VHD4.21 -Active Passive Bass Module


The Ultimate seismic Subwoofer to add to any KV2 Audio or third party manufacturers system. 

  • Large scale live music and playback performance
  • Dance Clubs and Nightclubs where Music comes first 
  • Hire and Production
  • Large Concert venues
  • Cinema
  • Fixed installation
  • Easily incorporated into multiple system projects with VHDSLES and ESR


The VHD4.21 Active Subwoofer Module consists of two purpose designed  'Low Loss-Band Pass' enclosures, one Active and one Passive, with each enclosure containing two specific custom designed large format 21" woofers.

The Low Q design has been applied to attain the optimum Loudspeaker loading, enabling a high sensitivity of 109dB 1w/1m. The design of our unique and innovative new power management system enables the Active Power Amplifier to deliver peak output levels of 14kW, whilst operating at a modest constant consumption of 3.6 kW from a 16A circuit. 

An impressive maximum 320V supplied (limited) peak to peak at 100A from the VHD4.21 Active Module represents a bullet- proof technology that has been fully developed and refined over 12 years of active operation in real life applications, providing maximum control over movement of the large mass of the speaker.

System Acoustic Performance

Max SPL Long-term 147dB
Max SPL Peak 150dB
-3dB Response 34Hz - 180Hz
-10dB Response 28Hz - 240Hz
Crossover Point 70Hz

Low Frequency Section

Acoustic Design Bandpass with low port losses
Woofer Size / Voice Coil Diameter / Design 4x 21" / 5.3"
Diaphragm Material Epoxy Reinforced Cellulose with Carbon Fiber and Double Surround
Magnet Type Neodymium Advanced Ventilated

Low Frequency Amplifier Specification

Type Direct power switching amplifier
Rated Continuous Power 3500W
Short Term Power 14000W
Distortion <0.05%

Signal Input

Input Sensitivity 1.55V RMS
Input Impedance 20 kΩ

Power Requirements

Power Connector Neutrik PowerCon® 32A
Operating Voltage 180V - 260V @ 50Hz | 60Hz
Recommended Amperage 16A


Cabinet Material Baltic Birch
Handles 12
Color Black

Physical Dimensions

Height 700mm (27.56")
Width 1080mm (42.52")
Depth 1200mm (47.24")
Weight (Active) 175kg (386lbs)
Weight (Passive) 155kg (342lbs)