Subwoofer placement isn't like placing any other speaker — bass behaves according to completely different physics, and where you put the sub matters more than which sub you buy. Here's how to actually get it right.
Bass wavelengths are enormous — a 40Hz tone is roughly 28 feet long — which means they interact with your room's walls in ways higher frequencies never do. Sound waves bounce off walls and combine with the original wave, reinforcing each other at some frequencies and canceling out at others depending entirely on where you're sitting and where the subwoofer sits. This is why bass can sound powerful in one seat and nearly disappear three feet away, and it's why more expensive subwoofers can't fix a placement problem.
This is the single best free technique for finding a good subwoofer spot in any room:
Corners reinforce bass because they combine reflections off two walls (or three, in a corner near the floor) into one location, which is why corner placement tends to produce the loudest output for a given subwoofer. The tradeoff is that corners often make room modes worse, not better — the same reinforcement that adds output can make bass boomy at certain frequencies while leaving gaps at others. Corners are a fine starting point for raw output, but the crawl method will usually reveal a more even-sounding spot elsewhere in the room.
A single subwoofer excites your room's bass modes from exactly one position, no matter how large or powerful it is. Adding a second subwoofer in an asymmetrical position excites different modes, and the combination smooths out response dramatically — reducing the peaks and nulls that make bass inconsistent from seat to seat. This is genuinely one of the most cost-effective upgrades in the entire hobby, often more impactful than swapping the sub itself for a bigger model.
"My own theater runs dual 18-inch subwoofers — not because one wasn't loud enough, but because two placed correctly fixed dead spots that one alone never could, no matter how hard it was pushed."
For the full picture on how sub count fits into an overall system, including how it shows up in format names like 7.2.4, see our speaker configuration guide.
Phase alignment makes sure your subwoofer's sound wave arrives in step with your main speakers instead of partially canceling it out where their frequency ranges overlap. Most subwoofers include either a simple 0°/180° phase switch or a continuously adjustable phase dial. Set it by playing a track with bass and midrange that overlap, and adjust until bass sounds fullest and most connected to the rest of the mix rather than thin or disconnected.
The crossover frequency determines where your main speakers hand off bass duties to the subwoofer. 80Hz is the THX-standard recommendation and works well for most systems with reasonably sized main speakers. Smaller bookshelf or satellite speakers, which can't reproduce deep bass cleanly on their own, often benefit from a higher crossover of 100–120Hz so the subwoofer takes over sooner. Most AV receiver room correction systems (Audyssey, YPAO, Dirac) will recommend a crossover automatically during setup — see our room correction guide for how that process works.