146th AES Convention Dublin
Klippel at AES Convention in Dublin
Dates: March 20th - 23rd 2019
Location: The Convention Centre Dublin
Paper and Workshop Presentations
Workshop W01 - Loudspeaker Reliability Test Signals
Wednesday, 20th March 2019, 9:15 - 10:45 am
Presenters: Laurie Fincham, Steve Hutt, Wolfgang Klippel, Richard Little, Roger Schwenke, Alexander Voishvillo
Test Signals used for loudspeaker system reliabilit testing utilize tailored attributes such as band width duty cycle, and crest factor to evaluate input capacity for loudspeaker systems. While noise can be shaped to emulate music's spectrum and crest factor, music has correlated time/frequency event cycles that impose different thermal and mechanical stress on a loudspeaker. Panelists will discuss correlation of music signals to different test signals as specified in AES and IEC standards or alternatives and comment on how anticipated duress of a loudspeaker system in the field affects useful life.
Paper P03-01 - Green Speaker Design (Part 1: Optimal Use of System Resources)
Wednesday, 20th March 2019, 2:30 - 3:00 pm
Presenter: Wolfgang Klippel
Increasing the efficiency and voltage sensitivity of the electro-acoustical conversion is the key to modern audio devices generating the required sound output with minimum size, weight, cost, and energy. Traditional loudspeaker design sacrifices efficiency for sound quality. Nonlinear adaptive control can compensate for the undesired signal distortion, protect the transducer against overload, stabilize the voice coil position, and cope with time-varying properties of the suspension. The paper presents a new design concept for an active loudspeaker system that uses the new degree of freedom provided by DSP for exploiting a nonlinear motor topology, a soft suspension and modal vibration in the diaphragm, panel, and in the acoustical systems.
Paper P03-02 - Green Speaker Design (Part 2: Optimal Use of Transducer Resources)
Wednesday, 20th March 2019, 3:00 - 3:30 pm
Presenter: Wolfgang Klippel
Green speaker design is a new concept for developing active loudspeaker systems that generate the required sound output with minimum size, weight, cost, and energy. This paper focuses on the optimization of the transducer by exploiting the new opportunities provided by digital signal processing. Nonlinear adaptive control can compensate for the undesired signal distortion, protect the transducer against overload, stabilize the voice coil position, and cope with time varying properties of the suspension. The transducer has to provide maximum efficiency of the electroacoustical conversion and sufficient voltage sensitivity to cope with the amplifier limitations. The potential of the new concept is illustrated on a transducer intended for automotive application.
Tutorial T10 - How to Rate the Maximum Loudspeaker Output SPLmax?
Wednesday, 20th March 2019, 4:30 - 6:00 pm
Presenters: Wolfgang Klippel, Steve Hutt
The new IEC standard IEC 60268-21 defines the maximum sound pressure level SPLmax generated by the audio device under specified condition (broadband stimulus, 1-m distance, on-axis under free-field condition). This value can be rated by the manufacturer according to the particular application under the condition that the device can pass a 100 h test using this stimulus without getting damaged. The SPLmax according to IEC 60268-21 is not only a meaningful characteristic for the end-user, marketing and product development but is also required for calibrating analogue or digital stimuli used for testing modern loudspeaker systems having a wireless input and internal signal processing. The workshop gives an overview on related standards (e.g., CEA 2010) and shows practical ways how to rate a meaningful SPLmax value giving the best sound quality, sufficient reliability, and robustness for the particular application. The methods are demonstrated on passive transducers and active (Bluetooth) speakers.
Workshop W07 - Impact and Audibility of Distortion in Automotive Audio Applications
Thursday, 21st March 2019, 2:30 - 4:00 pm
Chair: Alfred Svobodnick, Panelists: Rafael Kassier, Joachim Schlechter, Roger Shively, Steve Temme
Distortion effects, either linear or nonlinear, are an important aspect of audio quality. Especially for professional audio applications there are lots of research results available. However, the field of car applications is very specific, and not much research has been performed on this topic so far. This workshop will focus on automotive applications and discuss the current state of science on this topic. While the focus will be on audibility, we will especially tackle on active noise control applications and the specific aspects of loudspeaker distortion.
Tutorial T20 - Software Complements Loudspeaker Hardware
Thursday, 21st March 2019, 4:30 - 6:00 pm
Presenters: Wolfgang Klippel, Joachim Schlechter
Digital signal processing, amplification, and the electroacoustical conversion converge to one active transducer, providing more sound output at higher quality by using less size, weight, energy, and manufacturing cost. Adaptive nonlinear control technology based on monitoring the electric input current cancels undesired signal distortion, actively protects the transducer against mechanical and electrical overload, and stabilizes the voice coil at the optimum rest position to ensure maximum excursion over product life. This control software opens new degrees of freedom for the passive transducer and system development. The tutorial presents a new design concept that optimizes efficiency and voltage sensitivity while using a minimum of hardware resources. The design steps are illustrated through practical examples using new simulation, measurement, and diagnostic tools that analyze the performance of the audio device with nonlinear control.