Balanced Audio Technology VK-5 User manual

VK-5
WARRANTY REGISTRATION FORM
Unit Serial Number: _______________________________________
Customer Name: _______________________________________
Address: _______________________________________
_______________________________________
Date of Purchase: _______________________________________
Purchased From:
Dealer Name: _______________________________________
Address: _______________________________________
_______________________________________
IMPORTANT NOTE:
In order to receive the full five year product warranty, please mail this
completed form together with a copy of your sales receipt to Balanced Audio
Technology at the address below, within thirty days of purchase.
Failure to do so will result in the product being warrantied for one year
from the date of manufacture.

VK-5
Balanced Stereo Preamplifier
Owner's Manual

Introduction
Thank you for your purchase of the Balanced Audio Technology VK-5 preamplifier. Please
read this owner's manual to obtain the full benefit of the VK-5 in your system. It will provide
you with the needed safety information and operating procedures for this exceptional unit. For
more technical information on the circuit design, please read the Balanced Audio Technology
VK-5 white paper.
WARNINGS:
To prevent the possibility of serious injury, electrical shock or fire:
DO NOT operate with the cover removed.
DO NOT expose to rain or moisture.
DO NOT defeat the ground power-plug.
DO NOT replace fuse with anything other than the same type and rating as supplied by the factory.
Package Contents
Included in the box should be the following:
Description Quantity
VK-5 Preamplifier 1
Power Cord 1
Spare Fuse 1
Torx Wrench (T-10) 1
Spare Top Cover Screws 5
User’s Manual 1
Optional Accessories (as ordered)
Save all the packaging material in a safe dry area for the unlikely event that you need
to return the VK-5 to the factory for service.

Reseating Tubes
Normally, reseating tubes upon delivery is not required. However, if any tubes have
noticeably drifted out of position due to unusually high transportation stress, it will be
advisable to reseat the tubes. Use the supplied Torx wrench to remove the top cover.
Reseat the tubes in their sockets and reinstall the top cover.
NOTE: When using the Torx wrench, make sure it is fully inserted so that the screw head is
not stripped.
Physical Placement
It is recommended that you provide for at least 6" of free space around the unit for proper
ventilation.
Mount the unit on a hard surface with proper ventilation underneath.
Do not stack the VK-5 preamplifier on top of other units, nor vice versa.
Connecting the VK-5 to Your System
Balanced Components
Use balanced XLR interconnects. All input and output connectors are clearly marked on the
back panel.
Note: The VK-5 XLR connectors are wired as follows:
Pin 1: common/shield
Pin 2: positive
Pin 3: negative
Use either the Main 1 or Main 2 Output for connection to your power amplifier. Both yield
equivalent results.
Single-Ended Components
Single-ended components have RCA connectors. The VK-5 preamplifier is designed
to work with any mix of single-ended and balanced components connected to its inputs and
outputs. All that is required to connect a single-ended component with RCA connectors to
the VK-5’s inputs or outputs is the optional balanced to single-ended adapters. These
adapters are available from Balanced Audio Technology at a nominal charge.

Two types of adapters are available:
Input Adapters: RCA Female to XLR Male
Output Adapters: RCA Female to XLR Female.
Mixed Balanced and Single-Ended Systems
Any mix of single-ended and balanced components can be connected to the VK-5 by
following the above instructions.
Description of Controls
Power switch:
The power switch has three positions: Sleep, Off and On. There is no required sequencing
between these positions. For example it is not necessary to go from Off to Sleep to On,. The
VK-5 can be switched directly from Off to On as described below.
Turning the VK-5 On:
When you turn the unit On, the VK-5 will automatically go through a gentle power-on
sequence. At the end of this sequence the unit will automatically unmute, provided the Mute
switch is in Play position. However, since the source volume may be unknown at this time, it
is advisable to turn the volume control fully counterclockwise and place the mute switch in
"Mute" position before powering the unit On.
Turning the VK-5 Off:
The unit can be turned Off at any time (even while playing) without first activating the Mute
switch. It will automatically mute. It is also permissible to go directly from On into Sleep
mode.
Sleep Mode Operation:
It is important to understand that the "sleep" mode on the VK-5 is different from the usual
Standby mode. While Standby mode is commonly used to warm up the preamplifier prior to
turning it On, this is not required when operating the VK-5, which does all the power
sequencing automatically.
Typical Standby modes apply full filament voltage to tubes while disconnecting the plate
voltage sources. The Sleep mode on the VK-5 is different in that it is designed to keep the

tubes in the unit warm, but well below their full operating temperatures. The filament
voltage in this mode is reduced to about one half of its nominal value. This allows the user to
keep the preamplifier warm for prolonged periods of time without sacrificing tube life.
While the VK-5 will sound superb right after turning it On, some owners may prefer to keep
it warm (in Sleep Mode) when not in use.
Gain Controls:
Separate left and right gain controls replace the traditional balance control and provide up to
4 dB attenuation for each channel. Turning them counterclockwise will reduce the gain of
the corresponding channel. The preferred position is up fully clockwise (pointer at 12
o'clock).
Power indicator LED:
The power indicator light on the VK-5 works as follows:
In On mode the LED glows at full brightness indicating normal operation.
In Sleep mode the LED brightness is reduced and is roughly proportional to the
filament temperatures of the tubes.
When turning the cold unit into Sleep mode for the first time, the tubes will require several
minutes before reaching their normal Sleep mode temperatures. Accordingly, the LED power
indicator will not turn On immediately, but will gradually become brighter as the tube
filaments warm up.
On the other hand, when switching the running unit from On into Sleep mode, the brightness
of the LED power indicator will not change immediately, since tube filaments will gradually
start cooling off. As they do, the indicator brightness will continue decaying until settling at
a steady state, indicating that the tubes have reached their proper Sleep mode temperatures.
This may require several minutes.
Going from the Sleep to the On state will produce an immediate increase in the LED power
indicator brightness, signaling full power operation.

Mute function:
The VK-5 has two mute modes: manual and automatic. Putting the Mute switch in Mute
position will always override the automatic function and disable the outputs.
When the unit is powered up it automatically self-mutes until the proper operating points of
the circuitry are reached. It will then automatically go into Play mode, provided the Mute
switch is in the Play position.
Changing the power switch position from On to either Off or Sleep even for short time, will
make the unit reset its power sequencing circuit and mute its output. It will then require
about 45 seconds for the unit to become operational again.
The mute function is coupled to a low line voltage sensor. When line voltage drops below an
allowable value (for example during a brown-out condition) the unit will automatically mute
and remove the plate voltages from gain stages. Once the line voltage recovers to a normal
level, the VK-5 will resume its operation.
If the line voltage is insufficient for normal operation during turn-On, the unit will not
proceed beyond Sleep mode until the line voltage reaches a proper level.
Overcurrent Protection:
Both channels in the VK-5 are protected from certain overload conditions via electronic
current-sensing circuits. If an overcorrect condition is detected in either channel (for
example, a short in one of the regulator tubes), the unit will immediately be disabled, its high
voltage supplies disconnected and the output muted. The protection circuit may be reset by
turning the unit Off for a short period of time. However, if the fault condition remains, the
unit will again be disabled and therefore require professional service.

Fuse Protection:
A blown fuse in the VK-5 is an indication of a serious problem. If a replacement fuse fails as
well, no further attempts should be undertaken. Please contact the factory for professional
service.
The proper fuse ratings are as follows:
For 100-120 VAC Units: 2A 250V Slow Blow
For 200-240 VAC Units: 1A 250V Slow Blow
Factory supplied fuses should be only replaced with the same type and rating parts.
Servicing
The Balanced Audio Technology VK-5 should require no service other than changing tubes
to maintain its high performance. The vacuum tubes used in the VK-5 are quality 6922s and
5881s rated for approximately 5000 hours of use. Please direct any further service inquiries
to the factory.
Cleaning
To remove dust, occasionally wipe the front and top surfaces of your VK-5 with a damp soft
cloth. If fingerprints appear, you may use a mild, non-alkaline soap solution. Do not use
abrasive cleaners, as they may damage the fine finish of the unit.

Five Year Limited Warranty
Terms and Conditions
1. Limited Warranty
Upon receipt of the attached warranty registration form, Balanced Audio Technology warrants the purchased
product to be free from manufacturing, materials, and workmanship defects for five years from date of original
purchase, excepting vacuum tubes, subject to the following conditions. Failure to return the enclosed
registration form within 30 days from original purchase will result in a warranty period of one year from
the date of manufacture.
2. Vacuum Tubes
Vacuum tubes (including replacements under warranty) are warranted for one year from the date of the original
VK-5 purchase.
3. Limited to Original Purchaser
This warranty is for the sole benefit of the original purchaser of the covered product, and may not be transferred
to a subsequent purchaser of the product.
4. Conditions and Limitations
This warranty is subject to certain conditions and limitations, as follows. This warranty is void and inapplicable
if the product has not been used in accordance with the instructions found elsewhere in this manual, or if it has
been misused or abused, damaged by accident or neglect, or in transport once in possession of the purchaser.
The warranty is also void if the product has been repaired, modified, or tampered with by anyone other than
Balanced Audio Technology or its specifically authorized agents.
5. Remedy
If this product contains a materials, manufacturing, or workmanship defect that cannot be repaired at the
dealership where the product was purchased, it must be packed in original packaging and returned to Balanced
Audio Technology via insured freight, at the owners expense. If replacement packaging materials are required,
they will be supplied by the factory at a nominal charge. Returned products must be accompanied by a
written description of the defect, and a return authorization number (available from the factory via
phone or fax). Upon receipt of defective product, Balanced Audio Technology agrees to repair the product
without charge for parts (except vacuum tubes if the unit is more than one year old), or labor. The product will
then be returned via prepaid, insured freight, with carrier at the sole determination of Balanced Audio
Technology. This constitutes the purchasers sole remedy.
6. Design Changes
Balanced Audio Technology reserves the right to modify its products or change specifications at any time
without obligation or liability to previous purchasers.
7. Miscellaneous
Any implied warranties relating to the above product shall be limited to the duration of this warranty. This
warranty does not extend to any incidental or consequential costs or damages to the purchaser. This warranty
gives you specific legal rights. You may also have other rights which vary from state to state.