Akin to compressor and expander/noise gates with side chain control inputs for dynamic effects, TrackSpacer analyzes the audio frequency spectrum coming in on its side chain input from an Aux send bus (in my case of Pro Tools 11) and then applies a frequency-tracking corrective equalization that reduces the same set of frequencies on the track(s) or channels where it is inserted.

You can have TrackSpacer track the inherent changes in the frequencies of music or use the Freeze mode to lock it to a fixed band of frequencies. Based on your individual settings and preferences, TrackSpacer "carves" room or space in your mix by reducing the frequency buildup when two or more instruments or vocal tracks in the same octave and similar timbres compete to be heard at the same time

I've started using it in Pro Tools 11 for big background vocal stacks all sung by the same singer. Dulling the mid-range of the backing vocal tracks dynamically very slightly whenever the lead vocal sings, causes the lead vocal track to "project" without changing its level and without reducing the BG's overall volume, energy and impact.

TrackSpacer 2.0 adds 64-bit AAX support and a second GUI page, an Advance Panel with side-chain listen and Attack/Release time constant controls to tailor its operation even more specifically to your needs. I also laud the new M/S mode for more control over Mid/Side stereo post-recording--film mixers will love this! The L/R mode improvements in 2.0 are: you can pan the effect in the left channel, right channel, or anything in-between.

There are many uses for TrackSpacer 2.0 such as subtracting the kick drum's dominant set of frequencies from the bass instrument's track so that the kick drum sound is more in the "clear." As an effect when set on stun, TrackSpacer can sound anywhere between an auto wah or to very subtle such as modulating a reverb return triggered by a percussion instrument track.