Subsonic / Rumble Filter
A filter that reduces very low frequencies, helping limit rumble and unwanted woofer movement during record playback.
Also called: Low-Cut Filter
Also called low-cut or high-pass, it reduces lows while passing higher frequencies. Yes means the feature exists, not that it has a switch or a particular response. An omitted listing means unknown, not no.
Subsonic / Rumble Filter — Preamp
A preamp can reduce unwanted low-frequency signals before they reach the power amplifier and speakers. It cannot undo distortion already produced in an upstream phono stage. Check which inputs and outputs actually pass through the filter.
Compare the cutoff frequency, the point used to specify the response, and slope: how steeply reduction increases below it. A bass tone control adjusts tonal balance; a subwoofer crossover divides frequency ranges between speakers. Neither alone establishes a rumble filter. Filtering can also reduce musical bass in the affected range.
Sources
- C-2400 official brochure — Accuphase
- Project 99: Infrasonic Filter — Rod Elliott / Elliott Sound Products
Subsonic / Rumble Filter — Phono Preamp
Warped records and an unsuitable cartridge/arm combination can produce low-frequency interference and slow woofer pumping. A phono stage’s filter reduces the resulting signal; it does not flatten the record or correct the mechanical mismatch.
The filter may be switchable, always active or automatically engaged for protection. An IEC playback equalization curve alone does not establish this separate feature. Follow the manual’s settings and compare at modest volume: does woofer movement decrease without an unwanted loss of musical bass? Choose the documented setting that gives a useful balance; stronger filtering is not always better.
Sources
- HP 700 SE manual — Octave
- Lupe User’s Manual R1 — Mola Mola
Low-Cut Filter — Optical Equalizer
An optical cartridge needs an explicitly compatible optical equalizer, not an ordinary moving-magnet or moving-coil phono stage. Its low-cut filter can reduce warp-related woofer movement. Depending on the design, a switch, the chosen output sockets, or both select the curve.
A count of settings does not tell you their response. Compare the documented curves, cutoff frequencies and slopes; stronger attenuation can remove wanted bass as well as disturbance. Connect the equalizer’s output to a line input such as AUX, not a phono input. Follow the equipment manuals when changing connections.
Sources
- DS003 instruction manual — DS Audio
Sources
- Project 99: Infrasonic Filter — Rod Elliott / Elliott Sound Products