Making of Small Motor Library by Rabbit Ears Audio

Michael Raphael is a professional sound recordist and designer. After a long career in radio, he is the creative force behind the boutique sound effect studio Rabbit Ears Audio and the long-running field recording blog Field Sepulchra. Sonic Terrain is honored to have him on board as a contributor.

Hello Sonic Terrain readers! I’m very excited to be contributing to Sonic Terrain, and as my first order of business I want to share some of my experience recording the Small Motors Sound Library for Rabbit Ears Audio.

Sometimes a sound just reaches out and grabs you. Actually, that happens to me quite often and I’m guessing that is why I’m writing this now.

A few months back a good friend of mine told me about a local hacker space in Brooklyn, NY, and after doing a little bit of research I discovered the Maker Bot. I took a ride out to the offices of Maker Bot Industries and met some of the great people there who were  excited to have me record. After meeting the Bot, I knew it needed to be recorded and a sound library needed to be built around it.

The Maker Bot is essentially a 3D printer for prototyping objects out of plastic. It has 3 stepper motors that each move different attachments along an X,Y, or Z axis. One of the first sounds I heard it make was the sound of it printing a circular object:

Maker Bot by sepulchra

As soon I heard it, I knew it had to be recorded. Not only did it make those grinding sounds above, but it could it do so much more. It could sound like a 1970s movie imagining of a Robot:

REA_002 SMALL MOTORS 09 Maker Bot 3D Printer,Random Shapes,Print Stop,Long Duration,X3,CUB 01 by sepulchra

And it could also produced longer sustained “printer tones”:

REA_002 SMALL MOTORS 23 Maker Bot 3D Printer,Straight Lines,Print Stop,Speed 14,X4,CUB 01 by sepulchra

Those are just a few of many sounds this little bot can produce.

As excited as I was, I had a number of challenges to face. It needed to be programmed with a computer that would have to be near by, which might be noisy. The bot has an AC power supply and fan that needed to be tamed as well.  After some experimentation with Charles Pax of the Maker Bot team we decided to just jam the fan with a pencil, which eliminated the whine of the power supply. Next, we had to deal with the room, which wasn’t that noisy to begin with, but it needed some treatment. We “tented” the bot with moving blankets to deaden the space as much as possible. I ended up mounting a Sanken CUB-01 and a DPA 4060 inside the bot and recording with an MKH 60 on the exterior of the bot.

The entire time I was recording, I was wondering what it would sound like pitched down a few octaves.

Maker Bot Pitch Shift by sepulchra

Apparently, the answer is somewhere between a growly animal and old creaky, wooden ship.

Once I had the bot recorded, I needed to move on to other motor sounds. I’m lucky enough to have a few “gourmets” in my life, and I’m always surrounded by a wide selection of kitchen appliances that make killer sounds. Shortly after the kitchen appliances, I moved onto power tools.  The focus of the collection is small motors so I kept the power tools to the portable variety. I took a similar approach with the appliances and tools that I did with the bot: I knew I wanted to have at least one “onboard” perspective and two exterior perspectives. Each object was recorded with DPA 4060 (mounted somewhere directly near the motor), a Schoeps MS pair and an MKH 60. It sounds like quit a bit of coverage for small motors, but it ultimately provides great flexibility for designing mechanical sounds. Maybe a beefier onboard sound is needed, or maybe it needs to be softened a bit with the stereo recording from the Schoeps, or maybe the tone of the MKH 60 has the right feel.

I was really impressed with the sound of the DPA on the motors. I wrapped up the mic in foam and taped it down near the motor of each object and let her rip. Below are some of my favorites from the DPA 4060 mounted on board.

REA_002 SMALL MOTORS DPA by sepulchra

The key with onboard recordings is to keep the mic isolated from vibration. I chose the DPA in this case because it is small, can get into tight places and can handle hi-SPL for such a sensitive mic.

And here are the same sounds covered with the Schoeps MS pair that has been matrixed to LR.


You get the idea! Part of the joy of this work, however, is hearing how others use my work. How are you going to use this content?