SCA Seamless Sub

The Secret Chord Analogue Seamless Sub provides a solid foundation for the tube amp/full range loudspeaker combination by providing a boost to frequencies from 20 Hz to just over 100Hz. This quite extraordinary active sub woofer delivers an essentially flat response to over 100dB.

The SCA Seamless Sub is a uniquely engineered upward-firing subwoofer system housed in its own sealed enclosure. Powered by an articulate and muscular 150W plate amplifier, the sub integrates flawlessly with the open-baffle main driver—preserving the transparency and speed of the full range while extending low-frequency performance to true full-range capability. The plate amp offers a 40Hz–180Hz low-pass adjustment and a clean 90dB signal-to-noise ratio, allowing you to tailor bass presence to your room and listening preferences with precision.

The subwoofer itself features an 8-inch coated paper cone, a rigid steel basket, ferrite magnet, and aluminium shorting ring. With 90W rated input and a 20Hz–20kHz frequency spec, it provides articulate, tuneful bass that never overwhelms or muddies the midrange. Despite its compact 2.52kg frame, the SCA Seamless Sub produces depth and impact surprising for its size—designed not to dominate, but to support the full-range driver with musical elegance.

With careful adjustment of the frequency and gain controls the Seamless Sub will integrate to your listening environment and main speakers achieving a breathtaking presentation; and using a pair of Seamless Subs delivers enhanced bass imaging. 

Whether your preference is John Bonham in full flight, jazz or full orchestral, the SCA Seamless Sub delivers a serious lift in overall system performance. 

The plate amp, rated at 125W (240VAC) features a 24dB/octave low pass filter for accurate frequency attenuation and offers a switchable 6dB bass boost at 34Hz. The output stage is mono class AB for solid, well defined output. The variable gain crossover point and switchable phase controls provide optimised room integration. Combined with the 8”paper cone driver the system is fast with no hint of the mushiness common in subwoofers making it a natural adjunct to music playback as compared to movie surround sound special effects (though it will of course do that very well).

The SCA Seamless Sub (driver unit also available in white) is a recommended addition to any SCA Full Range loudspeaker pair. When connected using low level connectivity a pair of Seamless Subs can be individually driven optimum channel performance.

Cabling is available to be prepared to your length specifications. See SCA_SS_CABLE/1