CHECK / free utility
see where your stereo falls apart.
real-time correlation across 40 frequency bands. bass-weighted scoring tells you what will survive a club system, not just a single number.
no account needed. no iLok. just download.
as featured on
when CHECK finds a problem
SMOOTH fixes the resonance you just spotted.
CHECK tells you which frequencies are fighting. SMOOTH suppresses the resonant peaks dynamically — only when they poke through. try it free.
try smooth free
in action
see what your mix looks like in mono.
CHECK analyzing a stereo mix. the correlation curve shows safe frequencies in mint and problem areas dropping into the red zone. the bass-weighted score reads 55%. REVIEW MIX.
hover the numbered dots to explore the interface
features
what makes CHECK different.
01 / spectral correlation curve
see mono compatibility across 40 frequency bands in real time. not just a single number — a full picture of where your stereo image holds up and where it falls apart.
02 / bass-weighted score
the score weighs low frequencies 3x heavier than highs — because that's where mono collapse actually hurts. if your bass drops below 60%, your low end won't survive a club system.
03 / frequency-focused analysis
the FOCUS knob lets you zoom into LOW, FULL, or HIGH frequency ranges. isolate your bass mono compatibility or check just the stereo highs.
04 / instant mono and side monitoring
MONO button collapses to mono so you hear the damage. SIDE button solos the difference signal — everything that disappears in mono, isolated.
05 / colour-coded curve and bar chart view
the correlation curve changes colour as it crosses zone boundaries — mint where you're safe, amber for caution, red for phase cancel. flip to bar chart mode via the right-click menu to see all 40 ERB bands as discrete coloured rectangles. spot a single problem frequency at a glance.
06 / smart education that names the frequency
instead of generic warnings, CHECK tells you exactly what's happening: "phase cancel around 80 hz. often an out-of-phase kick and bass relationship." three message variants per problem rotate as you iterate, so you learn three common causes per region. bass is treated as more critical than highs because that's where mono collapse actually hurts.
specifications
the numbers.
system requirements
go deeper
full documentation.
controls, score zones, how spectral correlation works, mono compatibility tips, and installation guide.
read the docscomplete your toolkit
CHECK finds the problems. these fix them.
CHECK shows you where your mix has phase issues. the rest of the KERN series gives you the tools to fix them, without destroying what makes your mix yours.
featured on BPB, Rekkerd, KVR, RouteNote, and MuseHub
SMOOTH / $29
tame harsh resonances
dynamic resonance suppression across 40 psychoacoustic bands. when CHECK shows buildup in problem frequencies, SMOOTH removes it without killing the life.
learn more →WARM / $29
add harmonic richness
three analog saturation characters with spectral awareness. add warmth and presence that translates in both stereo and mono.
learn more →WIDE / $29
expand your stereo field
psychoacoustic stereo expansion with built-in mono protection. when CHECK says your stereo is too narrow, WIDE opens it up safely.
learn more →PUSH / $29
the step before your compressor
three compression characters: SETTLE, TIGHT, DRIFT. glue the mix before your main bus comp, without crushing transients or stealing punch.
learn more →or get all four
SMOOTH cleans. WARM adds character. WIDE places stereo. PUSH glues it together. one license key.
see the bundle →Field Notes from KERN Audio.
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what people are saying
This Mono Compatibility Analyzer Is FREE — CHECK by KERN / Free VST Plugins
84% mono safe on a full drum session / community member
This FREE Plugin Fixes Your Mix Instantly / CoinxDaProducer