DIGITAL PREAMPLIFIER, DIGITAL POWER AMPLIFIER AND SPEAKER SYSTEM BUILT-IN AMPLIFIER

摘要

PURPOSE:To obtain an original audio signal not subject to signal processing as it is at a post-stage by converting a signal conversion coefficient or an amplitude conversion coefficient obtained at a frequency characteristic input means through the setting input thereto into a digital information signal in a digital preamplifier, mixing the digital information into an audio signal and transferring the result to the post-stage. CONSTITUTION:A frequency characteristic input means 4a of a signal control section 4 in a preamplifier 1 obtains a signal conversion coefficient applying signal conversion in matching with a characteristic entered by the operator. An amplitude input means 4b receives an amplitude deciding the level of a reproduced sound similarly and obtains an amplitude conversion coefficient to realize the expected amplitude. Both the coefficients obtained are converted in a form of a digital information signal by an input characteristic conversion means 4c. An input signal selection means 2 selects one of modulated digital signals inputted from plural digital signal input terminals and outputs the selected signal and an audio signal demodulation means 3a demodulates an audio signal from the outputted signal. A digital signal mixture means 3b mixes the demodulated digital audio signal and the digital information signal and a digital signal modulation means 3c applies again digital modulation to the resulting signal.