After completing several tech support jobs where audio issues—especially phase problems—were the main culprit, we decided to put together a quick post on the topic. If you're cutting audio to disc and aren't fully familiar with how to check phase properly before sending audio to the lathe, here’s some useful information along with a great free tool to help you out.
Phase alignment is crucial when cutting audio to disc because it directly affects groove stability, sound quality, and playback reliability. Low-frequency phase issues are the most problematic, as they can cause excessive vertical groove movement, leading to tracking problems, stylus jumps, broken grooves and potential cutterhead damage. While high-frequency phase issues are less destructive, they can still result in loss of clarity, distortion, and tracking difficulties. If high frequencies are out of phase, they may partially cancel out, making cymbals, vocals, or other high-end elements sound dull or disappear in mono playback. Additionally, erratic high-frequency groove movements can stress the cutting stylus, leading to distortion or mistracking on certain turntables.
A great free tool to check phase is 'Correlometer' from Voxengo. It is a multi-band phase correlation meter that helps engineers analyse and correct phase issues across different frequency ranges—critical for vinyl mastering. Unlike a standard phase meter, it breaks the signal into multiple bands, allowing precise detection of out-of-phase low-end (which can cause groove instability) and high-end phase issues (which can lead to clarity loss or distortion during playback).
For anyone interested it is available here: www.voxengo.com/product/correlometer