AES Budapest 2012
Paper Session P12
P12 - Amps and Measurement
Friday, April 27, 14:00 — 16:30 (Room: Lehar)
P12-1 Current-Driven Switch-Mode Audio Power Amplifiers—Arnold Knott, Niels Christian Buhl, Michael A. E. Andersen, Technical University of Denmark - Lyngby, Denmark
The conversion of electrical energy into sound waves by electromechanical transducers is proportional to the current through the coil of the transducer. However virtually all audio power amplifiers provide a controlled voltage through the interface to the transducer. This paper presents a switch-mode audio power amplifier not only providing controlled current but also being supplied by current. This results in an output filter size reduction by a factor of 6. The implemented prototype shows decent audio performance with THD + N below 0.1%.
Convention Paper 8629 (Purchase now)
P12-2 Debugging of Class-D Audio Power Amplifiers—Lasse Crone, Jeppe Arnsdorf Pedersen, Jakob Døllner Mønster, Arnold Knott, Technical University of Denmark - Lyngby, Denmark
Determining and optimizing the performance of a Class-D audio power amplifier can be very difficult without knowledge of the use of audio performance measuring equipment and of how the various noise and distortion sources influence the audio performance. This paper gives an introduction on how to measure the performance of the amplifier and how to find the noise and distortion sources and suggests ways to remove them. Throughout the paper measurements of a test amplifier are presented along with the relevant theory.
Convention Paper 8630 (Purchase now)
P12-3 Investigation of Crosstalk in Self Oscillating Switch Mode Audio Power Amplifier—Thomas Haagen Birch, Rasmus Ploug, Niels Elkjær Iversen, Arnold Knott, Technical University of Denmark - Lyngby, Denmark
Self oscillating switch mode power amplifiers are known to be susceptible to interchannel disturbances also known as crosstalk. This phenomenon has a significant impact on the performance of an amplifier of this type. The goal of this paper is to investigate the presence and origins of crosstalk in a two-channel self oscillating switch mode power amplifier (class D). A step-by-step reduction of elements in an amplifier built for this task is used for methodically determining the actual presence and origins of crosstalk. The investigation shows that the crosstalk is caused by couplings in the self oscillating pulse width modulation circuits, but also that the output filter has a major impact on the level of crosstalk.
Convention Paper 8631 (Purchase now)
P12-4 Measuring Mixing Time in Non-Sabinian Rooms: How Scattering Influences Small Room Responses—Lorenzo Rizzi, Gabriele Ghelfi, Suono e Vita – Acoustic Engineering - Lecco, Italy
The goal of this work is to optimize a DSP tool for extrapolating from room impulse response information regarding the way in which the transition between early reflections and late reverberation occurs. Two different methods for measuring this transition (usually referred as mixing time, tmix) have been found in literature, both based on statistical properties of acoustic spaces. Appropriate changes have been implemented and the algorithms have been tested on I.R. measured in eight different environments. Particular attention is given to non-Sabinian environments such as small-rooms for music. It has been also measured a relationship between sound diffusion and tmix, showing how the presence of scattering elements contributes to lower tmix altering the statistical properties of I.R.
Convention Paper 8632 (Purchase now)
P12-5 Separation of High Order Impulse Responses in Methods Based on the Exponential Swept-Sine—Stephan Tassart, ST-Ericsson - Paris, France; Aneline Grand, Arkamys - Paris, France
Many real analog systems (e.g., electroacoustic loudspeaker, audio amplifiers, filters, etc.) exhibit weakly nonlinear features when driven by large amplitude signals. A large scale of such electromechanical devices are well modeled by the cascade of Hammerstein models. The exponential swept-sine is a natural excitation vector in order to identify the structural elements from those models. This paper extends the original swept-sine principle to the case of band-limited test vectors, suggests an intermodulation law for the generation of band-limited test vectors, and shows that a long-duration swept-sine can be replaced by a series of slightly phase-shifted short-duration swept-sines. High order impulse responses are separable even in case of temporal overlap with a linear combination of the measurements. The method is demonstrated on examples.
Convention Paper 8633 (Purchase now)
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