Introduction: Homemade Electronic Drum Kit

What is it?

A full-sized homemade electronic drum kit.

Why?

I am excited by the endless sounds available through electronic sampling. I’ve already been using keyboard-based MIDI controllers & an electronic hand-drum (Roland Handsonic) for many years. I wanted to expand my palate to include full-sized pads that I can hit with drumsticks, to augment the acoustic drums that I play with my band Battlehooch. Additionally, I'm employed as an accompanist for modern dance classes, so this would add to the laptop-piano-iPad-MIDI keyboard combo I currently use to compose music in real-time.

Approach:

This first iteration is roughly modeled after the Roland V-drum. The main features I extracted were:

1. Piezoelectric pressure sensors for velocity-sensitive note triggering.

2. Mesh drum heads for quiet, responsive hits.

3. Dual-zone pads in which two sensors are connected to each jack. This allows for triggering two separate notes over a single cable. Usually the hits are divided as snare & rim, or cymbal & bells. This kit also features double kick pedals that transmit over a single TRS cable.

4. A drum brain that converts analog signals from the piezos into MIDI messages that a computer can recognize. Software then interprets the messages to generate musical output. In this case, I am using an Alesis Trigger I/O, which feeds into my laptop via USB.

5. Typical drum kit form-factor. Based on the number of inputs on the Trigger I/O, my kit features three dual-zone cymbals, two kick pedals, one hi-hat pedal & five dual-zone drum pads. A total of nineteen independent notes.

Discussion:

I wanted to make a drum set controller that would have the same functionality as a professional kit, but at a fraction of the price. I also wanted to have control over the look and feel of the kit, as well as add more triggers than are typically offered. After much trial-and-error, I can say that I was successful in these goals. The main cost was the drum module. It’s also one aspect that’s not fully DIY. After looking at several options for custom microcontrollers, including Arduino & PCB-based solutions, I decided on the Alesis Trigger I/O simply because it’s an eloquent & affordable solution to a tricky electronics problem. I knew that building the kit itself would be a long process, so it made sense to go with a market-proven solution for the analog-MIDI-USB communication. All the other parts either came from Ebay, various hardware stores (Lowes turned out to be most helpful), or salvaged from my own workstation & my dad’s garage. My father turned out to be an immense help, offering his sage advice and expertise on materials, methods and tools. Most of the creative problem-solving was a joint effort between the two of us. It was quite a thrill to have all the pads work successfully on my first try playing a drum rack in Ableton Live. (To be fair, there was plenty of troubleshooting to get each pad working individually before trying them all together!) There are, however, some crucial areas that leave room for improvement. A fundamental goal of the project was to be able to transport the controller to live performances. However, my kit turned out to be quite fragile in several places. The TRS jacks are not as reliable as I’d like. Sometimes they fail to make the proper connection with the separate TRS cable sleeves. The cymbals feel less than solid. The kick pedal beater pads tend to loosen over time. I’ve also not figured out a way to safely transport the kit. The rack is clunky when disassembled, & each component has to be tediously removed. There are lots of cables to account for & reassembly is a chore. That being said, it's still a great instrument and I'm especially proud of the pads. They're much nicer than the plastic ones that come on most consumer kits.

What's Next?

For the reasons mentioned above, I am currently building a new, more compact version of the kit. It will have roughly the same number of triggers & large enough pads to play with drum sticks. However, the shape will be a single large rectangle containing 20 pads, arranged into four terraced rows of five pads each. All the wires & the brain module will be housed within the unit. The pads will be a sandwich of wood, metal & neoprene. Assembly and disassembly will be much simpler: just attach the pad to a stand, & connect to the computer. It won’t look as cool or have the same intuitive playability as the full kit, but will be much more portable. Look forward to a second Instructable outlining this project, coming soon! Further in the future, I would like to figure out how to add positional sensing to the pads, for additional X-Y control dimensions.

Step 1: Step 1: Drum Pads

Use a jigsaw to cut the basic shapes out of a large sheet of 3/4" MDF (Medium Density Fiberboard). Each pad is basically a circle with a rectangle jutting from one end. I made five pads total: three at 10.5" diameter and two at 12.5". To decrease weight, cut three small circles in each baseboard, and cut the jutting rectangles into a more triangular shape. Then, cut rings for the drum rims. On the inside edge of each rim, cut a right-angle indentation to house the drum head (see step 3). Use a router to round all the outside edges. My dad had some purple laminate (Formica) lying around, so I decided to use that for the shell. After etching a shallow circle into the top of each baseboard, cut long, thin strips of the laminate that you can bend and wedge into place. Drill several holes equidistant around the shell to allow for inserting machine screws and threaded inserts (1/4-20), as shown in the picture. These will connect the rim to the base and tighten the membrane around the shell. Once I had all the components cut correctly and tested with the drum heads from Step 3, I had my dad give them a lacquer spray. He wouldn't let me do it. Fine by me! I just photographed the toxic application from afar.

Step 2: Step 2: Add Sensors and Jacks to Drum Pads

I purchased a bunch of piezoelectric pressure sensors and TRS jacks from Ebay. These are the heart of the electronic kit. Pressure applied to the ceramic-metal disc generates an electrical signal that the drum module converts into a musical message. Using Tip-Ring-Sleeve jacks and cables (as opposed to Tip-Sleeve) means that two independent signals can be passed down the length of each cable. The drum brain that I am using can recognize these "dual-zone" pads, so separate notes can be triggered by hitting the center of the drum or the rim. For the center, I carved foam insulation into a cone shape so that hitting the drumhead will transfer pressure from the tip of the cone to the base, where a piezo trigger is sandwiched between squares of adhesive foam. The sensors are quite sensitive, and I've found that insulating them gives a better pressure response than hitting them directly. It's a little tricky, but try to make the sensor-cone-foam stack precisely as tall as the baseboard to the top of the shell, which is how high the drum head will be. A second piezo is attached to the inside of the rim, and both are soldered to a TRS jack as shown in the picture. Take note which TRS tabs correspond to which wires. Center piezo: ceramic-sleeve; metal-tip. Rim piezo: ceramic-ring; metal-sleeve. Attach the jack to the baseboard by drilling small holes in a washer and screwing the whole thing into the fiberboard. The piezos came with their own thin wires. In cases where they were not long enough, I used wire couplers and added extra length with salvaged wire from other projects.

Step 3: Step 3: Drum Head Membrane

Pet screen from Lowe's Hardware makes a great durable drum head. It's meant to protect window screens from the the sharp scratch of dog claws, so I figure it's rugged enough to withstand a drummer's barrage. Bend a length of thin copper tubing into a circle that will go around the shell while fitting snuggly inside the groove of the rim. Sand the ends of the tubing so they're smooth, then solder them together. Cut a circle of pet screen about an inch wider than the ring, then sew it as tight and evenly as you can. I found it helpful to use clamps to keep the head in place as you sew. Place the head over the shell and tighten the machine screws into the threaded inserts. The membrane should just graze the tip of the foam cone.

Step 4: Step 4: Rack Construction

A cheap rack for mounting your drums and cymbals can be assembled from PVC plumbing pieces. I used mostly 2" pieces for the base and 1" pieces to mount the cymbals and drum pads. With a circular drill bit, cut holes in the protruding portion of each drum pad. Add threaded inserts to the bottom of each hole, which will eventually house threaded knobs. To support the weight of the pad, cut short pieces of metal U-channel to cap the very top of the pad, then drill a hole through the U-channel, MDF and 1" PVC to allow screwing in the knobs. I used a tap to clean up the thread when I cut the threaded knobs to size. A final addition to the rack provides a board to hold the Alesis Trigger I/O drum module. Two-holed conduit straps work well to hold the board in place on the PVC below the two middle drum pads.

Step 5: Step 5: Cymbal Construction

Each cymbal unit contains a 3" 'bell', 6" 'cymbal' and a TRS jack embedded in a 1" PVC T-joint that can be freely inserted into the rack. This component had me stumped for a long time. I couldn't seem to find an appropriate material. Most plastic I tried was too brittle, too expensive or not the right shape. I first tried to make the cymbals out of vinyl records that were placed between actual ride cymbals in the oven (my band has a ton of self-titled albums laying around!). Unfortunately, the vinyl was too brittle and cracked soon after. My first successful attempt used a thrift store frisbee covered with Gorilla tape & rings of neoprene for the main cymbal. The bells were constructed from the same laminate as the drum rims. First, cut the PVC to size. You'll need three small lengths of 1" tubing, a T-joint and two caps. Cut out 1" holes in the center of your cymbal and bell. Cut three short pieces of pipe insulation tubing to sandwich the cymbal and bell between the T-joint and top cap. Piezos will eventually go under the cymbal and bell, so drill two small holes in the top piece of PVC where the pipe insulation will meet the bottom of the cymbal and bell, respectively. Run two wires through each hole to the jack. Use wire connectors to attach the piezo leads to the wires leading to the jack. Drill another hole in the T-joint cap, just wide enough to house the TRS jack. The wiring and soldering turned out to be challenging, so make sure you have enough length to work with. I regretted using the Gorilla tape and cheap frisbees. Later, after playing disc golf with some friends, decided to use disc golf drivers and mini drivers from Innova's online store instead.

Step 6: Step 6: Pedals

The kick pedals were also tricky, because I wanted to utilize the dual-trigger capability of the Trigger I/O, as I had with the pads and cymbals. I wanted to have two pedals at a distance sending separate notes over a single cable. The solution I settled on was to house the TRS jack on the right foot pedal and connect the the left foot pedal's piezo with removable lengths of wire using alligator clips and O-ring leads. It ended up working pretty good, but the beater stand I constructed is not as strong as it could be and will probably have to be changed eventually. I used random found pieces of wood and metal, and don't think I've found the optimal design yet. I will therefore leave it up to the reader to try your own design, using the principles I've outlined. For the 'high-hat' pedal, I tried out several types that I already had in my collection: a Line6 expression pedal, an electric piano sustain pedal that I use as a looper switch when I play dance classes, and a couple of XBox Rock Band pedals I found on the street. Each one has it's own MIDI messaging behavior when sent through the Trigger I/O. I like that the expression pedal sends control change (CC 0-127) messages, similar to a mod wheel. I'm still experimenting with different use cases in the Ableton Live software environment.

Step 7: Step 7: Software

Connect each drum unit to the Trigger I/O (a dozen cheap 4' TRS cables can be found online. I got some rainbow ones on Ebay). Then connect your laptop with a USB cable and open MIDI Monitor. You should be able to view each message sent by the Trigger I/O. You should now be able to control samplers and virtual instruments in your favorite DAW. My 'hello, world' moment came from an 808 drum rack in Ableton Live. So rad! I typically use an Apogee Duet interface for quality sound out of my laptop, but the built-in 1/8" line-out works fine too. Organizing all my sound banks so that they are easily accessible and playable by all my controllers is an ongoing project. I generally organize my drum patches according to general MIDI protocol: channel 10 is dedicated to percussion sounds and each type of drum gets a specific note #. When I play modern dance classes, I also use my iPad to control certain aspects of Ableton Live wirelessly over WiFi. For example, I can switch patches, change volumes and dynamically set effects and parameters such as delay, reverb, modulation, compression, EQ, etc. My new drums fit nicely into this system. The computer sees my DIY drum kit as another MIDI controller, just like the iRig Keys that I typically use. Fun !!!