Mirroring loudness maximizers means using several instances of the same - or similar - limiter in series, each adding a small amount of level, instead of one limiter doing all the work. Each instance becomes its own stage of loudness, and the gradual accumulation of volume keeps the texture controlled and the tone clear.
This is an advanced technique, outside the taught sequence. Learn conventional limiting first.
Why it works
A single maximizer pushed hard has to handle every peak at once, and its artefacts - distortion, pumping, dulled transients - grow quickly. Several limiters each doing a little share the work: each one only catches the highest peaks of what it receives. Between instances, small supporting processors can make complementary adjustments - additive or reductive - for extra detail and character.
The five steps
- Master as normal, with a clean maximizer at the end of the chain as a placeholder - it lets you hear your decisions at a realistic level.
- Remove the maximizer from the end of the chain.
- Render the whole project to a stereo file.
- Start a new session with that stereo file and your reference tracks.
- Mirror loudness - add limiters in series, each contributing a small, gradual increase in level, until you reach the reference target.
Guidelines
- Each stage adds roughly 1-3 dB, building from premaster level (around -18 to -9 on a VU meter calibrated to -18 dBFS) towards a commercial master (around -9 to -2).
- Keep each limiter clean. The aim is stages of loudness, not texture. Avoid stacking extra features such as heavy oversampling on every instance.
- Supporting processors support. Use them only to keep the content balanced, not to add colour.
- Different limiters, different textures. Using models from different manufacturers per stage offers different circuitry under the same conditions - a way to shape the final character.
- Gradual, not sudden. Each instance should be subtly progressive, preserving clarity as volume accumulates.
- Do not overdo it. Too many processors will produce an undesirable result.
- Stay level before the limiters. The mastering chain should not add overall volume before limiting; any EQ boosts should be rebalanced so the level going in matches the level of the original.
Know when to stop
Be willing to abandon mirroring and use a single, traditional limiter if it sounds better. The master should reflect the character and level of the reference target - not the engineer's attachment to a technique.
Do this now
- Take a finished master, remove its limiter, and render it.
- In a new session, reach your reference's loudness with one limiter. Save that version.
- Reach the same loudness with three clean limiters in series, each adding 1-3 dB.
- Compare the two at matched loudness. Listen to transients, low end and clarity.
Adapted, with thanks, from the lesson notes of J.M. Brooklyn Audio Mastering.