Passive High-End Immersive
Audio Subwoofer



The SMS G21 is a jewel in the pool of subwoofers designed for the highly educated customer that is on the quest for the highest performance and understands how to differentiate sound quality. When this customer experiences the SMS G21’s unparalleled output and uncolored sound, the measured test results we publish translate perfectly to realized performance. Ascendo’s policy is to be completely transparent and publish measurements done by independently certified third-party labs to provide factual data, thereby enabling informed, educated decisions. The SMS G21 subwoofer is so far above and beyond the competition in every aspect; refined musicality, tightness, and output levels suitable for a 21"" driver. It is also engineered to operate perfectly in sync (in phase) with our Infrasonic subwoofers; SMS G24, SMS G32, SMS G50 and SMS G80 when there is a desire to reproduce movie content below 20Hz with the same authority, precision, and musicality.

Compared to conventional subwoofer motor concepts, the ultra-modern double-gap motor of this custom-made 21" driver with two outer and two inner voice-coils enables more linear travel and much faster directional changes with higher sound power and significantly lower power compression.

SMS G21 Powered
Ascendo also offers a passive version SMS G21-P of this amazing subwoofer. In this case an appropriately powerful DSP and amplifier is needed to drive the beast.

Specifications (selection)

Speaker type

Custom built 21" woofer, dual gap motor structure with 2 inner and 2 outer voice coils, with AIA Speaker Management Technology




130dB Cont. / 133dB Peak 

Frequency range

18Hz - 200Hz / -10dB


Powerful DSP and amplifier is needed

Width x Height x Depth

600 x 1125 x 380mm



All speakers are supplied with a front grille as standard