It is common knowledge that low frequencies (below about 100 Hz) are non-directional, meaning they can hardly be located by the listener. It is, however, a common misunderstanding that therefore the placement of a subwoofer does not matter. It does matter.
Due to the fact that every room (geometry, furniture, etc.) is unique, the following descriptions intend to be a first introduction to the subject. The aim is to assist you in tackling the most frequent problems with subwoofers and room acoustics, notably interference and standing waves.
- Distance to satellites: In most setups, it is advisable to place the subwoofer not too far from the satellites to minimize the chance of interference. Interference means the superposition of two or more waves resulting in an attenuation/cancellation or enhancement of the specific frequency/frequencies. Furthermore, big reflection faces in close range of the subwoofer should be avoided if possible (for example, guitar cabinets, partition walls, and racks).
- Walls/Distance to walls: Generally, every wall at a relatively close distance to the subwoofer enhances its sound pressure by about 6 dB. For instance, placing the subwoofer in a corner of a room will make it about 18 dB louder. It is likely that this will result in an impairment of the precision of the musical reproduction. Another problem related to the geometrics of the room concerns the so-called ‘standing waves’. These are sound waves being reciprocated between reflecting objects, so they ‘stand’ (don’t seem to move) in between these objects. The speaker continues to produce new waves that combine their force with the first wave(s): a vicious circle that results in local imbalances of the particular frequencies.
- Give it a try! The most important tool for finding the best position for your subwoofer is your ears. There are two rather easy ways: You can determine your listening spot first and then compare the sound of the subwoofer at different positions. Another option is to place the subwoofer in the listening position and then move it around. Wherever the sound is the best the subwoofer should be positioned.