Nagra VPA User manual

P/N: 2055008151
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VPA
Ultimate 845 amplifiers
I structio ma ual

2
Nagra – VPA
Table of co te ts
Security war i gs ....................................................................... 3
Warra ty ................................................................................... 3
Co gratulatio s .......................................................................... 4
Package co te ts ....................................................................... 4
Setti g-up the amplifiers ............................................................... 5
I stallatio of the feet ................................................................ 5
I stallatio of the tubes .............................................................. 6
I stallatio of the tube protectio s ............................................... 7
VPA co ectio s ......................................................................... 8
Co ecti g the VPA to the source ................................................. 8
Co ecti g the loudspeakers ....................................................... 8
Co ecti g the AC mai s power ................................................... 9
Operation .................................................................................... 10
The mai selector ..................................................................... 10
Selecti g the correct speaker impeda ce ..................................... 11
Tube agei g a d replaceme t .................................................... 12
Tube compatibility .................................................................... 12
Tube bias adjustme t ............................................................... 12
Tech ical specificatio s ............................................................. 13
Declaratio of co formity ............................................................. 14

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Nagra – VPA
Security war i gs
•Carefully read this ma ual before i stalli g your ew VPA;
•Should you have a y questio s o how to set-up or use your
amplifiers, co tact your Nagra dealer;
•AUDIO TECHNOLOGY SWITZERLAND SA decli es all respo sibility i
the eve t of a accide t caused by the o -observa ce of these
i structio s or a y other form of user eglige ce;
•Do ot attempt to ope the u it u der a y circumsta ces. Refer a y
service/repair work to qualified perso el. There are o user
serviceable parts i side the amplifier;
•The Nagra VPA is desig ed to be used i door o ly;
•The Nagra VPA ru s very hot, i stall it i a safe place to avoid a y risk
of i jury, especially with childre a d domestic pets;
•Should you eed to ship or tra sport your amplifier, always use the
origi al packi g supplied by Nagra.
Warra ty
AUDIO TECHNOLOGY SWITZERLAND SA, certifies that this i strume t was
thoroughly i spected a d tested prior to leavi g its factory a d is i accorda ce
with the data give i the accompa yi g measureme t protocol a d test sheet.
We warra t the products of our ow ma ufacture agai st a y defect arisi g from
faulty ma ufacture for a period of three years from the date of delivery to the
user.
Warra ty will be void if the serial umber has bee removed from the u it.
This limited warra ty covers the repair of co firmed defects or, if ecessary, the
replaceme t of the faulty parts, excludi g all other i dem ities.
All freight costs, as well as customs duty a d other possible charges, are at the
customer's expe se.
We decli e a y respo sibility for a y a d all damages resulti g, directly or
i directly, from the use of our products.
We reserve the right to modify the product, a d / or the specificatio s without
otice.
Disposal of Old Electrical & Electro ic Equipme t (Applicable i the
Europea U io a d other Europea cou tries with separate collectio
systems).
This symbol o the product or o its packagi g i dicates that this
product shall ot be treated as household waste. I stead it shall be
ha ded over to the applicable collectio poi t for the recycli g of
electrical a d electro ic equipme t. By e suri g this product is
disposed of correctly, you will help preve t pote tial egative
co seque ces for the e viro me t a d huma health. The
recycli g of materials will help to co serve atural resources. For more
detailed i formatio about recycli g of this product, please co tact your
local authority, your household waste disposal service or the shop where
you purchased the product.

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Nagra – VPA
Co gratulatio s
Co gratulatio s, you have just purchased o e of the best amplifiers ever made!
The VPA were created by a e gi eeri g team with more tha 60 years of
experie ce desig i g world-class products for the professio al audio, atio al
security a d military busi esses.
Si ce its i ceptio i 1951, Nagra builds products that co ti ue to ear a
reputatio for deliveri g ultimate so ic performa ce. Numerous awards have
bee bestowed upo Nagra for its tech ical i ovatio , excelle ce i desig a d
flawless co structio i cludi g three Oscars
®
a d o e Emmy
®
.
The hi-fi products a d field recorders are developed by the same R&D
Departme t. Nagra philosophy is to provide i ovatio a d tech ology i order to
desig high quality products. The hi-fi ra ge was created to impleme t i ovative
desig s a d provide Nagra expertise to a ew field.
Tha k you for bei g our customer a d e joy your ew VPA amplifiers !
Package co te t
I additio to the user ma ual:
•2x VPA mo oblocks;
•2 mai s cables *;
•Set of spare fuses;
•Hex screwdriver (to i stall the tube protectio s);
•2x Sets of tube protectio s;
•2x Sets of feet;
•2x Sets of 845 tubes;
•Microfiber gloves (from Swiss Haute Horlogerie);
•Measureme t protocol, this is the actual electrical measureme t of
your amplifiers.
If a ythi g is missi g, please co tact your dealer.
*depe di g o your cou try, the AC mai s cable features either bare wired, US,
Europea or Swiss plug.

5
Nagra – VPA
Setting-up the amplifier
I stallatio of the feet
The VPA eeds to sta d o its feet to be stable, please i stall them.
Tur each of the two VPA mo o blocks o their side o the edge of a
table.
Step 1 Start by removi g the tra sportatio screws
Step 2 I stall the feet, usi g the lo ger screws provided

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Nagra – VPA
I stallatio of the tubes
Step 1 Usi g the hex screwdriver provided, remove the top ri gs.
Be careful ot to drop a screw i side the amplifier!
Step 2 I sert the 845 tubes
Please use the gloves provided; they are custom made for Nagra usi g
state of the art “Haute Horlogerie” micro-fiber fabric.
Each VPA has its ow set of tubes with a serial umber writte o the
socket. Each tube is also marked “FRONT” or “REAR” which i dicates
the correct locatio for the tube o the particular amplifier.
This de t must
face the rear of
the u it.
Step 1 I sert the tube, make sure the de t is i the correct positio
Step 2 Rotate the tube clockwise, u til it clicks.
1
2

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Nagra – VPA
I stallatio of the tube protectio s
845 tubes ru extremely hot, more tha 300° C, it is ma datory to
i stall the tube protectio s for safety reaso s. Eve with the tube
protectio , you should be careful ot to get too close to the tubes a d
especially to keep childre away from the amplifier.
You should also make sure to keep a y object or fabric (like curtai s
for i sta ce) away from the amplifiers to avoid a y fire risk.
Ge tly slide the tube protectio
dow .
Make sure the screw holes are
placed above those of the VPA.
Usi g the hex
screwdriver provided put
the screws back i place

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Nagra – VPA
VPA co ectio s
Co ecti g the VPA to the source
Co ect the source preamplifier to the XLR bala ced i put or the RCA
co ector.
I put pa el
Speaker termi als
Grou d co ector (ask your
dealer how to use it)
Voltage selector
Mai s switch a d IEC co ector
The white jumper allows
you to select either XLR
bala ce i put (as show
o the picture) or RCA
u bala ced

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Nagra – VPA
Co ecti g the loudspeakers
O the rear of each VPA mo o block there are four gold plated WBT
loudspeaker termi als. The loudspeaker cables should be co ected
betwee the right-most termi al marked “LO” for - a d the correct
termi al accordi g to the impeda ce stated by the ma ufacturer of the
loudspeaker for the + .
Should you have a y doubt about your speaker’s impeda ce, start with
8 Ohms. You will lear i the “Load Match Meter” sectio , how to take
full adva tage of the VPA u ique features to get the best performa ce
out of your speakers.
Co ecti g the AC mai s power
Before co ecti g the AC power cables, verify that the AC mai s
voltage selector (located o the rear pa el) is i the correct positio
correspo di g to the supply voltage available i your cou try.
Here the selector is o 220 V.
If the selector is ot i the
right positio , make sure to
cha ge it, a d check the fuse
value:
110 – 120V operatio two 10A fuses should be i stalled;
220 – 240V operatio two 5A fuses should be i stalled.
Fuse compartme t
Mai s electrical switch
Warning:
U its for Japa are factory adjusted for 100 V a d carry a special
sticker. If you live i Japa a d do ’t fi d this sticker, please co tact
your Nagra dealer a d do ot attempt to power the u it.

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Nagra – VPA
Operation
The mai selector
Tur the Mai s switch (o the rear) to the I positio . The , place the
mai selector o the “MUTE” positio , the tubes are ow powered a d
will light up. I this positio the amplifier is powered a d the audio
sig al is muted. Tur the mai selector to the ”ON” positio , the
amplifier is ow fully operatio al. The best performa ce will be
obtai ed after 15 mi utes operatio (warmi g-up time).
Mains switch
rear)
Main selector
position
What is happening
O A y The u it is completely off
I OFF The u it is i sta dby
I MUTE The u it is O , sou d is muted
I ON O
To preve t tube agei g, it is better leave the amplifier o for lo ger
periods rather tha tur i g it o a d off several times a day. For more
i formatio o tube agei g a d replaceme t, refer to Tube agei g a d
replaceme t o page 12.
Mai selector
Modulometer
Rear tube selector
(for bias)

11
Nagra – VPA
Selecti g the right speaker impeda ce
The Load Match Meter was specially desig ed to help you match your
amplifier with your speakers. The Nagra VPA’s output stage features a
custom ha d-made Nagra tra sformer that offers 3 differe t output
wi di gs for 4, 8 a d 16 Ohm speakers.
Start by verifyi g the omi al impeda ce of your loudspeakers, either
from their tech ical specificatio s or o the rear of the speaker. The
co ect the “+ve” speaker cable to the correct termi al o the VPA.
The modulometer features two poi ters, the red poi ter i dicates the
peak cathode curre t a d the black poi ter i dicates the peak a ode
voltage of the output tube. They will allow you to k ow if the
impeda ce match is right.
Whe playi g music (mai selector i the ON positio )
Needle position What is happening Solution
Red eedle > Gree
eedle*
Output impeda ce is
too high
Choose a lower
output (8 or 4 Ohms)
Gree eedle > Red
eedle
Output impeda ce is
too low
Choose a higher
impeda ce (8 or 16
Ohms)
Needles follow each
other
The match is perfect E joy your music
* as show o the picture
NB the two eedles will almost ever superimposed o e above the
other, but should ot be too far apart, this is subjective; spe d a little
bit of time to k ow how to “read” the eedles.

12
Nagra – VPA
Tube agei g a d replaceme t
845 tubes are supposed to operate for arou d 5’000 hours.
I ter al tubes ca last about the same.
As a rule, you should replace all tubes at o ce o both u its.
I ter al tubes must be replaced by a Nagra dealer.
It is ormal to adjust the bias o ce i a while. From time to time,
before liste i g, check the bias a d eve tually adjust it to make sure
you get 100% performa ce out of your amplifiers.
Tube compatibility
Nagra selected 845 tubes go through a rigorous selectio : 24 hour
bur -i , i dividual measureme t a d selectio a d are paired usi g a
Nagra u ique process. Usi g 845 from other suppliers will void
warra ty.
Tube bias adjustme t
Please refer to the i structio s fou d i the tube package to lear how
to set-up the bias.

13
Nagra – VPA
Tech ical specificatio s
The followi g table shows the ge eral specificatio s for all Nagra VPA amplifiers.
Your perso al amplifier’s measureme ts are provided o the accompa yi g
"measureme t protocol" docume t.
Type Pure class A
Tube type 845
Output power 50 W rms
Input impedance > 100 k Ohms
Inputs
1 RCA, 1 XLR bala ced Selectio by jumper
Frequency response 20 - 40 kHz +0 / -3dB
Signal-to-noise ratio > 100 dB ASA A
Output impedance 4, 8, 16 Ohms
Bare wires up to 4.2 mm
4mm ba a a plugs
6.35mm spade lugs
Driver tubes 2x ECC83, 1 E182CC
Voltage range
108
-
1
21
V or
216
-
24
2
V
(Japa 100 V) 50 – 60 Hz
Power consumption 250 W co ti uous
Dimensions 335 x 115 x 375 mm 13 x 4 ½ x 14 ¾ i ches
Net weight (each VPA) 13.5 Kg 30 lbs

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Nagra – VPA
Déclaration de conformité
Declaration of conformity
FABRICANT: AUDIO TECHNOLOGY SWITZERLAND SA,
1032 Roma el, SUISSE
MANUFACTURER: AUDIO TECHNOLOGY SWITZERLAND SA,
1032 Romanel, SWITZERLAND
APPAREIL : VPA
MODEL: VPA
Par la prése te ous déclaro s l'équipeme t co forme à toutes les
exige ces fixées da s les ormes:
We ereby declare t at t e equipment conforms to all t e requirements
outlined by t e following norms:
NORMES GENERIQUES APPLICABLES :
APPLICABLE GENERIC NORMS:
CENELEC EN 61000-3-2
61000-3-3
50081-1
50082-1
Avertissement.
Bie qu’éta t co forme aux ormes, cet appareil peut, da s des cas
exceptio els, provoquer des i terfére ces. Da s ce cas, il peut être
dema dé à l’utilisateur de pre dre des mesures appropriées.
Warning.
Alt oug t is equipment conforms to t e stated norms, under certain
exceptional circumstances it may provoke interference. In t is event
t e user may be asked to take appropriate measures.
Other electrical regulatory certificatio pe di g.
Cheseaux 1
er
trimestre 2000
C eseaux 1
st
quarter 2000