Schroeder JCRev - developed by Prof. John Chowning, consists of the following elements:

• A series connection of several allpass filters
• A parallel bank of feedback comb filters
• A mixing matrix

MM denotes the mixing matrix

which can be efficiently implemented using four adders and two negations:

OutA = s1 + s2
OutB = -OutA
OutC = -OutD
OutD = s1 - s2