The21 SUB PRO PASSIVE SEALED 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 The21 SUB PRO PS 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 The21 SUB PRO 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; The24 PRO, The32 PRO, The50 PRO, The80 PRO 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.
21-inch forward-firing, dual gap motor structure with 2 inner and 2 outer voice coiles, neodymium motor.
18 mm excursion each direction (36 mm linear), voice coil remaining in homogeneous magnetic field, linear and lowest distortion
Passive | Active
1Ch DSP + Amplifier are required. Min. recommended amplifier: 109 Vrms, 154 Vpk, 27,3 A; equivalent to 3000W@4Ω with correct RMS & Peak limiting & compression settings.
Recommended ASCENDO amplifiers
(With additional external 1CH DSP: AIA2-6004), DSP4-10K2
SPL (peak / half space 2 pi)
97 dB / 1W/m
Air volume displacement
2,88 L / in comparison 21" standard cinema subwoofer 1,76 L
Directivity horizontal x vertical in Deg°
Internally braced birch ply and MDF
23,62 " | 600 mm
43,31 " | 1100 mm
Hight with feet
44,29 " | 1125 mm
Depth without grille
14,57 " | 370 mm
Depth with plug
14,57 " | 370 mm
112,44 lbs | 51kg
Structural paint black
Custom colour options
Piano lacquer, colour of choice, matt or other finishes upon request
Floor standing with feet
The21 SUB PRO ACTIVE SEALED is supplied with a front cover as standard
Technical modiﬁcations subject to change without further notice