Download Black-box Modeling of Distortion Circuits with Block-Oriented Models This paper describes black-box modeling of distortion circuits. The analyzed distortion circuits all originate from guitar effect pedals, which are widely used to enrich the sound of an electric guitar with harmonics. The proposed method employs a blockoriented model which consists of a linear block (filter) and a nonlinear block. In this study the nonlinear block is represented by an extended parametric input/output mapping function. Three distortion circuits with different nonlinear elements are analyzed and modeled. The linear and nonlinear parts of the circuit are analyzed and modeled separately. The Levenberg–Marquardt algorithm is used for iterative optimization of the nonlinear parts of the circuits. Some circuits could not be modeled with high accuracy, but the proposed model has shown to be a versatile and flexible tool when modeling distortion circuits.
Download Circuit Simulation with Inductors and Transformers Based on the Jiles-Atherton Model of Magnetization The sound of a vacuum tube guitar amplifier may be significantly influenced by the non-linear behavior of its output transformer, which therefore should also be considered in digital simulations. In this work, we develop a model for inductors and transformers with the magnetization following the model of Jiles and Atherton. For this purpose, the original magnetization model is rewritten to a differential equation with respect to time which can then easily be integrated into a previously developed circuit simulation framework. The model thus derived is then exercised in the simulation of three simple circuits where it shows the expected behavior.
Download Signal-Matched Power-Complementary Cross-Fading and Dry-Wet Mixing The blending of audio signals, called cross-fading, is a very common task in audio signal processing. Therefore, digital audio workstations offer several fading curves to select from. The choice of the fading curve typically depends on the signal characteristics and is supposed to result in a mixed signal featuring power and loudness close to the input signals. This work derives a correlationbased design of the fading curves to achieve exact power consistency to avoid audible fluctuations of the signal’s loudness. This principle is extended to the problem of mixing original signals with effect-processed signals using the dry-wet balance. Weighting coefficients for dry and wet signals are derived which realize the desired dry-wet balance but maintain the signal power.
Download Time-Domain Implementation of a Stereo to Surround Sound Upmix Algorithm This paper describes a time-domain algorithm to upmix stereo recordings for an enhanced playback on a surround sound loudspeaker setup. It is mainly the simplified version of a previously published frequency-domain algorithm where the standard shorttime Fourier transform is now replaced by an IIR filter bank. The design of complementary filter blocks and their arrangement in a tree structure to form a filter bank are derived. The arithmetic complexity of the filter bank itself and of the complete upmix algorithm is analysed and compared to the frequency-domain approach. The time-domain upmix is less flexible in its configuration but achieves an audio quality comparable to the frequency-domain implementation at a fraction of its computational cost.
Download Monophonic Pitch Detection by Evaluation of Individually Parameterized Phase Locked Loops This paper describes a new efficient and sample based monophonic pitch tracking approach using multiple phase locked loops (PLLs). Hereby, distinct subband signals traverse pairs of individually parameterized PLLs. Based on the relation of the instantaneous pitch sample of respective PLLs to one another, relevant features per pitch candidate are derived. These features are combined into pitch candidate scores. Pitch candidates which exhibit the maximum score per sampling instance and exceed a voicing threshold, contribute to the overall pitch track. Evaluations with up to date datasets show that the tracking performance, compared to implementations which use only one PLL has significantly improved and nearly approaches the scores of a state of the art monophonic pitch tracker.