Krell KPS-25-SC Brochure

THE LEADER IN AUDIO ENGINEERING

KPS 25sc

Krell Playback System

An Integrated

Compact Disc Transport,

Digital-to-Analog Converter,

and Analog Preamplifier

THE KRELL PLAYBACK SYSTEM

TECHNOLOGY

CAST, or Current Audio Signal Transmission, solves two of the most pervasive

and difficult problems encountered in configuring and connecting an audio or

audio/video system. The first difficulty lies in the nature of the connection

between a system’s front end – the preamplifier and all the source components

feeding it – and the power amplifier(s). Here, basic impedance matching is

never a simple phenomenon. A prime culprit is the cable connecting

preamplifier and power amplifier. Indeed, a cable’s influence can be so

profound that it becomes a tone control – sometimes very unsubtle – instead of

a simple path for a musical signal. The second, and admittedly derivative,

problem is the length of cable between front end and amplifier. Although

longer cables have practical advantages – they allow placing front ends closer

to users and amplifiers closer to loudspeakers – they often degrade system

performance as their greater reactive effects have greater impact on sound

quality. CAST alleviates both concerns. Deceptively simple in concept, CAST

reverses conventional wisdom that says voltage transfer from source to load

demands that a preamplifier’s output be low impedance and that the power

amplifier’s input be high. Unfortunately, this combination places a large

burden on the connecting cable in that its impedance will alter or distort the

signal voltage operating the amplifier. In contrast, CAST transfers current

rather than voltage from a high impedance source to a low impedance load. In

doing so, a cable’s effect is minimized – if not totally eliminated – as its

impedance characteristic becomes but a minute portion of the total interface.

CAST results in far simpler – and far more accurate – signal transfer. It unveils

musical subtleties as it immunizes a system against cable-induced variables.

D/A CONVERTER

The KPS25sc’s D/A circuitry is the culmination of years of

dedicated effort to extract and preserve all the musical grandeur

contained in the vast CD repertoire available today. Beginning with

a high speed digital filter operating at 352.8 kHz (8 times faster

than the CD-standard 44.1 kHz sampling frequency), the KPS 25sc

delivers far more than expected from any compact disc. Composed

of two Motorola DSP 56009 microprocessors (one for each

channel), this filter is controlled by Krell-written software that

interpolates intermediate values between disc samples and

provides enhanced resolution. A third microprocessor decodes and

filters HDCD-encoded discs automatically. After filtration and now

in 24-bit format, digital data reaches four D/A modules, each

capable of 8x performance balanced configuration to fully preserve

the musical benefits of the filter’s 8x output. Digital data from

other sources is subject to the same rigorous yet revealing

process. Here, a low-jitter input module automatically senses and

adjusts to any common consumer or professional data format – up

to 24 bits and 96 kHz sampling frequency – before sending the

incoming data stream to the digital filter-D/A circuits. Finally, every

stage of digital circuitry derives its timing from a single master
clock. This eliminates beat frequencies that often obscure subtle
musical details in less well governed designs. The result? Simply

superb reproduction of any of today’s digital sources. And it

happens only when science serves art – when Krell serves music.

REMOTE
CONTROLS

TRANSPORT

Often overlooked when evaluating a CD component, the disc

transport/laser assembly is absolutely critical in beginning an

accurate playback process. The challenge is one of scale. All the

musical information on a CD resides in a pit spiral fully three miles

long! When you consider the disc’s less than 5 inch width, you begin

to appreciate the microscopic dimensions involved and the enormous

burden they place on the optical assembly. Krell’s solution is fully in

keeping with its reputation. The data-grade transport, exclusive to
Krell in North America, is anchored to a massive copper plate. The
high-torque disc motor, a cog-free design, benefits from rare-earth

neodymium magnets. The laser assembly itself rides on a belt-driven,

high-mass sled and is under the constant control of precise micro-

servos. Disc clamping – vitally important but often given low priority

in less-sophisticated mechanisms – is handled by a electrolyzed

aluminum weight that both flattens and stabilizes the disc. Held by

magnetic attraction when placed on the drive spindle over a disc, it is

instantly removable for easy disc changes. An ideal amalgam of high

mass for stability and high torque for quick response, and decoupled

from both internal and external vibration by precisely tuned elastomer

mounts, the entire assembly provides the highest level of accuracy by

eliminating almost all significant causes of data error.

A remarkable new feature
highlights the KPS 25sc’s elegant
design. The heavy prismatic acrylic
cover over the transport
mechanism contains an electronic
LCD shutter. Transparent when the
transport is stopped, it turns
opaque when a CD is playing, thus
protecting the disc‘s data integrity
from the effects of stray light!

PREAMPLIFIER

In addition to uncompromised digital performance, the KPS 25sc
contains the finest preamplifier Krell has ever produced. It provides
one-touch selection of either the internal CD transport or 10
external sources (5 digital, 5 analog). Even the normally mundane
volume control is a study in high-accuracy precision engineering.
And the KPS 25sc offers a choice of remote control options. A
plethora of analog and digital outputs allow the KPS 25sc to serve
as the heart of the most complex home music system. Outputs to
the power amplifier of your choice includes conventional single­ended and fully balanced connections. CAST circuitry assures
maximum signal integrity when the KPS 25sc functions with a
CAST-compatible Krell power amplifier. But the real reason d’être
behind this stunning preamplifier section is its remarkable sound
quality. All analog circuitry follows the Krell tradition of fully
balanced Class A design. In addition, the KPS 25sc features Krell
Current Mode topology to deliver a wide bandwidth, low noise
signal under all operating conditions. A unique combination of
exact yet imaginative engineering, the KPS 25sc presents an ideal
blend of cutting-edge performance and elegant simplicity. It is
supremely capable yet invitingly accessible. It is, after all else is
said, a Krell.

KPS 25sc Specifications:

FREQUENCY RESPONSE

0.1 Hz to 1 MHz +0 dB, -3 dB

TOTAL HARMONIC DISTORTION (THP/THD)

BALANCED, UNWEIGHTED
1 kHz < 0.005%
20 kHz < 0.008%

SIGNAL TO NOISE RATIO

BALANCED, “A” WEIGHTED 104 dB

CHANNEL SEPARATION

92 dB @ 1 kHz

DIGITAL TO ANALOG CONVERSION

Dual balanced conf. 24bit/96 kHz DACs

DIGITAL FILTERS

8 x oversampling employing dual Motorola
56009 DSPs, HDCD employing Pacific
Microsonics PMD 100

DIGITAL CLOCKING SYSTEM

Master clock synchronizes disc drive, laser
assembly, DSP circuit, and decoder circuit

OUTPUT VOLTAGE

BALANCED 13 Vrms

POWER CONSUMPTION

90 W

INPUT IMPEDANCE

98 kOhm

OUTPUT IMPEDANCE

17 Ohms

GAIN

BALANCED 12 dB
SINGLE-ENDED 6 dB

DISC DRIVE

Top loading mechanism featuring cog-free
motor assembly and belt driven laser
assembly

DISC CLAMP

Machined, electrolyzed aluminum
with neodymium magnet

DIGITAL INPUTS AND OUTPUTS

1 AES 110 Ohms, 3.5 V via XLR connectors
2 S/PDIF 75 Ohms, 0.5 V via RCA
connectors
2 EIAJ optical, via TosLink connectors

ANALOG INPUTS

1 pair balanced via XLR connectors
4 pair single-ended via RCA connectors

ANALOG OUTPUTS

1 pair fixed balanced and 1 pair variable
balanced via XLR connectors
2 pair fixed single-ended and 1 pair
variable
single-ended via RCA connectors
1 pair variable Krell CAST via 4-pin
bayonet connectors

VOLUME CONTROL RESOLUTION

16-bit

BALANCE CONTROL RESOLUTION

0.5 dB

REMOTE CONTROL

1 tabletop direct access wireless infrared
1 handheld wireless infrared
1 RC-5 via a DC power connector
1 12 VDC Input (12 V trigger)
via a 3.5 mm mini plug
1 Krell Link input
1 Krell Link output

DIMENSIONS WITH COVER CLOSED

19w x 5.3h x 15.4d in.

48.3w x 13.3h x 39.1d cm

HEIGHT WITH COVER OPEN

20 in., 50 cm

WEIGHT

Unit only 45 lb., 20.5 kg

All operational features, functions,
specifications, and policies are subject
to change without notification.

THE LEADER IN AUDIO ENGINEERING

TECHNOLOGY INFORMATION

The Krell Playback System 25sc: Technology
Serving Music

Engineering, the practical implementation of pure
science, is a rigorous and disciplined undertaking.
Enjoying music, on the other hand, is an emotional,
often fervent, experience.

Krell pursues both.

The KPS 25sc combines three components – an
advanced CD transport, a proprietary digital-to­analog converter, and a complete system
preamplifier/control center – in one chassis.
Although contrary to conventional wisdom touting
the advantage of separate components, Krell
transforms the KPS 25sc into a technical tour de
force. Not only is the KPS 25sc a magnificently
engineered product, it is a supremely musical one
as well, one that best serves the needs of even the
most demanding connoisseur.

The KPS 25sc offers the following technologies to
enhance your musical enjoyment:

The professional-quality disc reading mechanism
features a high power neodymium direct drive
motor, a belt driven laser mechanism, and viscous
damped suspension. This combination assures bit­perfect recovery of even the faintest musical
nuances from your most revealing CDs.

total compatibility with HDCD-encoded discs.

A unique implementation of four 24-bit/96kHz
digital-to-analog converters (two for each channel)
produces output equivalent in detail to that
previously available only to professional recording
engineers.

A reference-grade preamplifier with fully balanced
Class A circuitry features Krell Current Mode design
for unimpeded pass-through of all musical details.

The KPS 25sc has a unique feature for easy
integration into home theater systems: Theater
Throughput. In Theater Throughput mode, the main
output signal from an external surround sound
processor bypasses the volume and balance
controls, providing a direct connection, at unity
gain, to the amplifiers powering the front left and
right speakers.

Krell CAST (Current Audio Signal Transmission)
technology improves musical coherency by solving
the problems inherent in transferring delicate
musical signals from preamplifiers to external
power amplifiers.

Three totally independent regulated power supplies
(analog, digital, and disc transport sections) insure
circuit isolation and prevent sonically harmful
interactions.

A massive prismatic transport cover automatically
activates an electronic shutter to prevent data­corrupting light intrusion during CD playback.

A Krell-designed digital filter uses two Motorola
DSP (digital signal processing) engines and custom­contoured interpolation software to provide more
musical detail. In conjunction with another
advanced microprocessor, this filter also provides

Two remote controllers (one full-function tabletop
controller, a second hand-held device for basic
operating modes only) and a rear panel system
connector facilitate comprehensive remote
operation.

Thus, the KPS 25sc conclusively demonstrates the
scope of Krell’s vision – that penetrating ability to
think within a single box.

THE LEADER IN AUDIO ENGINEERING

Krell Industries, Inc.

45 Connair Road

Orange, CT 06477-3650

USA
tel [phone]
fax [phone]

email [e-mail]

website www.krellonline.com

Krell® is a registered trademark of Krell Industries, Inc. and is restricted for use by Krell Industries, Inc., its subsidiaries, and authorized agents. Krell CAST is a patent pending of Krell Industries, Inc.

Krell Playback System

™

is a trademark of Krell Industries, Inc. HDCD is a registered trademark of Pacific Microsonics, Inc.©1999 by Krell Industries, Inc. All rights reserved.