# Confused about how Echo filter diagram works [closed]

The picture above is the block diagram of an echo filter. My question is, how does the delay, and gain block affect the output signal? I think that when the input signal is outputted with a delay from when the user and a smaller amplitude.

• Can you please edit the question for clarity? The way it stands now, it requires a complete explanation of delay units and their effect on loops which can go on for a while. In the meantime, are you clear with the basics of the type of filter your question is about? – A_A Feb 12 '18 at 8:11

$$output = input + delayed~ input × gain$$The delay block delays your input signal by a specific number of samples and then the delayed signal is multiplied by the gain ($gain<1$ due to losses in the echo path). So you are basically adding a delayed version of your original signal to the original signal.
$$y[n] = 2 \cdot (x[n] + 0.8 \cdot x[n-4000])$$