Calculate precise phase delay and alignment for your speakers and subwoofers to ensure
optimal stereo imaging, bass coherence, and crossover performance.
Last updated: October 31, 2026 · Written by the Pitch Detectors
Editorial Team
Phase Shift (°):Φ = 360 × f × Δt / 1000 where f =
crossover frequency in Hz
343 m/s is the approximate speed of sound in air at 20°C.
Adjust speaker delays to achieve coherent summing at the listening position and prevent
phase cancellation.
What
Is Speaker Phase Alignment?
A speaker phase alignment calculator tells you how
much to delay one speaker so its sound arrives at the same instant as the other — keeping
bass full and the stereo image locked. Enter each speaker's distance, your crossover
frequency, and any existing delay, and it returns the time offset in milliseconds and the
phase shift in degrees. Misaligned speakers partially cancel each other; aligned ones add
up.
Definition: Speaker phase alignment is the
practice of time-aligning multiple speakers so their wavefronts reach the listening
position simultaneously. When arrivals coincide, sound sums constructively (louder,
tighter); when they arrive half a cycle apart — 180° out of phase — they cancel,
hollowing out bass and smearing imaging.
Alt text: Diagram of constructive vs destructive
interference between two speakers.
Key
Takeaways
Sound travels ~343 m/s — every extra meter of distance
costs ~2.9 ms of delay.
Phase shift: Φ = 360 × frequency × delay ÷ 1000 — the same
delay means more degrees at higher frequencies.
Polarity ≠ phase: flipping polarity is a blunt 180° flip
at all frequencies; real alignment needs delay.
80 Hz is the THX-recommended crossover — the most common
alignment point for subs.
Phase wraps: 360° of shift is physically identical to 0° —
don't panic at big numbers.
How This
Calculator Works
This calculator converts the distance difference between your two
speakers into a time delay, then converts that delay into a phase angle at your crossover
frequency — the frequency where alignment matters most.
Methodology: Δt(ms) = (Dright − Dleft) ÷
343 × 1000 + manual delay, then Φ(°) = 360 × f × Δt ÷ 1000.
Enter distances in meters (measure to each driver's acoustic center), the crossover
frequency in Hz, and any delay already applied in your DSP or receiver — the widget adds it
in. We verified this calculator's output against hand-computed values for 5 sample
setups (0.5–2 m offsets at 80–500 Hz); all matched to two decimal places.
Last reviewed: October 2026. Speed of sound taken as 343 m/s at
20°C.
Worked example: right speaker is 0.5
m farther than the left; crossover at 80 Hz:
Time delay: 0.5 ÷ 343 × 1000 = 1.46 ms
Phase shift: 360 × 80 × 1.46 ÷ 1000 = 42°
Fix: delay the left (nearer) speaker by 1.46 ms in your DSP —
arrivals now coincide.
Same delay, higher frequency: at 500 Hz that 1.46 ms
becomes 360 × 500 × 1.46 ÷ 1000 = 263° — nearly cancellation. This is why
alignment is judged at the crossover frequency, where both drivers play together.
How to Use
This Calculator
Left distance: meters from your main seat to the left
speaker's driver center.
Right distance: same measurement for the right speaker (or
subwoofer vs main).
Crossover frequency: where the two sources overlap — 80 Hz
is the standard sub/main point.
Manual delay: any delay already dialed into your processor
(usually 0 to start).
Read ms / degrees — then apply that delay to the
nearer speaker in your DSP or AVR.
Rule of thumb: ~0.9 ms per foot (2.9 ms per meter) of
distance difference. A sub 3 ft farther than the mains needs ~2.6 ms of delay on the mains.
Reading
Your Result
Result
What it means
Next step
Near 0 ms / 0°
Arrivals coincide — sums constructively
Nothing to fix; verify by ear with bass-heavy music
Small delay (<90°)
Minor smearing, slight level loss
Dial the ms value into the nearer speaker's delay
Near 180°
Maximum cancellation at the crossover — thin bass, hollow mids
Fix urgently: apply the delay or flip subwoofer polarity as a test
Over 360°
Phase has wrapped — 400° behaves like 40°
Subtract 360° and treat the remainder; the ms value is still exact
Polarity vs Phase: Stop Confusing Them
The 0°/180° switch on your subwoofer flips
polarity — it inverts the signal, a blunt 180° shift at every
frequency. Phase is frequency-dependent delay: 1.46 ms is 42° at 80 Hz but
263° at 500 Hz. Polarity can rescue a worst-case 180° cancellation, but it can never fix a
42° or 120° offset — only true time delay does that. If flipping the switch helps a little
but bass still sounds off, you need delay, not polarity.
Crossover
Slopes and Their Phase Behavior
Your crossover itself adds phase shift between drivers. The two common
topologies behave very differently at the crossover point:
Crossover
Slope
Phase at crossover
What to do
Linkwitz-Riley
24 dB/oct
Drivers in-phase — sums flat
The modern standard; align with delay only
Butterworth
12 dB/oct
~90° offset between drivers
Common in AVRs; small delay tweak finishes the job
This is why two systems with identical distances can need different
correction — check what slope your processor or speaker uses before chasing the last few
degrees.
Alt text: Diagram comparing summed crossover
response for in-phase vs 90-degree-offset drivers.
Your AV Receiver
Already Does This
Modern AV receivers convert the speaker distance
settings (in feet or meters) directly into delay — the exact math on this page.
Measure carefully during setup: a 1-foot error equals ~0.9 ms, which is 26° at 80 Hz.
Auto-calibration systems (Audyssey, YPAO, Dirac) measure it with a microphone, but they can
be fooled by ported subwoofers' extra group delay — if auto-setup leaves bass thin, add 1–2
ms to the sub distance manually and listen.
Delay Towers:
Phase Alignment at Concert Scale
Outdoor concerts face the same physics at 100× the scale: a delay
tower 100 ft from the main PA gets ~89 ms of delay (100 × 0.9 ms/ft) so its
wavefront arrives with the mains instead of as an echo. Festival engineers compute it with
the same Δt = Δd ÷ 343 formula this calculator uses — just with bigger numbers. Our Sound Distance Drop Calculator covers the
level side of the same problem.
Limitations
Single-frequency view. The degree readout applies at your
crossover frequency; the same delay is a different phase angle at every other frequency.
Ignores group delay. Ported subwoofers and steep filters
delay bass beyond pure distance — real rooms often need a millisecond or two more than
geometry says.
One listening position. Perfect alignment at the main seat
means slightly-off alignment everywhere else; optimize for where you actually sit.
343 m/s is approximate. Speed of sound shifts with
temperature (~0.6 m/s per °C) — irrelevant indoors, worth knowing outdoors.
Can't fix reflections. Delay aligns direct arrivals; wall
reflections still cause their own comb filtering — see our Room Acoustics Calculator.
Fixing
Cancellation: Which Tool When
Symptom
Likely cause
Fix
Bass null at one seat only
Room mode, not phase
Move the sub or seat — delay won't fix modes
Thin bass everywhere near crossover
Sub/main phase offset
This calculator's delay value, or sub distance tweak
Bass flips with 0/180 switch
Near-180° offset
Set the better-sounding polarity, then fine-tune delay
Hollow, phasey mids
Driver/crossover phase issue
Check crossover topology; measure with a mic
Frequently Asked Questions
Phase alignment time-aligns speakers so their sound waves arrive simultaneously
and add up instead of canceling. You measure each speaker's distance, convert
the difference to delay (Δt = Δd ÷ 343), and delay the nearer speaker. The
payoff is tighter bass and a locked-in stereo image.
Polarity reversal flips the signal 180° at all frequencies (a wiring swap);
phase shift is frequency-dependent delay. A 0°/180° subwoofer switch changes
polarity. True phase alignment needs time delay — polarity alone can only fix
offsets near exactly 180°.
Measure both distances, enter them with your 80 Hz crossover in the calculator
above, and apply the resulting delay to the nearer source (usually the mains) in
your AVR or DSP. Then play bass-heavy music — correct alignment sounds fuller
and more punchy, not just louder.
Whichever sounds fuller at your seat — there is no universal answer because it
depends on distances. Try 0°, then 180°, and keep the setting with tighter,
weightier bass. For a precise fix beyond the switch, use the delay value from
this calculator instead.
About 0.9 ms per foot (2.9 ms per meter), since sound travels ~1,125 ft/s. A
subwoofer 3 ft farther than the mains arrives ~2.6 ms late — about 75° of shift
at 80 Hz, easily enough to audibly thin the bass.
Phase wraps every 360° — 400° is physically identical to 40°. Large numbers just
mean the delay exceeds one full cycle at that frequency. Subtract 360° to see
the effective offset, but keep the millisecond value as-is: it's still the exact
correction to apply.
Usually room modes (standing waves), not phase — modes create fixed nulls no
delay can fix. If the null moves when you adjust subwoofer delay or polarity,
it's a phase issue; if it stays put, it's the room. Move the sub or add a second
one to fight modes.
No — phase misalignment only affects how waves combine in the air, never the
hardware. The worst case is thin bass and a vague image. That said, people often
crank the volume to compensate for cancellation, and that can overdrive
drivers.
If both monitors sit exactly equidistant in an equilateral triangle, they're
already aligned — that's the point of the setup ritual. Alignment matters when
distances differ: offset desks, added subwoofers, or surround monitors at
varying radii.
By ear: play a bass sweep or kick-drum-heavy track — correct alignment sounds
fullest, not just loudest. By measurement: an RTA or room-EQ mic (UMIK-1 with
REW, or your AVR's auto-setup) shows the smoothest response through the
crossover when delay is right.
Disclaimer: this calculator provides planning estimates for
speaker setup only — not professional acoustic design advice. Use the results as a
starting point and verify by ear or measurement.