| DC-Removal PlugIn | Sound LaundryÖ 2.5 |
The left part of Fig. 2 demonstrates signal with a positive DC-offset. All other non-zero samples are also shifted by the amount of the DC-offset. To avoid signal clipping, the input volume has to be decreased compared to an ideal converter, resulting in a narrowed dynamic range of the recorded signal. It is not uncommon for this to measure five bits of DC-offset. Frequently the DC-offset of the analog-to-digital converter is not constant and drifts with time and/or temperature.
A low-level audio signal including DC-offset or even a high-level signal attenuated digitally can produce very annoying sounds on the playback side due to asymmetry.
The DC-Removal PlugIn is a remedy for those recordings tainted with DC-offset. It removes DC-offset from sample strings, bringing your signal perfectly to the middle of the system's dynamic range as shown in Fig. 2 on the right.
The DC-Removal Filter is designed as a digital high-resolution (80 bits) highpass filter with a very low cut-off frequency (a few Hz). It removes DC components from poor recordings even if the value of the DC-offset permanently drifts.
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| Fig.2: A signal tainted with DC-offset (left) and after DC-filtering (right) |