Gain-staging calibrator

Type a level in any one unit and read it in all four, against whichever 0 VU reference your session is calibrated to.

0 VU reference

Enter a value in any column

dBFS Digital · 0 VU = −18 dBFS VU The reference itself dBu Analogue line · 0 VU = +4 dBu dBV Consumer · 1 V reference

        STAGE
        +0.0 VU
        ON TARGET
        ✓ staged
      

How to read this

A VU meter has no fixed relationship to a digital scale — the relationship is a decision, and the reference you choose is that decision. At the default, 0 VU sits at −18 dBFS, which is where analogue-designed equipment expects to be fed. Change the reference and nothing about the audio changes; what changes is where the meters call zero, and therefore what they prescribe.

The analogue columns follow from there. dBu = VU + 4, because 0 VU on a professional line corresponds to +4 dBu. dBV = dBu − 2.2184, the fixed offset between a 0.775 V and a 1 V reference. Both are locked to VU, so both move when you change the reference. The dBFS column is the one that stays put — it is the signal itself, and re-calibrating a meter cannot alter it. Switch from −18 to −24 with −24 dBFS in the field and the reading becomes 0 VU: same signal, different zero.

The STAGE readout underneath is the same grammar the plugin faces use: it names the state and prescribes the correction rather than leaving you a raw number to interpret.

The reference ladder

A VU meter reads an average, not a peak. The more a source peaks above its own average — its crest factor — the more room it needs above 0 VU, and the lower the reference should sit to give it that room.

ReferenceSourceWhy

−18 dBFS Program material — vocals, bass, guitars, busses, full mixes The default. Moderate crest factor; the average and the peaks are close enough that 0 VU leaves usable headroom.

−20 dBFS Broadcast delivery and post-production chains The common alignment level outside music, and the one to match when a chain expects it.

−21 / −24 dBFS Drum busses, percussive program, plucked and picked sources Peaks sit further above the average, so the whole scale drops to give those transients room above 0 VU.

−27 / −30 dBFS Individual snare and kick tracks, hard transient material The highest crest factors. At −18 the needle sits politely near zero while the real peaks are already near the ceiling.

The full reasoning — why analogue-designed tools expect this level, and what happens when a session runs 15–20 dB hotter — is in the OPTO Comp manual under Before anything else: get to zero.

This is the static rehearsal. The VU Meter does it live, on your own material, with the needle showing you the average as it moves. ZEROPINK | VU Meter →