A new vented-box loudspeaker system is introduced that can be tuned to provide a pre-determined frequency response shape over a fairly wide and continuous range of box volumes. A conventional high-pass filter only allows the system to be tuned to give a particular frequency-response shape if the box volume is correct. The conventional filter can be either isolated (i.e. buffered by the amplifier) or non-isolated (i.e. between the amplifier and loudspeaker). The latter could be a passive filter that interacts directly with the complex load-impedance of the loudspeaker. Consequently, the two cases require different box volumes. A new current-feedback filter is introduced that can provide a continuous range of alignments from isolated to non-isolated.
Convention Paper 5505

14:00 h
C2 A New Set of Fifth- and Sixth-Order Vented-Box Loudspeaker System Alignments Using a Loudspeaker Enclosure Matching Filter: Part II – Tim Mellow, Nokia, Farnborough, UK

In Part I, a new vented-box loudspeaker system was introduced that uses a Loudspeaker Enclosure Matching Filter to provide a pre-determined frequency response shape over a fairly wide and continuous range of box volumes. The Butterworth shape was used as an example as this is fairly well known. In this part, alternative frequency response shapes are discussed. Also, some other remaining topics are addressed such as box losses and diaphragm displacement.
Convention Paper 5506

14:30 h
C3 Ambient Temperature Influences on OEM Automotive Loudspeakers – Steven Hutt, Harman Becker Automotive Systems, Martinsville, IN, USA

Loudspeakers used in OEM Automotive sound systems are expected to endure and even perform throughout a wide ambient temperature range. These extreme temperatures can have significant effects on suspension linearity. Loudspeakers used in automotive audio systems are analyzed at various temperatures to study how ambient thermal conditions affect performance.
Convention Paper 5507

15:00 h
C4 Assessment of Voice Coil Peak Displacement Xmax – Wolfgang Klippel, Klippel GmbH, Dresden, Germany

The voice coil peak displacement Xmax is an important driver parameter for assessing the maximal acoustic output at low frequencies. The method defined in standard AES 2-1984 is based on a harmonic distortion measurement, which does not give a definite and meaningful value of Xmax. After a critical review of this performance-based technique, an amendment of this method is suggested by measuring both harmonic and modulation distortion in the near field sound pressure using a two tone excitation signal. Alternatively, a parameter-based method is developed giving more detailed information about the cause of the distortion, limiting and defects. The relationship between performance-based and parameter-based methods is discussed, and both techniques are tested with real drivers.
Convention Paper 5508

15:30 h
C5 Classification and Comparison of Real vs. Test Audio Signals – Jason Weida, Harman/Becker Automotive Systems, Martinsville, IN, USA

Audio test signals have long been used in reliability testing for loudspeakers and other parts of the audio reproduction chain. Several characteristics may be easily obtained from an audio signal in the digital domain including frequency content, word code histograms, and several different statistical values such as mean, skewness, kurtosis, and crest factor. The crest factor will be examined as a function of time for non-periodic signals. This collection of metrics will be examined to determine whether certain groupings occur, and the test signals will be examined to see if they encompass the greatest amount of qualities of real world signals as possible. Optimal metrics for a loudspeaker test signal are suggested.
Convention Paper 5509

16:00 h
C6 Improved Baffle Measurement for Loudspeakers – Juha Backman, Nokia Mobile Phones, Espoo, Finland

An improvement of loudspeaker baffle measurements is presented. The proposed method uses impedance-based measurement for low frequencies, and this response is used to correct an acoustically measured impulse response before the diffraction from the baffle edges is gated out. The low-frequency response can then be used to process the gated response, yielding an improvement in low-frequency responses over previous methods.
Convention Paper 5510