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Message: [QUOTE="Bombastus, post: 91033, member: 2178"] Parallel compression blends a compressed signal with its untreated original, so the dry path keeps the transient shape that heavy compression would otherwise reduce. Applied only to the Side channel, that structure can raise quiet stereo information without directly compressing the Mid signal. Mid/Side audio is not simply center audio on one fader and edge audio on another. The Side channel represents the difference between left and right, so reverbs, room microphones, doubled parts, panned instruments, and stereo effects can all contribute to it. That makes Side compression a spatial dynamics tool as much as a loudness tool. Used in parallel, it can make soft width more persistent while leaving the center path alone. [HEADING=2]Parallel Side compression differs from serial compression[/HEADING] Put a compressor directly across the Side channel, and every decibel of gain reduction changes the signal that reaches the decoder. When loud stereo material crosses the threshold, the Side level falls relative to Mid, so the image can narrow during those moments. Width now moves with the compressor envelope. Parallel processing keeps an untreated Side path and adds a compressed copy beside it. The compressed branch contributes proportionally more when the Side signal is quieter and less when large peaks are being reduced. After level matching, the result can lift lower-level Side material while the original branch continues carrying its peaks. That is why [B][URL='https://goldmidi.com/community/threads/panorama-audio-labs-introduced-panoramic.76252/']Panoramic's parallel side-compression design[/URL][/B] can target density without requiring the center of the mix to pass through the same compressor. Its Density processor works on the Side signal in parallel, with adjustable attack, release, ratio, and threshold behavior. This difference is easy to miss if you judge only the gain-reduction meter. Ten decibels of reduction on a quiet parallel return does not mean the master itself has lost ten decibels of Side energy. The dry path remains, and the return level determines how much compressed signal is added. Serial Side compression is better suited to controlling excessive stereo peaks when those peaks are the problem. Parallel Side compression instead adds body beneath an image whose peaks already behave but whose ambience, backing layers, or stereo texture disappear too quickly. [HEADING=2]Quiet stereo information becomes easier to hear[/HEADING] Parallel compression changes the relationship between peaks and quieter material. A dense compressed copy can hold reverb decay, drum-room texture, backing vocals, wide guitars, or synth tails at a more consistent level, while the uncompressed path preserves the original attacks. On the Side channel, that creates [B]low-level stereo detail recovery[/B] rather than a blanket widening move. A static Side boost raises loud and quiet information together. Parallel compression can favor quieter portions because the compressor reduces the wet branch more strongly when the input becomes louder. The stereo result follows from the M/S decode. Side is added to Mid for one output channel and subtracted from Mid for the other, so increasing Side contribution increases the difference between left and right. If the parallel branch contributes most during a reverb tail or fading doubled part, those moments can retain more apparent width without forcing the loudest hits equally wide. That can help a chorus feel spacious between phrases instead of collapsing inward whenever the arrangement thins. It can also keep background vocals or overhead texture present without pushing their loudest moments forward. The spatial change follows level rather than staying fixed across the song. Attack and release determine how that movement behaves. Faster attack reduces more transient energy inside the compressed branch, which shifts its contribution toward body and sustain. Release that is too fast can make ambience surge between peaks, while a slower release may keep the return suppressed through closely spaced events. [HEADING=2]The unwanted Side details rise as well[/HEADING] The compressor cannot distinguish a useful reverb tail from hiss, room spill, brittle cymbals, or an ugly stereo effect unless routing or detector filtering helps it. Parallel compression lifts low-level material as a category, so flaws in the Side signal can become more obvious alongside the details you wanted. This matters with drum overheads and live rooms. A return that makes shells feel larger can also expose abrasive cymbal decay or pumping ambience. Lowering the blend may help, but cleaning or filtering the compressed branch can be the more precise fix. Gain staging matters too. Changing the level feeding an external parallel compressor changes how hard its detector is driven, while changing the return fader changes how much compressed signal is mixed back. Treat those as separate controls rather than using one to compensate blindly for the other. Dry and compressed paths also need accurate time alignment. Uncompensated delay between two copies of the same Side signal can create phase cancellation when they recombine, turning a density treatment into unwanted spectral coloration. Built-in parallel controls simplify that routing, while external buses and hardware paths deserve an explicit latency check before you judge the stereo result. [/QUOTE]

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