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.

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