Spirit Level

A 1U stereo meter that listens, watches and stays out of the way. Audio passes through untouched; the device only looks.

Its centrepiece is a real spirit level: a bubble in a tilting vial that shows stereo balance, or how far you are from a loudness target. Level, and you are level. No numbers to interpret.

When you do want numbers, it has them: classic VU, PPM and Peak bar meters with peak hold and clip indicators, and a large LUFS readout with momentary, short-term and integrated loudness to broadcast standard. Readouts switch between dBFS, LUFS and dBu.

Show one meter or all three — they share the display automatically. Audio passes through completely untouched.

Three meters, one device.

Spirit Level has three display sections that you can show in any combination: a horizontal bar meter, the spirit level bubble, and a large 7-segment readout. Turn off what you do not need and the rest expands to fill the space.

The bubble. In BALANCE mode the vial tilts toward the louder channel, so a glance tells you whether your mix is sitting straight. In TARGET mode it shows how far your loudness is from a target you set, centred between the two lines means you are on target. Drag the vial to set it (hold Shift for fine steps), or step it with the arrows. The default is −14 LUFS, the common streaming reference.

Bar meter. Choose VU (300 ms RMS), PPM (fast rise, slow fall) or Peak. Green up to the warning zone, orange up to 0 dBFS, red above it — Reason’s rack is floating point, so levels above full scale are real and worth seeing. A peak-hold line marks your highest peak for five seconds, clip lamps latch until you clear them, and a numeric readout shows the held peak.

Loudness readout. Momentary (400 ms), short-term (3 s) and gated integrated loudness follow ITU-R BS.1770-4 and EBU R128, so the numbers line up with the targets streaming platforms and broadcasters publish. A plain 10-second RMS average is there too. Tap the digits to restart the integrated measurement.

Units. Numeric readouts switch between dBFS, LUFS and dBu. With dBu offered under both the EBU R68 and SMPTE RP155 alignment standards so you can read digital levels in the units your interface’s spec sheet uses.

Details that matter. A mono source is measured as dual mono instead of pinning the balance to one side. Silence is passed on as silence, so devices after it can idle. Your section layout, bubble mode, target and units are saved with the song.

Specifications

• 1 U, stereo in / stereo out, audio passed through unaltered
• Meters: VU, PPM, Peak (sample peak), peak hold, clip latch
• Loudness: momentary / short-term / integrated LUFS (ITU-R BS.1770-4, EBU R128), 10 s RMS average
• Bubble: stereo balance, or deviation from a −36…−6 LUFS target
• Units: dBFS, LUFS, dBu (EBU R68 / SMPTE RP155)
• All settings saved with the song