Non-Intrusive Rumble Filtering by VLF Crossfeed with High Filter Slopes

Self D. Non-Intrusive Rumble Filtering by VLF Crossfeed with High Filter Slopes. In: AES Convention 140. Audio Engineering Society; 2016.pp. 261:1-. Available from: https://aes.org/publications/elibrary-page/?id=18165

@inproceedings{Self2016_18165,
  author = {Self, Douglas},
  title = {{Non-Intrusive Rumble Filtering by VLF Crossfeed with High Filter Slopes}},
  booktitle = {AES Convention 140},
  pages = {261:1-},
  year = {2016},
  month = may,
  publisher = {Audio Engineering Society},
  url = {https://aes.org/publications/elibrary-page/?id=18165}
}

TY  - CPAPER
TI  - Non-Intrusive Rumble Filtering by VLF Crossfeed with High Filter Slopes
AU  - Self, Douglas
T2  - AES Convention 140
SP  - 1
M1  - Paper 261
PY  - 2016
DA  - 2016/05/06
UR  - https://aes.org/publications/elibrary-page/?id=18165
PB  - Audio Engineering Society
LA  - en
AB  - Vinyl discs create subsonic anti-phase signals because they are never perfectly flat and cause vertical stylus movement. This is often made worse by cartridge-arm resonance, giving amplitudes peaking around 10 Hz and requiring 40 dB of attenuation to reduce them to the vinyl noise floor. A conventional rumble filter needs very steep slopes to do this without unduly affecting the bottom of the audio band at 20 Hz. L-R crossfeed at low frequencies cancels the anti-phase signals, converting bass information to mono. This is not a new idea but has never caught on, probably because in published implementations the anti-phase filtering slope always comes out as –6dB/octave, no matter what order of lowpass filter is used to control the crossfeed. It is demonstrated that time-correction of the lowpass filter group delay with simple allpass filtering gives a much steeper slope of –18dB/octave for 2nd, 3rd, and 4th-order Butterworth filters, and intrusion into the audio band is minimized; this is believed novel. A practical design using 2nd-order filters was built and measured and gave the desired results.
ER  -