Most AV receivers ask you to set a “distance” for each speaker, including the subwoofer. It sounds trivial, but the subwoofer distance setting is really a timing adjustment, and it can make the difference between bass that hits with the speakers and bass that seems slightly late or hollow. Here’s how it works and how to set it.
- Run your receiver’s room correction first; it measures distance automatically.
- Don’t be surprised if the sub’s measured distance is longer than the tape-measure distance. That’s normal: it includes the sub’s processing delay.
- To fine-tune, play an 80 Hz tone and adjust the sub distance in small steps, keeping the setting where the tone is loudest at your seat.
What the distance setting actually does
Sound from speakers closer to you arrives sooner. The receiver delays nearer speakers so everything arrives at your seat at the same moment. For the subwoofer, there’s another factor: its amplifier, DSP and crossover filters add a few milliseconds of delay. The receiver compensates by treating the sub as if it were farther away.
Why the measured distance looks “wrong”
Room correction often reports the sub as several feet farther away than it physically is. That’s the sub’s electronic delay being accounted for, and it’s usually correct. Don’t “fix” it to the tape-measure distance without testing.
How to fine-tune it by ear
- Set the crossover (usually 80 Hz). See crossover settings.
- Play an 80 Hz test tone through both a main speaker and the sub (some receivers do this in their level test, or use a test-tone track in stereo).
- Adjust the sub’s distance in steps of about 1 ft (30 cm) either way.
- Keep the setting where the tone is loudest at your seat: that’s where the sub and speaker add together.
- Confirm with a track that has a strong bass line moving through 60–100 Hz.
Distance vs phase
Both adjust timing. Distance shifts all frequencies by the same time; phase shifts timing differently at different frequencies. On a receiver, distance is the finer, more reliable tool. Use the sub’s phase control too, but don’t fight between them. See phase explained.
Two subs
If your receiver supports independent distances for two subs, set each separately. If not, place them at similar distances from the main seat or use the phase control on the nearer one. See dual subwoofer setup.
Wireless subs
Wireless kits add a few milliseconds of delay. Re-run room correction after adding one so the receiver can compensate. See wireless kits.