Voice Coil Lab Notes: Improved Zobel Network

Passive crossover filter networks for multi-way loudspeakers generally require a resistive termination for optimum performance. The driver itself generally presents a reactive load. Inductive rise with frequency above resonance of the loudspeaker electrical impedance is semi-inductive due to eddy current losses. The L2/R2 impedance model represents the electrical impedance as seen by the amplifier output. An improved compensation network can be realized by using the analogous circuit “dual” of the L2/R2 model. This represents a dramatic improvement to the basic two-component Zobel network and compensates for the non-ideal semi-inductive behavior of the loudspeaker driver across the entire frequency band.

The March 2020 edition of Voice Coil is now available online and in print. In this edition, Vance Dickason gets hands-on with the Audio Precision APx500 Flex Audio Analyzer, Mike Klasco writes about Loudspeaker Enclosure Materials, and James Croft explores a new patent of a novel orientation of a cardioid speaker design. And in Test Bench, Dickason characterizes a home audio transducer from Eastech's Punktkilde line, the cosmetically pleasing AUGWL0016-JN02 6.5” midbass driver.