vSound: real-time digital emulation of the acoustic violin

vSound is an integrated stand-alone system that processes the raw electrical output from an electric violin and produces an output signal which, when fed to an amplifier and loudspeaker, approximates closely the timbre of an acoustic instrument. The system comprises a selectable high-impedance preamplifier, a 24-bit sigma delta codec and a digital signal processor (DSP) operating at 590 million multiplications-accumulations per second (MMACs). The device holds in its memory up to fifty far-field impulse responses of wooden instruments, any one of which may be convolved in real-time with the input to synthesize the modified output. In addition, the unit incorporates a suite of other functions to enhance the tonal quality of the final output, including a high-resolution equalizer, an adjustable blender and bass cut filter. The blender, which combines the original with the processed signal, extends the scope of the system for use with acoustic instruments fitted with pickups on the bridge. The unit is controlled by a set of navigator-style buttons in conjunction with a simple display screen. Windows-based control software also allows the user to download new responses and to adjust the settings of the graphic or arbitrary equalizer. Initial tests using an impulse response obtained from a Guarneri del Gesù violin constructed in the early-mid 18th century suggest that the system significantly enhances the tonal quality and timbre of an electric instrument.