SKU: 46561465479

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

$8955.00 $9950.00
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Ships within 48 hours · Estimated delivery Jul 11 - Jul 16

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Description

Ascendo ASC-21SPPS The21 SUB Ascendo 21" PRO - Passive Sealed SubwooferTHE 21 SUB PRO PASSIVE SEALED PASSIVE SEALED 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. ASCENDOs policy is to be

THE 21 SUB PRO-PASSIVE SEALED

  • PASSIVE
  • SEALED

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.

Specifications

Speaker type

21-inch forward-firing, dual gap motor structure with 2 inner and 2 outer voice coiles, neodymium motor.

Xmax

18 mm excursion each direction (36 mm linear), voice coil remaining in homogeneous magnetic field, linear and lowest distortion

Passive | Active

Passive

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  

Principle 

Sealed 

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

Efficiency 

97 dB  / 1W/m

Power handling 

 4000 W

Impedance 

4 Ω 

Air volume displacement 

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

Directivity horizontal x vertical in Deg°

360°

Input Terminal

Neutrik

Enclosure

Internally braced birch ply and MDF

Width 

23,62 " | 600 mm

Hight

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

Weight

112,44 lbs | 51kg

Finish 

Structural paint black

Custom colour options 

Piano lacquer, colour of choice, matt or other finishes upon request

Shape customisation 

Upon request 

Mounting 

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

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 46561465479

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4.6 ★★★★★
Based on 1819 reviews
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K
Verified Purchase
Krystal
West Palm Beach, US
★★★★★ 4
Good starter WDT
Color: Black, Color: Black
I very much think this is a good starter distribution tool! The needles are a bit flimsy so sometimes when you are distributing the coffee grounds, it tends to flick the coffee grounds around out of my Porter filters. That’s the only reason I deducted one star, but other than that I enjoy the fact that it has that sponge on the inside, so it cleans off the tool after each use, which is a nice feature. It’s pretty lightweight and good in size and easy to use. For the price and starting off my espresso at home journey I think this is good to start with. The photo I posted is of the inner bristles pushed up so you see what’s on the inside and what is actually cleaning off the tool every time you insert it back into the case and this is after I’ve used it for over a month ☺️
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 24, 2025
M
Verified Purchase
Memphis Tigers 🐯
Alexandria, US
★★★★★ 5
Amazing WDT Tool!
Color: Black
This WDT tool instantly improved the evenness of my puck prep, and the difference in my shots was obvious. The ultra‑fine needles fluff the grounds perfectly without creating channels. It has a nice weight to it and feels like a real upgrade compared to cheaper plastic options.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 7, 2026
L
Verified Purchase
Lisa Moore
Carnegie, US
★★★★★ 5
Has upped our coffee game :)
Color: Sliver, Color: Sliver
EDIT: Well, 2 months later, this is still performing okay, however some of the needles have gotten slightly bent, causing it to seem loose and wobbly as they rotate within their opening. . Not a great aspect of this design. If you loosen the head straighten any bent needles, it does help a little bit. So far so good. It’s made a little difference in our coffee. We buy espresso beans and so we really pay attention to the way the espresso acts from cup to cup. We notice that after using this tool our coffee is a little sweeter, probably because the way the grounds are so evenly distributed and the little channels that the wires create. Easy to use, store, and keep clean. And it’s cute on the counter!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 11, 2025
F
Verified Purchase
FINO
Pawtucket, US
★★★★★ 5
Big Improvement in Espresso Consistency
Color: Black
This WDT tool made a noticeable difference in the quality of my espresso shots. The needles are thin enough to break up clumps and create a very even coffee bed, and the distribution feels smooth and controlled. Build quality is solid, the handle feels comfortable, and it’s easy to clean. I’ve gotten more consistent extractions and better flavor since using it. For anyone looking to upgrade their espresso workflow, this is a simple but very effective tool. Definitely worth it.
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Reviewed in the United States on December 8, 2025
V
Verified Purchase
Vincent DiBona
San Leandro, US
★★★★★ 5
Impressed
Color: Black
I rarely give 5 star reviews. This product deserves it. A lot of thought has gone into the design. First, the material of it is quite good, metal. It has a contoured and knurled top for ease of use and good grip without being "grippy". The recepticle has little brushes inside which I think is unique to this product. Will those brushes created a problem in the future? I don't know. But there must be a way to clean out the coffee dust at some point. An air blower? Until now I had been using a home-made WDT with acupuncuture needles drilled into a cork. When I used the Nessus WTD I could immediately feel a difference as I stirred the grounds. While I have only made two double-shots so far, there was noticeably less channeling that I had before (I use a bottomless portafilter exclusively). Actually I had no channeling, but initially two streams that mergedi into one in about 3 seconds, so pretty good compared to what I had before. Nothing much more to say except the price was quite good compared to other WDT's. Even though I haven't used this product more than a few times, I can, at least at first blush, recommend it.
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Reviewed in the United States on February 9, 2026

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