MU2801 – Making Music With Machines – A23

Daniel Gorbunov, Ben Haugsjaahabink, and James Obermaier

For our project, we are taking inspiration from the drum machine Perc by Polyend, which has several solenoid-driven strikers positioned directly above drumheads. This method of actuation is extremely flexible and latency-free and is one of the main aspects we focused on while designing our machine, iDrum. iDrum is able to be mounted quickly onto an array of different drums or cymbals typically found in a drum set. To do this, we will utilize existing drum mounts from Latin Percussion, making our setup very flexible. For our project, we will play a minimum of a kick, hi-hat, and a snare. We want iDrum to be extremely accessible to people by making it playable through a MIDI keyboard. Anyone should be able to set up and play iDrum even if they have no experience with a drum set. iDrum is flexible in that it can be a cooperative instrument, played by a human, or it can be sequenced through a DAW like Ableton Live. iDrum is also incredibly simple and cost-effective, and could be sold as a kit for a very low cost. All of the components used in iDrum are components we found in our lab kits, or in the MPR lab.

From project conception, to initial design, creation, and then refinement, we had a little under two weeks to make iDrum a reality. Because of these time constraints, we made a percussion machine from readily available components that we either own, are in our lab kits, or are property of the MPR Lab at WPI. After coming together and creating a basic idea for our design, we spent the first week of our time refining and testing our mechanical designs for our drum and solenoid mounts. This was an effort between Ben and James to rapidly prototype, test, and iterate on mechanical components to ensure our drum strikers are well-mounted. During this time, Daniel started to assemble all of the circuitry for iDrum and begin researching and programming the Arduino to act as a MIDI device. We then worked together to test and iterate on any bugs or shortcomings of the system. From there, we put together several demos of percussive sequences that can be played through a DAW like Ableton Live in preparation for our final presentation during our last class on Thursday.

Due to the constraints in time, budget, and available material, our team opted to take a rapid-prototyping approach to the creation of iDrum for the presentation. The arms were made out of 3D-printed PLA and connected via small bolts, nuts, and washers. This arm was mounted on the Latin Percussion mounts mentioned above and the solenoid was mounted on the end with using the same small bolts through available mounting holes on the solenoids. The circuit was assembled on a solderless breadboard which consisted of 3 N-Channel MOSFETS (one for each solenoid), and external 12V DC source, and controlled using an Arduino TNC (this was selected as it can natively process MIDI information).

One of the biggest challenges in this design is the vibration associated with the activation of the solenoid. Because PLA is such a light and flexible material, the vibration impacted the solenoid’s ability to strike the drumhead when played rapidly. For the future I would recommend settling on a desired final design and machining the arms out of a much more rigid material like aluminum. It would also be beneficial to use lock washers or lock nuts in order to decrease the fatigue on the rotational joints in the arms. A secondary challenge we experienced was the lack of volume from the snare and kick drums. Because we used 12V solenoids, the striking force was not significant enough to produce the desired volume on these drums. This leads to the final recommendation for the future, higher voltage solenoids should be used in order to produce a greater striking force for these drums.