Piano is one of the most full-spectrum instruments in popular music. A grand piano covers seven octaves and has an inherent stereo width from the way the strings are laid out. That richness is also the problem — piano can fill the entire frequency range of a mix, leaving no space for vocals, guitars, or anything else. The art of mixing piano is mostly about deciding what role it plays in the mix and then carving away everything that does not serve that role.
The frequency anatomy of a grand piano: the lowest octave lives at 30 to 100 Hz (almost always too much in a full-band mix), the body lives at 200 to 500 Hz (where the chord recognition is — and where mud accumulates), the resonant ringing lives at 800 Hz to 2 kHz (the "honk" of an over-resonant piano), the harmonic body lives at 2 to 6 kHz (where the note becomes identifiable), and the air and percussive attack lives at 8 to 15 kHz.
Solo piano (no other instruments) gets minimal processing. High-pass at 30 to 40 Hz to remove rumble. Light compression (2:1, 2 to 3 dB reduction) to even out the dynamic range between soft passages and loud chord stabs. A small reverb (1.5 to 2 seconds plate or hall) for space. That is mostly it. The piano was already mixed when it was recorded by the mic placement.
Piano in a full-band mix needs much more aggressive carving. High-pass at 100 to 150 Hz to make room for bass and kick. Cut the 250 to 500 Hz mud zone by 3 to 5 dB to make room for the snare and the body of the vocal. If the piano is a rhythm part (chord stabs, comping), cut narrow at 2 to 4 kHz to make room for the vocal's presence band. If the piano is the lead element, leave the 2 to 4 kHz alone and carve other instruments instead.
Stereo image is where piano goes wrong most often. A close-miced grand piano captures real stereo from the spread of the keyboard, but in a band mix that natural width usually competes with overheads and other stereo elements. Either narrow the piano stereo image to about 60% width with a stereo imager, or hard-pan it to one side (left or right) and treat it like any other mono instrument. Full stereo piano + full stereo overheads + stereo guitars = mush.
The sustain pedal is your nemesis. When the pianist holds the sustain pedal, the strings ring out and accumulate harmonics. In solo piano this is beautiful. In a band mix it is mud. If the recording is muddy from too much sustain, you cannot fix it with EQ — the harmonic accumulation is fundamental to the recording. The fix is to ride the level down during sustained sections, or to use a transient designer plugin to enhance the attack and reduce the sustain. Or to ask the pianist to use less sustain on the next take.
Compression on piano should be musical and slow. 2:1 ratio, slow attack (20 to 40 ms) so the chord attack survives, slow release. 2 to 4 dB of gain reduction. The goal is to even out the dynamics so quiet ballad sections sit at the same perceived loudness as climactic chord stabs.
Electric piano (Rhodes, Wurlitzer, Nord) gets different treatment. Less worry about stereo (often recorded mono or DI), more worry about the upper midrange where these instruments can sound nasal. A 1 to 3 dB cut around 1 to 1.5 kHz tames the nasal honk of a Rhodes. Saturation, distortion, and amp simulators are common — Rhodes through a Fender Deluxe Reverb sim is a classic sound.
Reverb on piano. Plate reverb is the most flattering for grand piano (1.5 to 2.5 seconds). Hall reverb works for classical and ballad arrangements (2.5 to 4 seconds). Spring reverb works for vintage Wurlitzer or Rhodes parts. Send -15 to -25 dB below the dry piano. Pre-delay 30 to 60 ms to keep the dry attack intact.
Common mistakes: no low-end cut in band mixes (the piano covers the bass), too much stereo width (mush), no mud cut (the piano covers the snare), too much sustain pedal in the recording (unfixable mud), reverb without high-passing the return (smears the low end further).
Reference tracks: Adele's "Hello" for piano-led pop, Bruce Hornsby's "The Way It Is" for piano in a band, Coldplay's "Clocks" for rhythmic piano, Norah Jones' "Don't Know Why" for jazz-pop intimacy. Each represents a different role for piano in a mix.