Method to Control Audio Volume and Mix With a Personal Computer
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Fig. 1 is a functional diagram of a personal computer (PC)-controlled Audio Volume and Mix controller (VMX). D1 through D4, shown in Fig. 1, are digitally-controlled variable attenuation circuits. An implementation is shown in Fig. 2. The 12-bit DAC1230, shown in Fig. 2, provides 72 dB of attenuation, which is adequate for most audio applications. DACs with fewer bits or more bits may be used, depending on the application requirements. S1 and S2, shown in Fig. 1, are summing amplifiers. An implementation example is shown in Fig. 3. (Image Omitted) As shown in Fig. 1, D1 controls the amount of input A that appears in output L (left). D2 controls the amount of input B that appears in output L. D3 and D4 control the amounts of inputs A and B that appear in output R (right).