Krell Industries Stereo Amplifier KAV2250 User Manual

KAV–2250  
Stereo Power Amplifier  
THE LEADER IN AUDIO ENGINEERING  
KAV–3250  
Three-channel Power Amplifier  
Instructions for Use  
Owner’s Reference  
 
Contents  
Page  
INTRODUCTION  
1
2
4
5
5
7
9
DEFINITION OF TERMS  
UNPACKING  
PLACEMENT  
AC Power Guidelines  
FRONT PANEL DESCRIPTION  
BACK PANEL DESCRIPTION  
CONNECTING THE AMPLIFIER TO YOUR SYSTEM  
Input and Output Connections  
AMPLIFIER OPERATION  
11  
11  
13  
On/Off and Operation  
Using a Dedicated Wall Switch  
13  
13  
TROUBLESHOOTING SYSTEM NOISE  
14  
15  
RECONFIGURATION OPTIONS FOR THE KAV–2250 AND KAV–3250  
To Safely Access the Input Switch Banks  
Amplifier Factory Default Settings  
Reconfiguring the Amplifier for MAT Operation  
Reconfiguring the Amplifier for Bridged Operation  
Example of a Connection Scenario: Multi-power Mode  
15  
18  
18  
21  
22  
QUESTIONS AND ANSWERS  
WARRANTY  
23  
24  
25  
RETURN AUTHORIZATION PROCEDURE  
SPECIFICATIONS  
KAV–2250  
26  
27  
KAV–3250  
Krell KAV–2250 and KAV–3250  
iii  
 
Illustrations  
Page  
FIGURE 1 The KAV–2250 Front Panel  
6
6
FIGURE 2 The KAV–3250 Front Panel  
FIGURE 3 The KAV–2250 Back Panel  
8
FIGURE 4 The KAV–3250 Back Panel  
8
FIGURE 5 Amplifier Factory Default Settings  
FIGURE 6 Reconfiguring the KAV–2250 for MAT Operation  
FIGURE 7 Reconfiguring the KAV–3250 for MAT Operation  
FIGURE 8 Reconfiguring the KAV–2250 for Bridged Operation  
FIGURE 9 Reconfiguring the KAV–3250 for Bridged Operation  
16  
17  
17  
20  
20  
iv  
Krell KAV–2250 and KAV–3250  
 
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.  
Krell KAV–2250 and KAV–3250  
1
 
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.  
2
Krell KAV–2250 and KAV–3250  
 
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.  
Krell KAV–2250 and KAV–3250  
3
 
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.  
4
Krell KAV–2250 and KAV–3250  
 
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, trouble-  
free 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.  
Krell KAV–2250 and KAV–3250  
5
 
Figure 1 The KAV–2250 Front Panel  
KAV2250  
1
3
2
Figure 2 The KAV–3250 Front Panel  
KAV3250  
1
3
2
1
2
3
Power Button  
Stand-by LED  
Power Indicator  
6
Krell KAV–2250 and KAV–3250  
 
Front Panel Description  
See Figures 1 and 2 on page 6  
The front panel on the KAV–2250 and the KAV–3250 provides power on and indicates  
operating status.  
1 Power Button  
Use this button to switch the power between the stand-by and the operational modes  
and also to switch the 12 VDC output (12 V trigger) on and off.  
2 Stand-by LED  
The red stand-by LED illuminates when the AC power cord is plugged into the wall and  
the back panel power switch is in the up (on) position.  
3 Power Indicator  
The blue power indicator illuminates when the amplifier is in the operational mode.  
Krell KAV–2250 and KAV–3250  
7
 
Figure 3 The KAV–2250 Back Panel  
6
4
11  
12  
12VDC  
INPUT 2  
INPUT 1  
30 mA max. OUT  
IN  
KAV–2250  
Two-channel  
Power Amplifier  
KRELL INDUSTRIES, INC.  
45 CONNAIR ROAD  
ORANGE, CT 06477-3650  
USA  
OUTPUT 1  
OUTPUT 2  
AGC-12  
AGC-12  
50/60 Hz  
MADE IN USA  
NO USER SERVICEABLE PARTS INSIDE  
BRIDGE  
8
10  
8
10  
14  
13  
Figure 4 The KAV–3250 Back Panel  
7
5
11  
12  
12VDC  
INPUT 3  
INPUT 2  
INPUT 1  
30 mA max. OUT  
IN  
KAV–3250  
Three-channel  
Power Amplifier  
KRELL INDUSTRIES, INC.  
45 CONNAIR ROAD  
ORANGE, CT 06477-3650  
USA  
OUTPUT 1  
OUTPUT 3  
OUTPUT 2  
AGC-12  
AGC-12  
AGC-12  
50/60 Hz  
MADE IN USA  
NO USER SERVICEABLE PARTS INSIDE  
BRIDGE  
14  
13  
9
10  
9
10  
9
10  
Balanced Inputs  
4 Inputs 1-2  
5 Inputs 1-3  
Single-Ended Inputs  
6 Inputs 1-2  
7 Inputs 1-3  
Amplifier Channel  
Outputs  
8 Outputs 1-2  
9 Outputs 1-3  
Fuses  
Remote Connections  
11 12 VDC Remote Power Out  
12 12 VDC Remote Power In  
Power  
13 IEC Power Connector  
14 Back Panel Power Switch  
10 AGC-12 Fuses  
8
Krell KAV–2250 and KAV–3250  
 
Back Panel Description  
See Figures 3 and 4 on page 8  
The back panel on the KAV–2250 and the KAV–3250 provides connections for all inputs  
and outputs, remote connection input and output links, and the AC power supply. See  
Reconfiguration Options for the KAV–2250 and the KAV–3250, on pages  
15-22, for information on optional system configurations and amplifier channel output  
connections.  
Balanced Inputs  
4 Inputs 1-2  
The KAV–2250 has two channel inputs for output devices with balanced XLR  
connectors.  
5 Inputs 1-3  
The KAV–3250 has three channel inputs for output devices with balanced XLR  
connectors.  
Single-ended Inputs  
6 Inputs 1-2  
The KAV–3250 has two channel inputs for output devices with single-ended RCA  
connectors.  
7 Inputs 1-3  
The KAV–3250 has three channel inputs for output devices with single-ended RCA  
connectors.  
Amplifier Channel Outputs  
8 Outputs 1-2  
The KAV–2250 has two amplifier channel outputs. The loudspeaker binding post  
terminals accept spade lugs, bare wire, or pins. Use the red terminal for the positive  
connection and the black terminal for the negative connection.  
9 Outputs 1-3  
The KAV–3250 has three amplifier channel outputs. The loudspeaker binding post  
terminals accept spade lugs, bare wire, or pins. Use the red terminal for the positive  
connection and the black terminal for the negative connection.  
IMPORTANT  
Tighten loudspeaker binding posts by hand only.  
Krell KAV–2250 and KAV–3250  
9
 
Back Panel Description, continued  
Fuses  
10 AGC-12 Fuses  
The AGC-12 Amp loudspeaker fuses protect the amplifier against short circuits at the  
amplifier outputs.  
Back Panel Remote Connections  
11 12 VDC Remote Power Out  
The amplifier is equipped with an output that sends 12 VDC power on/off  
(12 V trigger) signals to other Krell components and other devices that incorporate  
a 12 V trigger.  
12 12 VDC Remote Power In  
The amplifier is equipped with an input that receives 12 VDC power on/off (12 V trigger)  
signals from other Krell components and other devices that incorporate a 12 V trigger.  
This allows you to turn the amplifier on and off using a Krell or other component in a  
custom installation.  
Notes  
When the component is in the operational mode, the 12 VDC Out provides 12 V of DC  
output. When the component is in the stand-by mode or off, the DC output is 0 V.  
12 VDC Out (12 V trigger) current is limited to 30 mA.  
Consult the owner’s manual of each component used in a custom installation to take full  
advantage of the amplifier’s remote capability.  
Power  
13 IEC Power Connector  
The amplifier is equipped with a standard female IEC power connector, for use with the  
provided AC power cord.  
14 Back Panel Power Switch  
Use this switch to turn the amplifier from off to the stand-by mode.  
10  
Krell KAV–2250 and KAV–3250  
 
Connecting the Amplifier to Your System  
INPUT AND OUTPUT CONNECTIONS  
The amplifier is equipped with balanced and single-ended inputs.  
Krell recommends using balanced interconnect cables. Balanced interconnect cables  
not only can minimize sonic loss but are also immune to induced noise, especially with  
installations using long cables. Balanced connections have 6 dB more gain than single-  
ended connections. When level matching is critical, please keep this gain value in mind.  
The amplifier is shipped with shorting pins in the XLR inputs. These pins should remain  
in the XLR inputs if the amplifier is operating in the single-ended mode. When the  
shorting pin is inserted, pins 1 (lower left) and 3 (top) are shorted together. Remove the  
shorting pins to connect the amplifier for balanced operation.  
The XLR pin configuration is described below:  
Pin 1 Shield (ground)  
Pin 2 Non-inverting (hot) (0°)  
Pin 3 Inverting (cold) (180°)  
Follow these steps to connect the amplifier to your system.  
1. Make sure all power sources and components are off before connecting inputs and  
outputs.  
2. Neatly organize the wiring between the amplifier and all system components.  
Separate AC wires from audio cables to prevent hum or other unwanted noise from  
being introduced into the system.  
3. Connect the interconnect cables from your output device to the amplifier inputs using  
the balanced or single-ended inputs located on the back panel: (4) and (6) on the  
KAV–2250 or (5) and (7) on the KAV–3250. The balanced inputs use three-pin XLR  
connectors; the single-ended inputs use RCA connectors.  
IMPORTANT  
Use only one input to each amplifier channel at a time.  
Krell KAV–2250 and KAV–3250  
11  
 
Connecting the Amplifier, continued  
4. Connect the loudspeaker cables to the amplifier channel output binding posts  
located on the back panel, (8) on the KAV–2250 or (9) on the KAV–3250.  
The binding post terminals accept spade lugs, bare wire, or pins. Use the red  
terminal for the positive connection and the black terminal for the negative  
connection.  
IMPORTANT  
Tighten loudspeaker binding posts by hand only.  
5. Plug the end of the AC power cord into the IEC power connector.  
The amplifier is now ready for operation. See Amplifier Operation, on page 13. You  
can also reconfigure the amplifier for Multi Amp Throughput or bridged operation. See  
Reconfiguration Options for the KAV–2250 and the KAV–3250, on page 15.  
12  
Krell KAV–2250 and KAV–3250  
 
Amplifier Operation  
ON/OFF AND OPERATION  
When powering up your system, turn amplifiers on last. When powering down your  
system, turn amplifiers off first. The procedures for amplifier operation follow.  
1. Plug the AC power cord into the AC power wall receptacle.  
2. Push the back panel power switch (14) up (on). The red stand-by LED (2)  
illuminates.  
3. Press the power button (1) on the front panel. The blue power indicator (3)  
illuminates and you hear a click.  
There will be a brief delay before the component can be put in the operational mode  
after the back panel power switch is first pushed up.  
Krell recommends leaving the amplifier in the stand-by mode unless you will not be  
playing music for a long time.  
IMPORTANT  
Always turn the amplifier off before changing input connections, and mute or fully  
attenuate the preamplifier level when switching sources.  
The amplifier has tremendous reserves of power and safely drives loudspeakers to  
extremely high sound pressure levels. However, use care when setting high playback  
levels and lower the volume level at any sign of loudspeaker distress.  
USING A DEDICATED WALL SWITCH  
The amplifier can also be powered on from an AC wall receptacle with a dedicated  
switch, rather than from the front panel power button. Please contact your authorized  
Krell dealer, distributor, or Krell for more information before you connect the amplifier to  
a dedicated AC wall outlet with a switch.  
Krell KAV–2250 and KAV–3250  
13  
 
Troubleshooting System Noise  
When you mix and match high-performance audio components, each with its own  
ground potential, a low frequency hum may occur in one or all loudspeakers. If this  
happens when you place the amplifier into your system, follow these simple  
troubleshooting steps:  
1. Check that all input and output connections are of sound construction.  
2. With the amplifier off, remove all the interconnect cables, then turn the amplifier  
on. If the hum disappears, turn the amplifier off and reinsert one of the  
interconnect cables. Turn the amplifier back on.  
3. If the hum reappears with the interconnect cable reinserted, the cable may need  
to be replaced. Turn the amplifier off and connect a different interconnect cable to  
the same location. Turn the amplifier back on.  
4. If the hum disappears with the interconnect cable reinserted, that cable most  
likely is sound.  
5. Turn the amplifier off, disconnect the interconnect cable, and re-connect one of  
the other interconnect cables.  
6. Repeat steps 3 through 5 until you have checked each interconnect cable  
individually.  
7. If all the interconnect cables appear to be sound, and if you still have hum, you  
may be experiencing a ground loop. Please contact your authorized Krell dealer,  
distributor, or Krell for suggestions on how to eliminate it.  
14  
Krell KAV–2250 and KAV–3250  
 
Reconfiguration Options for the KAV–2250  
and KAV–3250  
There are a number of options for reconfiguring the amplifier output:  
Multi Amp Throughput (MAT) is an internal connection option for the amplifier that lets  
you send 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.  
Bridging allows you to reconfigure two channels to operate as one combined amplifier  
channel. The bridged amplifier channels deliver 1,000 Watts into an 8 Ohm load. The  
remaining unbridged amplifier channel on the KAV–3250 can be connected to a  
separate loudspeaker.  
To reconfigure the amplifier for MAT or for bridged operation you need to remove the  
top cover of the amplifier and access the input switch banks.  
IMPORTANT  
Removing the cover of the amplifier to reconfigure for MAT or for bridged operation is  
the ONLY instance you are authorized to remove the cover of ANY Krell component  
without voiding your Warranty. For more information on product limitations and  
restrictions, see Warranty, on page 24.  
TO SAFELY ACCESS THE INPUT SWITCH BANKS  
Before reconfiguring the amplifier, please read the following important instructions to  
safely remove the amplifier cover and access the input switch banks to reconfigure the  
KAV–2250 or KAV–3250.  
Tool needed: T-15 Torx wrench  
1. Unplug the AC power cord from AC power.  
2. Krell suggests removing jewelry before reconfiguring your amplifier. Rings,  
necklaces, bracelets, and other metal jewelry can conduct an electrical charge.  
3. Using the T-15 Torx wrench, remove the 12 screws that secure the amplifier cover.  
4. Carefully remove the cover.  
5. Locate the green input circuit board, which has white input switches and red input  
switch banks, at the rear of the amplifier  
Krell KAV–2250 and KAV–3250  
15  
 
Figure 5 Amplifier Factory Default Settings  
KAV–2250  
Input Circuit Board  
MT1  
Channel 1 Input  
Bridge Channel 2 Input  
O
N
O
N
1
2
1
1
2
S3  
S2  
S1  
J5  
J6  
KAV–3250  
Input Circuit Board  
MT1  
Channel 1 Input  
Bridge  
1
Channel 2 Input  
Channel 3 Input  
O
N
O
N
O
N
1
2
3
1
2
3
1
2
3
S4  
S2  
S1  
J7  
J8  
S3  
J9  
Switch Up (On)  
Switch Down (Off)  
Bridge Switch Up (On)  
Bridge Switch Down (Off)  
O
N
1
2
KAV–2250 Input Switch Bank  
KAV–3250 Input Switch Bank  
O
N
1
2
3
16  
Krell KAV–2250 and KAV–3250  
 
Figure 6 Reconfiguring the KAV–2250 for MAT Operation  
Send One Input Signal  
to Both Output Channels via Input 1  
Input Circuit Board  
MT1  
Channel 1 Input  
Bridge Channel 2 Input  
O
N
O
N
1
2
1
1
2
S3  
S2  
S1  
J5  
J6  
Figure 7 Reconfiguring the KAV–3250 for MAT Operation  
Send One Input Signal  
to All Three Output Channels via Input 1  
Input Circuit Board  
MT1  
Channel 1 Input  
Bridge  
1
Channel 2 Input  
Channel 3 Input  
O
N
O
N
O
N
1
2
3
1
2
3
1
2
3
S4  
S2  
S1  
J7  
J8  
S3  
J9  
Switch Up (On)  
Switch Down (Off)  
Bridge Switch Up (On)  
Bridge Switch Down (Off)  
O
N
1
2
KAV–2250 Input Switch Bank  
KAV–3250 Input Switch Bank  
O
N
1
2
3
Krell KAV–2250 and KAV–3250  
17  
 
Reconfiguration Options, continued  
Accessing the Input Switch Banks, continued  
6. Reconfigure your amplifier, using the scenarios described below.  
7. After the component is configured, replace the cover and, using the T-15 Torx  
wrench, secure all 12 cover screws.  
IMPORTANT  
Operating the amplifier without the cover properly replaced and secured may void your  
Warranty.  
AMPLIFIER FACTORY DEFAULT SETTINGS  
See Figure 5 on page 16  
The KAV–2250 amplifier is shipped with input switch banks set to the following factory  
defaults:  
1. For input switch bank 1: switch 1 up (on), switch 2 down (off).  
2. For input switch bank 2: switch 1 down (off), switch 2 up (on).  
The KAV–3250 amplifier is shipped with input switch banks set to the following factory  
defaults:  
1. For input switch bank 1: switch 1 up (on), other switches down (off).  
2. For input switch bank 2: switch 2 up (on), other switches down (off).  
3. For input switch bank 3: switch 3 up (on), other switches down (off).  
RECONFIGURING THE AMPLIFIER FOR MAT OPERATION  
Reconfiguring the KAV–2250 for MAT: Send One Input Signal  
to Both Output Channels via Input 1  
See Figure 6 on page 17  
To send the signal from a source device connected to input 1:  
1. Push switch 1 up (on) for both input switch banks.  
2. Push switch 2 down (off) for both input switch banks.  
18  
Krell KAV–2250 and KAV–3250  
 
Reconfiguration Options, continued  
Reconfiguring the KAV–2250 for MAT: Send One Input Signal  
to Both Output Channels via Input 2  
Not illustrated  
To send the signal from a source device connected to input 2:  
1. Push switch 2 up (on) for both input switch banks.  
2. Push switch 1 down (off) for both input switch banks.  
Reconfiguring the KAV–3250 for MAT: Send One Input Signal  
to All Three Output Channels via Input 1  
See Figure 7 on page 17  
To send the signal from a source device connected to input 1:  
1. Push switch 1 up (on) for all input switch banks.  
2. Push switches 2 and 3 down (off) for all input switch banks.  
Reconfiguring the KAV–3250 for MAT: Send One Input Signal  
to All Three Output Channels via Any Input  
Not illustrated  
You can send the signal from any of the inputs, depending on your preference,  
for example:  
To send the signal from a source device connected to input 2:  
1. Push switch 2 up (on) for all input switch banks.  
2. Push switches 1 and 3 down (off) for all input switch banks.  
or  
To send the signal from a source device connected to input 3:  
1. Push switch 3 up (on) for all input switch banks.  
2. Push switches 1 and 2 down (off) for all input switch banks.  
Krell KAV–2250 and KAV–3250  
19  
 
Figure 8 Reconfiguring the KAV–2250 for Bridged Operation  
Bridge Channel 1 and 2  
Input Circuit Board  
MT1  
Channel 1 Input  
Bridge Channel 2 Input  
O
N
O
N
1
2
1
1
2
S3  
S2  
S1  
J5  
J6  
Figure 9 Reconfiguring the KAV–3250 for Bridged Operation  
Bridge Channel 1 and 2  
Input Circuit Board  
MT1  
Channel 1 Input  
Bridge  
1
Channel 2 Input  
Channel 3 Input  
O
N
O
N
O
N
1
2
3
1
2
3
1
2
3
S4  
S2  
S1  
J7  
J8  
S3  
J9  
Switch Up (On)  
Switch Down (Off)  
Bridge Switch Up (On)  
Bridge Switch Down (Off)  
KAV–2250 Input Switch Bank  
KAV–3250 Input Switch Bank  
O
N
1
2
O
N
1
2
3
20  
Krell KAV–2250 and KAV–3250  
 
Reconfiguration Options, continued  
Connecting the Amplifier Reconfigured for MAT  
1. Connect the cable from your source device to the balanced or single-ended input  
you have selected to receive the signal. (For example, if you use the switch settings  
shown in Figure 6 your source device is connected to input 1.)  
2. Connect each amplifier channel output to a separate loudspeaker.  
RECONFIGURING THE AMPLIFIER FOR BRIDGED OPERATION  
Reconfiguring the KAV–2250 or the KAV–3250 to Bridge Channels 1 and 2  
See Figures 8 and 9 on page 20  
To send the signal from a source device connected to input 1,  
with channels 1 and 2 bridged:  
1. For input switch bank 1, push switch 1 up (on).  
2. For input switch bank 2, push switch 1 up (on).  
3. Push the bridge switch up (on) between input switch banks 1 and 2.  
Notes  
Amplifier channels 1 and 2 may be bridged. Channel 3 on the KAV–3250 cannot be  
bridged.  
The unbridged channel on the KAV–3250 may be connected to a separate loudspeaker  
for normal operation.  
Connecting the Amplifier Reconfigured for Bridged Operation  
1. Connect the cable from the input device to the balanced or single-ended input you  
have selected to receive the signal.  
2. Connect the positive loudspeaker lead to the red binding post on the corresponding  
amplifier channel marked “BRIDGE +.” Connect the negative loudspeaker lead to the  
red binding post on the amplifier channel marked “BRIDGE -.”  
IMPORTANT  
Tighten binding posts by hand only.  
Krell KAV–2250 and KAV–3250  
21  
 
Reconfiguration Options, continued  
EXAMPLE OF A CONNECTION SCENARIO: MULTI-POWER MODE  
Multi-power mode is a possible connection scenario that uses the amplifier’s Multi Amp  
Throughput (MAT) feature. With multi-power mode, you can reconfigure the amplifier to  
independently power multiple pairs of stereo loudspeakers and extend the listening envi-  
ronment throughout your home. When the amplifier is reconfigured for MAT, each channel  
powers an individual loudspeaker, with one amplifier dedicated to driving outputs to the left  
loudspeakers and one amplifier driving outputs to the right loudspeakers.  
The diagram below illustrates a multi-power mode connection scenario:  
Left Speakers  
Kitchen (L)  
Patio (L)  
Gym (L)  
+
+
+
Left Amplifier  
Right Amplifier  
Kitchen (R)  
Patio (R)  
Gym (R)  
+
+
+
Right Speakers  
22  
Krell KAV–2250 and KAV–3250  
 
Questions and Answers  
Q. Should I turn the amplifier off when not playing music?  
A. No. Leave the amplifier in stand-by when not playing music. The stand-by mode  
avoids cold starts as well as minimizes heat output and power consumption. Krell  
recommends turning the amplifier off if you plan to be away for a period of time, for  
example, on vacation. See Amplifier Operation, on page 13.  
Q. When I turn the amplifier on there is a loud hum through the loudspeakers. What  
should I do?  
A. When a new component is introduced, a low frequency hum may occur in one or  
both loudspeakers. Check that all input and output connections and cables are of sound  
construction. See Troubleshooting System Noise, on page 14. If the connections and  
cables are sound, you may be experiencing a ground loop. This can often be easily  
eliminated. Please contact your authorized Krell dealer, distributor, or Krell for  
suggestions.  
Q. When I connect the amplifier to my system using the single-ended inputs, a loud  
buzz comes from my loudspeakers. What is it?  
A. Check that the shorting pins for the amplifier are inserted into the XLR inputs (the unit  
is shipped with the pins in place). When using the single-ended inputs, the shorting pins  
must be inserted between pins 1 and 3 to keep external noise from corrupting the  
signal. For more information, see Connecting the Amplifier to Your System, on page  
11.  
Q. Can I bridge all the channels on my KAV–3250 amplifier?  
A. No. You can bridge two of the amplifier’s channels: 1 and 2. Channel 3 cannot be  
bridged.  
Q. Will I be able to use the amplifier without reconfiguring the channels for MAT or  
bridged operation?  
A. Yes. The amplifier is shipped from the factory ready to play music. The default  
settings, see Figure 5, on page 16, allow you to connect each amplifier channel output  
to a separate loudspeaker. MAT and bridging reconfigurations are optional.  
Krell KAV–2250 and KAV–3250  
23  
 
Warranty  
This Krell product has a limited warranty of five years for  
parts and labor on circuitry. Should this product fail to per-  
form at any time during the warranty, Krell will repair it at no  
cost to the owner, except as set forth in this warranty.  
Krell will pay return freight to the U.S.A.-based freight for-  
warder of your choice. Freight and other charges to ship the  
unit from the freight forwarder to you are also your respon-  
sibility.  
The warranty does not apply to damage caused by acts of  
God or nature.  
Krell is not responsible for any damage incurred in transit.  
Krell will file claims for damages as necessary for units dam-  
aged in transit to the factory. You are responsible for filing  
claims for shipping damages during the return shipment.  
The warranty on this page shall be in lieu of any other war-  
ranty, expressed 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 con-  
sequential damages arising from purchase, use, or inability  
to use this product, even if Krell has been advised of the  
possibility of such damages.  
Krell does not supply replacement parts and/or products to  
the owner of the unit. Replacement parts and/or products  
will be furnished only to the distributor performing service on  
this unit on an exchange basis only; any parts and/or prod-  
ucts 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.  
Proof of purchase in the form of a bill of sale or receipted  
invoice substantiating that the unit is within the warranty  
period must be presented to obtain warranty service. The  
warranty begins on the date of the original retail purchase,  
as noted on the bill of sale or receipted invoice from an  
authorized Krell dealer or distributor. Previously owned  
equipment, when re-purchased from an authorized Krell  
dealer or distributor, has the balance of the original warran-  
ty, based on the original date of manufacture.  
Any unauthorized voltage conversion, disassembly,  
component replacement, perforation of chassis,  
updates, or modifications performed to the unit will  
void the warranty.  
The operating voltage of this unit is determined by the fac-  
tory and can only be changed by an authorized Krell distrib-  
utor or at the factory. The voltage for this product in the  
U.S.A. cannot be changed until six months from the original  
purchase date.  
The warranty for Krell products is valid only in the country to  
which they were 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 regulations within a specific country. Please  
check with your distributor for a complete understanding of  
the warranty in your country.  
In the event that Krell receives a product for warranty ser-  
vice that has been modified in any way without Krell autho-  
rization, all warranties on that product will be void. The prod-  
uct 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 fac-  
tory specifications will be charged to the customer, at cur-  
rent parts and labor rates.  
If a unit is serviced by a distributor who did not import the  
unit, there may be a charge for service, even if the product  
is within the warranty period.  
All operational features, functions, and specifications and  
policies are subject to change without notification.  
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.  
To register your product for warranty benefits,  
please complete and return the Warranty  
Registration Card enclosed in the shipping box  
within 15 days of purchase. Thank you.  
24  
Krell KAV–2250 and KAV–3250  
 
To return this product to Krell, please  
follow this procedure so that we may  
serve you better:  
Return Authorization  
Procedure  
1. Obtain a Return Authorization Number  
(R/A number) and shipping address  
from the Krell Service Department.  
If you believe there is a problem with your  
component, please contact your dealer, dis-  
tributor, or the Krell factory to discuss the  
problem before you return the component for 2. Insure and accept all liability for loss of  
repair. To expedite service, you may wish to  
complete and e-mail the Service Request  
Form in the Service Section of our website  
at:  
or damage to this product during ship-  
ment to the Krell factory and prepay all  
shipping charges. Please see the  
Warranty page in this manual, concern-  
ing liability for shipping damage and  
shipping charges.  
This product may also be hand delivered if  
arrangements with the Service Department  
have been made in advance. Proof of pur-  
chase will be required for warranty valida-  
tion at the time of hand delivery.  
To contact the Krell Service Department  
TEL  
203-799-9954  
Monday-Friday  
9:00 AM to 5:00 PM EST  
FAX  
203-799-9796  
E-MAIL  
IMPORTANT  
Use the original packaging to ensure safe  
transit of this product to the dealer, distribu-  
tor, or factory. Krell may, at its discretion,  
return this product in new packaging and bill  
the owner for such packaging if the product  
received by Krell was boxed in non-stan-  
dard packaging or if the original packaging  
was so damaged that it was unuseable. If  
Krell determines that new packaging is  
required, the owner will be notified before  
this product is returned.  
PRODUCT NAME  
MODEL NUMBER  
SERIAL NUMBER  
To purchase additional packaging, please  
contact your authorized Krell dealer, distrib-  
utor, or the Krell Service Department.  
Krell KAV–2250 and KAV–3250  
25  
 
Specifications  
KAV–2250  
FREQUENCY  
RESPONSE  
20 Hz to 20 kHz  
0.25 Hz to 170 kHz  
+0 dB, -0.09 dB  
+0 dB, -3 dB  
SIGNAL TO NOISE  
RATIO  
“A” WEIGHTED  
>112 dB  
TOTAL HARMONIC  
DISTORTION (THD)  
1 kHz  
20 kHz  
< 0.03%  
< 0.20%  
GAIN  
25.7 dB  
INPUT IMPEDANCE  
INPUT SENSITIVITY  
OUTPUT VOLTAGE  
100 kOhms  
2.32 Vrms  
Peak to Peak  
RMS  
127 V  
45 V  
OUTPUT POWER  
EACH CHANNEL  
8 Ohms  
4 Ohms  
8 Ohms  
250 W  
500 W  
1000 W  
BRIDGED  
POWER  
CONSUMPTION  
Standby  
Idle  
35 W  
80 W  
Max.  
2000 W  
INPUTS  
2 single-ended via RCA connectors  
2 balanced via XLR connectors  
OUTPUTS  
2 amplifier channels via five-way binding posts  
12 VDC Out (12 V trigger) via a 3.5 mm connector  
12 VDC In (12 V trigger) via a 3.5 mm connector  
17.3w x 5.6h x 17.1d in.  
REMOTE CONNECTORS  
DIMENSIONS  
43.8w x 14.3h x 43.4d cm  
WEIGHT  
SHIPPING  
UNIT ONLY  
74.0 lb., 33.5 kg  
64.0 lb., 29.0 kg  
All operational features, functions, specifications, and policies are subject to change without notification.  
26  
Krell KAV–2250 and KAV–3250  
 
Specifications  
KAV–3250  
FREQUENCY  
RESPONSE  
20 Hz to 20 kHz  
0.25 Hz to 170 kHz  
+0 dB, -0.09 dB  
+0 dB, -3 dB  
SIGNAL TO NOISE  
RATIO  
“A” WEIGHTED  
>112 dB  
TOTAL HARMONIC  
DISTORTION (THD)  
1 kHz  
20 kHz  
< 0.03%  
< 0.20%  
GAIN  
25.7 dB  
INPUT IMPEDANCE  
INPUT SENSITIVITY  
OUTPUT VOLTAGE  
100 kOhms  
2.32 Vrms  
Peak to Peak  
RMS  
127 V  
45 V  
OUTPUT POWER  
EACH CHANNEL  
8 Ohms  
4 Ohms  
8 Ohms  
250 W  
500 W  
1000 W  
BRIDGED  
POWER  
CONSUMPTION  
Standby  
Idle  
45 W  
115 W  
Max.  
2000 W  
INPUTS  
3 single-ended via RCA connectors  
3 balanced via XLR connectors  
OUTPUTS  
3 amplifier channels via five-way binding posts  
12 VDC Out (12 V trigger) via a 3.5 mm connector  
12 VDC In (12 V trigger) via a 3.5 mm connector  
17.3w x 5.6h x 17.1d in.  
REMOTE CONNECTORS  
DIMENSIONS  
43.8w x 14.3h x 43.4d cm  
WEIGHT  
SHIPPING  
UNIT ONLY  
78.0 lb., 35.3 kg  
68.0 lb., 30.8 kg  
All operational features, functions, specifications, and policies are subject to change without notification.  
Krell KAV–2250 and KAV–3250  
27  
 
Krell Industries, Inc.  
KAV–2250  
45 Connair Road  
Stereo Power Amplifier  
Orange, CT 06477-3650 USA  
TEL 203-799-9954  
KAV–3250  
Three-channel Power Amplifier  
FAX 203-891-2028  
v 01.2  
 

Learning Resources Games LER 0341 User Manual
Legacy Car Audio Car Video System LD53M User Manual
LG Electronics Projector 1024X768 XGA User Manual
Logitech Universal Remote 880 User Manual
LST Smoke Alarm 7251 User Manual
Marantz Stereo Amplifier PM4400 OSE User Manual
McCulloch Lawn Mower M3750SM User Manual
Memorex Stereo System MX3900 User Manual
Metabo Saw KGS 255 Plus User Manual
MicroNet Technology Network Router SP5001 S User Manual