Krell Industries 200c, 300c, 650Mc, 600c, 250Mc Instructions For Use Manual

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Full Power Balanced
Power Amplifiers
200c, 300c, 600c Stereo
250Mc, 350Mc, 650Mc Monaural
Instructions for Use
Owner’s Reference
Full Power Balanced Power Amplifiers
200c, 300c, 600c Stereo 250Mc, 350Mc, 650Mc Monaural
with Krell CAST Technology
v 00.0
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
This product complies with the EMC directive (89/336/EEC) and the low-voltage directive (73/23/EEC).
WARNINGS
The Full Power Balanced amplifier must be placed on a firm, level surface where it is not exposed to drip-
ping or splashing.
The ventilation grids on the top of the Full Power Balanced amplifier must be unobstructed at all times during
operation. Do not place flammable material on top of or beneath the component. Before making connections to the Full Power Balanced amplifier, ensure that ff is off and the 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.
The differential circuitry employed with Full Power Balanced amplifiers requires special attention when connect­ing speakers. DO not connect the negative speaker terminals together. Do not connect the negative speaker ter­minals to ground or attempt to bridge the left and right speaker binding posts of Full Power Balanced stereo ampli-
fiers. Do not connect a Full Power Balanced amplifier to a speaker selector device that employs a common
ground scheme, as it may short-circuit the amplifier output.
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 ;~roduct is manufactured in the United States of America. Krell~ is a registered trademark of Krell Industries. Inc.. and is restricted for use by Krell Indus­tdes. Inc., its subsidiaries, and authorized agents. Sustained Plateau Bias II is a patent of Krell Industries, Inc. Krell CAST
TM
is a patent pending of Krell
Industries, Inc. Krell Current Mode
TM,
Krell Link
TM,
and Krell Playback System
TM
are trademarks of Krell Industries, Inc. All other trademarks are registered
to their respective companies.
©2000 by Krell Industries, Inc. All rights reserved P/N 303969
Contents
INTRODUCTION
DEFINITION OF TERMS REVOLUTIONARY KRELL CAST TECHNOLOGY UNPACKING
PLACEMENT
AC Power Guidelines
FRONT PANEL DESCRIPTION
200c, 300c, and 600c Stereo Power Amplifiers 250Mc, 350Mc, and 650Mc Monaural Power Amplifiers
BACK PANEL DESCRIPTION
200c, 300c, and 600c Stereo Power Amplifiers
250Mc, 350Mc, and 650Mc Monaural Power Amplifiers
CONNECTING THE FULL POWER BALANCED AMPLIFIER TO YOUR SYSTEM
Input and Output Connections Krell Link Connections DC Protection Circuitry Using a Tube Preamplifier
AMPLIFIER OPERATION
On/Off and Stand-by Operation
Krell Link Operation
REMOTE CONTROL OPERATION
How to Tum Off the Amplifier LEDs How to Tum on the Amplifier LEDs How to Switch between Krell CAST and XLR Inputs
Using a Dedicated Wall Outlet and Switch
AMPLIFIER TROUBLESHOOTING
How to Troubleshoot System Noise How to Evaluate Amplifier Operation
QUESTIONS AND ANSWERS
WARRANTY
RETURN AUTHORIZATION PROCEDURE SPECIFICATIONS
Page
1 1
3 4
4 5
8 8 8
11 11
12
13
,13 13 14 14
15 15 15
16 16 16 16
16 17
17 17
19
20
21 22
Krell Full Power Balanced Power Amplifiers iii
Illustrations
FIGURE 1 Full Power Balanced Stereo Amplifier Front Panel FIGURE 2 Full Power Balanced Monaural Amplifier Front Panel FIGURE 3 Full Power Balanced Stereo Amplifier Back Panel FIGURE 4 Full Power Balanced Monaural Amplifier Back Panel
Page
6
7
9
10
iv
Krell Full Power Balanced Power Amplifiers
Introduction Definition of Terms
The Full Power Balanced series of amplifiers consists of three stereo amplifiers, the Full
Power Balanced 200c, 300c, and 600c, and
three monaural amplifiers, the Full Power Bal-
anced 250Mc, 350Mc, and 650Mc. Installation, connection, and operation of all amplifiers in the
Full Power Balanced series are identical; how­ever, a pair of Full Power Balanced Monaural
amplifiers are required for stereo operation. Full Power Balanced amplifiers can be config-
ured to accommodate any sophisticated music or home theater system and can be operated by an optional remote control or through the
remote control of other Krell com ponents.
This owner’s reference manual contains impor­tant information on placement, installation, and
operation of the Full Power Balanced ampli­fiers. Please read this information carefully. A
thorough understanding of these details will
help ensure satisfactory operation and long life
for your Full Power Balanced amplifier and
related system components.
Following are the definitions of key terms used in your owner’s reference manual.
CONFIGURATIONS
Krell Link
A method of synchronizing remote control oper­ation for Krell systems that include multiple pre-
amplifiers, amplifiers, and associated compo­nents. When Krell Link in/out connections are
used, the remote capabilities of the linked com-
ponents are controlled from one component, called the control component. The linked com-
ponents respond to stand-by and operational mode commands from the control component
via MIDI cables.
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.
Krell Current Audio Signal Transmission (CAST)
A proprietary Krell circuit technology for con­necting analog components, in which the audio waveform is transmitted between components in the current rather than voltage domain. The
speed and bandwidth provided by Krell CAST yields accurate, realistic music reproduction.
Krell components connected via CAST perform as if they are all part of a single circuit.
Krell Full Power Balanced Power Amplifiers
1
Definition of Terms, co,,tinuo,
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. Single­ended connections are not recommended for connections requiring long cable runs.
OPERATION
Off
When the power switch on the back panel is
placed in the down position and the blue power LEDs turn off, the component is off.
Operational Mode
When the power button on the front panel is
pressed and the three blue power LEDs illumi­nate, the component is in the operational mode
and ready to play music.
Stand-by Mode
A low power consumption status that keeps the
audio and regulator circuits at idle. Krell recom­mends leaving the component in the stand-by mode when it is not playing 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 Sustained Plateau Bias II
A proprietary Krell digital circuit that continually monitors the input signal and output impedance of a Krell amplifier and adjusts the bias accord­ingly to ensure Class A operation. Sustained Plateau Bias II provides the enormous sonic benefits of continuous Class A operation while minimizing the heat generation and power con­sumption normally associated with Class A designs.
2 Krell Full Powered Balanced Power Amplifiers
Revolutionary Krell CAST
Technology
Current Audio Signal Transmission, termed CAST, is a revolutionary method of connecting
analog audio components for unparalleled sonic performance. Innovative engineering
combines the new Krell CAST circuitry with existing Krell Current Mode technology to cre-
ate entire CAST systems that reproduce music with incredible range, tonality, and precision.
Voltage Signal Transmission and the Traditional Audio System
Traditionally, signal is transmitted in the voltage domain between two components. In an audio
system, each component is a discrete entity with unique characteristics that act upon the musical
signal independently. Each component is unaware of the other components in the system.
The cables that connect the components each have their own electrical characteristics, which
affect the sonic presentation of the entire sys-
tem.
CAST: A New Approach
CAST circuitry recognizes signal transmitted in the current domain instead of the voltage domain between each component. CAST trans-
mission unifies the individual components and their interconnects into an electrically linked whole. The sonic presentation of the entire sys­tem remains intact.
CAST Basics
Here’s how a CAST audio system works. Inter-
nally, each CAST source transfers, or amplifies, current using Krell Current Mode circuitry. This current signal is then output using CAST cir­cuitry. When the signal is received by a CAST
input, Krell Current Mode circuitry again takes over until the signal reaches the loudspeaker.
By maintaining the musical signal in the current domain from beginning to end, an entire CAST system behaves as if it is one component. With CAST, anomalies of signal transmission between
components are eliminated. Cable impedances and their effects on the transmitted signal are
non-existent.
How CAST and Krell Current Mode Interact
While CAST is a new method of transferring the
musical signal between components, its origin
stems from Krell Current Mode, the technology developed to transfer the musical signal within
a component. CAST combined with Krell Cur-
rent Mode takes circuitry signal transmission to the next evolutionary level. In essence, Krell Current Mode maintains the integrity of the sig-
nal within the component and CAST preserves the transmitted signal between components.
Together, CAST and Krell Current Mode tech-
nologies unify separate Krell components into a
single global circuit.
CAST Cable Construction
A CAST system uses cables manufactured by
Krell and other manufacturers specially licensed by Krell. Thin and flexible CAST cables
are constructed with the same build quality as other Krell products and are aesthetically matched to the components that Krell manufac­tures. An all-metal body and locking connectors with gold contacts are part of the standard no­compromise specification developed for evenj CAST cable made.
The Best Musical Performance
When you operate a CAST system, you will hear significant improvements in every perfor­mance area: speed, precision, dynamic range, depth and width of the sound stage, transient impact, tonal balance, harmonic distortion, and more. The goal for CAST is the same company goal used for all Krell products. Krell strives for the delivery of the best performance of a musi­cal event for you, using the full expression of technology to date.
Krell Full Power Balanced Power Amplifiers 3
Unpacking Placement
Two people are needed to remove the Full Power Balanced amplifier from its shipping box safely and easily.
1. Open the shipping box and remove the top layer of foam. You see these items:
1 Full Power Balanced Amplifier
1 Packet containing the owner’s
reference manual and the warranty registration card
2.
Orient the shipping box so that one person stands at the front of the amplifier and one person stands at the rear of the amplifier. Both people need to grab a pair of the card­board handle cutouts (one pair located at the
front of the amplifier and one pair located at the rear of the amplifier) and simultaneously
lift the amplifier straight up, out of the carton.
3. Place the amplifier in a safe location and remove the protective plastic wrapping.
Notes
ff any of the items mentioned above 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 Full Power Balanced amplifier in the future, repack
the unff in its original packaging to prevent tran­sit damage. See Return Authorization Proce­dure, on page 21 for more information.
Before you install the Full Power Balanced amplifier into your system, please follow the guidelines in this section to choose its proper
location. This will facilitate a clean, trouble-free installation.
The Full Power Balanced amplifier requires at least two inches (5 cm) of clearance on each
side and at least eight inches (20 cm) of clear­ance above the component to provide ade-
quate ventilation. Although Sustained Plateau Bias II circuitry
reduces the high heat dissipation and heat out­put of traditional Class A circuitry, Full Power
Balanced amplifiers still can become hot under normal operation.
When the front and rear of a cabinet are open the air space between the chassis an~l shelf
must be unobstructed. If you place the amplifi-
er in a closed cabinet, you may need to modify
shelf spacing or use small fans to increase ven-
tilation. For the dimensions of your Full Power
Balanced amplifier, see Specifications, on pages 22-23.
Place the amplifier as close to the speakers as possible. Krell CAST technology permits you to use interconnect cables of any length, see Flev- olutionary CAST Technology on page 3; however, try to keep the cable length to a mini-
mum.
All Full Power Balanced amplifiers drive the
lowest impedances with ease. When imped-
ance is added due to long speaker cable
lengths, amplifier power is wasted in the cable. Long speaker cables reduce the maximum
power that is delivered in the speakers.
4 Krell Full Power Balanced Power Amplifiers
Placement, continued
AC POWER GUIDELINES
The Full Power Balanced 200c and 250Mc amplifiers need to be operated from a dedicat-
ed AC power line rated at a minimum of 15 amps. The Full Power Balanced 300c, 350Mc,
600c, and 650Mc amplifiers need to be operat-
ed from a dedicated AC power line rated at a
minimum of 20 amps.
Please contact your authorized Krell dealer, dis­tributor, or Krell before using any devices designed to alter or stabilize the AC power for
Full Power Balanced amplifiers.
Krell Full Power Balanced Power Amplifiers 5
FIGURE 1 FULL P( IWER BALANCED STEREO AMPLIFIER FR()NT PANEL
123 456
1 Power Stand-by LED 2 Bias LED 3 Power Button
4 Infrared Sensor 5 Krell CAST LED 6 Regulator LED
6
Krell Full Powered Balanced Power Amplifiers
FIGURE 2 FULL POWER BALANCED MONAURAL AMPLIFIER FR( INT PANEL
789 10 11 12
7 Power Stand.by LED 8 Bias LED
9 Power Button
10 Infrared Sensor
11 Krell CAST LED
12 Regulator LED
Krell Full Powered Balanced Power Amplifiers 7
Front Panel Description
The front panel accesses power on/stand-by and infrared sensor (remote control) functions.
The power stand-by, bias, regulator, and Krell CAST LEDs, arranged in a triangle on the front panel above the power button, illuminate to indi­cate amplifier status.
FULL POWER BALANCED 200c,
300c, AND 600c STEREO POWER AMPLIFIERS
See Figure 1 on page 6
1 Power Stand-by LED
The blue power stand-by LED (top of LED tri­angle) illuminates when the back panel power
breaker switch has been moved to on, engag­ing the input circuitry and placing the amplifier
in stand-by mode.
2 Bias LED
The blue bias LED (lower left of triangle) illumi­nates after the front panel power button is
pressed, indicating that the Sustained Plateau
Bias II is engaged.
3 Power Button
Use the silver power button, to power on the
amplifier from stand-by mode.
4 Infrared Sensor
The infrared sensor receives the signal from a remote control.
5 Krell CAST LED
The red Krell CAST LED (center of triangle) illu- minates when a Krell CAST input on the back panel is connected to another Krell product with a Kreil CAST output.
6 Regulator LED
The blue regulator LED (lower right of triangle) illuminates after the front panel power button is
used to power on from stand-by mode, indicat­ing that the regulator is providing power to the output stage.
Note
An optional remote control is available for Full
Power Balanced amplifiers.
FULL POWER BALANCED 250Mc,
350Mc, AND 650Mc MONAURAL
POWER AMPLIFIERS
See Figure 2 on page 7
7 Power Stand-by LED
The blue power stand-by LIED (top of LED tri­angle) illuminates when the back panel power
breaker switch has been moved to on, engag­ing the input circuitry and placing the amplifier in stand-by mode.
8 Bias LED
The blue bias LED (lower left of triangle) illumi­nates after the front panel power button is pressed, indicating that the Sustained Plateau
Bias II is engaged.
9 Power Button
Use the silver power button to power on the amplifier from stand-by mode.
10 Infrared Sensor
The infrared sensor receives the signal from a
remote control.
11 Krell CAST LED
The red Krell CAST LED (center of triangle) illu­minates when a Krell CAST input on the back panel is connected to another Krell product with
a Krell CAST output.
12 Regulator LED
The blue regulator LED (lower right of triangle) illuminates after the front panel power button is
used to power on from stand-by mode, indicat­ing that the regulator is providing power to the output stage.
8 Krell Full Power Balanced Power Amplifiers
FIGURE 3 FULL POWER BALANCED STEREO AMPLIFIER BACK PANEL
19 13 14 15 16 17 18 16 14
13 19
13
Left and Right Speaker Binding Posts
14
Krell CAST Inputs
15 Back Panel Power Breaker Switch
16 Left and Right Balanced Inputs
17
Krell Link Out/In
18 AC Mains Power Cord
19 Handles
Krell Full Powered Balanced Power Amplifiers
FIGURE 4 FULL POWER BALANCED MONAURAL AMPLIFIER BACK PANEL
20 21 22 23 24 25 26
20 Handle
21 Speaker Binding Posts
22
Krell CAST Input
23
Balanced Input
24 AC Mains Power Cord 25 Krell Link Out/In 26 Back Panel Power
Breaker Switch
10 Krell Full Powered Balanced Power Amplifiers
Back Panel Description
The back panel provides connections for all
inputs and outputs, power on/oft, and remote control links. The back panel also has handles
that allow you to safely and easily move the
amplifier.
FULL POWER BALANCED 200c,
300c, AND 600c STEREO POWER
AMPLIFIERS
See Figure 3 on page 9
13 Left and Right Speaker Binding Posts
Full Power Balanced 200c, 300c, and 600c stereo amplifiers are equipped with four pairs of speaker binding posts (upper left, lower left,
u pper right, and lower right).
Notes
Two pairs of speaker binding posts are used for each channel of amplification. On the stereo or monaural Full Power Balanced amplifiers, either the upper or the lower pair can be used with speakers having two pairs of binding posts. For biwiring applications, with speakers having more than one pair of binding posts, use both upper and lower pairs of speaker binding posts. See the speaker’s instruction manual for biwiring connections.
Speaker binding posts for stereo and monaural amplifiers accept spade lugs only. Bare wire, banana lugs, or pins will not work. Use the red terminal for the positive connection and the blue terminal for the negative connection.
14 Krell CAST Inputs
Full Power Balanced 200c, 300c, and 600c
stereo amplifiers are equipped with one left Krell CAST input and one right Krell CAST input via 4-
pin bayonet connectors. The Krell CAST inputs allow the Full Power Balanced amplifier to be
connected to the KPS 25sc Krell Playback Sys­tem and other CAST-equipped components.
15 Back Panel Power Breaker Switch
Full Power Balanced amplifiers are equipped
with a back panel power breaker switch, for powering on the amplifier. Placing the back
panel power breaker switch in the up position places the amplifier in stand-by mode, where it
remains until the front panel power button (3) pressed.
Note
Krell recommends that the amplifier remain on,
in stand-by mode, even when not in use, once it is powered on from the back panel power
breaker switch (15).
16 Left and Right Balanced Inputs
Full Power Balanced 200c, 300c, and 600c stereo amplifiers are equipped with one left bal­anced input and one. right balanced in pr~t via XLR connectors.
17 Krell Link Out/In
Full Power Balanced amplifiers are equipped with Krell Link Remote out/in connectors that allow the remote control to operate a linked amplifier configuration. See Krell Link Connec-
tions, on page 13 for more information.
Note
An optional remote control is available for Full
Power Balanced amplifiers.
18 AC Mains Power Cord
All Full Power Balanced amplifiers are equipped with a permanently attached AC power cord.
19 Handles
All Full Power Balanced stereo amplifiers are equipped with two handles, located beside the speaker binding posts, to help you easily and safely move the amplifier.
Krell Full Power Balanced Power Amplifiers 11
Back Panel Description, continued
FULL POWER BALANCED 250Mc,
350Mc, AND 650Mc MONAURAL
POWER ,AMPLIFIERS
See Figure 4 on page 10
20 Handle
All Full Power Balanced monaural amplifiers are equipped with a handle, located beside the speaker binding posts, to help you easily and safely move the amplifier.
21 Speaker Binding Posts
Full Power Balanced 250Mc, 350Mc, and 650Mc monaural amplifiers are equipped with two pairs of speaker binding posts (one upper pair and one lower pair). For stereo operation, two monaural amplifiers are required.
22 Krell CAST Input
Full Power Balanced 250Mc, 350Mc, and 650Mc monaural amplifiers are equipped with
one Krell CAST input via a 4-pin bayonet con­nector. The Krell CAST input allows the Full Power Balanced amplifier to be connected to the KPS 25sc Krell Playback System and other CAST-equipped components.
23 Balanced Input
Full Power Balanced 250Mc, 350Mc, and 650Mc monaural amplifiers are equipped with one bal-
anced input via an XLR connector.
24 AC Mains Power Cord
All Full Power Balanced amplifiers are equipped
with a permanently attached AC power cord.
25 Krell Link Out/In
Full Power Balanced amplifiers are equipped
with Krell Link Remote out/in connectors that
allow the remote control to operate a linked amplifier configuration. See Krell Link Connec-
tions, on page 13 for more information. Note
An optional remote control is available for Furl
Power Balanced amplifiers.
26 Back Panel Power Breaker Switch
Full Power Balanced amplifiers are equipped
with a back panel power breaker switch, for
powenng on the amplifier. Powering on u§ing
the back panel power breaker switch places the amplifier in stand-by mode, where it remains
until the front panel power button is pressed.
Note
Krell recommends that, once the amplifier is
powered on from the back pane/power breaker
switch, it remains on, in stand-by mode, even when not in use.
12
Krell Full Power Balanced Power Amplifiers
Connecting the Full Power Balanced Amplifier to Your System
INPUT AND OUTPUT CONNECTIONS
Krell recommends using its proprietary Krell CAST system for unparalleled sonic perfor­mance between the Full Power Balanced amplifiers and other CAST-equipped compo­nents and the KPS 25sc Krell Playback Sys-
tem.
Full Power Balanced amplifiers also offer bal­anced operation. The circuitry and connections
associated with balanced operation not only can minimize sonic loss but also are immune to
induced noise, especially for installations using long cables.
A one piece RCA-to-XLR adapter is available from Krell Industries, to allow single-ended oper-
ation using the balanced XLR inputs. The following steps describe how to connect
cables to the Full Power Balanced Amplifiers.
1. Neatly arrange and organize wiring to and from the amplifier and all components. Sep-
arate AC wires from audio cables to prevent hum or other unwanted noise from being introduced into the system.
2. Connect the Krell CAST cables from your CAST-enabled preamplifier/source compo­nent to the left and right Krell CAST 4-pin bayonet inputs on the am plifier back panel. For balanced operation, connect the inter-
connect cable from your preamplifier to the
left and right balanced XLR input on the
amplifier back panel.
3.
Connect the speaker cables to the Full
Power Balanced amplifier’s speaker binding
posts, located on the amplifier back panel.
Speaker binding posts for both stereo and
monaural amplifiers accept spade lugs only.
4.
Insert the end of the AC mains power cord into the AC wall receptacle.
5.
Proceed with Krell Link Connections, if desired, or turn to Amplifier Operation, on
page 15.
KRELL LINK CONNECTIONS
Krell Link Remote out/in connectors on the back panel of the Full Power Balanced amplifi-
er allow you to synchronize remote control operation for systems that include multiple
amplifiers and associated components. When the Krell Link Remote out/in connectors are
used, the remote capabilities of the linked com­ponents are controlled from one amplifier or
preamplifier, called the control component. The linked components respond to stand-by and
operational mode commands from the control component via MIDI cables.
Note
Kre// Link uses standard five pin M/D/ commu­nication cab/es, sometimes referred to as M/D/ P/us cab/es. M/D/ cab/es can be purchased from your authorized distributor or dea/er, or from an audio supp/y store.
How to Connect Components through Krell Link
1. Turn all components off, using the back panel power breaker switch. This ensures
that the components are synchronized when the MIDI cable is connected.
2. Select the component to be the control com- ponent. The control component must be in
plain view for proper remote control opera-
tion.
3. Connect one end of the MIDI cable to the
Krell Link out connector on the back panel of
the component.
Krell Full Power Balanced Power Amplifiers 13
Connecting, continued
4. Connect the other end of the MIDI cable to the Krell Link in connector on the next com-
ponent. To link another corn ponent, connect a sec-
ond MIDI cable to the Krell Link out con­nector on the back panel of the second component. Connect the remaining end of
the MIDI cable to the Krell Link in connec­tor on the back panel of a third component.
5.
Link additional components, if desired, as described in Steps 3 and 4.
The components are now ready for operation with Krell Link.
DC PROTECTION CIRCUITRY
Full Power Balanced amplifiers use unobtrusive direct current (DC) protection circuitry that
strips DC from the signal without corrupting sound reproduction. Full Power Balanced
amplifiers feature direct coupled circuitry from input to output. This topology eliminates all cou-
pling capacitors from the audio signal path. Coupling capacitors block damaging DC but
have sonic characteristics that corrupt sound reproduction.
Note
For more information about DC protection cir­cuitry features, see Amplifier Troubleshooting,
on page 17.
USING A TUBE PREAMPLIFIER
The high DC output of tube preamplifiers may exceed the DC protection circuitry of Full Power Balanced amplifiers. Excessive DC
level in a signal can damage amplifiers, speak­ers, or both. The coupling capacitors in Full
Power Balanced amplifiers must be engaged when using a tube preamplifier. An authorized
Krell dealer, distributor, or Krell must activate
these capacitors.
Coupling capacitors must be inserted into the signal path by your authorized Krell dealer, dis-
tributor, or Krell before you can use your Full
Power Balanced amplifier with a tube preampli-
fier.
IMPORTANT
Please read the Warranty, on page 20, to understand the warranty limitations of Full Power Balanced amplifiers when used with tube preamplifiers.
14 Krell Full Power Balanced Power Amplifiers
Amplifier Operation
Full Power Balanced amplifiers are easy to
install and operate. However, it is important to exercise care during operation, due to the amplifiers’ enormous power output. Switching
between active sources (such as a CD player, tape monitor, or VCR) without muting the pre­amplifier output, or bumping or miscuing a source can generate large transients at low fre­quencies. Full Power Balanced amplifiers may generate enough power with these transients to damage loudspeakers.
IMPORTANT
Always mute or fully attenuate the preamplifier level when switching sources.
Do not change input connections to the amplifi-
er when the amplifier is on.
Use care when setting high playback levels.
Because of their tremendous reserves of clean power, Full Power Balanced amplifiers can safe-
ly drive speakers to higher sound pressure lev-
els than other amplifiers. Always lower the vol-
ume level at the first sign of speaker distress.
ON/OFF AND STAND-BY OPERATION
When powering on any system, turn on ampli-
fiers last. Turn off amplifiers first.
1.
Move the back panel power breaker switch
to the up position to engage the input cir­cuitry and place the amplifier into the stand-
by mode. The front panel blue power stand­by LED illuminates.
2. Press the silver power button on the amplifi­er front panel. The blue regulator LED illumi-
nates. Once the regulator provides power to
the output stage, the blue bias LED illumi-
nates. The Sustained Plateau Bias II system
is now engaged. After the protection circuitry
has confirmed that safe operating conditions exist, the input relays engage. You hear a click. The am plifier is ready for operation.
If the Krell CAST input is being used, the Krell CAST red LED illuminates and
remains illuminated at all times during the
stand-by or power on modes.
3.
With the preamplifier muted or volume con­trol completely lowered, select a source.
Increase the volume control to the desired listening level.
4.
When turning off the system, mute or com-
pletely lower the preamplifier volume, or place the Full Power Balanced amplifier in
the stand-by power mode by pressing the
power button on the front panel. It is now
safe to turn off the rest of the system.
Note
For best performance of Full Power Balanced
amplifiers, leave the back panel power br~eaker switch on at all times.
KRELL LINK OPERATION
1. When all components are linked, place each component in the stand-by mode by
moving the back panel power breaker switch to the up position. This ensures that all components will be synchronized when signals from the control component are sent to the linked components in the system.
2. When the components are in stand-by, switch the control component to the opera­tional mode from the control component’s
front panel or by using the component’s
remote control. The linked corn ponents switch to the oper-
ational mode simultaneously.
A linked component can be switched between the operational mode and stand-by, individual-
ly, from its front panel. Switching a linked com­ponent temporarily breaks the chain of linked
components. To re-establish linked operation, return all components to stand-by.
Krell Full Power Balanced Power Amplifiers 15
Remote Control Operation
Full Power Balanced amplifiers are compatible
with the remote controls included with Krell pre­amplifiers, the Krell Audio + Video Standard,
the KAV-300r Remote Control Receiver, the Home Theater Standard, and the KPS 25sc Krell Playback System.
Please contact your authorized Krell dealer, dis-
tributor, or Krell to purchase a remote control for Full Power Balanced am plifiers.
Full Power Balanced amplifiers can be located in a room or space close to the speakers but out
of sight, and powered on or off remotely from
the listening room, through a control amplifier.
See Krell Link Connections, on page 13.
HOW TO TURN OFF
THE AMPLIFIER LEDs
The amplifier must be in the stand-by mode with the rear panel power breaker switch on. While holding the silver power button in, press the power key on the remote control. After the amplifier finishes its turn-on sequence, the front
panel blue LEDs turn off. The blue LEDs remain off throughout normal operation as long as the amplifier’s rear panel power breaker switch is
not turned off.
HOW TO TURN ON THE AMPLIFIER LEDs
With the amplifier in the stand-by mode, turn the rear panel power breaker switch to the off
position. Then turn the rear panel power break­er switch back to the on position. The next time
the amplifier is powered up from the front panel or the remote control, the blue LEDs illuminates
during the turn-on sequence.
HOW TO SWITCH BETWEEN KRELL CAST AND XLR INPUTS
Press the meter key on a Krell remote to switch between CAST inputs and the balanced XLR inputs.
Full Power Balanced amplifiers default to CA~ST
operation upon startup, if the amplifier is tumed off from the rear panel power breaker switch and a CAST source and cable are connected to the CAST inputs. The operational mode does not change if the Full Power Balanced amplifier is in stand-by mode.
USING A DEDICATED WALL
OUTLET AND SWITCH
Full Power Balanced amplifiers can be powered on from an AC wall receptacle with a dedicated switch, rather than from the front panel power button or optional remote control.
Please contact your authorized Krell dealer, dis-
tributor, or Krell for more information before you
connect your Full Power Balanced amplifier to a dedicated AC wall outlet with a switch.
16
Krel Full Power Balancec~ Power Amplifiers
Amplifier Troubleshooting
HOW TO TROUBLESHOOT SYSTEM NOISE
AC grounding becomes critical when connect­ing high performance audio components. When
you mix and match audio components, each
with its 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 a low frequency hum emanates from the speakers when you place the Full Power Bal­anced amplifier into the system, follow these
simple troubleshooting steps:
Note
During these steps, the back panel power breaker switch remains in the on position.
1. Check all input and output connections, making sure they are of sound construction.
With the amplifier in stand-by mode, remove the interconnect cables, then press the front
panel power button. If the hum disappears, press the power button to return to stand-by mode, and reinsert one of the interconnect cables. Press the power button again. If the hum reappears with one or both intercon­nects inserted, there may be a defective cable. Have the interconnect cables checked before proceeding.
2. If the interconnect 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 on how to solve this problem.
HOW TO EVALUATE AMPLIFIER OPERATION
The amplifiers are protected by a series of non-
intrusive circuits that constantly evaluate the
amplifier’s operation. This circuitry protects
against damaging DC input or output and short circuits, see also DC Protection Circuitry, on page 14, and monitors regulator operation, ensuring constant voltage to the output stage.
The protection circuitry in a Full Power Bal-
anced amplifier is designed to prevent damage
to the amplifiers or speakers caused by other
defective components, faulty wiring, system mishandling, or amplifier failure.
In addition, when a Full Power Balanced ampli-
fier’s DC protection circuitry senses a problem within the system, it identifies, then indicates the
problem by illuminating the front panel blue LEDs, as described in the following table.
Notes
The Krell CAST LED illuminates only ff a Krell
CAST input is being used.
There are no output fuses in Full Power Bal-
anced amplifiers.
Krell Full Power Balanced Power Amplifiers 17
If the course of action listed in the table below does not correct the situation, please con-
tact your authorized Krell dealer, distributor, or Krelh
AMPLIFIER CONDITION POSSIBLE CAUSES COURSE OF ACTION The output mutes during
playback and the following LEDs illuminate: Power
Stand-by, and
Regulator Bias
Excessive DC at the
amplifier input
Have source unit and preamplifier checked for high DC output
If preamplifier is a tube model, see Using a Tube Preamplifier, on page 14.
The amplifier switches to stand-by mode and the
Power Stand-by LED illuminates
Electrical short in speaker
cables or inside speaker
Check all speaker cables for any cuts or frayed edges that might form a connection between the positive and neg­ative speaker binding post ter-
minals
The amplifier switches to stand-by at high volumes
and the Power Stand-by LED illuminates
Insufficient AC current from
the wall outlet
Excessive heat
Make sure the AC line is at least 15 am ps for 200c and 250Mc amplifiers; 300c,
350Mc, 600c, and 650Mc amplifiers should be
operated from a dedicated 20-am p line.
Allow amplifier to cool before resuming operation. See Placement, on page 4 for ven-
tilation requirements
The amplifier powers down completely and no LEDs illuminate
DC present at the output stage
Internal amplifier problem
Contact your authorized Krell dealer, distributor, or Krell
Contact your authorized Krell dealer, distributor, or Krell
18 Krell Full Power Balanced Power Amplifiers
Questions and Answers
Q. Should I leave my Full Power Balanced amplifier on at all times?
A. For maximum amplifier performance, leave the back panel power breaker switch on at all times. This places the amplifier in stand-by mode. Full Power Balanced amplifiers are designed to be powered on and off from stand-
by, using the front panel power button. This eliminates "cold start" degradations. The ampli-
fier will operate at full performance within min-
utes. Q. When I turn on the amplifier there is a loud
hum through the speakers. What should I do?
A. When a new component is introduced, a low frequency hum may occur in one or both speak-
ers. Check all input and output connections and cables, making sure they are of sound con-
struction. See How to Troubleshoot System
Noise, on page 17. If the interconnects 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 on how to solve this problem.
Q. My system includes multiple pairs of speak­ers. Can I connect them to my Full Power Bal­anced amplifiers through a speaker selector
box? A. No. Most speaker selector boxes use a com-
mon ground scheme. The differential circuitry in
Full Power Balanced amplifiers prohibits the use of these devices. Do not connect a Full Power
Balanced amplifier to a speaker selector
device that employs a common ground scheme, as it may short-circuit the amplifier
output.
Q, My speakers have only one pair of binding posts, but my Full Power Balanced stereo
amplifier has two pairs. Which pair of speaker binding posts should I use, the upper or the
lower? A. The upper and lower pair of speaker bind-
ing posts on Full Power Balanced stereo ampli­fiers are identical. You can use either the upper
or lower pair; they work and sound the same. See Connecting the Full Power Balanced
Amplifier to Your System, on page 13. Q. My speakers are rated for 150 Watts. Are
the Full Power Balanced 300 or 600 models too powerful for them?
A. No. A speaker seldom is damaged from overdriving. More often, damage occurs when an amplifier that lacks sufficient power is asked to handle heavy demand situations such as high playback levels. These amplifiers may have very high 8 Ohm power ratings, but in heavy demand situations they can be driven into clipping (in which DC current goes to speakers due to loss of amplifier power). Clip­ping can damage speakers. Avoid damage to your speakers by reviewing your speaker’s specifications and exercise caution in heavy
demand situations.
Krell Full Power Balanced Power Amplifiers 19
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.
The warranty does not apply to damage caused by acts of God or nature.
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 consequential damages arising from pur­chase, use, or inability to use this product, even if Krell has been advised of the possibility of such damages.
IMPORTANT
The user is responsible for notifying his or her Krell deal-
er, distributor, or Krell that a tube preamplifier will be used
with the Full Power Balanced amplifier, so that the Krell dealer, distributor, or Krell can activate the coupling capac­itors. If the user does not notify the Krell dealer, distributor, or Krell and uses a tube preamplifier without the Full
Power Balanced amplifier’s coupling capacitor engaged,
Krell reserves the right to refuse warranty related service due to DC-related damage.
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 retail purchase, as noted on the sales slip provided by an authorized Krell dealer or distributor.
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.
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.
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 unit from the freight forwarder to you are also your respon­sibility.
Krell is not responsible for any damage incurred in transit.
Krell will file claims for damages as necessary for units dam­aged in transit to the factory. You are responsible for filing claims for shipping damages during the return shipment.
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 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, m~suse, natural or personal disaster, or unauthorized modification.
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 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 until six months from the original purchase date.
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 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 fac-
tory specifications will be charged to the customer, at cur-
rent parts and labor rates.
All operational features, functions, and specifications and
policies are subject to change without notification.
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.
20 Krell Full Power Balanced Power Amplifiers
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 retum 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:
www.krellonline.com
To contact the Krell Service De }artment
TEL 203-799-9954
Monday-Friday
9:00 AM to 5:00 PM EST FAX 203-799-9796 E-MAIL
service@ krellonline.com
WEBSITE www.krellonline.com
Full Power Balanced Amplifier
PRODUCT NAME
MODEL NUMBER SERIAL NUMBER
To return this product to Krell, please follow this procedure so that we may serve you
better:
1. Obtain a Return Authorization Number (R/A number) and shipping address from the
Krell Service Department.
2. Insure and accept all liability for loss of or damage to this product during shipment to the Krell factory and prepay all shipping charges. Please see the Warranty page in this manual, concerning 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 purchase may be required for warranty validation at the
time of hand delivery.
IMPORTANT
Use the original packaging to ensure safe tran-
sit of this product to the dealer, distributor, 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-standard 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
this product is returned.
To purchase additional packaging, please con-
tact your authorized Krell dealer, distributor, or the Krell Service Department.
Krell Full Power Balanced Power Amplifiers 21
Specifications
Full Power Balanced 200c, 300c, 600c Stereo Amplifiers
FREQUENCY RESPONSE
SIGNAL TO NOISE RATIO "A" WEIGHTED
GAIN TOTAL HARMONIC
DISTORTION (THD) ALL BALANCED, UNWEIGHTED
INPUT IMPEDANCE INPUT SENSITI VITY OUTPUT POWER
EACH CHANNEL DRIVEN
OUTPUT VOLTAGE
POWER CONSUMPTION
INPUTS
OUTPUTS SPEAKER BINDING POSTS
REMOTE CONTROL DIMENSIONS
INCHES CENTIMETERS
FPB 200c
20 Hz to 20 kHz +0 dB, -0.05 dB
0.1 Hz to 240 kHz +0 dB, -3 dB
113 dB
FPB 300c
20 Hz to 20 kHz +0 dB, -0.05 dB
0.1 Hz to 240 kHz +0 dB, -3 dB
117 dB
26.4 dB 1 kHz <0.02%
20 kHz <0.15%
26.4 dB 1 kHz <0.02%
20 kHz <0.15%
100 kOhms
1.92 Vrms
8 Ohms 200 W 4 Ohms 400 W
2 Ohms 800 W
100 kOhms
2.35 Vrms 8 Ohms 300 W
4 Ohms 600 W 2 Ohms 1,200 W
Peak to Peak 138 V
Peak to Peak 170 V
RMS 49 V RMS 60 V Stand-by
60 W
Idle 175 W Max. 1,700 W
1 pair balanced via XLR connectors
1 pair CAST Via 4-pin
bayonet connectors 4 pair (upper left,
lower left, upper right lower right)
Stand-by 75 W Idle 350 W Max. 3,000 W
1 pair balanced via
XLR connectors
1 pair CAST via 4-oin bayonet connectors
4 pair (upper left,
lower left, upper right
lower right)
FPB 600c
20 Hz to 20 kHz +0 dB, -0.05 dB
0.1 Hz to 240 kHz +0 dB, -3 dB
120 dB
26.4 dB 1 kHz <0.02%
20 kHz <0.15%
100kOhms
3.39 Vrms
8 Ohms 600W 4 Ohms 1,200 W-
2 Ohms 2,400 W Peak to Peak 240 V
RMS 84 V Stand-by
85 W Idle 430 W Max.
6,000 W
1 pair balanced via
XLR connectors
1 pair CAST via 4-pin bayonet connectors
4 pair (upper left lower left, upper right
lower right)
Optional Optional Optional
19.0w x 10.3h x 17.0d
48.3w x 26.2h x 43.2d
19.0w x 10.3h x 19.7d
48.3w x 26.2h x 50.0d
19.0w x 10.3hx 25.5d
48.3wx 26.2hx 64.8d
WEIGHT SHIPPING 107.0 lb., 48.6 kg 127.0 lb., 57.7 kg 200.0 b., 90.9 kg
UNIT ONLY 90.0 lb., 40.9 kg 110.0 lb., 50.0 kg 180.0 lb., 81.8 kg
All operational features, functions, specifications, and policies are subject to change without notification.
22 Krell Full Power Balanced Power Amplifiers
Specifications
Full Power Balanced 250Mc, 350Mc, 650Mc Monaural Amplifiers
FPB 250Mc FPB 350Mc FPB 650Mc
FREQUENCY RESPONSE
SIGNAL TO NOISE RATIO "A" WEIGHTED
GAIN
TOTAL HARMONIC
DISTORTION (THD) ALL BALANCED, UNWEIGHTED
INPUT IMPEDANCE INPUT SENSITIVITY
OUTPUT POWER
EACH CHANNEL DRIVEN
OUTPUT VOLTAGE
POWER CONSUMPTION
INPUTS
20 Hz to 20 kHz +0 dB, -0.05 dB
0.1 Hz to 240 kHz +0 dB, -3 dB
20 Hz to 20 kHz +0 dB, -0.05 dB
0.1 Hz to 240 kHz +0 dB, -3 dB
20 Hz to 20 kHz +0 dB, -0.05 dB
0.1 Hz to 240 kHz +0 dB, -3 dB
114 dB
118 dB 121 dB
26.4 dB
26.4 dB 26.4 dB
1 kHz <0.03% 1 kHz <0.03% 1 kHz <0.03%
20 kHz <0.03% 20 kHz <0.03% 20 kHz <0.03%
100 kOhms 100 kOhms 100 kOhms 2,14 Vrms 2.6 Vrms 3.39 Vrms 8Ohms 250W 8Ohms 350W 8Ohms 650W
4Ohms 500W 4Ohms 700W
4Ohms 1,300W
2 Ohms 1,000 W 2 Ohms 1,400 W 2 Ohms 2,600 W Peak to Peak 138 V
Peak to Peak 170 V
RMS 49 V RMS 60 V Stand-by 30 W Stand-by
37.5 W Idle 150 W Idle 175 W Max.
1,700 W Max. 3,000 W
1 balanced via
XLR connectors
1 Krell CAST via 4-pin
bayonet connectors
1 balanced via
XLR connectors
1 Krell CAST via 4-pin bayonet connectors
Peak to Peak240 V RMS 84 V
Stand-by 42.5 W Idle 220 W Max. 6,000 W
1 balanced via XLR connectors
1 Krell CAST via 4 p~n bayonet connectors
OUTPUTS SPEAKER BINDING POSTS
2 pair (one upper, one lower)
2 pair (one upper, one lower)
2 pair (one upper, one lower)
REMOTE CONTROL DIMENSIONS
INCHES CENTIMETERS
WEIGHT S HIPPING
UNIT ONLY
Optional
12.5w x 10.5h x 16.0d
31.8w x 26.7h x 40.6d
79.0 lb., 35.9 kg
68.0 lb., 31.0 kg
Optional
12.5w x 10.5h x 19.0d
31.8w x 26.7h x 48.3d
110.0 lb., 50.0 kg
98.0 lb., 44.5 kg
Optional
12.5w x 10.5h x 25.0d
31.8w x 26.7h x 67.3d
155.0 lb., 70.5 kg
140.0 lb., 63.6 kg
Krell Full Power Balanced Power Amplifiers
23
Krell Industries, Inc. 45 Connair Road Orange, CT 06477-3650 USA
TEL 203-799-9954
FAX 203-891-2028 E-MAIL krell @ krellonline.com
WEB SITE http://www.krellonline.com
Full Power Balanced
Power Amplifiers
200c, 300c, 600c Stereo
250Mc, 350Mc, 650Mc Monaural
with Krell CAST Technology
v 00.0
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