Krell KAV-2250 Owners manual

Instructions for Use

Owner’s Reference

THE LEADER IN AUDIO ENGINEERING

KAV–2250

Stereo Power Amplifier

KAV–3250

Three-channel Power Amplifier

KAV–2250
Stereo Power Amplifier

KAV–3250
Three-channel Power Amplifier

Instructions for Use

v 01.2

Krell Industries, Inc.
45 Connair Road
Orange, CT 06477-3650 USA

TEL [phone]
FAX [phone]
E-MAIL [e-mail]
WEBSITE http://www.krellonline.com

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™ and Krell Current Mode™ are trademarks of Krell Industries, Inc. All other
trademarks and tradenames are registered to their respective companies.

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 and bottom of 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 stabi-

lize the AC power for the KAV–2250 and the KA V–3250.
Before connecting the KA V–2250 and the KAV–3250, make sure the amplifier is turned 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 input to each amplifier channel at a time.
Make sure that only one switch on an input switch bank is in the up (on) position at one 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.

© 2001 by Krell Industries, Inc. All rights reserved P/N 305573

Krell KAV–2250 and KAV–3250 iii

Contents

Page

INTRODUCTION 1
DEFINITION OF TERMS 2
UNPACKING 4
PLACEMENT 5
AC Power Guidelines 5
FRONT PANEL DESCRIPTION 7
BACK PANEL DESCRIPTION 9
CONNECTING THE AMPLIFIER TO YOUR SYSTEM 11
Input and Output Connections 11
AMPLIFIER OPERATION 13
On/Off and Operation 13

Using a Dedicated Wall Switch 13
TROUBLESHOOTING SYSTEM NOISE 14
RECONFIGURATION OPTIONS FOR THE KAV–2250 AND KAV–3250 15
To Safely Access the Input Switch Banks 15

Amplifier Factory Default Settings 18
Reconfiguring the Amplifier for MAT Operation 18
Reconfiguring the Amplifier for Bridged Operation 21
Example of a Connection Scenario: Multi-power Mode 22

QUESTIONS AND ANSWERS 23
WARRANTY 24
RETURN AUTHORIZATION PROCEDURE 25
SPECIFICATIONS

KAV–2250 26
KAV–3250 27

iv

Krell KAV–2250 and KAV–3250

Illustrations

Page

FIGURE 1 The KAV–2250 Front Panel 6
FIGURE 2 The KAV–3250 Front Panel 6
FIGURE 3 The KAV–2250 Back Panel 8
FIGURE 4 The KAV–3250 Back Panel 8
FIGURE 5 Amplifier Factory Default Settings 16
FIGURE 6 Reconfiguring the KAV–2250 for MAT Operation 17
FIGURE 7 Reconfiguring the KAV–3250 for MAT Operation 17
FIGURE 8 Reconfiguring the KAV–2250 for Bridged Operation 20
FIGURE 9 Reconfiguring the KAV–3250 for Bridged Operation 20

Krell KAV–2250 and KAV–3250 1

Introduction

Thank you for your purchase of the Krell KAV–2250 Stereo Power Amplifier or the KAV–
3250 Three-channel Power Amplifier.

The KAV–2250 and KAV–3250 amplifiers provide substantial two- and three-channel
output power that delivers realistic music reproduction at an exceptional value. These
amplifiers can be customized with two optional system configurations: Multi Amp
Throughput (MAT) and bridged operation. These configurations provide a wider range of
power outputs and connection options. Both the KAV–2250 and KAV–3250 amplifiers
have balanced and single-ended inputs, for complete compatibility with other
components. The KAV–2250 and KAV–3250 amplifiers can be operated using the 12
VDC trigger on other components. Either amplifier integrates seamlessly into home
theater or whole-house systems.

This reference manual contains important information on placement, installation, and
operation of the KAV–2250 and KAV–3250 amplifiers. Please read this information
carefully. A thorough understanding of these details helps ensure satisfactory operation
and long life for your amplifier and related system components.

2

Krell KAV–2250 and KAV–3250

Definition of Terms

Following are the definitions of key terms used in your owner’s reference manual.

CONFIGURATIONS

Bridging

A method of linking two amplifier channels by distributing the speaker load between the
positive binding posts. Bridging the channels quadruples the power rating at 8 Ohms.
Bridged configurations should not be used with loads under 4 Ohms.

Krell Multi Amp Throughput (MAT)

An internal configuration 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.

INPUT AND OUTPUT CONNECTIONS

Balanced

A symmetrical input or output circuit that has equal impedance from both input terminals
to a common ground reference point. The industry standard for professional and sound
recording installations, balanced connections have 6 dB more gain than single-ended
connections and allow the use of long interconnect cables. Balanced connections are
completely immune to induced noise from the system or the environment.

Single-ended

A two-wire input or output circuit. Use care when using single-ended connections as the
ground connection is made last and broken first. Turn the system off prior to making or
breaking single-ended connections. Single-ended connections are not recommended for
connections requiring long cable runs.

Krell KAV–2250 and KAV–3250 3

Definition of Terms,

continued

OPERATION

Off

When the back panel power switch is in the down (off) position and the red stand-by
LED turns off, the component is off.

Stand-by Mode

When the AC power cord is plugged into the wall and the back panel power switch is in
the up (on) position, the red stand-by LED illuminates, indicating that the component is
in stand-by mode. This low power consumption status keeps the audio and regulator
circuits at idle. Krell recommends leaving the component in the stand-by mode when it
is not playing music.

Operational Mode

From the stand-by mode, when the power button on the front panel is pressed and the
blue power indicator illuminates, the component is in the operational mode and ready to
play music.

TECHNOLOGY

Krell Current Mode

A proprietary Krell circuit topology in which the audio gain stages of a component
operate in the current rather than voltage domain. This unique technology provides the
component with exceptional speed and a wide bandwidth.

4

Krell KAV–2250 and KAV–3250

Unpacking

1. Open the shipping box and remove the top layer of foam. You see these items:

1 amplifier unit (packed in foam end-caps)
1 IEC connector (AC power) cord

1 12 VDC output (12 V trigger) cable
1 T-15 Torx wrench
KAV–2250 fuses:
2 AGC-12 (12-amp)
or
KAV–3250 fuses:
3 AGC-12 (12-amp)
1 packet containing the owner’s reference manual
and the warranty registration card.

2. Locate the cutouts in the foam end caps.

3. Slip hands under cutouts and lift the amplifier straight out of the box.

4. 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 transit damage. See

Return Authorization Procedure,

on page 25, for more information.
The KAV–2250 weighs 64 lbs. and the KAV–3250 weighs 68 lbs. It may be more

convenient for two people to lift the amplifier out of the shipping box.

Krell KAV–2250 and KAV–3250 5

Placement

Before you integrate your new amplifier into your system, please review the following
guidelines to choose the location for the component. This will facilitate a clean, trouble­free installation.

The amplifier requires at least two inches (5 cm) of clearance on each side and at least
two inches (5 cm) of clearance above and below the component to provide adequate
ventilation.

The amplifier does not require any type of special rack or cabinet for installation. For the
dimensions of your amplifier see

Specifications

,

on pages 26 and 27.

Place the amplifier as close to the loudspeakers as possible and keep the loudspeaker
cable length to a minimum. Loudspeaker 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 loudspeaker cables reduce the maximum power that is
delivered to the loudspeakers.

AC POWER GUIDELINES

Krell recommends operating the amplifier from a dedicated 15-amp AC power line.
Please contact your authorized Krell dealer, distributor, or Krell before using any
devices designed to alter or stabilize the AC power for the KAV–2250 and KAV–3250.
`

Power Cord

The KAV–2250 and KAV–3250 should be operated only with the power cord supplied.

KAV–2250

132

Figure 1 The KA V–2250 Front Panel

KAV–3250

132

Figure 2 The KA V–3250 Front Panel

1 Power Button
2 Stand-by LED
3 Power Indicator

6 Krell KAV–2250 and KAV–3250