Recent advances in wideband amplifier design make it more important than ever before that turntable rumble and other subsonic components caused by record warps and tonearm/cartridge resonances be removed from the phonograph signal.
Even the most sophisticated turntable and tonearm designs often suffer from rumble, which can quite audibly "muddy' the reproduction, even though the rumble may lie primarily at frequencies below the audible range. The SF-100 can be connected in a tape monitor loop, between the preamplifier and power amplifier or between the preamplifier and tape deck. its unique active circuitry attenuates response at 10Hz by as much as 50dB when activated. The SF-100 also provides switchable low frequency compensation, which is useful in playback systems that can benefit from a slight low end boost (+5 dB at 30 Hz). A second switch permits the user to bypass the filter. The SF-100 incorporates a muting circuit which eliminates annoying thumps when the unit is powered.