Krell Industries KAV-250a-3 User Manual
KAV-250a
Leader in Audio Engineering
Instructions for Use, v 99.2
Stereo Power Amplifier
KAV-250a/3
Three-Channel Power Amplifier
Owner’s Reference
KAV-250a Stereo Power Amplifier and
KAV-250a/3 Three-Channel Power Amplifier
Instructions for Use, v 99.2
Cover: KAV-250a/3 Three-Channel Power Amplifier
Krell Industries, Inc.
45 Connair Road
Orange, CT 06477-3650 USA
TEL 203-799-9954
FAX 203-799-9796
E-MAIL krell @ krellonline.com
WEBSITE http://www.krellonline.com
This product complies with the EMC directive (89/336/EEC) and the low-voltage directive
(73/23/EEC).
WARNINGS
The amplifier must be placed on a firm, level surface where it is not exposed to dripping or
splashing.
The ventilation grids on the top of the amplifier and the space underneath the amplifier must be
unobstructed at all times during operation. Do not place flammable material above or beneath
the amplifier.
Contact your authorized Krell dealer, distributor, or Krell before using any devices designed to
alter or stabilize the AC power for the KA V-250a or KA V-250a/3.
Before connecting the KA V-250a or KA V-250a/3, make sure the amplifier is off and any output
device (such as a preamplifier) is in mute or stand-by mode. Make sure all cable terminations
are of the highest quality and free from frayed ends, short circuits, or cold solder joints.
Use only one set of inputs to the amplifier at a time.
After reconfiguring for MAT, do not use more than one input at the same time.
After bridging, do not use both inputs at the same time.
THERE ARE NO USER SERVICEABLE PARTS INSIDE ANY KRELL PRODUCT
Please contact your authorized Krell dealer, distributor, or Krell if you have any questions not
addressed in this reference manual.
This product is manufactured in the United States of America. Krell® is a registered trademark of Krell
Industries, Inc., and is restricted for use by Krell Industries, Inc., its subsidiaries, and authorized agents.
Multi Amp Throughput
TM
is a trademark of Krell Industries, Inc. All other trademarks and tradenames are
registered to their respective companies.
© 1999 by Krell Industries, Inc. All rights reserved P/N: I960101710688
Contents
Page
INTRODUCTION ’
DEFINITION OF TERMS
UNPACKING
PLACEMENT
AC Power Guidelines
FRONT PANEL DESCRIPTION: KAV-250a
BACK PANEL DESCRIPTION: KAV-250a
FRONT PANEL DESCRIPTION: KAV-250a/3
BACK PANEL DESCRIPTION: KAV-250a/3
CONNECTING THE KAV-250a or KAV-250aJ3 AMPLIFIER
TO YOUR SYSTEM
Input and Output Connections
OPTIONAL SYSTEM CONFIGURATIONS
Multi Amp Throughput
1
1
2
3
3
5
7
10
12
14
14
15
15
Bridged Operation
Examples of Connection Scenarios
AMPLIFIER OPERATION
On/Off and Operation
AMPLIFIER TROUBLESHOOTING
How to Troubleshoot System Noise
QUESTION AND ANSWER
WARRANTY
RETURN AUTHORIZATION PROCEDURE
SPECIFICATIONS
KAV-250a and KAV-250a/3 Amplifiers iii
20
22
25
25
26
26
28
29
30
27
Illustrations
Page
FIGURE 1
FIGURE 2
FIGURE 3
FIGURE 4
FIGURE 5
or Bridged Operation
FIGURE 6 Reconfiguring the KAV-250a/3 for MAT
or Bridged Operation
The KAV-250a Front Panel
The KAV-250a Back Panel
The KAV-250a/3 Front Panel
The KAV-250a/3 Back Panel
Reconfiguring the KAV-250a for MAT
4
6
9
11
16
19
iv KAV-250a and KAV-250a/3 Amplifiers
Introduction
Thank you for your purchase of the Krell KAV-250a Stereo Power Amplifier or
KAV-250a/3 Three-Channel Power Amplifier..
The KAV-250a and KAV-250aJ3 amplifiers provide substantial two- and three-channel
output power that delivers realistic music production at an exceptional value. These
amplifiers can be customized with a variety of optional system configurations: Multi
Amp Throughput (MAT), bridged operation, and high power mono operation. These
options provide a wider range of power outputs and connection options. Both the KAV-
250a and KAV-250a/3 amplifiers provide balanced and single-ended inputs for
complete compatibility with other components. The KAV-250a and KAV-250a/3
amplifiers can be operated using the 12 VDC trigger for other components. Either
amplifier integrates seamlessly home theater or whole-house systems.
This reference manual contains important information on placement, installation, and
operation of the KAV-250a and KAV-250a/3 amplifiers. Please read this information
carefully. A thorough understanding of these details helps ensure satisfactory operation
and long life for your KAV-250a or KAV-250aJ3 amplifier and related system
components.
Definition of Terms
Multi Amp Throughput
An internal connection option that sends the same music signal to all amplifier channels
using one balanced or single-ended connection. MAT reduces installation complexity
and cabling requirements in systems containing multiple amplifiers. MAT also allows a
variety of connection scenarios, including powering loudspeakers that have two sets of
binding posts and independently powering multiple pairs of stereo loudspeakers to
extend the listening environment throughout your home.
Bridging
An internal connection option that links two amplifier channels to operate as one
combined amplifier channel, greatly increasing the channel’s power output.
On
When the power button on the front panel is pressed and the blue power LED
illuminates, the amplifier is on and ready to play music.
Off
When the power button on the front panel is pressed and the blue power LED turns off,
the amplifier is off.
KAV-250a and KAV-250a/3 Amplifiers 1
Unpacking
Open the shipping box, which contains:
1 amplifier unit (packed in foam end-caps)
2 ribbon connection cables
KAV-250a fuses:
2 AGC-8 (~ ’amp)
1 slow-blow (20 amp for 100/120 V or 12 amp for 220/240 V)
or
KAV-250a/3 fuses:
3 AGC-.8 ~ amp)
1 slow-blow (20 amp for 100/120 V or 12 amp for 220/240 V)
1 12 VDC output (12 V trigger) cable
1 IEC connector (AC power) cord
1 T-15 Torx wrench
1 packet containing the owner’s reference manual and the warranty registration
card.
Grasp the underside of the foam end-caps that encase the amplifier and lift the
amplifier straight out of the shipping box.
Place the amplifier in a safe location and remove the protective plastic wrapping.
Notes
If any of these items are not included in the shipping box, please contact your
authorized Krell dealer, distributor, or Krell for assistance.
Save all packing materials. If you ship your amplifier in the future, repack the unit in its
original packaging to prevent trans# damage. See Return Authorization Procedure,
on page 29, for more information.
2
KAV-250a and KAV-250aJ3 Amplifiers
Placement
Before you integrate the KAV-250a or KAV-250a/3 into your system, review the
following guidelines to choose the location for the component. This will facilitate a
clean, trouble-free installation.
The KAV-250a and KAV-250aJ3 require at least two inches (5 cm) of clearance
each side and at least two inches (5 cm) of clearance above the component to provide
adequate ventilation.
Your amplifier does not require any type of special rack or cabinet for installation. For
the dimensions of your amplifier see Specifications, on pages 30 and 31.
Place the amplifier as close to the loudspeakers as possible and keep the speaker
cable length to a minimum. Speaker cable adds impedance to the load the amplifier
must drive, regardless of the cable’s gauge. Krell amplifiers drive the lowest
impedances with ease, but long speaker cables reduce the maximum power that is
delivered to the loudspeakers.
AC POWER GUIDELINES
Krell recommends operating each amplifier from a dedicated 15-amp AC power line.
For maximum power output, operate the KAV-250a or KAV-250a/3 amplifier from a
dedicated 20-amp AC power line.
KAV-250a and KAV-250a/3 Amplifiers
3
FIGURE 1 THE KAV-250a FRONT PANEL
1 2
1 Power Button
2 Power LED
Front Panel Description: KAV-250a
See Figure 1 on page 4
1 Power Button
Use this button to turn the KAV-250a power on and off and also to switch the 12 VDC
output (12 V trigger) on and off.
2 Power LED
The blue power LED illuminates when the amplifier is on.
KAV-250a and KAV-250a/3 Amplifiers 5
FIGURE 2 THE KAV-250a BA(;K PANEL
5
11 12 10 13
Balanced Inputs
3 Right Input
4 Left Input (Bridged)
Single-ended Inputs
5 Right Input
6 Left Input (Bridged)
Amplifier Channel Outputs
7 Right Output (Bridged-)
8 Left Output (Bridged+)
Fuses
9 AGC~ Fuses
10 Line Fuse
Remote Controls
11 12 VDC Remote Power Out
12 12 VDC Remote Power In
Power
13 IEC Power Connector
Back Panel Description: KAV-250a
See Figure 2 on page 6
The KAV-250a back panel provides connections for all inputs and outputs, remote
control input and output links, and AC power supply. Inputs and outputs labeled left and
right are on the left and right side of the amplifier, respectively, when viewing the
amplifier from the front panel.
Balanced Inputs
3, 4 Inputs
These are the right (3) and the left (4) KAV-250a channel inputs for output devices
balanced XLR connectors.
Single-ended Inputs
5,6 Inputs
These are the right (5) and the left (6) KAV-250a channel inputs for output devices
single-ended RCA connectors.
The left balanced or single-ended inputs are used for bridged operation. See
Reconfiguring the KA V-250a for Bridged Operation, on page 20.
Amplifier Channel Outputs
7 Output Bridged(-)
8 Output Bridged(+)
These are the right (7) and left (8) KAV-250a amplifier channel outputs with five-way
loudspeaker binding posts. The loudspeaker binding post terminals accept spade lugs,
bare wire, banana plugs, or pins. Use the red terminal for the positive connection and
the black terminal for the.negative connection. For information on loudspeaker
connections for bridged operation, see Reconfiguring the lEA V-250a for Bridged
Operation, on page 20.
Fuses
9 AGC-12 Fuses
The AGC 12 Volt loudspeaker fuses protect the KAV-250a against short circuits in
loudspeaker output.
10 Line Fuse
The line fuse protects the KAV-250a against short circuits in internal power supplies.
Note
Fuses must be replaced with the fuse value specified on the KA V-250a back panel. Use
a 20 amp slow-blow line fuse for 100/120 V systems or a 12 amp slow-blow line fuse for
220/240 V systems.
KAV-250a and KAV-250a/3 Amplifiers 7
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