KAV–2250 THE LEADER IN AUDIO ENGINEERING Stereo Power Amplifier KAV–3250 Three-channel Power Amplifier Instructions for Use Owner’s Reference
KAV–2250 Stereo Power Amplifier KAV–3250 Three-channel Power Amplifier Instructions for Use Krell Industries, Inc. 45 Connair Road Orange, CT 06477-3650 USA TEL 203-799-9954 FAX 203-891-2028 E-MAIL krell@krellonline.com WEBSITE http://www.krellonline.com v 01.2 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.
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 Input and Output Connections AMPLIFIER OPERATION On/Off and Operation Using a Dedicated Wall Switch 11 11 13 13 13 TROUBLESHOOTING SYSTEM NOISE 14 RECONFIGURATION OPTIONS FOR THE KAV–2250 AND KAV–3250 15 To Safely Access the Input Switch Banks Amplifier Factory Default Settings Reconfiguring the Ampli
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 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.
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.
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.
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.
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.
Figure 1 The KAV–2250 Front Panel KAV–2250 1 3 2 Figure 2 The KAV–3250 Front Panel KAV–3250 1 3 2 1 Power Button 2 Stand-by LED 3 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.
Figure 3 The KAV–2250 Back Panel 6 4 11 12 12VDC INPUT 2 INPUT 1 30 mA max. OUT KAV–2250 IN 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 KAV–3250 IN Three-channel Power Amplifier OUTPUT 3 AGC-12 AGC-12 KRELL INDUSTRIES, INC.
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.
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.
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 singleended connections. When level matching is critical, please keep this gain value in mind.
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.
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.
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.
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 singleended 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.
Figure 5 Amplifier Factory Default Settings KAV–2250 Input Circuit Board MT1 Channel 1 Input O 1 N S1 Bridge Channel 2 Input 1 2 J5 S2 S3 O 1 N 2 J6 KAV–3250 Input Circuit Board MT1 Channel 1 Input S1 O 1 N 2 Channel 2 Input Bridge 1 3 J7 S4 S2 O 1 N 2 Channel 3 Input 3 J8 S3 O 1 N 2 3 J9 Switch Up (On) Switch Down (Off) Bridge Switch Up (On) Bridge Switch Down (Off) O 1 N 2 KAV–2250 Input Switch Bank O N 1 2 3 KAV–3250 Input Switch Bank 16 Krell KAV–2250 and KAV–32
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 S1 O 1 N Bridge Channel 2 Input 1 2 J5 S2 S3 O 1 N 2 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 S1 O 1 N 2 Channel 2 Input Bridge 1 3 J7 S4 S2 O 1 N 2 Channel 3 Input 3 J8 S3 O 1 N 2 3 J9 Switch Up (On) S
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.
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.
Figure 8 Reconfiguring the KAV–2250 for Bridged Operation Bridge Channel 1 and 2 Input Circuit Board MT1 Channel 1 Input S1 O 1 N Bridge Channel 2 Input 1 2 J5 S2 S3 O 1 N 2 J6 Figure 9 Reconfiguring the KAV–3250 for Bridged Operation Bridge Channel 1 and 2 Input Circuit Board MT1 Channel 1 Input S1 O 1 N 2 Channel 2 Input Bridge 1 3 J7 S4 S2 O 1 N 2 Channel 3 Input 3 J8 S3 O 1 N 2 3 J9 Switch Up (On) Switch Down (Off) Bridge Switch Up (On) Bridge Switch Down (Off) O 1
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.
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 environment throughout your home.
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.
Warranty This Krell product has a limited warranty of five years for parts and labor on circuitry. 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. Krell will pay return freight to the U.S.A.-based freight forwarder of your choice. Freight and other charges to ship the unit from the freight forwarder to you are also your responsibility.
Return Authorization Procedure If you believe there is a problem with your component, please contact your dealer, distributor, or the Krell factory to discuss the problem before you return the component for repair. To expedite service, you may wish to complete and e-mail the Service Request Form in the Service Section of our website at: http://www.krellonline.com 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 service@krellonline.
Specifications KAV–2250 FREQUENCY RESPONSE 20 Hz to 20 kHz 0.25 Hz to 170 kHz SIGNAL TO NOISE RATIO “A” WEIGHTED >112 dB TOTAL HARMONIC DISTORTION (THD) 1 kHz 20 kHz GAIN 25.7 dB INPUT IMPEDANCE 100 kOhms INPUT SENSITIVITY 2.32 Vrms OUTPUT VOLTAGE Peak to Peak < 0.03% < 0.20% RMS OUTPUT POWER EACH CHANNEL +0 dB, -0.09 dB +0 dB, -3 dB 127 V 45 V 8 Ohms 4 Ohms 8 Ohms 250 W 500 W 1000 W POWER CONSUMPTION Standby Idle Max.
Specifications KAV–3250 FREQUENCY RESPONSE 20 Hz to 20 kHz 0.25 Hz to 170 kHz SIGNAL TO NOISE RATIO “A” WEIGHTED >112 dB TOTAL HARMONIC DISTORTION (THD) 1 kHz 20 kHz GAIN 25.7 dB INPUT IMPEDANCE 100 kOhms INPUT SENSITIVITY 2.32 Vrms OUTPUT VOLTAGE Peak to Peak < 0.03% < 0.20% RMS OUTPUT POWER EACH CHANNEL +0 dB, -0.09 dB +0 dB, -3 dB 127 V 45 V 8 Ohms 4 Ohms 8 Ohms 250 W 500 W 1000 W POWER CONSUMPTION Standby Idle Max.
Krell Industries, Inc. 45 Connair Road Orange, CT 06477-3650 USA TEL 203-799-9954 FAX 203-891-2028 E-MAIL krell@krellonline.com WEBSITE http://www.krellonline.com KAV–2250 Stereo Power Amplifier KAV–3250 Three-channel Power Amplifier v 01.
