Pi is the multi-track version and it improves the sound of multi-track mixes by constantly monitoring and reducing phase/frequency cancellations between tracks in your mix. It "instantly" works in VST, RTAS and AU formats in Mac & PC DAW host computers in 32 or 64-bit sessions.

SoundRadix Pi--Phase Interactions Mixer

Good phase correlation between audio tracks summed into a single stereo mix bus can be variable and always changing due to instruments overlapping and interacting with each other across their frequency ranges. Phase cancelling or buildup depends on two or more signals (tracks) being at the exact same frequency, level and occurring at the same time.

Often, a bass track could be temporarily out-of-phase with the kick drum only on certain bass notes and only when the bass plays that note and the kick drum sounds at that frequency and plays at the same time and both of those signals are about the same level. If the two cancel one another out, you'd hear a momentary loss of level and if they get louder, you might reach for a compressor setting trying to control the situation.

Sometimes I find with real multi-track drums recordings I'm given to mix, at certain moments the kick or snare loses energy (level) for no apparent reason--each in solo sound fine but when combine together or with the rest of the drum kit tracks, they don't hold level or even cancel out.

Also sometimes with poorly recorded drum kits, the snare or a tom-tom hits at the same time and approximate level and there is partial cancelation. Pi measures and then dynamically rotates the phase of individual mixer channels to achieve maximum phase correlation between them within the mix.

I first tried it on a drum kit I recorded originally but was 'modified' (chopped up and processed off line by the producer) and I noticed that when I mixed the all drum track as I wanted, the snare sound just wasn't up front enough; it always sounded distant.

SoundRadix Pi--Phase Interactions Mixer

Pi communicates phase information over any of its own 24 nameable, internal buses called Groups (nothing to do with your DAW's buses). You can maintain phase coherency within only a Group or, within the group relative to the rest of the mix, or keep the group phase-locked within itself but coherent with the rest of the tracks in your mix. (I.e. M/S stereo recordings must maintain accurate phase coherency).

You can optimize coherence over the full range, or low frequencies such as for bass and kicks. I like the 'trippy-lookin' four mode multi-channel phase correlation display, inter-channel sample accurate routing and, as geeky as all this sounds, the wonderful way the sound instantly is better for all the right reasons!!!

Pi requires 150-ms of look ahead time to do its magic so Pro Tools TDM users will run out of delay comp and will have to instantiate a Pi plug-in (at the last insert point) on every channel---- OR get Pro Tools 10 Native (or HDX) that has more than enough delay comp. Apple's Logic, Ableton Live, MOTU and PreSonus work fine with certain minor caveats and special considerations.

All totally worth it, Pi is available for $240 and is another awesome tool from SoundRadix. Check out: www.soundradix.com/.

Try The SoundRadix SurferEQ Pitch-Tracking Equalizer Plug-in.