Polarity vs Phase
Definition
Polarity vs Phase
Polarity describes whether a positive electrical input produces a positive acoustic output (correct polarity) or a negative one (reversed polarity). Unlike phase, which varies with frequency, polarity is an all-or-nothing inversion equivalent to 180 degrees at every frequency simultaneously. SonaVyx detects polarity errors using cross-correlation peak sign analysis in its problem detection suite.
How Polarity Is Measured
SonaVyx checks polarity by computing the cross-correlation between the reference signal and the measured response. If the cross-correlation peak is negative, polarity is reversed. This works for any broadband stimulus including pink noise and sweeps. The impulse response also reveals polarity — a positive initial peak indicates correct polarity, while a negative peak indicates reversal.
Practical Example
Two speakers in a stereo pair produce thin, hollow sound when played together but sound full individually. SonaVyx cross-correlation analysis shows one speaker has reversed polarity — the impulse response peak is negative. Swapping the positive and negative wires on the reversed speaker immediately restores full bass response and solid center imaging.
Common Causes of Polarity Reversal
Polarity reversal most commonly results from incorrectly wired speaker cables (swapped positive and negative conductors), reversed XLR pin wiring (pin 2/3 swapped), or internal wiring errors in speaker cabinets. Some equipment intentionally inverts polarity — many mixing console inserts, certain processor units, and transformer-coupled devices may invert signal polarity. Cascading multiple polarity inversions can cancel out, making systematic checking essential.
Audible Effects
A single reversed speaker in a multi-speaker system causes destructive interference at frequencies where the speakers overlap in coverage. Bass frequencies are most affected because their long wavelengths maintain consistent phase relationships across wide areas. The result is thin, weak bass and an unfocused stereo image. At higher frequencies where speakers have narrower coverage patterns, polarity reversal may be less audible because there is less overlap between speakers.
Polarity Convention
The AES standard convention defines positive polarity as: positive voltage on pin 2 of an XLR connector produces outward speaker cone movement (positive acoustic pressure). However, not all manufacturers follow this convention, and some transducers inherently invert polarity. The important thing is not absolute polarity but relative polarity — all speakers in a system must have the same polarity for coherent summation.
Testing with SonaVyx
The SonaVyx problem detector includes a dedicated polarity checker that analyzes the impulse response or cross-correlation function. A green indicator confirms correct polarity; red flags reversal. For multi-speaker systems, test each speaker individually against the same reference to ensure all speakers share consistent polarity before checking alignment and delay.
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