The synthesis of sound textures, such as flowing water, crackling fire, an applauding crowd, is impeded by the lack of a quantitative definition. McDermott and Simoncelli proposed a perceptual source-filter model using summary statistics to create compelling synthesis results for non-tonal sound textures. However, the proposed method does not work well with tonal components. Comparing the residuals of tonal sound textures and non-tonal sound textures, we show the importance of residual modeling. We then propose a method using auto regressive modeling to reduce the amount of data needed for resynthesis and delineate a modified method for analyzing and synthesizing both tonal and non-tonal sound textures. Through user evaluation, we find that modeling the residuals increases the realism of tonal sound textures. The results suggest that the spectral content of the residuals has an important role in sound texture synthesis, filling the gap between filtered noise and sound textures as defined by McDermott and Simoncelli. Our proposed method opens possibilities of applying sound texture analysis to musical sounds such as rapidly bowed violins.

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The Fender Bassman model 5F6-A was released in 1958 and has become one of the most revered guitar amplifiers of all time. It is the progenitor of a long line of related Fender designs in addition to inspiring Marshall’s first amplifier design. This paper presents a Wave Digital Filter study of the preamplifier circuit of 5F6-Abased amplifiers, utilizing recent theoretical advances to enable the simultaneous simulation of its four nonlinear vacuum tube triodes. The Dempwolf triode model is applied along with an iterative Newton solver to calculate the scattering at the 25 port R-type adapter at the root of the WDF tree. Simulation results are compared to “ground truth” SPICE data showing excellent agreement.

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In this paper, iterative zero-finding techniques are proposed to resolve groups of nonlinearities occurring in Wave Digital Filters. Two variants of Newton’s method are proposed and their suitability towards solving the grouped nonlinearities is analyzed. The feasibility of the approach with implications for WDFs containing multiple nonlinearities is demonstrated via case studies investigating the mathematical properties and numerical performance of reference circuits containing diodes and transistors; asymmetric and symmetric diode clippers and a common emitter amplifier.

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Wave Digital Filters (WDF) [1] are a popular approach for virtual analog modeling [2]. They provide a computationally efficient way to simulate lumped physical systems with well-studied numerical properties. Recent work by Werner et al. [3, 4] enables the use of WDFs to model systems with complicated topologies and multiple/multiport nonlinearities, to a degree not previously known. We present an efficient, portable, modular, and open-source C++ library for real time Wave Digital Filter modeling: RT-WDF [5]. The library allows a WDF to be specified in an object-oriented tree with the same structure as a WDF tree and implements the most recent advances in the field. We give an architectural overview and introduce the main concepts of operation on three separate case studies: a switchable attenuator, the Bassman tone stack, and a common-cathode triode amplifier. It is further shown how to expand the existent set of non-linear models to encourage custom extensions. Index Terms— wave digital filter, software, real time, virtual analog modeling, multiple nonlinearities

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