Passive Crossover Acoustic Targets
Canonical Definition
The acoustic target is the desired installed magnitude, phase, polarity, directivity, and summation behavior of each driver and the combined system through the crossover region. The passive components are selected and adjusted to produce that measured result.
Choose The Crossover Region From Driver Behavior
Use the region where both drivers can satisfy the required output and coverage with acceptable distortion, excursion, compression, and directivity. Do not choose the point only from driver diameter, nominal frequency range, or a multiplier of tweeter resonance.
- individual magnitude and phase
- distortion and compression versus level
- excursion and thermal margin
- horizontal and vertical directivity
- center-to-center spacing and acoustic-center geometry
- baffle, grille, trim, and listening-position effects
Write Separate Driver Targets
| Driver | Target record |
|---|---|
| Low-frequency driver | upper acoustic slope, breakup control, level, phase, and off-axis behavior |
| High-frequency driver | lower acoustic slope, resonance protection, level, phase, and power margin |
| Combined system | normal-polarity sum, reverse-polarity behavior, listening window, impedance, and maximum level |
Normal And Reverse-Polarity Checks
The normal-polarity result should meet the intended magnitude and coverage target. A reverse-polarity measurement is a useful sensitivity test for relative phase and level, but the deepest possible null is not an independent quality score.
Interpret the reverse result with the individual traces, timing reference, microphone position, driver spacing, and intended acoustic alignment.
Directivity Is Part Of The Target
A flat trace at one point can hide a narrow vertical lobe or a passenger-seat hole. Measure the axes and seats that matter. A passive crossover cannot make two widely spaced drivers behave like one point source, but the crossover region and slopes can reduce or worsen the coverage problem.
Use Matching Measurement Conditions
- Keep microphone coordinates, level, gate, smoothing, timing reference, and driver polarity documented.
- Measure drivers individually through their final network branches.
- Measure the normal sum and reverse-polarity sum.
- Measure nearby vertical and horizontal positions or representative vehicle seats.
- Repeat with the final grille, trim, adapter, and board installed.