Mixer4 Sum Test
This page describes the results of a summing test with Mixer4.
127 tracks were mixed. Only one of the 127 tracks
was a 1 kHz test tone. The rest were 2 kHz, 4 kHz, and 8 kHz tones.
The polarity was reversed on half of the 126 tracks so that the
only frequency to appear in the final mix should be the 1 kHz tone.
The test was performed on a Raspberry Pi and took just under 3 minutes
to mix 127 30-second test files on a regular SD card.
Test files were 24-bit full-scale .wav files generated in Audacity.
All tracks were set to -14 dB and a 3 dB pan law was used.
Tracks were staggered in groups of 3 tracks with opposite polarity
between groups so that they would cancel each other out and
therefore permit a fairly high channel level overall.
Screenshot (.png) of FFT of 1 kHz source
Screenshot (.png) of FFT of mix output
Mixer4 output levels
Try it yourself
1 kHz wave
2 kHz wave
4 kHz wave
8 kHz wave