BK Electronics Monolith-DF vs Funk Audio Ultra 24.0

Last updated: October 1, 2026

Short answer: the Funk Audio Ultra 24.0. It ranks #11 of 139 subwoofers by sound quality (rated 4.5/5) at $18,565 and is still sold new; the BK Electronics Monolith-DF ranks #137 (rated 3.3/5) and is discontinued, so it is only an option used.

BK Electronics Monolith-DF vs Funk Audio Ultra 24.0

What the BK Electronics Monolith-DF does well: Independent CEA-2010 testing records 102.0 dB at 20 Hz and 108.4 dB through 40-80 Hz. Watch for: Deep-bass output is more limited than the strong 40-80 Hz result suggests, so it is not the right choice when the lowest movie effects are the priority.

The Funk Audio Ultra 24.0 is the better-sounding choice. Published CEA-2010 specifications list 120.0 dB at 20 Hz and 127.9 dB through 40-80 Hz. The tradeoff: The 787.4H x 660.4W x 609.6D mm cabinet and 297.6 lbs (135 kg) mass make this a serious placement and moving commitment.

Buy the Funk Audio Ultra 24.0. It is rated higher for sound quality; the BK Electronics Monolith-DF is no longer sold new.

Still deciding? The full Subwoofers rankings cover every ranked option.

Check Funk Audio Ultra 24.0 price at Funk Audio ($18,565) →

Specifications Side By Side

BK Electronics Monolith-DF Funk Audio Ultra 24.0
Price£406.95 Discontinued$18,565
Ranked#137 of 139 in Large Home Subwoofers (Over 75 lbs)#11 of 139 in Large Home Subwoofers (Over 75 lbs)
Enclosureported, bottomsealed
Output SPL at 15 Hz91.3 dB111.8 dB
Output SPL at 20 Hz102.0 dB120.0 dB
Output SPL at 25 Hz106.4 dB122.0 dB
Output SPL at 31.5 Hz108.3 dB123.0 dB
Output SPL at 40 Hz108.6 dB127.1 dB
Output SPL at 50 Hz108.7 dB129.9 dB
Output SPL at 63 Hz108.6 dB127.6 dB
Output SPL at 80 Hz107.7 dB127.0 dB
CEA-2010-A Average (40-80Hz)108.4 dB127.9 dB
Dimensions23.8”H x 21.3”W x 16.5”D (603.8 x 539.8 x 419.9 mm)31”H x 26”W x 24”D (787.4 x 660.4 x 609.6 mm)
Weight103.2 lbs (46.8 kg)297.6 lbs (135 kg)
Warranty23
Cabinet Colorblack, woodwood, custom
CountryUnited KingdomCanada
Measurement SourceIlkka RissanenManufacturer
Drivers12” (305mm) driver with ported design24” (610mm) driver
InputsXLR (balanced), RCA (unbalanced)XLR (balanced)
XLR InputYesYes
RCA InputYesNo
TRS InputNoNo
Optical InputNoNo
Coaxial InputNoNo
USB InputNoNo
HDMI InputNoNo
AES InputNoNo
Aux InputNoNo
Output SPL at 10 Hz-101.0 dB
Output SPL at 12.5 Hz-104.9 dB
Output SPL at 100 Hz-128.2 dB
Check Funk Audio Ultra 24.0 price at Funk Audio ($18,565) →

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The Two Speakers In Full

BK Electronics Monolith-DF: £406.95 Discontinued eBay

BK Electronics Monolith-DF ranking card

Pros: Independent CEA-2010 testing records 102.0 dB at 20 Hz and 108.4 dB through 40-80 Hz. The ported, bottom enclosure with 12” (305mm) driver with ported design delivers substantial upper-bass output for movie effects and music.

Cons: Deep-bass output is more limited than the strong 40-80 Hz result suggests, so it is not the right choice when the lowest movie effects are the priority. The 603.8H x 539.8W x 419.9D mm cabinet and 46.8 kg mass still require deliberate placement and calibration. Discontinued.

Full BK Electronics Monolith-DF review and specifications →

AES InputNo
Aux InputNo
CEA-2010-A Average (40-80Hz)108.4 dB
Cabinet Colorblack, wood
Coaxial InputNo
CountryUnited Kingdom
Dimensions23.8”H x 21.3”W x 16.5”D (603.8 x 539.8 x 419.9 mm)
Drivers12” (305mm) driver with ported design
Enclosureported, bottom
HDMI InputNo
InputsXLR (balanced), RCA (unbalanced)
Measurement SourceIlkka Rissanen
Optical InputNo
Output SPL at 15 Hz91.3 dB
Output SPL at 20 Hz102.0 dB
Output SPL at 25 Hz106.4 dB
Output SPL at 31.5 Hz108.3 dB
Output SPL at 40 Hz108.6 dB
Output SPL at 50 Hz108.7 dB
Output SPL at 63 Hz108.6 dB
Output SPL at 80 Hz107.7 dB
RCA InputYes
TRS InputNo
USB InputNo
Warranty2
Weight103.2 lbs (46.8 kg)
XLR InputYes
Search eBay for BK Electronics Monolith-DF →

Funk Audio Ultra 24.0: $18,565 Funk Audio eBay

Funk Audio Ultra 24.0 ranking card

Same family: the Funk Audio Ultra 21.0LX (smaller subwoofer, ranked lower, rated 4.4/5).

Pros: Published CEA-2010 specifications list 120.0 dB at 20 Hz and 127.9 dB through 40-80 Hz. The sealed enclosure with 24” (610mm) driver has the headroom for demanding film bass in a large room.

Cons: The 787.4H x 660.4W x 609.6D mm cabinet and 135 kg mass make this a serious placement and moving commitment. A sealed cabinet still needs careful placement and calibration to avoid room-mode peaks.

Featured on:

Full Funk Audio Ultra 24.0 review and specifications →

AES InputNo
Aux InputNo
CEA-2010-A Average (40-80Hz)127.9 dB
Cabinet Colorwood, custom
Coaxial InputNo
CountryCanada
Dimensions31”H x 26”W x 24”D (787.4 x 660.4 x 609.6 mm)
Drivers24” (610mm) driver
Enclosuresealed
HDMI InputNo
InputsXLR (balanced)
Measurement SourceManufacturer
Optical InputNo
Output SPL at 10 Hz101.0 dB
Output SPL at 12.5 Hz104.9 dB
Output SPL at 15 Hz111.8 dB
Output SPL at 20 Hz120.0 dB
Output SPL at 25 Hz122.0 dB
Output SPL at 31.5 Hz123.0 dB
Output SPL at 40 Hz127.1 dB
Output SPL at 50 Hz129.9 dB
Output SPL at 63 Hz127.6 dB
Output SPL at 80 Hz127.0 dB
Output SPL at 100 Hz128.2 dB
RCA InputNo
TRS InputNo
USB InputNo
Warranty3
Weight297.6 lbs (135 kg)
XLR InputYes
Check current price at Funk Audio ($18,565) →Search eBay for Funk Audio Ultra 24.0 →