Nagra TUBE DAC User manual

P/N: 2055111159
All rights reserved –© 2019 rev 3
TUBE DAC –D/A converter
User manual

2
Nagra –TUBE DAC
Safety warning ..................................................................................... 3
Warranty ............................................................................................. 3
Congratulations .................................................................................... 4
Package contents .................................................................................. 4
Installation...................................................................5
Positioning ........................................................................................... 5
Powering the TUBE DAC ......................................................................... 5
Connecting to a Nagra MPS/CLASSIC PSU ............................................. 5
Rear panel connection block ................................................................... 7
Audio inputs ......................................................................................... 8
Front panel........................................................................................... 9
Setting your TUBE DAC ...............................................10
The controller knob ..............................................................................10
Accessing the menu mode.....................................................................10
How to operate the Controller knob ........................................................10
Menu tree or map ................................................................................11
Setting the language ............................................................................12
Naming of the digital inputs...................................................................13
Reset of input names .........................................................................14
Input assignment .................................................................................15
Audio settings......................................................................................17
Line level .........................................................................................17
Line mode ........................................................................................18
Absolute phase .................................................................................19
USB power .......................................................................................20
Remote...............................................................................................21
About .................................................................................................22
USB set-up with computers ...................................................................23
Connecting the TUBE DAC to your system ...............................................24
Setting the headphones amplifier level ...................................................24
Operating your TUBE DAC...........................................26
Front selector ......................................................................................26
Nagra Modulometer ..............................................................................26
Modulometer & display intensity adjustment............................................27
Phase mode selection ...........................................................................27
Headphones output selection .................................................................27
IR remote control unit ..........................................................................28
Use of an universal IR remote control unit ............................................29
TUBE DAC channel selection ...............................................................29
Burn-in period .....................................................................................30
Tube ageing ........................................................................................30
Case cleaning ......................................................................................30
Technical specifications..............................................31
Declaration of conformity ...........................................32

3
Nagra –TUBE DAC
Safety warning
Read this manual carefully before operating the TUBE DAC;
Should you have any questions on how to setup or use your TUBE
DAC, please contact your Nagra dealer;
Audio Technology Switzerland SA declines any responsibility in the
event of an accident caused by the non-observance of these
instructions or any other form of user negligence;
The TUBE DAC shall not be exposed to dripping or splashing and no
objects filled with liquids, such as vases, shall be placed on the
apparatus;
Never try to open your TUBE DAC when it is powered to prevent risk
of electric shock and burn. Switch it OFF, switch off the external
power supply and remove DC power cables from TUBE DAC back
panel. Wait for 15 minutes before any intervention into your device,
as tube exchange, or headphones amplifier level setting. If you are
not sure what to do, please contact your Nagra dealer.
Warranty
Audio Technology Switzerland SA certifies that this device has been inspected
and tested before leaving the factory.
Every Nagra unit goes through our test laboratory. The result of the
measurements is recorded in the “Protocol” documentation that comes with
your device.
We guarantee our products against all manufacturing defects, for a period of
three years for the TUBE DAC and six months for the tube, running from the
date of delivery to the customer (validated by the serial number on the device
casing and the invoice from an official Nagra dealer). This warranty is only valid
for the original purchaser of new equipment.
This limited warranty covers the repair and replacement of defective parts,
excluding any other remedy.
The absence of a serial number invalidates the warranty.
We decline any responsibility for damages resulting directly or indirectly from
the use of our products and from the use of any components or spare parts
other than those designated as original/approved parts by Audio Technology
Switzerland SA.
As we constantly strive to improve our products, we reserve the right to modify
them or change their specifications without notice.

4
Nagra –TUBE DAC
Congratulations
Congratulations! You have just acquired one of the best digital-to-analog
converters ever built.
The TUBE DAC was created by an engineering team with more than 60 years’
experience designing world-class products for the professional audio, national
security and military businesses. The professional and Hi-Fi product ranges are
designed by the same Research and Development department.
Nagra launched its Hi-Fi range to allow the wider public to benefit from
technical advances that are often the privilege reserved for professionals. In so
doing, the ultimate sonic excellence has been shared throughout the Hi-Fi
range.
Ever since its creation in 1951, Nagra has been building devices that offer
unparalleled performance, and the company has received many awards for its
technical innovations and the excellence of its products over the years. Among
the most prestigious, Nagra has been awarded three Oscars® and an Emmy®.
Our experience, precision and dedication to detail has been implemented to do
service to music, your music. This is why we wish you many hours of listening
pleasure and memorable moments enjoying your TUBE DAC.
Thank you for your trust.
Package contents
In addition to this User manual and the TUBE DAC itself, the box contains:
A printed record of the exact measurements, response curve
characteristics of your device, measured in the Nagra
laboratory;
A DAC IR Remote control unit (2 x AAA dry-cells inside);
A pair of “Haute Horlogerie“ grade microfiber gloves;
An Allen key (Hex) driver to open the TUBE DAC (for dealer use
preferably);
An USB key with PC and MAC configuration information.
Please contact your Nagra dealer if anything is missing.

5
Nagra –TUBE DAC
Installation
Positioning
In order to avoid risks of fire and electric shock, the TUBE DAC should be used
exclusively indoors. It has been designed for a usage in moderate climate.
If possible, it is preferable not to place other HiFi elements on top of your TUBE
DAC and free access to the ventilation holes, located under the device and on
the top surface (above the tube), must be maintained at all times to allow
sufficient natural cooling during operation.
The Nagra TUBE DAC must be placed on a stable horizontal surface. We
strongly recommend the use of the special anti-vibration support plates, HD
VFS, Vibration Free Supports, developed by Nagra. These consist of two solid
aluminum isolated plates that use the same silicon base damping material as
the Nagra CD mechanics. These plates will eliminate any mechanical vibrations
that may interfere with the sonic excellence of your TUBE DAC.
Powering the TUBE DAC
The TUBE DAC has a unique powering system, with totally independent supply
sources for the digital and analog portions of the electronics. This dual powering
system was developed to eliminate any interference between the different
elements and guarantee an uncompromising audio transparency.
Connecting to a Nagra MPS/CLASSIC PSU
The TUBE DAC will reveal its full potential with the full chassis power supply
Nagra MPS or Nagra CLASSIC PSU which were specifically designed to provide
several independent power sources for different Nagra Hi-Fi elements.
Connection
Verify that both TUBE DAC & MPS/CLASSIC PSU front selectors are in the OFF
position. Insert the LEMO plug with a black Ring (connector sleeve) from
both cables supplied with the MPS/CLASSIC PSU unit into two LEMO socket
outputs on the backside of the MPS/CLASSIC PSU unit.
Then, insert the second LEMO plugs of cables into both LEMO socket inputs on
the backside of the TUBE DAC by applying following recommendations:
For TUBE DAC: The second side of LEMO cable can have either a
black or another colour connector sleeve. It does not matter!
Only with MPS:If available, we recommend using MPS output 1 for
the TUBE DAC DC digital input and MPS output 2 for the TUBE DAC
DC analog input (noise).

6
Nagra –TUBE DAC
With MPS and CLASSIC PSU: Always use the first available output of
the power supply device for the TUBE DAC DC digital input and the
consecutive one for the TUBE DAC DC analog input (sequential start
of MPS/CLASSIC PSU outputs, it is better to first start digital section
of TUBE DAC).
First start up power supply unit by turning front selector to ON position. Wait
for the end of starting process (MPS: when the 4 output LEDs on front panel
are switched ON, CLASSIC PSU: when the blinking LED on the right side of
front panel switches OFF).
Now you can start up the TUBE DAC by selecting the desired position on front
selector.
Disconnection
First, turn the TUBE DAC front selector to OFF and wait for its complete
shutdown (when display and modulometer backlight switch OFF).
Then, turn the power supply unit front selector to OFF and wait for its complete
shutdown (when LEDs and modulometer backlight switch OFF).
Now you can safely remove LEMO plugs from the TUBE DAC and MPS/CLASSIC
PSU back panels:
Grip the fluted section of the plug, between thumb
and index fingers as shown in the picture and pull
the crown of the connector backwards.

7
Nagra –TUBE DAC
Rear panel connection block
1. Ground connector (see note below)
2. The analog output section provides both RCA or XLR which should
NOT be used simultaneously. The XLR outputs are unbalanced
(asymmetrical). Should you need transformer balanced outputs,
please contact your Nagra dealer.
3. Digital inputs section (from left to right):
-The USB (UAC2*) connector is for receiving digital audio
from a PC, a MAC computer, a NAS
-TOSLINK is a standard optical data connection
-AES / EBU XLR input conforming to the AES-3 standard
-Four optical Nagra links
-Two S/PDIF inputs, 1 on BNC, 1 on RCA
4. DC power inputs
-Analog, powers the TUBE DAC analog section
-Digital, powers the TUBE DAC digital section
*UAC2 stands for “USB Audio Class 2” works to connect computers PC or Mac
as well as other computer type devices.
Note about the Ground connector
This connection is seldom used but may solve specific setup issues concerning
“hum”. Your Nagra dealer will assist you on when and how to use this
connector.
1.
3.
2.
4.

8
Nagra –TUBE DAC
Audio inputs
9
1 2 3 4 5 6 7 8
Input type
Input format
1:
USB B-type
DSD: up to DSD256 (DSD4x)
PCM: up to PCM 384kHz
2:
TOSLINK EIAJ optical
(MM fiber)
PCM: up to PCM 192kHz
3:
AES/EBU
PCM: up to PCM 192kHz
4-7:
ST (MM fiber)
DSD: up to DSD256 (DSD4x)
PCM: up to PCM 384kHz
8:
S/PDIF 1 BNC
PCM: up to PCM 192kHz
9:
S/PDIF 2 RCA
PCM: up to PCM 192kHz

9
Nagra –TUBE DAC
Front panel
1. This switch adjusts the intensity of the Modulometer back-light and the
main display. Pushed up increases the intensity, while down will reduce it,
there are 7 levels of intensity.
2. Nagra Modulometer indicates the digital input level in dB FS (Full Scale)
of the currently selected input. 0 dB being the maximum level. The black
needle corresponds to the signal on the left channel and the red needle to
that of the right channel.
3. Dual line LCD display for operating mode and menu display.
4. Controller knob, which has several features, described below.
5. PHASE switch.
6. Volume adjustment potentiometer.
7. This switch selects the routing of the analog outputs: OUTPUT is for the
line (RCA or XLR) output, PHONES for headphones jack.
8. The front selector is the principal activation switch for TUBE DAC. In the
OFF position the TUBE DAC is in “Standby” mode*.
9. Headphones output jack.
10. Infra Red sensor window for the remote control, and its activation LED
*In standby mode the power consumption is less than 100 mW.
Please note that when turned ON, the TUBE DAC will go through a 2 minute
pre-heating phase. This is in order to optimize the warming-up of tubes and
critical components. This will allow your TUBE DAC to offer excellent
performance for a longer period, by managing the critical components gently.
HEADPHONES OUTPUT
This equipment is capable of
producing high sound levels which
can be harmful to your hearing
3.
2.
4.
5.
6.
7.
8.
9.
10.
1.

10
Nagra –TUBE DAC
Setting your TUBE DAC
Using the rotary controller knob along with the display, your TUBE DAC can be
personalized to integrate it into your system. Please take a moment to learn
more about the settings that you can change to enjoy your music even better.
The controller knob
AES
NO SIGNAL
The controller knob can be rotated
or pressed to access different
functions of your TUBE DAC.
Accessing the menu mode
All menu related features are managed using the controller knob, which can be
rotated or pressed.
Press and hold the Controller knob for 2 seconds to access the menus.
You can navigate within the menu tree through the different topics by rotating
the Controller. To exit the menus, press the Controller knob for 2 s.
How to operate the Controller knob
Controller
Normal operation
Inside menus
Press and hold (2 s)
Access menus
Exit menu (1 step up)
Rotate
Change input
Scroll up or down
Press once (briefly)
Go forward / validate
We suggest you to navigate inside the menus to get familiar with the navigation
controller, then you can start setting-up the various possibilities.