DC•BLOCK is an in-line device that is located right at the DACs coaxial signal input. It's a 2nd order Butterworth filter integrated in a BNC adapter that blocks DC leakage and filters RF noise below 1Mhz. DC (and low frequency AC) may be caused by symbol correlated fluctuations in the signal, degradation of the source blocking capacitor, transfer of energy along the dielectric or EMF from proximate components inducing currents in the coax cable itself. (The latter is a reminder to keep coax cables ultra short and well shielded).
LP•FILTER is an in-line BNC adapter device that contains a RLC low pass filter with a 100MHz cut-off frequency. It can be coupled in series with DC•BLOCK or located at the source output.
The combination of DC•BLOCK and LP•FILTER provides the near perfect filter for digital audio; bested only by the combination of DC•BLOCK and OPTO•DX which adds optical galvanic isolation and an improved (steeper) cut-off.
Zero unwanted current flow into a coax DAC and Zero RF noise outside the S/PDIF passband helps you extract the last bit of transparency from your system. Refer to the connection drawings below.
Source Coax to DAC:
Recommend DC•BLOCK. Add LP•FILTER if your source is noisy -or- if you want to ensure maximum filtering.
SRC•DX to DAC:
Recommend DC•BLOCK. Add LP•FILTER if your source is noisy -or- if your USB is not well isolated -or- if you want to ensure maximum filtering.
OPTO•DX to DAC:
Recommend DC•BLOCK. Add LP•FILTER if you want to ensure maximum filtering. OPTO•DX optical modulation is a low-pass filter.