Krell KPA, KPL Owners manual

KBL & KPA OWNERS’ MANUAL

45 Connair Road

Orange, CT 06477-0533, USA

KBL & KPA OWNERS’ MANUAL

INTRODUCTION

Thank you for your purchase of a new KRELL preamplifier. This Owners’
Manual covers both the KBL and KPA preamplifiers, as they have been
designed to be companion pieces and can be utilized in varying
combinations. For each user there will be information that does not pertain
to their specific situation. Therefore, in the interest of clarity, details

relating to different combinations are presented in well-defined sections.

The KBL and KPA represent significant departures from traditional
preamplifier design. The time invested in carefully reading this manual

will yield an important understanding of the functions and design features

of the units. Due to the high level of performance of which these units are
capable, careful placement and installation are crucial. Your thorough

understanding of the operations of the KBL and KPA will help insure their
maximum performance and long life.

ABOUT THE OWNERS’ MANUAL

The KBL/KPA Owner’s Manual is divided into various groups of
information. The purpose of the document as a whole is to familiarize you
with the units and guide you through their set-up, installation and

operation in a logical progression. The Table of Contents is as follows:

A. Serial Number(s) and Factorv-Shi~ed Confia~ration

General Information: a description of the basic design and performance

B.

features of the KBL and KPA

C. Unpacking: detail of accessories shipped with the KBL and KPA in

various configurations

D. Installation: 1. Caution

2. Connector Details

3. Connector Termination Types
Cable Requirements for Inputs and Outputs

4.

Setting of Internal Switches

5.

6. Unit Location Guidelines and Installation

Connection of Inputs and Outputs

7.
Turn-on of the Preamplifiers

8.

E. Operation: 1. KPA Functions

2. KBL Functions
F. ,W~rranty ~nd Service Information
G. Termination Drawings

A. SERIAL NUMBERS & FACTORY-SHIPPED CONFIGURATION

KBL preamplifier serial number was shipped from the
factory set-up for stereo operation
operation.

dual-mono

Please refer to information specific to this mode of operation throughout the
manual.

Should you wish to change between stereo and monaural operation please
refer to section D. 5. This is only necessary when changing either unit
from stereo to mono operation.

All KPA are shipped from the factory set-up for stereo operation. Please

refer to section E. 1. d for information regarding dual-mono operation.

B. GENERAL INFORMATION

The KRELL KBL (Krell Balanced Line) and KPA (Krell Phono Amplifier)
present many new concepts in preamplifier design. The traditional
preamplifier contains both a phono section and a line section. The KBL and
KPA divide these functions into two separate units. This was done for
several reasons. The primary motivation was to allow adequate space to
accommodate the latest evolutions of preamplifier circuitry and functions.

2

These units are the current state-of-the-art. No compromise was allowed in
their design. Details concerning their technical performance are covered

in more detail below, A second important consideration was to introduce
the programmable concept employed in our current KSA/KMA amplifier

line into our preamplifier line. A single KBL and KPA are used for stereo
operation. A second unit of either can be added to achieve dual-mono, fully
balanced operation. They can be easily changed without being returned to
the factory. There are many advantages to dual-mono operation. The
capability of the KBL and KPA to operate in either mode allows you to plan
the development of your system over time, without the waste of money and
time associated with trading or selling used gear. It also allows you to
optimize your system more closely to your needs. For example, if line

sources are most important, you can purchase two KBLs’, with or without a

KPA. If phono is most important you can purchase two KPA’s and one

KBL creating a completely balanced path for the phono signal. The

ultimate configuration, of course, is two KBL and two KPA. This creates a

completely dual-mono, balanced preamplifier system for all inputs and
outputs. Other details concerning the functions of the units are covered

below and in the Installation and Operation sections.
The method used to switch a KBL or KPA from stereo to dual-mono

operation is unique. For stereo operation each chassis has complete circuit
paths for the left and right channels. When switched to dual-mono,
balanced operation the left channel circuitry is assigned to the non-inverted

path and the right channel circuitry is assigned to the inverted path. This
changes the rear panel connector assignments on both the KBL and KPA.

See the sections on Installation and Operation below for more details.
The KBL and KPA use high-bias, pure Class A circuits throughout,

including the power supplies and regulators. Circuits are DC coupled,

meaning there are no capacitors in the signal path. The power supply
system and output circuits are extremely high-power when compared with
conventional preamplifier designs. The output section of the KBL, for
example, is really a small power amplifier, capable of swinging 60 volts

peak-to-peak. This allows the KBL to maintain exceptional linearity under

all conditions and drive virtually any length of cable without signal
degradation. The external supply has two stages of regulation. Within
each preamp chassis there are independent tracking regulators for each
section of circuitry, separated channel-to-channel.

The KPA has completely passive RIAA equalization. Maximum deviation
from the standard is +/- .1 dB from 10Hz to 20KHz. All parts are 1%

tolerance.

3

Both preamplifiers have innovative operational features. The KBL has two
balanced inputs and one set of balanced outputs in addition to four single-

ended inputs and one set of single-ended outputs. This allows one KBL to
accommodate balanced line sources and amplifiers, which Krell believes to

be the standard for high-end audio gear. Therefore, it is only necessary to
purchase a second KBL to achieve dual-mono, fully balanced operation.

The KBL input labeling is a departure from the norm as well. Instead of

the conventional "phono, tuner, tape, aux, etc." we have labeled the inputs
B-l, B-2, S-l, S-2, S-3, S-4. These refer to Balanced Input #1, Balanced Input
#2, Single-ended Input #1, etc. Components in audio systems today are
unpredictable. This input labeling allows KBL Selector can to be set-up or
changed by each user to create the order he desires.

The KBL has front panel adjustments for output gain and absolute phase.
The Gain switch provides a course adjustment to compensate for systems of

different efficiencies and for level differences in source components.
The KPA has inputs for two different cartridges. There is a front panel

switch to adjust between the gains required for moving coil and moving
magnet cartridges. Adjustment for cartridge impedance loading is on the
front panel as well. Perhaps the most interesting features on the KPA are
the front panel adjustments for high and low RIAA trim. These allow you
to tailor the RIAA equalization to specific records in small increments.

Single-ended/Balanced switching are also on the front panel.

C. UNPACKING

Remove the units from the shipping container. Keep the shipping
materials in a safe, dry place for future use. The following is a list of the
materials that are included in the packaging.

1 each:

1 KBL ~ 1 KPA ~acked together

I each:

preamplifier chassis
KBL power supply with DC cable installed

AC line cord
"T" shaped Allen driver

Spare fuse for the power supply
Owner’s Manual

KBL & KPA preamplifier chassis
KBL power supply with DC cable installed

AC line cord

DC jumper cable (KBL to KPA)
"T" shaped Allen driver
Spare fuse for the power supply

Owner’s Manual

4

1 KP~ without _vower supvlv

1 each:

1 KPA with ~ower su~pl_v

1 each:

Inspect the unit(s) and power supply(s) for damage. If any is evident, or

some of the accessories are missing, contact your dealer or the factory

immediately. If everything is in order you can proceed with the next steps.

D, IN/~TALLATION

1. Cautions

Note: These are important points of which you should always be aware.

They are presented before the actual installation procedures, should you

not read through the Manual entirely.

preamplifier chassis
DC jumper cable (KBL to KPA)

"T" shaped Allen driver
Owner’s Manual

preamplifier chassis
KPA power supply with AC and DC cables attached

DC jumper cable (KBL to KPA) *not used when the

dedicated KPA supply is used*
"T" shaped Allen driver

Owner’s Manual

a. When installing the KBL always connect the DC cable between the
preamp chassis and the power supply before plugging the power supply

into the AC mains.
b. When installing a KBL/KPA combination ~ connect the DC

cables between the KPA and the KBL, and between the power supply
and the KBL before plugging the power supply into the AC mains.

c. ~ disconnect the AC from the mains before disconnecting the

DC cable(s) from the preamp(s).
d. A single KPA cannot be operated in balanced mode. The "Balanced"

push-button should not be activated unless two KPA are used.
e. These points are true for both the initial installation of the KBL or

KPA and for revisions of your system that require their relocation.