2002 June, Vol 50 Number 6

CONTENT

PAPERS

Magnetic Circuit Design Methodologies for Dual-Coil Transducers
Douglas J. Button   427
Renewed interest in the old idea of using dual voice coils, axial not concentric, leads to reconsidering this architectural approach to modern consumer and professional applications. The author reviews and analyzes numerous design tradeoffs in magnetic materials, magnetic geometries, and voice-coil topologies in order to illustrate potential advantages of this approach to driver design. Advantages, when compared to single-coil drivers, include weight, power handling, power compression, and distortion. An additional shorted coil between the two drive coils acts as dynamic braking.

Loudspeaker Voice-Coil Inductance Losses: Circuit Models, Parameter Estimation, and Effect on Frequency Response
W. Marshall Leach, Jr.   442
Modeling of the losses in a loudspeaker voice coil is not straightforward, even when the series resistance is separated from the inductor and when both are viewed as discrete elements. The parametric representation of the inductor must include a frequency-dependent resistance and inductance in parallel. A SPICE analysis is compared to experimental data in order to validate the proposed parameters that incorporate the frequency-dependent impedance and phase.

Similarity Evaluation of Room Acoustic Impulse Responses: Visual and Auditory Impressions
Akira Omoto, Chizuko Hiratsuka, Hiroaki Fujita, Tetsuhiko Fukushima, Masataka Nakahara, and Kyoji Fujiwara   451
A comparison between the original impulse response of a room and its simulation must be made in order to evaluate the quality of the simulation. However, this leads to the dilemma of using a listening or visual method for judging similarity. In this study a single frequency band was deliberately changed in amplitude to create a controlled difference between the two cases, which then served as a basis for evaluating the two methods of judgment. Results show a very high level of correlation between visual inspection and subjective listening.

A New Nonstationary Test Procedure for Improved Loudspeaker Fault Detection
Manuel Davy and Christian Doncarli   458
Manufacturing efficiencies require a general method to automatically detect production faults without any prior information about the nature of such faults. The authors propose a method that uses a mixture of four chirped signals covering the complete frequency range as a brief signal that mimics a speech or musiclike stimulus. The method was evaluated by comparing aged loudspeakers with varying levels of fatigue with new loudspeakers. The approach does not require a special environment or a model of the loudspeaker or its failure modes. Yet the results are accurate.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   470
Radio traffic data; preservation and restoration; analog recording; transfer technologies

FEATURES

112th Convention Report, Munich   474
     Exhibitors   492
     Program   495
Updates and Corrections to Review of Society's Sustaining Members   526
114th Convention, Amsterdam, Call for Papers   535

DEPARTMENTS

Review of Acoustical Patents   472
Upcoming Meetings   526
News of the Sections   527
Sound Track   531
New Products and Developments   532
Advertiser Internet Directory   534
Available Literature   534
Membership Information   536
In Memoriam   537
Sections Contacts Directory   538
AES Conventions and Conferences   544

FPO For the cover:

2002 June, Vol 50 Number 6

spine: 2002 June, Vol 50 Number 6