Product Concept And Description - Cello Encore Amplifier Owner's Manual

ENCORE TRUE DUAL MONO AMPLIFIER

Product Concept and Description

CONCEPT
Cello developed the Performance
Amplifier (PA) to obtain the most natural
sound and widest dynamic range from
the finest speaker systems. The Encore
True Dual Mono Amplifier (ETDMA)
offers similar sonic qualities for music
listeners who require the ultimate in
medium power amplification.
DESCRIPTION
The ETDMA consists of two separate
mono amplifiers, each in its own chassis,
held together by a common front plate,
top plate, and rear serial number plate.
Each chassis has its own line cord and, if
separated from the other chassis, operates
as a mono amplifier. Unlike some. "dual
mono" amplifiers on the market which are
really stereo amplifiers with separate
power supplies in a single chassis, the
ETDMA offers true mono amplifier
performance in the size of a stereo unit.
The ETDMA incorporates a number of
engineering advances which allow high
performance in a compact and efficient
design, without fan cooling, providing a
practical and appealing product for
inclusion in music systems of the
finest quality.
2
■ Power Rating. 50 Watts into 8 Ohms.
20-20KHz with no more than 0.3% .THD
■ Gain. 28.50 dB, unbalanced source,
34.50 dB, balanced source.
■ Input Sensitivity. 752 mV
■ Input Impedance.,
330 KOhms, + Audio
5 KOhms, -Audio.
■ Fuse Type. 3AB 2.5A SB, 100V-120V.
3AB 1.5A SB, 200V-240V.
■ Dimensions. Front Plate is 4.75" high
by 19" wide by .25" deep. Chassis 3."
high by 17.25" wide by 12" deep.
AUDIO CIRCUITRY
The heart of the ETDMA is the actual
driver board from the PA, without the
heatsink tunnels, driver transistors and
output transistors required for the highest
voltage and current (power) levels. The
ETDMA sounds like the PA because it
utilizes the same circuit board, parts, and
associated circuitry for medium power
performance. A solid copper, nickel-plated
heatsink bracket, specially designed for this
product, takes heat out of the transistors
and evacuates it into the entire chassis
including the top and bottom plates.
Balanced inputs are provided using Fischer
3-pin connectors. Whether driven from
balanced or unbalanced outputs, the
3-wire input system offers sonic advan-
tages not to be missed by critical listeners
(see Balanced Lines, a paper by Mark
Levinson and Tom Colangelo, available
from Cello, Ltd.). The output power of
the ETDMA is rated at 50W @ 8 Ohms.
Speakers can be driven which present
loads as low as 1 Ohm. The ETDMA
circuitry is exceptionally stable and can be
operated 24 hours a day in residential and
professional applications.
POWER SUPPLY
The ETDMA utilizes a dual choke system
similar to the PA supply, but scaled down
for reduced power requirements of the
audio circuitry.
Most power amplifiers use a capacitor
input system which includes a power
transformer, bridge, and filter capacitors.
They deliver DC operating voltages to
the audio circuitry. Larger and larger
transformers are used to charge bigger
and bigger capacitors, but the peak
demands of musical signals exceed the
energy storage of the capacitors. Some
companies use active, regulated power
supplies for improved sonic quality, but it