start Polarity Check above, feed headphone-out into the system, point this mic at the speaker

peak hold: — dB

—

⚠ Uncalibrated — showing relative level only

⚠ Input near clipping — level reads low; move back from the source

Play a steady source, type your SPL meter's reading, tap MATCH. Or nudge the slider to trim.

uses the Delay tab's temperature & humidity

locating…

lay the phone on the surface — 0.0° is level

Geometry estimate — verify critical rigs by measurement.