Comb Filter Calculator
When your left and right speakers sit at different distances from the driver, certain notes fight each other and drop out — and the center image falls apart at every dip. Drag the delay slider to watch it clean up, or use the other tabs to predict, diagnose, or see the trick OEMs use.
in
📏
Tape-measure each speaker to your ear at the driver's seat, then enter the difference. Example: near door 20 in, far door 48 in → enter 28. Not speaker-to-speaker. Typical door mids land near 28 in; kick panels near 6 in.
How much farther sound travels from one speaker than the other to reach the driver. Once you delay the closer speaker to match the far one, both sounds land at the same instant and the center of the stage snaps back. Not sure of the number? Use the Find the cause tab to read it off your RTA.
0% of the fix — drag right to delay the near speaker and watch the comb flatten.
°F
Sound moves faster in a hot cabin — a summer tune drifts. (68 °F ≈ 343 m/s)
500
first dip — where sound drops out (Hz)
dips repeat every
1,000 Hz
i
Dips (sound drops out here)
Touch or hover the graph to read the exact frequency and how deep the dip is (dB).
Where the sound drops out
| Event | Frequency | Multiple of f₁ |
|---|
The dips repeat all the way up — the first one, then again at 3×, 5×, 7× that frequency, evenly spaced. So one measurement (the spacing between two dips) often tells you more than any single dip on its own.
This only covers dips caused by your two speakers sitting at different distances (left vs. right, or mid vs. sub). Real cars also bounce sound off the glass, dash, and seats, which adds its own dips on top — and those reflection dips can't be EQ'd or delayed away, because you can't get between a speaker and its own echo. The dips below ~1 kHz are the ones you really hear; above that, your head moving around smooths them out.
This only covers dips caused by your two speakers sitting at different distances (left vs. right, or mid vs. sub). Real cars also bounce sound off the glass, dash, and seats, which adds its own dips on top — and those reflection dips can't be EQ'd or delayed away, because you can't get between a speaker and its own echo. The dips below ~1 kHz are the ones you really hear; above that, your head moving around smooths them out.