Crown dl2 audio

Page 1

crown

SECTION 4
THEORY OF OPERATION

4.1 General _

The DL2 is a precision, high-quality audio
preamplifier.The Crown designed and developed

circuitry represents a level of quality and performance '
presently unequaled in the field of audio preamplifier

design.

4.2 Principles of the DL2 Controller

The DL2 uses digital logic to control the analog signal,

path with the use of high quality reed relays. The main
signal path is not affected by filters, tone circuits or
external signal processors unless the function is switched
manually. By using this straight signal path in
conjunction witbr'verwaast, high quality 1C audio
amplifiers, the 01.2 produces the most sonically pure
signal that technology will allow. All forms of distortion
including slew-induced distortion (TIM) in the DLZ are
not perceptable by the human ear and most test
equipment.

The tone circuits are Crowns famous hinge point
shelving circuits similar to the EQ-Z equalizer. The high
and low cut filters have selectable center frequencies. The
loudness contour switch. provides selectable contours for
various loudness levels. '

By using an external phono module, the DLZ system

realizes many advantages over the imboard preamp. The .

resulting sonic purity is truly state of the art; The
module is deSigncd to be mounted as close to the

turntable as possible. This allows short leads to the

cartridge reducing cartridge loading, high frequency loss.
and RF interference

The power supply module is a separate module that can
be placed on the floor out of sight or rack mounted with
the DLZ. By separating the power supply from the
circuitry, Crown has again improved signal noise and
hum rejection.

4.3 Block Diagram Circuit Theory

The signal source is fed to the input control section. This
section is controlled by both the digital logic control and
manual switches. See Fig. 4.1. Notice that the main signal
path is straight through with no circuits that will color or
alter the signal in line. Circuits that are used to alter the
signal, such as the tone system, filters, etc, are switched
in and out of the signal path manually.

The signal goes to the buffer amplifier where several
outputs occur. The low filter system is switched into the
buffer amp. A buffered output is provided from this point
to the rear panel and the external processor control gets
its output. The external processor control can return the
signal after the buffer amp or return it to the input control
so that the signal is before the tape outputs.

From the buffer amp the signal goes to the panorama
control system. Here the signal is switched to effect
Channel-balance, normal, mono and reversed stereo
modes and mixing with the X and Y input feeds. From
the panorama system the signal goes to the first gain
amplifier section The loudness contour system is
switched at this point. From here the main signal
proceeds to the second, third and fourth gain amps. At
this point the high filter is switched in or out Not: that
the digitally controlled volume control system primarily
controls the gain of thofour gain amps.

The signal now How; to the output section. Hero is where
the Crown hingc'point shelving tone control systems is
switched. This is a precision switched system that allows
the user to return to an exact setting. The signal continues
to the output amp. inverting amp, mixing amp and to the
headphone amp. From these amplifiers, the signal goes to
the rear panel through the muting relay and output
control switches.