Test Signals, Crest Factor, Duty Cycle, And Thermal Stress
Canonical Definition
Duty cycle is the active time divided by a defined total interval. A complete test-signal record also includes waveform, spectrum, crest factor, RMS and peak level, ramp, event duration, repetition, rest period, channel count, and route.
Signal Types
| Signal | Useful for | Primary caution |
|---|---|---|
| sine tone | clipping, voltage, resonance, narrowband output | concentrated energy, low crest factor, high thermal demand, frequency-specific excursion or load |
| burst | short controlled output and recovery tests | ramp, hold, repetition, and total dose still matter |
| sweep | response, distortion, timing, compression | level, sweep rate, bandwidth, and repeated passes change stress |
| pink noise or multitone | broadband response, limits, and system checks | spectrum, crest factor, averaging, and weighting must be documented |
| music | program behavior and user state | mastering, normalization, crest factor, source mode, and track section vary |
Same Peak Does Not Mean Same Heat
A sine wave has a 3.01 dB peak-to-RMS voltage crest factor. Typical music often has a larger crest factor. At the same peak voltage, the sine can deliver substantially greater average power and voice-coil heating.
Duty cycle = active time / total interval
Crest factor (dB) = 20 log10(Vpeak / Vrms)Choose The Least Stressful Valid Test
- State the measurement question.
- Select only the needed bandwidth and duration.
- Begin with protected low-level routing.
- Increase one variable at a time while monitoring the complete chain.
- Stop before the first electrical, thermal, mechanical, acoustic, structural, or exposure limit.
- Repeat only after measured recovery, not merely after a fixed pause.
No-Clip Is Not No-Risk
A clean waveform proves only that the measured node did not meet the chosen clipping criterion.
It does not prove safe hearing exposure, driver excursion, voice-coil temperature, amplifier load, battery current, cable temperature, enclosure behavior, or structural safety.