A plurality of audio inputs which require gain applied are coupled together,
the
gain is applied and that weighted signal is summed with the output of similar circuits
running with different gains. For typical overall gain requirements of 0 to +22.5
dB to be applied in 1.5 dB increments, the new circuit reduces by over two-thirds
the number of analog switches required in the level adjusting portion of an audio
mixer. More generally, the complexity of the new circuit, in terms of the number
of analog switching elements is 2m(1+log2n) for m channels with n gain
steps/channel. The number of stages of differing gain is reduced from 2m variable
gain amplifiers to 2(1+log2n) fixed gain amplifiers.