General Comb Filter

• Consider now, adding to the filter a delay element which delays the input by $M_1$ samples, with some gain $g_1$.
• The general comb filter is given by the difference equation
  $$y(n) = x(n) + g_1x(n-M_1) - g_2y(n-M_2)$$
  where $g_1$ and $g_2$ are the feedforward and feedback coefficients, respectively.

  Figure 24: Signal flow diagram for digital comb filters.