Loop Baby
2021 January 22

The Loop Baby is a portable and affordable audio sampler/looper, inspired by the Loop Daddy.

How it works:

  • Internally, the Loop Baby is a Raspberry Pi (with Raspbian) routing audio with Jack to/from Sooperlooper
  • Audio input/output requires a USB audio interface of your choice
  • Pressing the buttons controls Sooperlooper (via some custom Python code), allowing recording/playback/saving/loading/etc.

To me, the key feature is quantization, which means the looper’s recording and playback can be quantized to the nearest beat (e.g., by providing a clock signal from a drum machine). This is a feature I couldn’t find in a multi-track looper for less than $400 or so. The Loop Baby, by comparison, cost me about $75 (plus, you know, hundreds of hours of labor/debugging).

All code and design files are available here.

Demo

In the video above, I have my phone’s output fed into the looper’s audio in, and the looper’s output is connected to the speakers. I then record four different samples from the music playing on my phone. The first three samples are from Hiroshi Yoshimura’s album Green (1986), and the drum sample is from The Blackbyrd’s “Dreaming About You” (1977).

How to use it

The general idea is that you play audio into the looper, record a snippet of it to one of your 8 tracks, and then build up songs by looping or playing your different tracks together.

Here’s what the buttons do, working from the bottom up:

  • PLAY: Plays/pauses playback
  • REC/ADD: Recording/overdubbing mode
  • UN/REDO: Undo/redo whatever you just did
  • MUTE/DEL: For muting or deleting samples
  • ONCE: Oneshot mode (plays samples once instead of looping)
  • BANK: Saves/loads recorded samples to/from disk
  • SET: For modifying settings related to quantization/sync, or rebooting/shutting down the system
  • GAIN: For setting the input gain when recording, or the volume of each track during playback
  • 1-8: Each button corresponds to a different track; in record mode, pressing will start/stop recording to that track; in playback mode, pressing toggles the track on/off

Unfortunately, the pandemic happened before I had a chance to figure out how to etch the button names on the board, so you have to just remember what all 16 buttons do. 🙄

Enclosure design

My design for the enclosure basically just combined two different designs I found: One for a Raspberry Pi enclosure, and a second for the Trellis button matrix. My final design file, which I made in Illustrator, can be found here.

The enclosure was cut out using a laser cutter I had access to at CMU’s IDeATe, and then assembled mostly by snapping the pieces together. (The exception—and the worst part of the design—is that the NeoTrellis attaches to the enclosure using some extremely tiny/finicky screws.)

Parts list

Minimum cost: $70 (without optional midi cable)

@mobeets