A music room needs a split that stays quiet on the fan speed you can actually use, mounted so vibration does not travel into the structure. Microphones and quiet practice hear the indoor fan and they hear a compressor on the other side of the same wall. Ask for low-fan dB(A), anti-vibration mounts, and a position off the party wall and off the wall you record against. The unit does not soundproof the room. F-gas installation applies. In England, outdoor siting follows the Planning Portal, which matters because neighbours hear practice and plant together.
A hiss between takes on a quiet vocal
Practice rooms and small studios run at low levels between takes. The indoor fan that was fine in a kitchen becomes a hiss on a vocal. Ask for the low-fan sound pressure in dB(A) on that exact model, and ask whether that speed holds the room when people and amplifiers add heat. The brochure minimum is often a mode the unit leaves as soon as the load rises. Ask for the low-fan dB(A) you will actually run, then listen on a survey if you can. The brochure minimum is not the figure once the room warms up.
Aim the throw away from the microphone and away from the player. A draught on a reed or on a singer is a complaint as real as the noise. A quiet indoor unit is quiet enough to record only after that low-fan figure, and after vibration from the outdoor unit is dealt with. Vibration matters as much as the fan.
The practice wall, the party wall and the amplifier
A bracket on the practice-room wall couples the compressor into the plaster the microphone faces. Isolation mounts and a different wall, or a ground stand, are the controls. Tightening the bolts does not help. A stud wall can buzz at certain fan speeds even when the outdoor unit is elsewhere. Ask the installer to check for that rattle before they leave. Keep the outdoor unit off the practice wall. Use anti-vibration mounts. The condenser on the studio wall is the vibration path into the microphone. Prefer another wall or a ground stand, with anti-vibration mounts, if the Planning Portal conditions allow it.
Party walls are the worst bracket. The neighbour gets structure-borne hum on top of whatever sound leaves the room. Put the condenser on a heavier wall you do not record against, if planning and the boundary allow it. Do not expect the split to isolate the neighbour. A solo practice room is a small load plus a warm amplifier. A band in a garage-sized room is a different survey. Do not buy a huge unit for a cello corner, and do not buy a bedroom unit for a drum kit and four people. Size the occupation you actually have.
Acoustic treatment, mass and seals are a separate project. The split will not close a gap under the door. It cools the air. Seals, mass and the door are a different job. Do not wedge fire doors or block required vents to chase quiet. Use an F-gas certified company for the circuit. Read Planning Portal conditions in England so the outdoor unit is not the thing the neighbour complains about first.
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How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.