SpeaD 1.0 · Power Handling

Power Handling
Heat, Compression & Ratings

How hot the driver gets under a test signal, what the heat costs, and the highest level it survives under the published power tests.

A thermal model of the whole driver

The Power Handling page runs a 2-D axisymmetric thermal model of the whole motor, voice coil, former, cone, dust cap and basket, in the true geometry the Assembly Drawing shows, driven by the real electrical heat your signal puts into the coil and the pole tips. Every run answers four questions:

  • How hot does it get? Coil hot spot and mean, magnet, front plate, pole, back plate, former, gap air, cone and basket.
  • What does the heat cost? Hot voice-coil resistance, power compression and the loss of force factor as the magnet warms.
  • How far does the cone move? Peak excursion against Xmax10, Xmax20 and Xcrash.
  • Is the magnet safe? A demagnetisation check against the magnet grade’s coercivity, cold and hot.
SpeaD Power Handling page after a steady pink-noise run, with inputs, results and a temperature-coloured cross-section
A steady pink-noise run at 6.32 Vrms — inputs on the left, results and the thermal cross-section on the right.

Standard and proposed tests

Choose Custom for full control, or one of nine standard and proposed tests, each applying its own signal, crest factor, filters and timing:

  • IEC 60268-5 rated noise, short-term and long-term
  • IEC 60268-21 accelerated life
  • CTA-426-B accelerated life and CTA-426-B compression
  • AES2-2012
  • Klippel stepped +1 dB
  • Keele short-term peak (proposed AES test)
SpeaD Power Handling test list: Custom plus nine standard and proposed tests
The Test list.

Signals, mounting and run types

Pink, white and IEC 60268-1 programme noise, CTA-426-B life noise, sine, multitone, or your own WAV or MP3 file, with Butterworth high- and low-pass filters and crest-factor clipping. The driver can run in free air, a sealed box (by volume or Qtc), a vented alignment (B3, C4, BB4, SBB4) or your own vented box. Run straight to steady state, step through time with ON / OFF cycles, or raise the level step by step until the first limit.

Find max rating

Tick Find max rating and SpeaD searches for the highest drive at which the whole test runs without reaching a limit — coil temperature, magnet temperature, demagnetisation or excursion — and names the limit that stops it. The rating is given on your choice of power basis: rated impedance, Re, Zmin or real power.

SpeaD IEC 60268-5 long-term test with Find max rating, showing the rating line
IEC 60268-5 long-term with Find max rating — rated voltage and power, what limited it, and the levels tried.

Klippel thermal parameters

A steady run also fits Klippel’s two-node thermal model and reports the voice-coil and magnet thermal resistances, capacities and time constants — the numbers to compare with a Klippel LSI or PWT measurement.

Results on other pages

The latest run of each test is saved with the design. Specifications lists them in a Power Handling table, and Impedance draws an at-power curve beside each cold curve.

Power Handling table on the SpeaD Specifications page
The Power Handling table on Specifications.

Read the Power Handling chapter of the SpeaD Owner’s Manual for every control on the page.