The Spheres Dataset

The Spheres dataset is a novel multitrack orchestral recording resource designed to advance machine learning research in music source separation and related MIR tasks within the classical music domain. The dataset is composed of musical pieces performed by the Colibrì Ensemble at The Spheres recording studio, capturing two canonical works—Tchaikovsky’s Romeo and Juliet and Mozart’s Symphony No. 40—along with chromatic scales and solo excerpts for each instrument. The recording setup employed 23 microphones, including close spot, main, and ambient microphones, enabling the creation of realistic stereo mixes with controlled bleeding and providing isolated stems for supervised training. In addition, room impulse responses were estimated for each instrument position, offering valuable acoustic characterization of the recording space. The signals are provided as lossless FLAC files at 48 kHz and structured as in the EnsembleSet and SynthSOD datasets: a folder per music piece, inside them and folder per microphone, and, inside them, an audio file per instrument line. Metadata files in JSON format, similar to the ones included in SynthSOD, are also provided.