The Sunset Recorder

Put a limiter across a finished mix and push the input. Nothing about the recording changes except the distance between its quietest passages and its loudest ones, which shrinks. The peaks that used to leap out of a snare or the front edge of a piano note get held down, the average level rises to fill the space they vacated, and the track sounds louder without the fader having moved. That single operation, repeated across a few decades of records, is the whole argument.

Two measurements describe what is happening. Dynamic range is the span between the soft parts and the loud parts of a piece of music, both across a song and within a single bar. Crest factor is the narrower and more useful figure: the difference between a signal's peak level and its average level. An unaccompanied drum kit has a high crest factor, because the sticks produce brief spikes far above the general loudness of the room. A heavily limited rock mix has a low one, because those spikes have been flattened toward the average. Compression and limiting lower crest factor, and lowering crest factor is what allows a master to be turned up.

What gets traded away

The cost is transient detail. The attack of a snare, the pick against a string, the click of a kick beater and the breath before a vocal line all live in the first few milliseconds of a sound, and that is exactly the material a limiter is built to catch. Take enough of it and instruments lose their sense of physical impact even as the track gets louder. The stereo image can narrow. Bass and kick begin to fight, because a limiter reacting to low frequency energy pulls the whole mix down with every note. Listeners rarely call this distortion. They call it fatigue, or a record that is somehow tiring after two songs.

The practice escalated on compact disc, which gave engineers a fixed digital ceiling and a clear way to measure how close they were to it. Level became competitive because loud sounded better in the moment of comparison, and comparison was how records were auditioned: in a shop, on a radio playlist, across a mastering room's monitors against the last thing the label released. Given two masters of the same music, the louder one usually wins a quick listen even when the quieter one holds up better across an album. Mastering engineers who resisted lost work to engineers who did not.

Normalisation did not settle it

Streaming services introduced loudness normalisation, which measures a track's integrated loudness and adjusts playback so that everything in a queue arrives at roughly the same perceived level. The common reading was that this ended the incentive to master loud, since a louder file simply gets turned down. That reading was too tidy for several reasons.

Targets are not uniform. Services set their own reference levels and change them over time, some apply normalisation per track and some per album, and users can switch the feature off. Music also gets consumed far outside those systems, in DJ sets, in film and television edits, in games, on radio, on physical media and in files traded around before release. A master has to survive all of it.

More to the point, turning a limited master down does not give it back what limiting took. Crest factor is a property of the file, not of the playback gain. A flattened master played quietly is a quiet flattened master. Meanwhile the aesthetic preference has not gone anywhere. A dense, controlled, forward master sounds decided and finished when it comes up on monitors in a room full of people, and quite a lot of contemporary production is built that way from the start. Limiting is baked into the mix long before the mastering engineer is involved: on the drum bus, on the vocal chain, on the sample library itself, inside the plugin presets. By the time a file arrives for mastering, most of the dynamics argument has already been resolved by someone else.

What this means at the desk

For a mix engineer the practical position is to know the loudness a mix is already carrying rather than to defend a number. That means metering integrated loudness and true peak alongside the usual meters, and checking the mix with a limiter engaged and then bypassed to hear what it costs. It means leaving the mastering engineer somewhere to work rather than delivering a mix already pinned to the ceiling. It means arranging for contrast, since a chorus reads as bigger only if something before it was smaller, which is an arrangement decision and not a processing one. Level can be added later by anyone. The transients cannot.

■  The Sunset Recorder