Cello Encore Amplifier Owner's Manual

ENCORE AMPLIFIER

OWNERS MANUAL

Serial Number

TABLE OF CON

CONTENTS

Introduction
Product Concept and Description

Unpacking
Installation
Selection of Audio Cables
Connection
Operation
Bridged Operation
Service
Warranty
Maintenance
Physical Specifications
Electrical Specifications

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Connection Identification Diagram - Stereo and Mono
Connection Identification Diagram - Bridged Mode

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Al
A2

Introduction

ENCORE TRUE DUAL MONO AMPLIFIER

Congratulations on choosing the
Encore Amplifier. Your unit has

been individually handmade from
the finest parts and materials. The

Encore utilizes proprietary Cello
circuitry that represents true state­of-the-art in audio electronics, and

is designed to perform to "as-new"
specifications for decades of musi-

cal enjoyment.

We want your Encore Amplifier

to provide you with complete satis-

faction. Please read this manual

carefully and care for your Encore
so that it will retain its value,

beauty, and performance.

If you have any questions,

contact your authorized Cello

Designer or call the factory. It is
our wish to assist you in every

way, now and in the future.

1

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.

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.

■

Input Impedance.,

330 KOhms, + Audio
5 KOhms, -Audio.

■

Fuse Type.

3AB 1.5A SB, 200V-240V.

■

Dimensions.

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

752 mV

3AB 2.5A SB, 100V-120V.

Front Plate is 4.75" high

3-pin connectors.
balanced or unbalanced outputs, the
3-wire input system offers sonic advan­tages 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.

Whether driven from

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

2

Product Concept and Description, cont.

ENCORE TRUE DUAL MONO AMPLIFIER

is not practical to use this approach for
higher power amplifiers. A great deal of
money is spent on taking up space and
creating heat, without addressing AC
mains problems which affect sonic
quality.
system utilizes the entire AC waveform,
not just the peaks (like the capacitor input
system) and is very efficient so that no

cost, space, or heat is wasted (as in the
active regulator system). The high
quality, custom-made transformers and
chokes provide energy storage far beyond

the impression of their physical size. The

advantages of the dual choke input
system are quite apparent on a listening

basis, providing controlled, powerful,

deep bass and other sonic refinements.

SONIC

The first reaction of most listeners is,

"Flow can such a sound come from such a
compact package?" In fact, when Cello

engineers first connected the prototype of

Cello's dual choke power supply

QUALITY

the ETDMA for Mark Levinson to audi­tion, he got up and checked to make sure
that it really was the ETDMA playing and
not his PA set. After auditioning the

ETDMA, one can appreciate and under­stand the significance of the PA technol­ogy better, since it is now available in a
power range that corresponds to what the
largest number of listeners need for their
music systems. The speed and clarity of
the ETDMA is astonishing, with no
hardness in the higher frequencies. The
sound presentation has effortless qual-

ities associated with amplifiers having
higher power ratings, yet with the sonic
refinements and transparency associated
with all Cello products.

CONSTRUCT

The ETDMA utilizes bar-and-plate chassis
construction so that individual panels can
be replaced if necessary. Stainless steel
hardware, gold contacts, and many

premium parts ensure as-new sonic

ION

performance for decades of trouble
free operation.

Most audio products use the same

family of circuits and parts, metalwork
and hardware. If you inspect Cello

products on the inside and outside, you
will find very few parts common to other
audio products on the market. Cello
products cost more because they are built
with superior circuit designs, parts, and
manufacturing techniques for those who
want higher performance, reliability,
freedom from obsolescence, and complete,

long term satisfaction.

SUMMARY

The ETDMA is a compact power amplifier

offering state-of-the-art performance and
construction in the medium power class.
Balanced line inputs, dual choke supplies,
mono construction, copper heatsinks, and
advanced engineering are combined to
offer Cello quality in an attractive and
elegant package.

3

ENCORE TRUE DUAL MONO AMPLIFIER

Instructions

UNPACKING

The packing box for the Encore Amplifier
should arrive in good condition. Please
look for damage to the carton, although
this is most unlikely due to the strength of
the carton construction. Cut and open
packing carefully and save all foam pieces

and boxes for reuse in the event that the
unit must be shipped in the future.

Should the boxes become lost, please
contact the factory for replacement
cartons.

The carton should contain:

■

Encore Amplifier

■

2 A.C. cables

■ torx wrench

INSTALLATION

Be certain that the amplifiers are installed
so that they have proper ventilation.
Placing the units in small, close-fitting

enclosures is not recommended. Room air

temperature should not exceed 122

degrees F./50 degrees C.

SELECTION OF AUDIO CABLES

Any high quality RCA cables may be used.
For balanced line connections, we strongly
suggest using Cello Strings cable made to
factory specifications. Improperly
constructed cables cause problems. It
takes equipment and experience to make
high quality balanced line terminations.
Cello Strings are available in any desired
length, with a variety of connectors, for
different system requirements.

CONNECTION

(See connection identification diagram
on page A1.)

1)

Make sure the power switches located
on the rear panel of the amplifiers
are "OFF."

2)

Verify that the amplifiers are set to the
same A.C. mains voltage as the A.C.
mains in your home or studio. (A.C.
mains voltage is labeled on the rear
panel of the amplifier.)

3)

Connect the preamplifier outputs or
other driving equipment outputs to
the amplifier inputs located on the
rear panel.

4)

Connect speaker cables to speaker
outputs on the rear panel. Be sure to
keep the spade terminal from rotating
while turning the the screw. Tighten
until there is zero play, then apply an

additional 1/8th

turn to make the

connection snug.
CAUTION: Do not over-tighten, as

you will break the terminal strip.

5)

Install the A.C. cords into the I.E.C.
mains connectors located on the
rear panel.

6)

Connect the A.C. cords to the A.C.
outlets in your home or studio.

NOTE: Do not run A.C. cords, audio
signal or speaker cables under rugs or
sharp objects where they may be damaged.

OPERATION

CAUTION: Do not operate this device if
physical damage has occurred to unit, or

if the unit has been exposed to water or
other liquids, until proper repairs and/or
unit integrity tests have been effected by
authorized personnel.

1)

Be sure all electrical connections are
correct and secure. Triple check them.

2)

Turn peripheral units on first. Avoid

switching these units on and off while
amplifier is on.

3)

Set volume control on preamplifier to
minimum.

4)

Turn amplifier switches to "ON"
position.

5)

Begin source material (turntable, tuner,
CD, etc.) and raise preamplifier volume
control to desired listening level. Enjoy!

NOTE: To remove amplifier from
system, turn down volume then turn
amplifiers "OFF" and reverse steps for
connection.

BRIDGED OPERATION

(See connection identification diagram

on page A2.)

One pair of Encore Amplifier units may

be used as a mono amplifier in bridged

mode. This provides four times the
regular power.

CAUTION: Bridged operation should

only be carried out with the recommen­dation of the speaker manufacturer.

A bridging kit (P/N: 75-3410-00) is
required to operate Encore Amplifiers in
bridged mode. The kit may be purchased
from your Cello System Designer or
ordered directly from the factory.

4

Instructions, cont.

ENCORE TRUE DUAL MONO AMPLIFIER

The following bridged operation
instructions are for connecting one pair
of amp units (one channel).

1)

With power "OFF" connect AC cord
as instructed in Encore Amplifier
manual.

2)

Connect input to one amplifier only.
We will call this amp unit "Amp 1."

The second amp unit will be called
"Amp 2."

3)

Connect the input jumper cable,
included in the bridging kit, from the
bridging connector of
input of"Amp 2.

"

Amp 1"to the

"

Both are labeled on

the rear panel of your Encore unit.

4)

Connect one speaker's positive (+) or
high lead (usually marked in red) to
the output terminal labeled "H"

(

High) of "Amp 1."

5)

Connect the same speaker's negative
(-) or low lead (usually marked in
black) to the output terminal labeled

"H" (High) of "Amp 2."

6)

Connect the output ground jumper
cable, included in the bridging kit,
from the output terminal labeled "L"

(Low) of "Amp 1" to the output

terminal labeled "L" of "Amp 2."
This channel is now ready for

operation.

To connect for stereo, simply repeat
the procedure in steps 1-6 on the second
set of amps.

CAUTION: Make certain preamplifier
volume is turned down before AC
power of bridged amplifiers is

switched "ON."

SERVICE

Do not attempt to modify the Encore
Amplifier. Should you have any ques­tions or problems with your Encore,
please contact Cello's Customer Service
Department and allow us to assist

you.

If your Encore requires service, this
department will provide you with a
Return Authorization (R.A.) number and
instructions on how to return your unit
to the factory. All returns to the factory
require an assigned R.A. number.

Returns received without original
packing will be shipped out in Cello
cartons at owner's expense. Replace­ment packing materials are available
by calling the Customer Service

Department.

CELLO LIMITED WARRANTY

Parts: Five years 100% coverage for
all parts.

Labor:

Five years 100% coverage for

all labor.
Shipping: One year 100% coverage for

all shipping and insurance charges pre­paid to and from the factory from
anywhere in the world via reasonable
carrier. (Note: Special freight or rush
shipments will incur customer charge.)

After one year, units coming into the
factory must arrive with shipping
charges pre-paid. Return shipping
charges will be paid by the factory.

Warranty of Replacement Parts from
the

factory: The remainder of the

warranty period for the unit or one year

whichever is longer) shall be the

(

warranty applied to any replacement
part(s) issued.

Warranty of Repair

Work Performed:

Any specific repairs or modifications
effected by the factory or authorized
service facility shall be guaranteed for
100% parts and labor for the remainder
of the warranty period for the unit or
one year (whichever is longer).

Transferability:

All of the above war-

ranties are transferable to any succession
of subsequent owners. Please contact

your nearest Cello Designer or the
Customer Service Department at the

factory for details of subsequent owner
warranty registration.

Tampering: Any unauthorized modifi­cations, repairs or tampering with any
Cello product will void its warranty.

Abuse/Misuse: Any indications of
obvious owner abuse, negligence or

i

mproper usage, as determined by the

factory, shall void the warranty.

MAINTENANCE

The finish of the Encore Amplifier is of
brushed and anodized aluminum.

Ammonia-based glass cleaner or alcohol
and a soft cloth work well to restore

the shine and remove finger prints. Be

sure that the unit is off and unplugged

before cleaning. Avoid getting excess

cleaning fluid inside the amplifier. Take
care when cleaning rear panel. Do not
rub so hard as to remove the silkscreen
lettering.

5

ENCORE TRUE DUAL MONO AMPLIFIER

Physical Specifications

ENCORE AMPLIFIER

ENGLISH

MONO

Height (chassis)

Height (max.)

Width (chassis)

Width (max.)

Depth (foothold)

Depth (chassis)

Depth (max.*)

Box dimensions:

Weight: Net

Boxed

All weights are approximate and do not include exterior cabling.

*

Measurement from the rear of terminal strip covers to front plate.

Does not account for space cabling.

3.0 in.

4.4 in. 4.9 in.

8.5 in.

9.5 in.

10.5 in. 10.5 in.

12.0 in.

13.3 in. 13.3 in.

22.0" x 19.0" x 10.5"

55.9 cm x 48.3 cm x 26.7 cm

28 lbs.

43 lbs.

STEREO

3.0 in.

17.0 in.

19.0 in.

12.0 in.

12.7 kg

19.5 kg

METRIC

MONO

7.6 cm

11.1 cm

21.6 cm 43.2 cm

24.2 cm

26.7 cm

30.5 cm

33.7 cm

STEREO

7.6 cm

12.4 cm

48.3 cm

26.7 cm

30.5 cm

33.7 cm

6

ENCORE

TRUE

DUAL

Electrical Specifications

ENCORE AMPLIFIER

Power Output

Single Amp

I

MP (Ohms)

8
4

Bridged Set

I

MP (Ohms)

8

I

MD SMPTE

60Hz & 7kHz
20V ouput

THD

20Hz - 20kHz
8 Ohms 20V output
4 Ohms 20V output<0.3%

Frequency Response

20kHz
100kHz

Channel Separation

L-R

Signal to noise

20V output
1kHz

Input Impedance

Non-inverting
Inverting

Input Sensitivity

20V output, 8 Ohms
50W (RMS)

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Gain

NOTE: All measurements are for one mono amp unless otherwise indicated.
(All specifications subject to change without notice.)

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Rated

Watts (RMS)

50

100

Watts (RMS)

200

3%

<0.3%

-0 .3d B

-6.0dB

Infinite

<-100dB

330kOhms

5kOhms

1.485V

28.5dB unbalanced

34.5dB balanced

MONO AMPLIFIER

7

Cello, Ltd.

315 Peck Street, Bldg. 23

New Haven, CT 06513

203 865-1237 FAX [phone]