Adam and I gave a tutorial to our classmates on how to work the devices and when they were ready, we all performed the piece entitled, Whole Tone Etude No. 1. I did actually improvise in one of the latter sections when I thought the piece was starting to drag, but everything else was performed as I had composed it. The great thing was that everyone really seemed to enjoy the performance. In retrospect, Adam and I both wished that we had made the devices a little louder, however, I suspect that the room were in had something to do with the lack of volume. When I tested the instruments at home, they seemed loud enough.

CLICK HERE To Listen to Performance

Conclusion

I would have to say that our project was a resounding success. The key was that the performance went off without a hitch and our classmates and teacher really enjoyed it. Constructing the instruments required a lot of hard work, but it had been well worth it. Speaking personally, it was nice to perform again, although I’m certain I never could have imagined in years past that I would one day take part in a performance where I directed musical instruments that I helped create. Adam and I worked well as a team and I think what we were able to accomplish together was amazing.

Of course, now we still have the 2-note analog synthesizers. The great thing about their construction is that they can be reused in any number of ways. The trim potentiometers allow us to retune them to a multiplicity of different notes. Thus, it would not be too difficult to put together a new performance or compose a new piece for it. The circuit, too, is not difficult to design and construct, nor would it be difficult to find new containers for the instruments.

That fact leads me to my final point, which is this: I believe that devices like these could be used in schools with children. I can imagine a bunch of First Graders wielding these instruments in a concert where all they had to do was follow directions on a screen, like our classmates. These new instruments could be more robust in construction and also have an easy tuning ability. The key, however, would still be that in order to create a pitch, all a child would have to do is press a button. Now these electronic instruments would by no means take the place of regular analog instruments, however, they could provide young children with a stepping-stone for learning how to perform music in groups.

My father once said that a great way for children to learn how to work together was to get them to play instruments and perform as part of an orchestra. This idea is by no means as advanced as that, but for a five or six-year-old, the message is the same. To verify this idea’s validity, all I have to do is remember the smile on my classmates’ faces and the smile on my own after the performance of Whole Tone Etude No. 1.