Nagra Classic AMP User guide

P/N: 2055028151

All rights reserved – © 2020 rev1

CLASSIC AMP

Instruction manual

Table of contents

Important safety warnings 4
Warranty 4
Congratulations 5
Package contents 5

Installation 6

Positioning the CLASSIC AMP 6
Presentation of your CLASSIC AMP 6
Input panel 8
Ground connector 8
Output section 9

Operating the CLASSIC AMP 11

Switching ON 11
Security 12
Troubleshooting 13
Technical specifications 14

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Nagra – CLASSIC AMP

Important safety warnings

Before operating the CLASSIC AMP, read this manual carefully

Should you have any questions on how to setup or use your CLASSIC AMP, please
contact your Nagra dealer.

Do not attempt to open the amplifier under any circumstances. Refer any service
/ repair work to Nagra qualified personnel. There are no user serviceable parts
inside the amplifier

Audio Technology Switzerland SA declines all responsibility in the event of an
accident caused by the non-observance of these instructions or any other form of
user negligence

To work correctly in your country, the CLASSIC AMP has a specific power supply
for 100, 115 and 230V. The power supply voltage can only be changed at the
factory. Make sure you have the right operating voltage before switching your
amplifier on.

Warranty

AUDIO TECHNOLOGY SWITZERLAND SA, designer and manufacturer of Nagra
products, certifies that this instrument was thoroughly inspected and tested prior
to leaving its factory and is in accordance with the data given in the
accompanying measurement protocol and test sheet.

We warrant the products of our own manufacture against any defect arising from
faulty manufacture for a period of three years from the date of delivery to the
user.

Warranty will be void if the serial number has been removed from the unit.

This limited warranty covers the repair of confirmed defects or, if necessary, the
replacement of the faulty parts, excluding all other indemnities.

All freight costs, as well as customs duty and other possible charges, are at the
customer's expense.

We decline any responsibility for any and all damage resulting, directly or
indirectly, from the use of our products.

We reserve the right to modify the product, and / or the specifications without
notice.

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Nagra – CLASSIC AMP

Congratulations

Congratulations, you have just purchased one of the best amplifiers ever made!

The CLASSIC AMP was created by an engineering team with more than 60 years
of experience designing world-class products for the professional audio, national
security and military businesses.

Since its inception in 1951, Nagra builds products that continue to earn a
reputation for delivering ultimate sonic performance. Numerous awards have
been bestowed upon Nagra for its technical innovation, excellence in design and
flawless construction including three Oscars® and one Emmy®.

The hi-fi products and field recorders are developed by the same R&D
department. The Nagra philosophy is to provide innovation and technology in
order to design high quality products. The hi-fi range was created to implement
innovative designs and provide Nagra expertise to a new field.

Thank you for being our customer and enjoy your new Nagra CLASSIC AMP
amplifier!

Package contents

In addition to the CLASSIC AMP and manual, each box should contain the
following:

If anything is missing, please contact your dealer.

*depending on your country, the AC mains cable features either US, European or
Swiss plug.

 Microfiber gloves (from Swiss Haute Horlogerie);
 AC power cable*;
 Set of fuses (for 100 - 120 or 220 – 250 V, depending on your

country);

 1x Bridge jumper.

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Nagra – CLASSIC AMP

Installation

1

2

3

4

Positioning the CLASSIC AMP

If you have a thick carpet, it is mandatory to place the CLASSIC AMP on a stand
to allow an optimal thermal dissipation.
We recommend you to ask your Nagra dealer for a demonstration of the VFS L
anti-vibration platform that offers a perfect match for your CLASSIC AMP.
The CLASSIC AMP is designed to be used exclusively indoors.

Presentation of your CLASSIC AMP

Front panel

1 – Main selector
2 – Clipping (orange) and alarm (red) LED
3 – Modulometer
4 – Modulometer intensity switch

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Nagra – CLASSIC AMP

Rear panel

Main switch
O is OFF
I is ON

3

1 2 4

5

1 - IEC Mains connector, fuse holder and Mains switch
2 – Output section
3 – Input section
4 – Remote section
5 – Ground connector

Fuse type

Replacement fuses are provided with your CLASSIC AMP.
Make sure to use:

FST 5x20mm 250V / T 10A L for 100 – 120V Mains.
FST 5x20mm 250V / T 5A L for 220 – 250V Mains.

The fuse holder itself contains a spare fuse. The active fuse is
on the left-hand side on the picture.

Should the fuse blow twice for no apparent reasons, please
contact your Nagra dealer for advice.

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Nagra – CLASSIC AMP

Input panel

Input type RCA or XLR

The CLASSIC AMP is a fully balanced
amplifier. The inputs are provided on two
balanced XLR connectors.
If your source is unbalanced, you can use the
RCA input, and then switch the TYPE selector
to RCA. Please note that this is not an input
selector to connect different sources, it is to
connect one component, either RCA or XLR.

Sensitivity

Depending on the source, you can adjust the
CLASSIC AMP’s input sensitivity. This will
guarantee a perfect match with your
preamplifier. You can change the input
sensitivity at any time by moving the LEFT
and/or RIGHT channel switches on the back

In this picture the sensitivity is set to 1V rms.

(see position in the adjacent picture - SENS).

MODE selector BiAmp - NORM or BRIDGE

The MODE selector allows you to change the CLASSIC AMP mode. This selector
should be moved when the amplifier is OFF (from the back panel’s switch).

BiAMP The amplifier will use the left input to power both channels
NORM Normal mode, standard stereo amplifier
BRIDGE This is the bridge mode, when two amplifiers are combined

Ground connector

In some specific situations the ground connector can be used to
connect different pieces of equipment to avoid unwantred earth­loop hum.

Your Nagra dealer will advise you during set-up whether this
connector needs to be used.

Remote connection

The CLASSIC AMP can be set ON of OFF with an external signal from a Nagra

MPS. Use the IN to connect the MPS’ AMP output.
Use the CLASSIC AMP’s output to trigger a second CLASSIC

AMP (in bridged mode).

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Output section

Right speaker

Left speaker

Left bass

Left mid / high

Left bass

Right bass

The CLASSIC AMP can operate in three different modes.

NORM normal mode or stereo, this is the standard mode

BiAmp for BiAmping this mode is intended for using two CLASSIC AMPs.

If your speakers allow the connection of bass and high/mid sections separately,
you can use two CLASSIC AMPs to power either one speaker each, or one
amplifier for bass and one for highs (or mids and highs).

You may also decide to use the amplifiers in bridge mode, using one method or
the other, depends very much of your speakers, you should try different solutions
to find the best match. In any case, use the LEFT input on both amplifiers.

Option 1 (one channel represented)

Option 2 (the other amplifier is used to power the mids and highs)

Connect the speakers on the LEFT and RIGHT
Cardas connectors.

If you use banana plugs, use the white
connectors.

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Nagra – CLASSIC AMP

Bridge mode

Speaker Left

or right

In this mode, both channels are used in parallel to double the output current,
thus doubling the power. The CLASSIC AMP will deliver 200 W rms into 8Ω on one
channel. Doubling the current allows a better drive of your speakers. You do need
to connect one CLASSIC AMP to each speaker. Use the LEFT input.

Then connect one loudspeaker to either connector (they are used in parallel).
Do the same on both CLASSIC AMPs.

NB. You may also replace the jumper with a link connector of the same range as
your speaker cable. Many cable manufacturers offer such a part.

Make sure to turn the amplifier OFF (using the
MAINS switch on the back) before changing the
Mode.

Change the MODE to BRIDGE.

Place the bridge jumper

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Nagra – CLASSIC AMP

Connecting the Mains cable

Mains
Switch

Front
Selector

Action

O Any

The CLASSIC AMP is shut down

I

OFF

This is the Standby position in which the CLASSIC AMP
will use less than 1 W

I

AUTO

Automatic On/Off the CLASSIC AMP will detect signal on
the input and turn ON automatically, it uses less than 1
W like in standby, it shuts down in the absence of signal
after about 15 minutes

I

AUTO
with MPS
remote

When the REMOTE input is connected to the Nagra MPS
power supply, it will automatically turn the CLASSIC AMP
On and Off

I

MUTE

The CLASSIC AMP is ON but the inputs are muted

I

ON

The CLASSIC AMP is ON

Make sure the switches are in the OFF position prior to connecting the mains
cable.

This is the Mains switch, when set to the off O position, the
amplifier is totally off and does not draw current from the Mains.
Fuse compartment

IEC connector

Operating the CLASSIC AMP

Proceed only once you have completed the installation steps described in the
previous chapter Installation.

Switching ON

The Mains switch is located on the rear panel (see above section).

This table sums-up the different positions

To use your amplifier, you must first, put the Mains
switch in the ON (I) position.

Then you can use the Front Selector on the front panel.
In Nagra’s tradition, we call this selector the “péclette”.

Nagra – CLASSIC AMP

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Security

The CLASSIC AMP is loaded with different protection systems, to allow for smooth
and secure operation for the amplifier itself and your loudspeakers.

Protection mode

When does the CLASSIC AMP go into the “Protection mode”?

 If it is connected to the wrong mains supply voltage;
 Continuous clipping;
 Short-circuit protection;
 DC current appears on the output(s);
 Internal temperature is too high.

What should you do in this event?
On the rear of the unit, turn the Mains switch OFF (O), wait for 30 seconds and
turn it ON (I) again.

Note Should the CLASSIC AMP go into the Protection Mode without apparent
reason or several times consecutively, turn it OFF (from the Mains switch) and
contact your Nagra dealer.

Wrong voltage

The CLASSIC AMP power supply is designed to work for a specific Mains voltage,
either 100-120 V or 220-240 V. To avoid potential component destruction, it
won’t turn on if it is connected to the wrong voltage. The front red LED will light,
and the unit won’t start. If this is the case, please contact your Nagra dealer.

Clipping protection

Clipping will occur when you push the amplifier to its limit, the front LED will start
to blink orange. While a short “clip” will not even be heard, a long clip can

damage the amplifier or the loudspeakers. That’s why, after one second of

continuous clipping, the LED will turn to red and the CLASSIC AMP will self­protect by going into the Protection Mode.

Short-circuit protection

In the event of a short-circuit on the speaker connectors, the front red LED will
light up; after one second, the amplifier will go into the Protection Mode. Before
turning the unit ON again, you should check the speaker connections.

DC protection

A DC (direct current) component generated from the amplifier could damage your
loudspeakers. If a DC component of more than +/- 2.5 V appears on the output
of the CLASSIC AMP, the front LED will blink in red and the amplifier will go into
Protection Mode.

Whenever a potential danger arises, for the amplifier
or the loudspeakers, the CLASSIC AMP will shut down.
This is called “Protection mode”. The front red LED
will light up as shown in the picture.

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Nagra – CLASSIC AMP

Thermal problem

LED status

Cause

Amp. Status

What to do

RED on

Wrong voltage

The amplifier
does not start

Wrong Mains voltage, contact
your Nagra dealer

The amplifier is playing music

Blinks orange

Light clipping

ON

It is ok, consider reducing the
listening volume

The amplifier shuts down - Protection Mode

Orange on

Heavy clipping

Protection Mode

You need to restart the
amplifier and reduce the
volume

Blinks orange

Overheating

Protection Mode

The amp is overheating, it will
start again when the
temperature is below 60° C
(140° F)

Blinks red

DC problem

Protection Mode

To avoid damage to your
speakers, the amplifier turns
off, contact your Nagra dealer

If the amplifier runs too hot, it will shut down automatically. In this case, don’t do

anything; it will turn on again when the temperature drops down. Make sure the
amplifier is positioned on a solid platform and that fresh air can circulate inside
the unit. In this case, the amplifier LED will blink in red and shut down, wait until
the temperature cools down and it will turn on automatically.

NB If the room temperature is high, the amplifier operating range will be smaller
and the risk of the amplifier over-heating higher. Make sure the room is at a
comfortable temperature, preferably below 30° C.

Modulometer

The modulometer provides two scales to display the
rms power on the output of the amplifier. The upper
scale is into 8 Ohms the lower is for 4 Ohms in
BRIDGE mode.

Right channel - black needle
Left channel - red needle

Adjusting the modulometer brightness

The toggle switch located on the left-hand side of the modulometer allows you to
adjust the backlight intensity.

From full blown to a complete extinction it provides 7 levels of intensity.

This setting is automatically memorized by the CLASSIC AMP when you turn the
amplifier OFF.

Troubleshooting

The following table will help you to solve any problems of set-up and operation.

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Nagra – CLASSIC AMP

Technical specifications

Class

AB

Power

100 W rms into 8Ω

Sensitivity

1V or 2V rms

Bandwidth

<10 Hz to 80 KHz

+0 / -3 dB

Crosstalk

>70 dB

Signal-to-noise ratio

Typically 110 dB

Measured in ASA A

THD+N

< 0.05 %

@100 W

Input impedance

>100 KΩ

Output impedance

60 mΩ

Input connectors

XLR

Balanced

RCA

Unbalanced

Jack 3.5 [mm]

External Remote IN and OUT

Monitoring

Stereo level meter

Red/ Orange LED on
front panel

Clipping indication,
temperature, saturation

Automatic start

For input level > 10mV

Protection
Deactivates the amplifier

Overheating

Above 60°C (140°F)

DC protection for
loudspeakers

Above +/- 2.5 V DC

Output connectors

Cardas CPBP

Rhodium terminals

Consumption

400 W max

Sine wave current draw
complies with EN61000-3-2
regulation

Less than 1W in Standby
and Auto

Weight

15 Kg (33 lbs)

Net weight

Size

27.7 x 39.5 x 17.4 cm

11 x 15.5 x 7 inches

Operating range

90-110 or 110 - 132V
or 180-264V

50 - 60 Hz

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Nagra – CLASSIC AMP

DECLARATION DE CONFORMITE
DECLARATION OF CONFORMITY

FABRICANT: Audio Technology Switzerland 1032 Romanel, SUISSE
MANUFACTURER: Audio Technology Switzerland 1032 Romanel, SWITZERLAND

APPAREIL : Nagra CLASSIC AMP ou CLASSIC AMP
MODEL: Nagra CLASSIC AMP or CLASSIC AMP

NORMES APPLICABLES :
APPLICABLE NORMS:

Champ électromagnétique rayonné EN 55022 Cl. B

Radiated electromagnetic field EN 55022 Cl. B

Perturbations conduites sur secteur EN 55022 Cl. B

Disturbance voltage on mains terminal EN 55022 Cl. B

Immunité aux champs électromagnétiques EN 61000-4-3

Immunity to electromagnetic fields EN 61000-4-3

Immunité aux décharges électrostatiques EN 61000-4-2

Immunity to electrostatic discharges EN 61000-4-2

Immunité aux transitoires électriques
rapides en salves sur câble d’alimentation EN 61000-4-4 level 2 (1000V)

Immunity to burst on mains line EN 61000-4-4 level 2 (1000V)

Immunité aux transitoires électriques rapides en salves sur câbles d’entrées/sorties
signaux EN 61000-4-4 level 1 (500V)

Immunity to burst on input/output signal line EN 61000-4-4 level 1 (500V)

Immunité aux ondes de choc EN 61000-4-5 level 2 (1000V)

Immunity to surge EN 61000-4-5 level 2 (1000V)

Romanel 2
Romanel 2nd quarter 2015

Nagra R&D team

ème

trimestre 2015

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Nagra – CLASSIC AMP