The dc blocker is an indispensable tool in digital waveguide modeling  and other applications.B.4 It is often needed to remove the dc component of the signal circulating in a delay-line loop. It is also often an important tool in multi-track recording, where dc components in the various tracks can add up and overflow the mix.
The dc blocker is a small recursive filter specified by the difference equation
where is a parameter that is typically somewhere between and (for a 44.1 kHz sampling rate, is good). The transfer function is