Passive Crossover Power, Heat, And Compression
Canonical Definition
Passive crossover power handling is the ability of the complete network to carry a defined voltage, current spectrum, crest factor, duration, ambient temperature, and load without unacceptable temperature, value shift, saturation, arcing, insulation failure, compression, or damage.
Amplifier Watts Do Not Divide Evenly
Every crossover branch sees a different frequency-dependent voltage and current. Calculate from the actual network:
P_resistor(f) = I(f)² × R
P_DCR(f) = I(f)² × DCR
P_real = average[v(t) × i(t)]For reactive branches, voltage, current, and real dissipation are not interchangeable.
Separate The Limits
| Limit | Typical evidence |
|---|---|
| Average heating | temperature rise and resistance or value drift over time |
| Pulse or transient load | energy and peak power for a defined pulse shape and duration |
| Inductor saturation | inductance reduction or added distortion at current |
| Capacitor stress | voltage, RMS current, ESR loss, and internal temperature |
| Board and connection limit | hot joints, discoloration, arcing, loose terminals, or trace damage |
Cold Response Is Not The Whole Result
Heating changes driver Re, resistor value, inductor DCR, and sometimes inductance or capacitor behavior. That can move level, crossover frequency, impedance, and summation before anything visibly fails.
Thermal Layout
- Keep power resistors and hot inductors away from heat-sensitive capacitors and plastics.
- Provide convection or conduction paths consistent with the component rating method.
- Do not bury the network in foam or sealed trim without testing the resulting temperature.
- Secure heavy components while preserving insulation and thermal clearance.
- Inspect solder joints, terminals, adhesives, and wire insulation after heat and vibration.
Controlled Verification
- Record source waveform or program, spectrum, crest factor, voltage, load, duration, and ambient.
- Measure branch current and component voltage where practical.
- Monitor component temperature and network impedance.
- Measure acoustic level, compression, and distortion in fixed steps.
- Stop at the first approved limit, cool the system, and inspect.
- Repeat the final network response after thermal soak and recovery.