Why check correlation?
Stereo width feels great on headphones, but plenty of listeners hear music in mono: phone speakers, club systems, smart speakers and some broadcast paths. If parts of your mix are out of phase, they can partially cancel when summed to mono, and your bass or vocal may suddenly become thin or vanish.
A correlation meter shows how similar the left and right channels are, giving you an early warning. This article looks at 2BusControl and at the concept behind it; confirm the plugin's exact features and price on the developer's official page.
Confirm before you install
This was shared as a free plugin promotion. Offers can end and versions can change. Use the official developer page or store, and avoid unofficial download sites.
How to read a correlation meter
| Reading | Meaning | Action |
|---|---|---|
| +1 | Left and right identical (mono) | Fine, but the mix has no width |
| 0 | Independent, wide stereo | Usually healthy for wide sounds |
| -1 | Opposite polarity | Serious phase problem; investigate |
Healthy music generally sits between 0 and +1, dipping toward zero for wide moments. Short dips below zero are not always a problem, but a meter that lives in negative territory deserves attention.
Common causes of phase problems
- Stereo wideners and chorus on bass sounds.
- Recording the same source with two microphones placed carelessly.
- Layering samples that have opposite polarity.
- Extreme use of Haas-style delays.
- Some reverbs and modulation effects on low frequencies.
A simple mono-check routine
- Put the correlation meter on the master.
- Play the loudest section.
- Switch your DAW's master or a utility plugin to mono.
- Listen for elements that get quieter or thinner, and check the meter.
- Fix by narrowing the offending sound, flipping polarity on a layer, or making low frequencies mono.
Keep the low end centred
Bass and kick carry most of your energy, and they are the first to suffer from phase cancellation. A common practice is to keep everything below roughly 100 to 150 Hz mono. Use a stereo-width plugin or your DAW's utility to collapse the low end, and then widen the mids and highs. If your levels are uneven, revisit the gain staging guide before making imaging decisions.
Where this fits in your workflow
Use a correlation meter during mixing and again before you export. It complements a spectrum analyzer and loudness meter. You do not need to obsess over a perfect number: the ears decide, and the meter just flags problems. For more free tools, browse our 500 free VST plugins.
Key takeaways
- Correlation shows how compatible your mix is in mono.
- Keep bass and kick centred.
- Check mono before release.
- Confirm 2BusControl's features and price on the official page.
FAQ
What is a good correlation value?
Mostly positive, usually above zero. Brief dips are fine, but staying near minus one signals cancellation.
Can a correlation meter fix my mix?
No, it only diagnoses. You still fix the problem by ear.
Is stereo width bad?
No. Just check that the mix survives being played in mono.
Where do I put the meter?
On the master bus, or on individual stereo tracks to find culprits.
Get 2BusControl from MAAT
