Pi

Name: Pi
Price: 249 USD
Author: Sound Radix

by Sound Radix · Utility · Multi-track phase optimizer

Not rated yet

Pi is a multi-track phase optimizer: instances on different tracks talk to a central processor and adjust phase to reduce cancellation between them.

It can work on the full range or only the low end, groups related tracks, and costs $249.

Best for: Drums, Bass, Mix Bus, Guitars, Keys & Synths. Genres: all genres.

Keywords: bass, drums, mono-compatible, synths, kick, metering, punchy, bus processing, full mix, mix bus, mixing, multi-band, tight, utility.

What it does

Pi is a multi-track phase optimizer that reduces cancellation between tracks that were not recorded together, such as a kick and a bass line. Sound Radix says it works "to improve the summing" of your DAW, handling phase interactions that change over time and that a fixed phase rotator or EQ cannot fix.

Multi-track awareness: every instance feeds a central background processor that analyses phase sample-accurately across the session.
No side-chain setup: routing between instances is internal and sample-accurate.
Grouping: up to 64 groups keep related tracks, such as the mics on a drum kit, together so their own phase relationship is kept.
Optimization modes: Full Range or Low Frequency only, set globally.
Metering: a multi-band phase correlation meter shows correlation per frequency band and overall, with a multi-channel display of the phase relationships.
Aims: fewer frequency cancellations, better mono compatibility and less loss of depth.

The current version is 1.1.3 (December 2022). A free trial is available.

Source: Sound Radix product page

When to use it

Pi is the pick when separate sources, such as kick and bass or layered synths, dull each other through phase interaction. Compared with Sound Radix Auto-Align 2, Waves InPhase or NUGEN Audio Aligner, which line up mics that captured the same source, Pi works across many unrelated tracks at once and keeps adjusting as the music changes. Unlike a meter such as Voxengo SPAN or iZotope Insight 2, it fixes the problem rather than only showing correlation. The price of that is latency and, on sustained pitched parts, possible artifacts, so it is a selective tool rather than one for every track.

Best for: kick and bass relationships, layered drums and synths, and tightening low end and mono compatibility across a mix.
Genres: any style, especially bass-heavy electronic and hip-hop.
Look elsewhere if: you only need to align mics on one source; Auto-Align 2 is the tool for that.
Tip: group parts that belong together, such as the drum kit, to keep artifacts down (Computer Music).

What producers say

Reviewers found it can make mixes punchier but needs care and ears, since results vary by source.

Computer Music (2013) said that "deployed with care, it can be pretty useful", praising the punchier results and the grouping, but found it unpredictable for many users.
Criticisms (Computer Music): audible pitch artifacts on sustained pitched sounds such as piano, guitar, bass and synth, and substantial processing delay, especially with plugins before it.

MusicRadar (Computer Music) review

Where to buy

Sound Radix: $249

Tutorials and reviews

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X-Phase by Solid State Logic · All-pass filter phase alignment · $99
Little Labs IBP Phase Alignment Tool by Universal Audio · Phase alignment tool · $49
Align by Apollo View · Phase alignment tool · $66.23
Precision Time Align by Eventide · Sub-sample time alignment · $49
InPhase LT by Waves · Phase alignment · $27.28

All metering & utility

Pi