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Message: [QUOTE="Bombastus, post: 92046, member: 2178"] Downward compression reduces level above a threshold, while upward expansion raises level above a threshold, so both can react to the same peaks. Their directions oppose each other, but their audible jobs do not have to. It is easy to assume the pair should cancel out. In a stripped-down static model, a matched upward expansion stage can reverse a compressor’s transfer curve when threshold and ratio behavior are deliberately paired. Real dynamics processing adds time, knees, separate thresholds, hold behavior, and level detection, which is where the combination becomes useful rather than redundant. [HEADING=2]Opposite gain moves do not guarantee opposite results[/HEADING] A compressor does not simply turn a whole signal down. Once the detector crosses its threshold, the processor changes gain according to its ratio and envelope timing. An upward expander can watch the same loud region and push selected peaks farther upward instead. Put their thresholds in different places, and you create distinct operating zones. Moderate peaks might enter compression while remaining below the expansion threshold, so they get restrained. Stronger hits can cross both thresholds, letting expansion add some movement back at the top. This gives you a bent dynamic response instead of a single slope. You can narrow one part of the level range while widening another, which is useful when a performance has an overgrown middle but weak accents. A snare can have an unruly body and still need more crack at the front. The useful part of [B][URL='https://goldmidi.com/community/threads/the-note-audio-rolls-out-verbknife-and-toneknife.77437/']ToneKnife’s dual dynamics design[/URL][/B] is this independence. Comp and DComp have their own threshold, ratio, attack, release, hold, and makeup controls, so there is no requirement for the gain changes to mirror one another. You can make one section broad and slow while the other reacts to a smaller, faster slice of the envelope. [HEADING=2]Timing separates the transient from the body[/HEADING] Attack time changes the whole argument. A downward compressor with a slower attack can let the first few milliseconds through before gain reduction develops, while a faster upward expander can increase the level of the same onset. The body arriving behind the transient may then meet more compression than expansion. Release creates another split. A compressor that stays engaged through the body of a drum hit can control sustain and ringing, while a quicker expander can fall back soon after the attack. The combined result can be a stronger peak followed by a more controlled tail, even though both processors respond to signal above their thresholds. A detector does not experience a drum hit as one fixed level. It follows an envelope through time, so two processors can read the same performance and still apply gain at noticeably different moments. [B][URL='https://eecs.qmul.ac.uk/~josh/documents/2012/GiannoulisMassbergReiss-dynamicrangecompression-JAES2012.pdf']Dynamic processors behave as nonlinear systems with memory[/URL][/B] because their output depends on recent signal history as well as the current level. Attack and release therefore change more than how quickly a meter moves. They alter which parts of a note receive gain and how one event influences the next. A static transfer curve cannot show all of this. Two settings can look nearly symmetrical on a graph yet sound very different once one envelope opens quickly and the other recovers slowly. Dense hi-hats expose this immediately because the release from one hit can still be active when the next arrives. [HEADING=2]The pair works best when each stage has one job[/HEADING] Start by deciding what sounds wrong before moving both processors. If the source has swollen peaks or inconsistent body, set compression first and listen without makeup gain fooling you into preferring the louder version. Get the restraint working before asking expansion to return excitement. Bring upward expansion in for a narrower purpose. On drums, it might lift only the harder strikes. On picked bass, it can exaggerate the strongest attacks while compression keeps sustained notes from lurching forward. Avoid matching every control out of symmetry. Identical thresholds and closely matched timing push the two sections toward fighting over the same events, often creating extra peak level without a clear musical benefit. Separate thresholds and deliberately different envelopes give each processor somewhere to work. Headroom becomes the boring part that can wreck the experiment. Expansion raises peaks, and compression makeup gain can raise the entire processed signal afterward. If the next stage is already close to its ceiling, the fresh transient contrast can disappear into limiting or clipping before you hear the benefit. The combination is most useful when the compressor owns density, and the expander owns emphasis. Neither processor needs to undo the other. One can keep a performance from spreading too far while the other preserves the few moments that deserve to jump out. [/QUOTE]

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