Krell Industries Amplifier KAV-250a Owner's Reference Manual

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KAV-250a

Amplifier

CONTENTS

KrelP Industries, Inc.
45 Connair Road

Orange, CT 06477-3650 USA

TEL [phone]

FAX [phone]
E-MAIL krell @ krellonline.com

INTRODUCTION
UNPACKING

PLACEMENT

Cabinetry Considerations
AC Power Guidelines

CONNECTING THE KAV-250a
TO YOUR SYSTEM

Input and Output Connections
Linking Multiple Amplifiers

Configuring the KAV-250a

for Bridged Operation

AM PLIFIER OPERATION

On/Off and Stand-by Operation
System Noise Considerations

WARRANTY

RETURN AUTHORIZATION

PROCEDURE
SPECIFICATIONS

Page

3
3
3

4
4

4
4

5

6
7

"7

7
8

9

12

ILLUSTRATIONS

THE KAV-250a BACKPLATE AND
CONNECTIONS FOR BRIDGED

OPERATION

Page

6

© 1997 by KRELL® Industries, Inc. All rights reserved

P/N 19608,0230,0000

CE Marking

This product complies with the EMC direc­tive (89/336/EEC) and the low-voltage

directive (73/23/EEC).

Introduction

Thank you for your purchase of the Krell

KAV-250a. To obtain the best performance
from your KAV-250a amplifier, pay careful
attention to its placement, installation, and
operation. A thorough understanding of
these details will help insure satisfactory
operation and long life for the KAV-250a
and related system components.

THERE ARE NO USER-SERVICEABLE

PARTS INSIDE ANY KRELL PRODUCT.

Please contact your authorized dealer,
distributor, or KrelP, if you have any
questions not addressed in this refer­ence manual.

Unpacking

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

1 KAV-250a
1

AC power cord

1 packet containing the Owner’s

Reference and the Warranty
Registration Card .~ ,’~ x ~’ ~x~

NOTE: If any of these items are n~cld~ed,
please contact your authorized Krefl dealer

or distributor immediately for assistance.

2. Carefully remove the unit and acces­sories from the box. Remove the protec­tive plastic wrap from the unit.

NOTE: Save all packing materials. If you
must ship your ~V-250a in the future,
repack the unff in its original packaging to
prevent transit damage.

Placement

WARNINGS

The amplifier must not be located where it
could be exposed to dripping or splashing
fluids.

Before you install the KAV-250a into your
system, review the following guidelines to
choose the location for the KAV-250a. This
will facilitate a clean, trouble-free installation.
The KAV-250a does not require any type of
special rack or cabinet for installation. For the

dimensions of the KA V-250a, see

Specifications on page 12.

Place the KAV-250a amplifier on a firm level
surface away from dirt or moisture. When

using custom racks or cabinetry, keep in
mind the weight and ventilation requirements
for this amplifier. Ideally, the amplifier should

KRELL® KAV-250a English Page 3 of 12

Placement, continued

be placed as close to the speakers as pos­sible. Run long balanced interconnect

cables to the amplifier 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. All Krell amplifiers will drive
the lowest impedances with ease, but when

impedance is added due to long cable
lengths, amplifier power is wasted in the
cable. Long speaker cables reduce the

maximum power that can be delivered to
the speakers.

CabMetry Considerations

The KAV-250a amplifier can become quite
warm under normal operation. Install the
KAV-250a in a location that provides unob­structed ventilation. If you place the amplifi-

er in a closed cabinet, extra ventilation such
as modified shelf spacing may be neces-

sary. In extreme instances, small fans help
to removing excess heat from enclosed
spaces. In general, when the front and rear
of a cabinet is open, the amplifier has ade­quate ventilation with two inches of clear­ance on each side and eight inches of
clearance above and below.

AC Power Guidelines

For best performance, Krell® recommends
using a dedicated AC power line rated at a
minimum of fifteen amps with the KAV-250a
amplifier. For maximum power output, the
KAV-250a should be operated from a dedi-

cated twenty amp AC power line. The

KAV-250a amplifier should only be operated
with the power cord supplied. Please consult
your dealer, distributor, or Krell® before using
any devices designed to alter or stabilize the
AC power for the KAV-250a.

Connecting the KAV-250a

to Your System

WARNING

When making connections to this compo-

nent or any other, make sure the power

amplifier is Off and the preamplifier is in the

Mute or Stand-by mode. Make sure all cable
terminations are of the highest quality, free
from frayed ends, shorts, or cold solder joints.

Input and Output Connections

To prevent the introduction of hum or other

noise into the system, organize all wiring

between the KAV-250p and other system
components neatly. Separate AC wires from
audio cables.

1. Connect the cables from your speakers
to the output terminals of the amplifier.

The KAV-250a amplifier utilizes five­way binding post speaker terminals for
the left and right channels. The speaker
terminals accept spade lugs, bare wire,
banana plugs, or pins. The red terminals
are used for positive connections and
the black terminals are used for the neg­ative connections.

2. Connect the interconnect cables from
your preamplifier to the input terminals of
the amplifier.

The KAV-250a amplifier is equipped with
balanced and single-ended inputs. The
balanced inputs use three pin XLR con­nectors and the single-ended inputs use

RCA connectors. Krell® recommends the
use of balanced interconnects. Balanced
interconnects not only have the ability to

Page 4 of 12 English

KRELL® KAV-250a

minimize sonic loss but also have immu­nity to induced noise, especially for instal­lations using long cable lengths..Balan­ced connections have 6dB more gain
than single-ended connections. When
level matching is critical, keep this speci­fication in mind.

WARNING

Use only one set of inputs to the amplifier at a
time. The KAV-250a amplifier is shipped with
shorting pins in the XLR inputs. These pins
should remain in the XLR inputs if the
KAV-250a amplifier is operating in the single­ended mode. When the shorting pin is insert­ed, pins 1 and 3 are shorted together. The
shorting pins must be removed to connect the
KAV-250a amplifier for balanced operation.

The XLR pin configuration is described below:

Pin 1 Ground
Pin 2 Non-inverting (0

°)

Pin 3 Inverting (180

°)

3. Insert the AC power cord into the recepta­cle located on the back of the KAV-250a
amplifier. Insert the other end into the AC
wall receptacle.

4. The amplifier is now ~eady for operation.

See Amplifier Operation, on page 7.

Linking Multiple Amplifiers-­Multi Amp Throughput

TM

(MAT

Ti)

For systems containing multiple amplifiers,
Multi Amp Throughput

TM

(MAT

~M)

simplifies

installations. MAT

~-M

provides a daisy-chain

system option that reduces installation

complexity and cabling requirements. To

use this option, connect the outputs of the

amplifier (either balanced via XLR or single-

ended via RCA connectors) to the inputs of
another amplifier. The output of the first
amplifier sends the preamplifier signal to

the next amplifier in the chain.

12 VDC REMOTE POWER IN

This input accepts 12 volt power on/off sig-

nals from other Krell components, as well
as from other devices that incorporate a 12

volt power on/off trigger output. This allows
for remote turn on/off of the KAV-250a with

the power activation of another Krell com-

ponent as well as with with other compo­nents used in a custom installation.

12 VDC REMOTE POWER OUT

This output sends 12 volt power on/off sig-

nals to other Krell components, as well as
other devices that incorporate a 12 volt
power on/off trigger input. This allows for

remote turn on/off of the KAV-250a with the
power activation of another Krell compo~

nent as well as with other components used
in a custom installation,

NOTE: Consult the owner’s manual of any
device used in a custom installation to take

full advantage of the remote capability of
the KA V-250a.

KRELL® KAV-250a English Page 5 of 12

Configuring the KAV-250a
for Bridged Operation

The KAV-250a may be configured to operate
in a bridged mode. When bridged, the amplifi-

er will deliver 1000 watts to an 8 ohm load. To
implement this configuration:

1. Turn the KAV-250a off.

2. Locate the red switch on the back of the
amplifier and slide it from the NORMAL

position to the BRIDGED position. The

numeral 2 will appear on the switch, when
the switch is in the BRIDGED position.

Connect the interconnect cable to the

BRIDGED input, either balanced via the

XLR connector or single-ended via the

RCA connector. Do not use both inputs

simultaneously. Connect the speaker
cables to the speaker terminals labeled

BRIDGED(-) and BRIDGED(+). The
lifier is now ready for bridged operation.

THE KAV-250a BACKPLATE AND CONNECTIONS FOR BRIDGED OPERATI()N

NOTE: The KAV-250a may be configured for bridged operation using either
a single-ended input (1) or a balanced input (2)

1 Single-ended input, for connection to a preamplifer
2 Balanced input, for connection to a preamplifier
3

5-way binding post speaker terminals

4 Red switch in bridged position, (with the numeral 2 displayed)

5

Single-ended output, for connection to another amplifier
6 Balanced output, for connection to another amplifier
7 12 volt trigger input
8

12 volt trigger output

1

LINE IN

2

RIGHT LEFT

OUTPUT OUTPUT

C)

RIGHT ~ED LEFT ~NPUT)

(BRIDGED

(~

0 0

33

KAV-250a

Power Amplifier

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

No user serviceable parts inside

VOLTAGE FUSE

100-120 MDA-20
200-240 MDA-12

Q 50/60Hz

MADE IN USA

12VDC REMOTE

POWER

Page 6 of 12 English KRELL® KAV-250a

Amplifier Operation

It is easy to understand the operation of the
KAV-250a amplifier. However, great care
needs to be exercised when operating a sys-

tem that includes the KAV-250a, because of
the amplifier’s enormous power output.

Switching between active sources without
muting the preamplifier output, or bump­ing/miscuing a cartridge, can generate large

transients at low frequencies. The KAV-250a

amplifier may generate enough power with
these transients to damage most loudspeak­ers. All switching of sources should be done
with the preamplifier level either muted or fully
attenuated. Do not change inputs to the ampli­fier while the amplifier is On.

NOTE: Care must be taken when setting

high playback levels. Because of their

tremendous reserve of clean power, Krell

amplifiers can safely drive speakers to high-

er sound pressure levels than other ampli-

fiers. Always turn the level down at the first

sign of speaker distress.

On~Off and Standby Operation

When powering up any system, amplifiers
should always be turned on last and turned off
first.

1. Press the power button on the front panel
of the amplifier. You will hear a click. The

amplifier is ready for operation.

2. With the preamplifier in the Mute position,
or ’the volume control fully attenuated,
select a source. Turn the volume control

up to the desired listening level.

3.

When turning the system off, lower the
volume of the preamplifier completely or

place it into the Mute or Stand-by posi-

tion. Switch the amplifier to Stand-by by

pressing the power button. It is now safe

to turn off the rest of the system.

System Noise Considerations

AC grounding becomes critical when con-

necting high performance audio components.
When mixing and matching audio compo­nents, each with their own ground potential, a
low frequency hum may occur in one or both
speakers. This often occurs when introducing

¯ a new component into a system.

If there is a low frequency hum emanating
from the speakers when the KAV-250a
amplifier is placed into the system, follow
these simple trouble-shooting steps before
contacting your authorized Krell dealer, dis-

tributor, or Krell®:

1.

Check all input and output connections,
making sure they are of sound construc-

tion. With the amplifier Off, remove the
interconnect wiring and turn the amplifier
On. If the hum disappears, turn the ampli­fier Off and reinsert one of the intercdn­nect cables. Then turn the amplifier back
On. If the hum reappears with one or both
interconnects reinserted, there may be a

defective cable. Have the interconnect
cabling checked before proceeding.

2. If the interconnects prove to be sound,
you may be experiencing a ground loop.
This can often be easily eliminated. Con­tact your authorized Krell dealer, distribu­tor, or Krell

®.

English Page 7 of 12 KRELL® KAV-250a

Warranty

Krell® warrants this product to be free from
defects in material or workmanship for a

period of five years for circuitry and three
years for all mechanical components from
the original date of purchase. Should this

product fail to perform at any time during the
warranty, Krell® will repair it at no cost to the

owner, except as set forth in this warranty.
Transfer of warranty to a second owner occurs

automatically. Please contact Krell® to have
the name on the warranty changed. Transfer

of warranty does not extend the duration of
the original warranty period.

NOTE: This warranty does not apply to

damage caused by acts of God or nature.

The warranty period begins on the date of

retail purchase as noted on the retail sales

slip provided by an authorized Krell dealer

or distributor, or on the warranty registration

card sent to Krell

®.

In the event that an ade-

quate proof of purchase date is unavailable,
the warranty period will begin on the date
the product was originally shipped from the

factory. The warranty described in this para-

graph shall be in lieu of any other warranty,

express or implied, including, but not limited
to, any implied warranty of merchantability

or fitness for a particular purpose. There are

no Warranties which exceed beyond those

described in this document. If this product

does not perform as warranted herein, the

owner’s sole remedy shall be repair. In no

event will Krell® be liable for incidental or

consequential damages arising from pur-

chase, use, or inability to use this product,

even if Krell® has been advised of the pos-

sibility of such damages.

The warranty for this Krell product is valid
only in the country to which the product was
originally shipped, through the authorized

Krell distributor for that country, and at the

factory. There may be restrictions on or
changes to Krell’s warranty because of reg-

ulations within a specific country. Please

check with your distributor for a complete
understanding of the warranty in your coun­try.

Freight to the factory is your responsibility.
Return freight within the United States

(U.S.A.) is included in the warranty. If you
have purchased your Krell product outside
the U.S.A. and wish to have it serviced at
the factory, all freight and associated
charges to the factory are your responsibili­ty. Krell® will pay return freight to the U.S.A.­based freight forwarder of your choice.

Freight and other charges to ship the prod-

uct from the freight forwarder to you ai’e
also your responsibility.

The operating voltage of this product is
determined at the factory and can only be
changed by an authorized Krell distributor or
at the factory. The voltage for this product in
the U.S.A. cannot be changed for six months
from the original purchase date.

Any unauthorized voltage conversion, dis-
assembly, component replacement, perfo­ration of chassis, updates, or modifica­tions performed to the product will void
the warranty.

KRELL® KAV-250a English Page 8 of 12

Return Authorization
Procedure

IMPORTANT: If you befieve thero is a prob­lem with your unit, please contact your deal-

er, distributor, or the Krell factory immedi-

ately Do not return any unit to KrelP for

repair without first discussing the problem
and obtaining a Return Authorization
Number.

To return a product, the owner
is required to:

¯ Obtain a Return Authorization Number

(R/A number) and shipping address
from the Krell Service Department.

¯ Insure and accept all liability for loss or

damage to the product during shipment
to the Krell factory and prepay all ship­ping charges. The product may also be
hand delivered if arrangements with the
Service Department have been made in
advance. Proof of purchase may be re­quired for warranty validation at the time
of hand delivery.

¯ Use the original packaging to insure the

safe transit of the product to the factory,
dealer, or distributor. The use of any
packaging material other than the original
packaging materials is not recommend­ed. Krell® may, at its discretion, return a
product in new packaging and bill the
owner for such packaging if the product
received by Krell® was boxed in non­standard packaging or if the original
packaging was so damaged that it was
unusable. If Krell® determines that new
packaging is required, the owner will be

notified before the product is returned.
To purchase additional packaging,

please contact your authorized Krell

dealer, distributor, or the Krell Service

Department for assistance.

Krell® is not responsible for any damage
incurred in transit. Krell® will file claims for

damages as necessary for products dam­aged in transit to the factory. The owner is

responsible for filing claims for shipping dam-

ages that occur during the return shipment.

Replacement parts and/or products will be

furnished on an exchange basis only; any

parts and/or products returned to Krell® for

exchange become the property of Krell

®.

No expressed or implied warranty is made
for any Krell product damaged by accident,
abuse, misuse, natural or personal disaster,
or unauthorized modification.

In the event that Krell® receives a product
for warranty service which has been modi­fied in any way without Krell authorization,
all warranties on that product will be void.
The product will be returned to original fac­tory layout specifications at the owner’s
expense before it is repaired. All repairs

required after the product has been returned
to original factory specification will be
charged to the customer, at current parts
and labor rates.

To contact the Krell Service De ~artment

TEL [phone]

Monday-Friday
9:00 AM to 5:00 PM EST

FAX [phone]
E-MAIL krell @ krellonline.com

KAV-250a

PRODUCT SERIAL NUMBER

To register your product for warranty benefits,
complete and return the Warranty

Registration Card enclosed in the shipping
box within 15 days of purchase.

Page 9 of 12 English KRELL® KAV-250a

Krell® Industries, Inc.

45 Connair Road
Orange, CT 06477-3650USA

TEL [phone] FAX [phone]

E-MAIL krell @ krellonline.com

Specifications

FREQUENCY RESPONSE

20Hz-20KHz

.4Hz-170KHz

KAV-250a

+0.0, -0.1 dB
+0.0, -3.0dB

OUTPUT POWER, each channel driven

8 ohms 1,000W

(bridged)

8 ohms

250 W

SIGNAL TO NOISE RATIO

-118dB "A" weighted

DISTORTION

1KHz 0,06% THD

20KHz 0.25% THD

GAIN

26.4dB

INPUT SENSITIVITY

2.15 Vrms

INPUT IMPENDENCE

100K ohms

OUTPUT VOLTAGE

Peak to peak
RMS

138 V

49 V

4 ohms 500 W

POWER CONSUMPTION

Idle 210 W

Max. 1850 W

DIMENSIONS

19w x 6.3h x 15.3d in.

48.3w x16h x 38.9d cm

WEIGHT

Shipped
Unit only

57 Ibs., 25.9 kg
43 Ibs., 19.5 kg

All operational features, functions, specifications, and

3olicies are subject to change without notification.