ARHUM

ARHUM removes 50 or 60 Hz mains hum and its harmonics without cutting the recording with traditional notch filters. Instead, it continuously models the amplitude and phase of each harmonic, builds an estimate of the unwanted hum, and subtracts it from the signal. This allows musical content occupying the same frequencies to remain largely intact. DETECT measures the actual mains frequency rather than assuming an exact 50 or 60 Hz. LOCK then follows changes in that frequency over time, helping maintain suppression when the mains drifts during a recording. Choose from one to forty harmonics and adjust the suppression depth, tracking speed, and high-frequency limit to suit the source. In testing with a 100 Hz musical note directly overlapping a hum harmonic, ARHUM reduced the hum by 42.6 dB while the note lost only 1.5 dB. With drifting mains from 50.0 to 50.4 Hz, LOCK achieved 37.5 dB of reduction compared with 0.1 dB when tracking was disabled. ARHUM operates with zero latency, making it suitable for both recorded material and tracks being monitored live. DELTA monitoring lets you hear only what is being removed.