Compression Driver Simulation Including Air Damping in Phase Plug

R.Christensen, and U. Skov
iCapture ApS
Gadstrup, Denmark
Published in 2011

A compression driver is a certain type of electrodynamic loudspeaker which has a phase plug with slits in front of the diaphragm. The slits are narrow enough that the so-called viscothermal effects are of significant importance. In this paper a 2D axisymmetric finite element model of a commercial compression driver is established where the vibroacoustic behavior can be evaluated.

The simulation model includes standard acoustics, viscothermal effects, porous materials and structural part, along with the needed couplings between structural, acoustic and viscothermal domains. For the viscothermal domain, a linearized Navier-Stokes model is applied. The sound pressure level in the plane wave tube near the driver outlet as well as the impedance of the driver have been measured and modeled.