Short answer: the JBL 4645C. It ranks #24 of 109 subwoofers by sound quality, rated 4.4/5, at $4,999; the BK Electronics Extreme ranks #106, rated 3.4/5, and costs $5,995, so there is little reason to consider the other one.
The case for the JBL 4645C: Independent CEA-2010 testing records 98.9 dB at 20 Hz and 127.3 dB through 40-80 Hz. Watch for: Deep-bass output is limited relative to its midbass result, so it is not the right choice for the lowest movie effects.
Why pick the BK Electronics Extreme: Massive 15-inch with 1000W RMS delivers startling speed like fast car with powerful engine.
Buy the JBL 4645C. It is rated higher for sound quality than the BK Electronics Extreme and costs less, which makes it the one to get unless you need something the other one does better.
Looking for alternatives? See the complete Subwoofers rankings.
Specifications Side By Side
| JBL 4645C | BK Electronics Extreme | |
|---|---|---|
| Price | $4999 Passive | $5995 |
| Ranked | #24 of 109 in Large Home Subwoofers (Over 75 lbs) | #106 of 109 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | - |
| Passive | Yes | - |
| Output SPL at 20 Hz | 98.9 dB | 100.7 dB |
| Output SPL at 25 Hz | 114.0 dB | 106.6 dB |
| Output SPL at 31.5 Hz | 118.7 dB | 110.7 dB |
| Output SPL at 40 Hz | 122.0 dB | 111.4 dB |
| Output SPL at 50 Hz | 123.7 dB | 111.1 dB |
| Output SPL at 63 Hz | 129.7 dB | 110.5 dB |
| Output SPL at 80 Hz | 133.9 dB | 109.0 dB |
| Output SPL at 100 Hz | 135.1 dB | - |
| Output SPL at 125 Hz | 135.8 dB | - |
| CEA-2010-A Average (40-80Hz) | 127.3 dB | 110.5 dB |
| Dimensions | 39.7”H x 26.5”W x 17.7”D (1009.6 x 673.1 x 450.8 mm) | - |
| Weight | 138 lbs (62.6 kg) | 200.6 lbs (91 kg) |
| Warranty | 5/3/2 | - |
| Cabinet Color | black | - |
| Country | United States | United Kingdom |
| Measurement Source | Data-bass | Ilkka Rissanen |
| Drivers | 18” (457mm) driver | 15” (381mm) driver |
| Output SPL at 15 Hz | - | 92.8 dB |
| Amplifier Power | - | 1000W RMS |
Related Speaker Comparisons
How JBL 4645C compares with other leading options:
- JBL 4645C vs WW Speaker Cabinets X21 - B&C 21DS115-4
- JBL 4645C vs Pro Audio Technology LFC-24sm
- JTR Speakers Captivator S2 vs JBL 4645C
- JBL 4645C vs JTR Speakers Growler (2015)
- Danley Sound Labs DTS10 vs JBL 4645C
Prices on this page were last checked September 29, 2026 at 3:43 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
As an eBay Partner, we may be compensated if you make a purchase.
The Two Speakers In Full
JBL 4645C: $4999 Passive eBay
Pros: Independent CEA-2010 testing records 98.9 dB at 20 Hz and 127.3 dB through 40-80 Hz. The ported, front enclosure with 18” (457mm) driver is best suited to upper-bass support in a modest room.
Cons: Deep-bass output is limited relative to its midbass result, so it is not the right choice for the lowest movie effects. The 1009.6H x 673.1W x 450.8D mm cabinet and 62.6 kg mass still need deliberate placement and calibration.
Full JBL 4645C review and specifications →
| CEA-2010-A Average (40-80Hz) | 127.3 dB |
|---|---|
| Cabinet Color | black |
| Country | United States |
| Dimensions | 39.7”H x 26.5”W x 17.7”D (1009.6 x 673.1 x 450.8 mm) |
| Drivers | 18” (457mm) driver |
| Enclosure | ported, front |
| Measurement Source | Data-bass |
| Output SPL at 20 Hz | 98.9 dB |
| Output SPL at 25 Hz | 114.0 dB |
| Output SPL at 31.5 Hz | 118.7 dB |
| Output SPL at 40 Hz | 122.0 dB |
| Output SPL at 50 Hz | 123.7 dB |
| Output SPL at 63 Hz | 129.7 dB |
| Output SPL at 80 Hz | 133.9 dB |
| Output SPL at 100 Hz | 135.1 dB |
| Output SPL at 125 Hz | 135.8 dB |
| Passive | Yes |
| Warranty | 5/3/2 |
| Weight | 138 lbs (62.6 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Independently measured by Data-bass; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons
- JBL 4645C vs Reaction Audio PV-15X
- JBL 4645C vs Monoprice Monolith 16 THX Ultra
- JBL 4645C vs Chase Home Theater SS18.1
- JBL 4645C vs Danley Sound Labs DTS10
- JBL 4645C vs JTR Speakers Growler (2015)
- JBL 4645C vs JTR Speakers Captivator S2
- JBL 4645C vs Pro Audio Technology LFC-24sm
- JBL 4645C vs WW Speaker Cabinets X21 - B&C 21DS115-4
- See all 10 comparisons
BK Electronics Extreme: $5995 eBay
Pros: Massive 15-inch with 1000W RMS delivers startling speed like fast car with powerful engine. Continuous 0-180 degree phase control for flexible system integration. Beautiful compact design aids placement in listening room.
Full BK Electronics Extreme review and specifications →
| Amplifier Power | 1000W RMS |
|---|---|
| CEA-2010-A Average (40-80Hz) | 110.5 dB |
| Country | United Kingdom |
| Drivers | 15” (381mm) driver |
| Measurement Source | Ilkka Rissanen |
| Output SPL at 15 Hz | 92.8 dB |
| Output SPL at 20 Hz | 100.7 dB |
| Output SPL at 25 Hz | 106.6 dB |
| Output SPL at 31.5 Hz | 110.7 dB |
| Output SPL at 40 Hz | 111.4 dB |
| Output SPL at 50 Hz | 111.1 dB |
| Output SPL at 63 Hz | 110.5 dB |
| Output SPL at 80 Hz | 109.0 dB |
| Weight | 200.6 lbs (91 kg) |
- Reviews, Comparisons and Sound Samples
- Independently measured by Ilkka Rissanen; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons