In quasi-bandlimited classical waveform oscillators, the aliasing distortion present in a trivially sampled waveform can be reduced in the digital domain by applying a tabulated correction function. This paper presents an approach that applies the correction function in the differentiated domain by synthesizing a bandlimited impulse train (BLIT) that is integrated to obtain the desired bandlimited waveform. The ideal correction function of the BLIT method is infinitely long and in practice needs to be windowed. In order to obtain a good alias-reduction performance, long tables are typically required. It is shown that when a short look-up table is used, a windowed ideal correction function does not provide the best performance in terms of minimizing aliasing audibility. Instead, audibly improved alias-reduction performance can be obtained using a look-up table that has a parametric control over the low-order generations of aliasing. Some practical parametric look-up table designs are discussed in this paper, and their use and alias-reduction performance are exemplified. The look-up table designs discussed in this paper providing the best alias-reduction performance are parametric window functions and least-squares optimized multiband FIR filter designs.

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An efficient reverberator structure is proposed for approximating measured reverberation. A fixed convolution matching the early portion of a measured impulse response is crossfaded with a switched convolution reverberator drawing its switched convolution section from the late-field of the measured impulse response. In this way, the early portion of the measured impulse response is precisely reproduced, and the late-field equalization and decay rates efficiently approximated. To use segments of the measured impulse response, the switched convolution structure is modified to include a normalization filter to account for the decay of the late-field between the nominal fixed/switched crossfade time and the time of the selected segment. Further, the measured impulse response late-field is extended below its noise floor in anticipation of the normalization. This structure provides psychoacoustically accurate synthesis of the measured impulse response using less than half a second of convolution, irrespective of the length of the measured impulse response. In addition, the structure provides direct control over the equalization and late-field frequency dependent decay rate. Emulations of EMT 140 plate reverberator and marble lobby impulse responses are presented.

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