Controls the lowpass frequency. Tones above this frequency are removed.
This filter is very steep. The volume starts to drop a few hundred Hz below the configured frequency, and no frequencies above the set frequency should be coming through. The lowpass filter is always phase linear.
Some special values are:
15000 This is the lowpass frequency that should officially be used for FM stations. Since the filter is very steep, slightly higher frequencies should also work, and result in a better output quality.
4000 Hz, 4500 Hz The lowpass frequency for AM stations, for Europe and the US.
Phase linear Highpass filter Determines whether highpass filtering is done phase linear (with artifacts), or non-phase linear (without artifacts).
Phase linear means that the shape of the bass is not changed (except that low frequencies are removed). This causes some artifacts (chopper like sounds), especially at lower latency or quality settings.
Non-phase linear means that the shape of the bass is allowed to change. It will still sound the same, but the locations of peaks in the signal will move.
Possible settings:
Automatic selection Phase linear at latencies 2048 and 4096 samples, non-phase linear at latencies 512 and 1024 samples.
Always phase linear
Never phase linear
An additional advantage of non-phase linear filtering is that it moves different bass frequencies around in time. This is not or hardly noticeable, but it does offer an advantage to the Error: Panel 'Loudness' not found filter for short bass spikes: Because the bass is spread over time, Loudness can boost it further, resulting in louder bass levels without affecting the rest of the sound.
