BK Monolith

[Ilkka]

Manufacturer: BK Electronics
Model: Monolith
Provided by: Marek Sound
Manufacturer link: BK Electronics
Price: 750 EUR

Manufacturer specs:
• System Type: 95 Litre reflex tuned to 20Hz, cabinet manufactured from veneered 25mm MDF and Critically braced
• Distortion: 5% 102dB @ 20Hz
• Frequency Response at -3dB: 20Hz / In Room at 15Hz
• Amplifier Input / Output Impedance: High Level 100K - Low Level 10K - Balanced 10K
• Gain Control Range: 80dB
• Drive Unit Impedance: 4 Ohm
• Mains Input: 230V / 50Hz
• Dimensions: 560D X 540H x 420W
• Weight: 42.75kg
• Finishes: Black Ash Veneer, Light Oak Veneer and Cheery Veneer
• True 300W continuous discrete Mosfet amplifier
• Truly hand built in Great Britain, when we claim hand built we mean hand built, as there are no SMD components or other automatic placement devices
• Forward Firing 300mm (12")
• Continuously variable frequency control
• Audiophile grade toroidal transformers
• Gas Tight Neutrik connection for long term consistency of sound quality
• Separate controls for high and low-level input adjustment
• Simultaneous connection of high and low level sources
• Balanced Inputs
• Thermal Protection
• Anti Thump
• ASP automatic speaker protection audibly transparent driver protection
• 4 x 16A output devices for effortless current control
• IEC Power Socket
• Doubled flared 4” port for reduced port noise

Configuration as tested:
Phase: 0 degrees
Front grill removed
Orientation: Woofer/port facing right

[Ilkka]

+/- 3 dB points: 19 Hz - >200 Hz

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[Ilkka]

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[Ilkka]

The frequency response stays inside the 6 dB window all the way from 19 Hz to over 200 Hz. The crossover works as promised, though the low pass slope is on the shallow side. The maximum output touches the 105 dB barrier in mid bass range, but can’t quite reach 100 dB at 20 Hz. Not that there would be many 12” subwoofers that could, so the Monolith is among the very best I’ve measured thus far. The power compression stays quite low up to the max output. The BK Monolith doesn’t have a typical high pass (also called “sub-sonic”) filter below its tuning frequency. That means that it is possible to mechanically bottom the woofer (which accidentally did happen during testing) if a high amplitude <20 Hz sine wave is inputted to the subwoofer. With normal program material subwoofer’s efficient output limiters should prevent this from happening.

The THD profile is pretty good, though there is a slight hump in THD in lower mid bass range. Below the tuning frequency distortion naturally grows rapidly. The group delay is really good for a ported subwoofer, mostly because there is no high pass filtering. The spectral decay shows only little ringing around 20 Hz, though much less than for most ported subwoofers.

The BK Monolith is a very good subwoofer. It has a very rigid and good-looking enclosure, nice features, and a performance that doesn’t have many weak spots. When one looks at the price of the subwoofer, the decision should be even easier to make.

+ Good frequency response
+ High output and low power compression
+ Extremely low group delay and fast decay rate for a ported subwoofer

+/- No high pass filter below the tuning frequency
- High distortion in 30-40 Hz range