With so many instant online mastering services available, a simple question follows: why pay more for a human? Humans take longer, are less consistent and cost more. Those apparent weaknesses are part of the answer.
Less consistent - on purpose
Algorithms react according to maths. Humans react to the music. Sometimes the "wrong" decision sounds better, and a human can hear that. Every day is a little different for an engineer - mood, ears, experience - and those differences make each master a piece of work rather than a calculation. The skill is balancing that personal judgement with consistent technical standards.
Humans care about the result
A mastering engineer succeeds through the work they deliver. Most of the time it is not their own music, so their success lies in making the artist sound good enough to break through. An algorithm does not care whether your record succeeds.
Humans give feedback
Mastering engineers are famously obsessed with levels - and generous with mix feedback, because a better mix makes their job easier and brings the artist closer to what they hear in their head. "The kick is fighting the bass at 60 Hz" or "the vocal drops out in the second verse" is feedback no algorithm will give you. Many engineers will ask for a revised mix rather than master around a problem.
Humans make versions
A human can make specific versions for specific uses: streaming, club play, vinyl, instrumental, clean, TV mix, stems mastering. An algorithm can only do what its developer designed it to do.
Algorithms have limits
- They are built by coders, not usually by mastering engineers - though many are developed with professional input.
- They need maintaining - services change, update and sometimes disappear.
- They apply general rules to a specific piece of music.
When an algorithm is the right choice
Instant mastering plays a real role. It suits demos, quick releases, content, tight budgets, and artists who want results immediately. Many producers also use one to hear roughly how a mix will master before sending it to an engineer.
Use it to learn
The best test is to try both: master a song with an instant service, have the same song mastered by an experienced engineer, and compare at matched loudness. Listen for low-end control, clarity, width, and how the master handles the loudest sections. Then try your own master and compare all three.
Algorithms are not the enemy. They have become a baseline - and a human mastering engineer's job is to match and surpass it.
Do this now
- Run one of your mixes through an instant mastering service.
- Master the same mix yourself.
- Compare the two at matched loudness and write down three differences.
Adapted, with thanks, from the lesson notes of J.M. Brooklyn Audio Mastering.