Ascendo Ascendo ASC-21SPPS The21 SUB Ascendo 21" PRO - Passive Sealed Subwoofer Subwoofers
Ascendo Ascendo ASC-21SPPS The21 SUB Ascendo 21" PRO - Passive Sealed Subwoofer Subwoofers
Ascendo Ascendo ASC-21SPPS The21 SUB Ascendo 21" PRO - Passive Sealed Subwoofer Subwoofers

Ascendo ASC-21SPPS The21 SUB Ascendo 21" PRO - Passive Sealed Subwoofer


Regular price$19,900.00

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  • Free Delivery Australia Wide
  • Local Australian Warranty
  • 1800 100 998 For Assistance

We take pride in our customer service and shipping times. Most products will ship within 1-2 business days. If there are any potential delays with products in your order, we will contact you.

All orders now come with free shipping Australia Wide.

We use a variety of shipping methods depending on the types of items purchased and their delivery location. This helps to ensure your items arrive safely and in a timely manner. If you are on a tight deadline or would like to know an estimated delivery date for your order, contact our friendly staff and they will be happy to assist.



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.


Speaker type

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


Recommended amplifiers 

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)

Measurement data
139 dB @ 63 Hz peak 

Frequency range

Measurement data
55 Hz - 500 Hz / -3 dB
28 Hz - 500 Hz / -15 dB


97 dB  / 1W/m

Power handling 

 4000 W


4 Ω 

Air volume displacement 

2,88 L / in comparison 21" standard cinema subwoofer 1,76 L

Directivity horizontal x vertical in Deg°


Input Terminal



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

Shape customisation 

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

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Customer Reviews

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CHT Solutions has been very prompt to respond and ship the items. I will never hesitate to buy from them again. More power to CHT Solutions!

Richard Y.
Thornleigh, NSW

CHT delivery was incredibly fast, Many thanks all for such an easy purchase process and super fast delivery. 5 stars from me

Chris N.
Malaga, WA

Buying from CHT Solutions was easy and their price was great and I would recommend then to anyone seeking good Hi Fi equipment.

John L.
Woonona, NSW

Fast delivery and great products. Would recommend them to anyone needing great service for sound advice.

Oscar F.
Truganina, VIC

CHT delivered the unit to South Australia within a couple of days. Amazing! Their phone customer service was professional and courteous. Will happily purchase from them again

Robert F.
Tranmere, SA