KV2 Audio VHD4.21 User manual

User Guide
VHD4.21
The Future of Sound.
Made Perfectly Clear.
At KV2 Audio our vision is to constantly develop technologies
that eliminate distortion and loss of information providing
a true dynamic representation of the source.
Our aim is to create audio products that absorb you,
place you within the performance and deliver a listening
experience beyond expectations.

Important safety instructions
Before using your VHD4.21, be sure to carefully read the applicable items of these operating
instructions and the safety suggestions.
1. Read all product instructions.
2. Keep printed instructions, do not throw away.
3. Respect and rewiew all warnings.
4. Follow all instructions.
5. Do not use this unit near water, in unprotected out door areas or in rain or wet conditions.
6. Clean only with dry cloth.
7. Do not block any ventilation openings.
8. Install in accordance with KV2 Audio's recommended installation instructions.
9. Do not install near any heat sources such as heat radiators, heat registers, stoves or other apparatus
that produce heat.
10. Do not defeat the safety purpose of the grounding type plug. A grounding type plug has two blades
and a third grounding connector. The third connector is provided for your safety. If the provided plug
does not t into your outlet, consult an electrician for replacement of the obsolete outlet.
11. Protect the power cord from being walked on or pinched, particularly at plugs, convenience receptacles.
The AC mains plug or appliance coupler shall remain readily accessible for operation.
12. Only use accessories specied by KV2 Audio.
13. Install the product only with rigging specied by KV2 Audio, or sold with the loudspeaker.
14. Unplug this loudspeaker during lightning storms or when unused for long periods of time.
15. Refer all servicing to qualied service personnel. Servicing is required when the loudspeaker has been
damaged in any way, such as when the power-supply cord or plug has been damaged; liquid has been
spilled or objects have fallen into the loudspeaker; rain or moisture has entered the loudspeaker;
the loudspeaker has been dropped; or when for undetermined reasons the loudspeaker does not operate
normally.
16. Do not remove front or back panels. Removal of the panel will expose hazardous voltages.
There are no user serviceable parts inside and removable may void the warranty.
17. An experienced user shall always supervise this professional audio equipment.
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE THE PANELS.
NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL.
WARNING: To prevent re or electric shock, do not expose this equipment to rain or moisture.
SAFETY SUMMARY
To reduce the risk of electric shock, disconnect the loudspeaker from the AC mains before installing audio cable.
Reconnect the power cord only after making all signal connections. Connect the loudspeaker to a twopole, three- wire
grounding mains receptacle. The receptacle must be connected to a fuse or circuit breaker. Connection to any other
type of receptacle poses a shock hazard and may violate local electrical codes. Do not allow water or any foreign object
to get inside the loudspeaker. Do not put objects containing liquid on or near the unit. To reduce the risk of overheating
the loudspeaker, avoid exposing it to direct sunlight. Do not install the unit near heat-emitting appliances, such as
a room heater or stove. This loudspeaker contains potentially hazardous voltages. Do not attempt to disassemble
the unit. The unit contains no user serviceable parts, repairs should be performed only by factory trained service
personnel.
VHD4.21 · Important safety instructions
VHD4.21 · Important safety instructions

VHD4.21 · Contents
Contents
Overview 4
Applications, Introduction, Electronics 4
Acoustic Components 5
Enclosure Design 5
AC Power Requirements 6
AC Power 6
Voltage Requirements 6
The Power Connector 6
Current Requirements 7
AC Cable Color Coding 7
VHD4.21 Control Panel / Inputs and Outputs 8 - 9
Drawings 10
Specications 11
Accessories 12
Warranty · Service 13
VHD4.21 · Contents

VHD4.21 · Overview
VHD4.21 ACTIVE - part number KVV 987 333
VHD4.21 PASSIVE - part number KVV 987 336
Introduction
The VHD4.21 is a high output, high denition ultra low frequency active subwoofer system. Through the use of
proprietary amplier technology, a precision manufactured state of the art woofer component and the innovative
implementation of a high eciency, twin chamber acoustic design, the VHD4.21 delivers tight, fast, controlled bass
response at very high output levels. The system establishes new performance standards for an active powered
subwoofer that can only be achieved through the integration of new amplier and power supply topologies,
transducer designs and electronic control technologies.
Originally designed as part of a VHD system it is voiced for live music but also excels in the eld of club and dance
music. In any situation it works very eectively, operating down to 28Hz, alongside other VHD products, the SL range,
or as an incredible stand-alone subwoofer that can complement any other manufacturers systems.
Application
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 rst
• Hire and Production
• Large Concert venues
• Cinema
• Fixed installation
• Easily incorporated into multiple system projects with VHD, SL, ES
and ESR
VHD4.21 · Overview
4
Electronics
The VHD4.21 Active Bass Module consists of two purpose designed Very High Denition enclosures, one active and
one passive, each containing two custom designed 21“ woofers. A Low Q design has been applied to attain the
optimum speaker loading, enabling a high sensitivity of 109dB 1w/1m. Running at close to 100% eciency on any
voltage from 160 to 270 Volts, the amplier for the VHD4.21 is a revolution in electronic engineering, utilising a huge
bank of capacitors as a power store. This unique and innovative new power management system enables the onboard
amplier to deliver peak output levels of 14 kW, whilst operating at a modest constant power consumption of 3.5 kW
from a16 A circuit. The VHD4.21 Active Module represents proven KV2 Subwoofer Amplifer technology that has been
consistently improved over the last decade to provide maximum control over the movement of large mass speakers.
The end result is a fast, dynamic, Very High Denition subwoofer, truly capable of reproducing the articulation in a bass
guitar, whilst also extending down to 28Hz.

VHD4.21 · Overview
Acoustic Components
The VHD4.21's woofer technology is based around high eciency, high power woofer designs. The device features
high temperature polymide voice coil assemblies that undergo multiple baking and curing processes as well as
advanced magnetic structures with complex cooling systems. The woofer cones have been specially developed to
withstand the demanding environment created by the high acoustic loading inside the VHD4.21 chambers. The
VHD4.21 was designed using new concepts in twin asymmetrical acoustic chambers that deliver very high speaker
loading and output from a relatively small cabinet footprint. It is ideal for use in live applications that require
reproduction of low frequencies with very high transient content at high output levels.
Enclosure Design
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 specic custom designed large format 21" woofers.
VHD4.21 · Overview
5

VHD4.21 · AC Power Requirements
VHD4.21 · AC Power Requirements
Voltage Requirements
The VHD4.21 operates safely and without audio discontinuity if the AC voltage stays within the operating window
of 160V-260V at 50 or 60Hz. The VHD4.21 operates in 230V mode. The VHD4.21 features constant power source array
ensuring the power remains the same in case of power drops.
CAUTION: If the On LED does not illuminate or the system does not respond to audio input, remove AC power
immediately. Verify that the voltage is within the proper range. If the problem persists, please contact KV2
Audio or an authorized service center.
If the voltage drops below the low boundary of its safe operating range, the loudspeaker will shut down if the voltage
does not rise above the low boundary before storage circuits are depleted. How long the loudspeaker will continue to
function during brownout depends on the amount of voltage drop and the audio source level during the drop.
If the voltage increases above the upper boundary of the range, the power supply can be damaged.
NOTE: It is recommended that the voltage supply be within the rated voltage window. This ensures that AC
voltage variations from the service entry-or peak voltage drops due to cable runs-do not cause the amplier to
cycle on and o or cause damage to the power supply.
Make sure that even with the AC voltage drop, the AC voltage always stays within recommended operating ranges.
The minimum electrical service amperage required by a VHD4.21 speaker system is the sum of each loudspeaker's
maximum continuous rms current. An additional 50 percent above the minimum amperage is recommended to
prevent peak volt-age.
AC Power
The VHD4.21 is an advanced self-powered loudspeaker system with on-board amplication and control systems.
Understanding power distribution, voltage and current requirements, as well as electrical safety issues, is critical to the
safe operation of the VHD4.21.
The VHD4.21 uses a PowerCon 3-pole AC main system with locking connectors to prevent accidental disconnection.
The main AC connector (blue) serves as the power input.
The Power Connector
The VHD4.21 requires a grounded outlet. It is very important that the loudspeaker AC supply be properly grounded
in order to operate safely and correctly. PowerCon 32A AC cable-wiring diagram to create international or special-
purpose power connectors:
Power connector assembly
6

VHD4.21 · AC Power Requirements
Current Draw 230 V Mode
Max Long Term Continuous 8 A rms
Burst Current 15 A rms
Short Term Peak 26 A peak
Current Requirements
Each VHD4.21 requires approximately 15 Amps max at 230V AC for proper operation.
The VHD4.21 presents a dynamic load to the AC mains, which causes the amount of current to uctuate depending
on quiet or loud operating levels. Since dierent cables and circuit breakers heat up at varying rates, it is essential to
understand the types of current ratings and how they correspond to circuit breaker and cable specifícations.
The maximum long-term continuous current consumption is the maximum rms current during a period of at least ten
seconds. It is used to calculate the temperature rise in cables, in order to select a cable size and gauge that conforms to
electrical code standards. It is also used to select the rating for slowreacting thermal breakers.
The burst current consumption is the maximum rms current during a period of approximately one second, used to
select the rating of most magnetic breakers and to calculate the peak voltage drop in long AC cables according to the
formula: V pk (drop)= I pk x R (cable total).
The ultimate short-term peak current is used to select the rating of fast reacting magnetic breakers. Use the table
below as a guide when selecting cable gauge size and circuit breaker ratings for your operating voltage.
AC Cable Color Coding
If the colors referred to in the diagram don't correspond to the terminals in your plug, use the following guidelines:
Connect the blue wire to the terminal marked with a N or colored black. Connect the brown wire to the terminal marked
with an L or colored red. Connect the green and yellow wire to the terminal marked with an E or colored green or green and
yellow.
Power cable color coding
CAUTION: The VHD4.21 requires a ground connection. Always use a grounded outlet and plug.
VHD4.21 · AC Power Requirements
7

VHD4.21 PASSIVE
OUTPUT
RESIDUAL-CURRENT
CIRCUIT BREAKER
ON
OFF
WARNING - MAINS VOLTAGE
CONNECT ONLY WITH VHD4.21 PASSIVE
USING AN OFFICIAL KV2 AUDIO CORD
WARNING
VERY HIGH ACOUSTIC PRESSURE LEVELS. TO ENSURE PROPER
OPERATION ALLOW A MINIMUM OF 6 INCHES OF CLEARANCE
FROM THIS SURFACE AND ADEQUATE VENTILATION. TO REDUCE
THE RISK OF ELECTRIC SHOCK DO NOT REMOVE THIS PANEL OR
ANY ATTACHED COMPONENT. NO OPERATOR SERVICEABLE
PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL. TO
REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE
THIS APPLIANCE TO RAIN OR MOISTURE.
SERIAL NUMBER CAUTION
WARNING:
RISK OF ELECTRIC SHOCK
DO NOT OPEN
MAIN INPUT
THROUGH OUT
POWER ON / THERMAL
LIMITER
SIGNAL PRESENT
The VHD4.21 features an easy to use rear control panel featuring audio input and output connections, LED status lights
and residual-current circuit breaker.
VHD4.21 · Control Panel / Inputs and Outputs
VHD4.21 · Control Panel
8
Audio signal can be daisy-chained using the through output connector on the input panel. A single source can drive
multiple VHD4.21 subwoofers with a paralleled input loop. If you are driving multiple VHD4.21's in an array, make
certain that the source device can drive the total load impedance presented by the paralleled input circuit of the array.
1) Audio Input and Output
The VHD4.21 uses balanced, female XLR connectors for audio signal input, and a male XLR connector to provide
through output signal. The VHD4.21 features Left and Right stereo inputs and outputs allowing the product to be
integrated into stereo systems that require one subwoofer.
The through output connector, wired in parallel to the audio
input, will continue to provide the input signal if
the VHD4.21 is turned o. The audio input circuit presents
a 20 kOhm balanced input impedance to a three-pin XLR
connector with the following connectors:
The VHD4.21 also features Left and Right High Pass Outputs
that can be used to provide audio signal to full range
speakers being used in conjunction with the VHD4.21.
The high pass lter provides a crossover point of 70Hz.
VHD4.21 Amplier Control Panel
56
7
4
3
1
2
XLR Connectors
Pin 1 - Ground
Pin 2 - Signal (+)
Pin 3 - Signal (-)
Case - Earth (AC) ground and chassis

2) Signal Present
There are individual LED's for each the Left and Right signal inputs. The LED turns green when there is audio signal
present in the VHD4.21. This signal indicator can be used to troubleshoot wiring problems.
3) Limiter
Should the rms limiting system be engaged due to overdriving of the VHD4.21, the LED will light up yellow. The
audible eect of the rms limiter is a lowering of overall output level. The rms limiter will disengage only if the input
level is turned down.
Please contact KV2 Audio or a local service representative should the system enter a thermal condition under
normal operating conditions.
4) Power On / Thermal
This LED turns green when the speaker is turned ON. The light will continue to be green during normal operation of
the speaker system. The LED will change from green to yellow under a thermal condition resulting from overheating
of the amplier system. Under this condition, the speaker system will shut down. You can expect for the system to be
down for at least 2-3 minutes depending the ambient temperature and whether the system is being exposed to direct
sun light.
5) Clicon 8 pole connector socket
For connection between Active and Passive Module - cable is included with the product (part no. KVV 987 337).
6) Residual Circuit Breaker Switch
It disconnects current to prevent serious harm from an ongoing electric shock.
7) PowerCON 32 A socket
The connectors comprise of contacts for phase, neutral and protective earth (ground) conductors rated for currents up
to 32 A and for voltages up to 250V.
VHD4.21 · Control Panel
9
Most source equipment is safe for driving loads no smaller than 10 times the source's output impedance. For
example, cascading an array of 10 units consisting of VHD4.21 subwoofers produces an input impedance of
2000 ohms (20kOhms divided by 10). The source equipment should have output impedance of 200 ohms or
less. This is also true when connecting VHD4.21's in parallel (loop out) with other KV2 Audio ampliers, active
speakers and subwoofers.
If the loudspeaker produces noises such as hiss and popping, disconnect the audio cable from the loudspeaker,
if the noise stops, then most likely the problem is not with the loudspeaker. Check the audio cable, source, and
AC power for the source of the problem.
Ensure that all cabling carrying signal to multiple ampliers and active speaker systems is wired correctly. Make
sure that the polarity has not been reversed. Reversed polarity can cause severe degradation in frequency
response and can also impact the dispersion characteristics of the speaker.
VHD4.21 · Control Panel / Inputs and Outputs

VHD4.21 Active/Passive · Drawings
VHD4.21 Active · Drawing
Drawing VHD4.21 Active/Passive
10
DETAIL REAR PANEL VHD4.21 ACTIVE
MAIN INPUT
THROUGH OUT
POWER ON / THERMAL
LIMITER
SIGNAL PRESENT
VHD4.21 PASSIVE
OUTPUT
RESIDUAL-CURRENT
CIRCUIT BREAKER
ON
OFF
WARNING - MAINSVOLTAGE
CONNECT ONLYWITH VHD4.21 PASSIVE
USING AN OFFICIAL KV2 AUDIO CORD
WARNING
VERY HIGH ACOUSTIC PRESSURE LEVELS. TO ENSURE PROPER OPERATION ALLOW A MINIMUM OF 6 INCHES OF CLEARANCE FROMTHIS SURFACE AND ADEQUATEVENTILATION. TO REDUCE THE RISK OF ELECTRIC SHOCK DO NOT REMOVETHIS PANEL OR ANY ATTACHED COMPONENT. NO OPERATOR SERVICEABLE PARTSINSIDE. REFER SERVICING TO QUALIFIED PERSONNEL. TO REDUCETHE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE
THISAPPLIANCE TO RAIN OR MOISTURE.
SERIALNUMBER CAUTION
WARNING:
RISKOF ELECTRIC SHOCK
DONOT OPEN
VHD4.21PASSIVE
OUTPUT
RESIDUAL-CURRENT
CIRCUITBREAKER
ON
OFF
WARNING-MAINSVOLTAGE
CONNECTONLYWITHVHD4.21PASSIVE
USINGANOFFICIALKV2 AUDIOCORD
WARNING
VERYHIGHACOUSTIC PRESSURE LEVELS. TOENSURE PROPER OPERATIONALLOWAMINIMUM OF 6 INCHES OF CLEARANCE FROMTHISSURFACEANDADEQUATEVENTILATION. TO REDUCE THERISKOFELECTRIC SHOCK DO NOT REMOVETHIS PANEL OR ANYATTACHED COMPONENT. NO OPERATORSERVICEABLE PARTSINSIDE.REFERSERVICINGTO QUALIFIED PERSONNEL. TO REDUCETHERISKOFFIREOR ELECTRIC SHOCK, DO N OTEXPOSE
THISAPPLIANCETORAINORMOISTURE.
SERIALNUMBER CAUTION
WARNING:
RISKOFELECTRICSHOCK
DONOTOPEN
MAININPUT
THROUGHOUT
POWERON/THERMAL
LIMITER
SIGNALPRESENT
VHD4.21PASSIVE
OUTPUT
RESIDUAL-CURRENT
CIRCUITBREAKER
ON
OFF
WARNING-MAINSVOLTAGE
CONNECTONLYWITHVHD4.21PASSIVE
USINGANOFFICIALKV2 AUDIOCORD
WARNING
VERYHIGHACOUSTIC PRESSURE LEVELS. TOENSURE PROPER OPERATIONALLOWAMINIMUM OF 6 INCHES OF CLEARANCE FROMTHISSURFACEANDADEQUATEVENTILATION. TO REDUCE THERISKOFELECTRIC SHOCK DO NOT REMOVETHIS PANEL OR ANYATTACHED COMPONENT. NO OPERATORSERVICEABLE PARTSINSIDE.REFERSERVICINGTO QUALIFIED PERSONNEL. TO REDUCETHERISKOFFIREOR ELECTRIC SHOCK, DO N OTEXPOSE
THISAPPLIANCETORAINORMOISTURE.
SERIALNUMBER CAUTION
WARNING:
RISKOFELECTRICSHOCK
DONOTOPEN
MAININPUT
THROUGHOUT
POWERON/THERMAL
LIMITER
SIGNALPRESENT
Connect only with supplied audio cord Clicon (part no. KVV 987 337)!

VHD4.21 · Specications
Specications
System Acoustic Perfomance
Max SPL Long-term 147dB
Max SPL Peak 150dB
-3dB Response 34Hz to 180Hz
-10dB Response 28Hz to 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 Amplier Specication
Type Direct power switching amplier
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
Cabinet Material Baltic birch
Handles 12
Color Black
Physical Dimensions
Height 700mm (27.56")
Width 1080mm (42.52")
Depth 1200mm (47.24")
Weight (Active) 175 kg (386lbs)
Weight (Passive) 155 kg (342lbs)
VHD4.21 · Specications
11

PADDED HEAVY DUTY COVERS
Cover for VHD4.21 used without cart
part name:
Cover VHD4.21
part number:
KVV 987 282
description:
- heavy duty
- padded
VHD4.21 · Accessories
12
VHD4.21 · Accessories

VHD4.21 · Warranty · Service
Warranty
Your VHD4.21 is covered against defects in material and workmanship.
Refer to your supplier for more details.
Service
In the unlikely event that your VHD4.21 develops a problem, it must be returned to an authorised distributor, service
centre or shipped directly to the KV2 Audio factory. Because of the complexity of the design and the risk of electrical
shock, all repairs must be attempted only by qualied technical personnel.
If the unit needs to be shipped back to the factory, it must be sent in its original carton. If improperly packed, the unit
may be damaged.
To obtain service, contact your nearest KV2 Audio Service Centre, Distributor or Dealer.
VHD4.21 · Warranty · Service
13

KV2 Audio International
Nádražní 936, 399 01 Milevsko
Czech Republic
Tel.: [phone]
Email: [email protected]
www.kv2audio.com
KVV120112-00-02-0
The Future of Sound.
Made Perfectly Clear.