VISTEK V1638 User manual

1
VISTEKV1638 ANALOGUE
AUDIODISTRIBUTION
AMPLIFIER USER GUIDE
www.pro-bel.com

VISTEKV1638 analogue audio
distribution amplifier
2 Issue 8
Contents
1. DESCRIPTION...........................................................................................................3
2. INSTALLATION.........................................................................................................4
2.1 RearPanel Connections..................................................................................4
Table2.1.1.........................................................................................................5
Figure2.1.2........................................................................................................6
Table2.1.2.........................................................................................................6
2.2 InputImpedance...............................................................................................7
2.3 InputMode........................................................................................................7
2.4 Lowpass Filter..................................................................................................8
Figure2.4.1........................................................................................................8
3. OPERATION..............................................................................................................9
3.1 FrontPanel.......................................................................................................9
3.2 LEDIndications................................................................................................9
3.3 GainAdjustment............................................................................................10
3.4 MonitoringJack.............................................................................................11
3.5 DartInterface..................................................................................................11

VISTEKV1638 analogue audio
distribution amplifier
HU-V1638 3
1. DESCRIPTION
The V1638 isabroadcast qualityanalog audiodistribution amplifierwhichformspart ofthe VistekV1600
range ofinterfaceproducts. It isa3U high cardwhichisfitted intoeitheraV1601 orV1603 rack, from
whichit receivesitspower. The V1638 isfullycontrollablebythe DART remotecontrolinterfaceand either
the V1605 remotecontrolpanelorthe VistekViewFind PC-based host. . Apassiverearmodulewithscrew
terminalconnections, isrequired forall signalinterconnections. Rearassemblieswithscrewterminal
connectorsproviding 8outputsand rearmoduleswithD-sub connectorsproviding 10 outputsareavailable.
The unit acceptstwodifferentialmono audioinputsand distributeseachofthesesignalsto5differential
mono outputs. The cardcan thereforebe used asastereo 1:5distribution amplifier. Modeswherebyeither
input orthe sumofbothinputsisdistributed to10 outputsareprovided and areselected byon-boardDIL
switchesorthe DART remotecontrolinterface.
The V1638 has2population options:
The baseversion hasdirect balanced inputsand outputsintended forlocaldistribution applications.
The line version hastransformercoupling on bothinputs. Oneitherversion input impedancemaybe set to
600 or20k bymeansofon-boardjumpers.
INPUTS:
Base version: 2xbalanced analog channels, Zin =20k or600 , maxinput 28dBu
Lineversion: 2xtransformercoupled channels, Zin=20k or600 , maxrecommended input
is+20dBu
OUTPUTS:
Monitoring: 3.5mm Stereo jack socket -18dBuinto600 w.r.t. mainoutputs
Main outputs: 2x5xbalanced analog channels, Zout £50 , maxoutput 28dBuinto10k
Resistorcoupled expander panel:
Arearpanelexpanderisavailablewhichisfitted witha96WayDIN41612 connectorand comes
completewithalocking, cable-mounted 96WayDIN41612 plug assemblywithsolderbucket
terminations. The expanderhas4resistor-coupled outputsforeachofthe 5mainoutputsfor
channelsAand B. Using thisexpanderpanel, the V1638 can function asa20+20 DAwhen driving
high input impedances(³10k ).
Theresistorcoupled outputsoftheexpander panel should notbeused to drive 600 W loads
Adigitallycontrolled gainblock allowsindependentusercontrolofthe gainofeachinputchannel,overa
range -95.5to+31.5dB.The gainisadjustablebyfrontpanelrotary switches(Localmode)orviathe
DARTcontrolinterface(Remotemode).Standardversion offersgainresolution of0.5dBfromboth
remoteinterfaceand panel,and hi-resolution version offersgainresolution of 0.25dBoverremoteinterface
and 0.5dBfrompanelcontrols.
The input foreachoutput group (Aout[1..5], Bout[1..5])maybe sourced fromAin, Binor(Ain+Bin)and is
selected byon-boardDILswitches(Localmode)orviathe DART controlinterface(Remotemode).
The V1638 hasan activefirst orderlowpass filteron eachinput channel. Rolloff point (-3dB) maybe set to
60 kHzor120kHzbyjumperoption. LEDsforindication ofclipping and lowinput foreachchannelare
provided.
Notmore than two outputsper card may beused to drive 600 loadsat+20 dBu ormore

VISTEKV1638 analogue audio
distribution amplifier
4 Issue 8
The V1638 iscompatiblewiththe VistekDART remotesystem, allowing cardID, status, gainand input
selection tobe read and gainand input selection tobe set byaDART compatiblerack controller.
2. INSTALLATION
2.1 RearPanel Connections
The 3U screwterminaland DSUBrearpanelsareshownbelow. 1U panelsaresimilarlymarked. Table
2.1.1detailsconnectionstothesestandardpanels. Figure2.1.2and Table2.1.2describe signalsand
connectionstothe DIN41612 cablemounted plug supplied withthe resistor-coupled expanderpanel. Note
that thesepinnumbersrefertothosestamped on the back ofthe supplied cable-mount connectorwith
solderbuckerterminals:
A (IN)
B (IN)
A1(OUT)
A2(OUT)
A3(OUT)
A4(OUT)
B1/A5(OUT)
B2/A6(OUT)
B3/A7(OUT)
B4/A8(OUT)
+
S
-
+
S
-
+
S
-
+
S
-
+
S
-
+
S
-
+
S
-
+
S
-
+
S
-
+
S
-
1
25
1
15
AudioOutputs
AudioInputs

VISTEKV1638 analogue audio
distribution amplifier
HU-V1638 5
Table2.1.1
Connectionstostandardrearpanels
SIGNAL DSUB
pin
SOURCE COMMENTS
Power Rack PWRheader +15Vnominal(9-35V) at 5Wmax
DARTbus Rack DART header VistekDART rack controller
Ain(+) 9
Ain(-) 1
2,3,4,5,6,8 Externalaudiosource All screensfromexternalaudiosourceshould
GND 10,11,12, be grounded on the V1638 i/pconnector
13,14
BIn(+)15 Externalaudiosource ChannelBdifferentialinput
BIn(-) 7 Zin=20k /600 ; max. input +28dBu
A1out (+)
14 V1638 Group Aoutputs
A1out (- )
1 Zout =50 ; maxoutput +28dBu
A2out (+)
16
A2out (- )
3
A3out (+)
17
A3out (- )
4
A4out (+)
18
A4out (- )
5
A5out (+)
19 A5output isnot availableon screwterminal
A5out (- )
6 rearmodules. OnlyDSUBrearmodulehasA5
GND 2,7,13,15 V1638 All screensfromV1638 shouldbe grounded
20 on the V1638 o/pconnector
B1out (+)
21 V1638 Group Boutputs
B1out (- )
8 Zout =50 ; maxoutput +28dBu
B2out (+)
22
B2out (- )
9
B3out (+)
23
B3out (- )
10
B4out (+)
24
B4out (- )
11
B5out (+)
25 B5output isnot availableon screwterminal
B5out (- )
12 rearmodules. OnlyDSUBrearmodulehasB5

VISTEKV1638 analogue audio
distribution amplifier
6 Issue 8
Figure2.1.2
Structureof resistorcoupled outputson expanderpanel
Table2.1.2
Connectorassignmentson resistor-coupled expanderpanel
Cablemounted DIN41612 TypeCconnectorassignments
Pin No. Row a Row b Row c
1 A11 out + B51 out + B11 out +
2 A11 out - B51 out - B11 out -
3 A12 out + B52 out + B12 out +
4 A12 out - B52 out - B12 out -
5 A13 out + B53 out + B13 out +
6 A13 out - B53 out - B13 out -
7 A14 out + B54 out + B14 out +
8 A14 out - B54 out - B14 out -
9 A21 out + GND B21 out +
10 A21 out - GND B21 out -
11 A22 out + GND B22 out +
12 A22 out - GND B22 out -
A1
A2
A3
A4
A5
A11
A12
A13
A14
A21
A22
A23
A24
A31
A32
A33
A34
A41
A42
A43
A44
A51
A52
A53
A54
B1
B2
B3
B4
B5
B11
B12
B13
B14
B21
B22
B23
B24
B31
B32
B33
B34
B41
B42
B43
B44
B51
B52
B53
B54

VISTEKV1638 analogue audio
distribution amplifier
HU-V1638 7
Cablemounted DIN41612 TypeCconnectorassignments
Pin No. Row a Row b Row c
13 A23 out + Ain+ B23 out +
14 A23 out - Ain- B23 out -
15 A24 out + GND B24 out +
16 A24 out - GND B24 out -
17 A31 out + GND B31 out +
18 A31 out - GND B31 out -
19 A32 out + Bin+ B32 out +
20 A32 out - B in- B32 out -
21 A33 out + GND B33 out +
22 A33 out - GND B33 out -
23 A34 out + GND B34 out +
24 A34 out - GND B34 out -
25 A41 out+ A51 out + B41 out+
26 A41 out - A51 out - B41 out -
27 A42 out + A52 out + B42 out +
28 A42 out - A52 out - B42 out -
28 A43 out + A53 out + B43 out +
30 A43 out - A53 out - B43 out -
31 A44 out + A54 out + B44 out +
32 A44 out - A54 out - B44 out -
2.2 InputImpedance
The standardsetting ofdifferentialinput impedanceofChannelAand ChannelBinputson the V1638 is
20k , whichshouldbe used when the inputsaredriven fromanydirect coupled sources(electronically
balanced orquasi-balanced line driverswithlowoutput impedance.)Ifthe inputsaredriven froma600
balanced line, the input impedancemaybe set to600 byusing the jumpersettingsshownbelow. Note
that the input impedanceofthe twochannelsmaybe set independently. Figure2.4.1showsthe location of
the jumpers.
Impedance Jumpers
ChannelAZin=20k LK6OPEN
ChannelBZin=20k LK1OPEN
ChannelAZin=600 LK6CLOSED
ChannelBZin=600 LK1CLOSED
2.3 InputMode
The V1638 Output groupsA[1..5] and B[1..5] mayeachbe sourced fromAin, Binor(Ain+Bin). DILSwitch
SW4controlsthe input mode asperthe following table. The Ain+Binmode foragiven output group is
obtained byswitching on boththe Ainand Binswitches. Figure2.4.1showsthe location ofthe SW4
switches.
InputMode SW4action
Ain=> A[1..5] out SW4-1on
Bin=> A[1..5] out SW4-2on
Ain=> B[1..5] out SW4-3on
Bin=> B[1..5] out SW4-4on

VISTEKV1638 analogue audio
distribution amplifier
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2.4 Lowpass Filter
The lowpass filter-3dBrolloff point on eachinput channelmaybe set to60kHzor120kHz. The 120kHz
position maybe usefulinapplicationswherethe V1638 isrequired topass timecode spooling. The filteris
set byjumpers, asperthe tablebelow. Notethat the filtersofthe twochannelsmaybe set independently.
Figure2.4.1showsthe location ofthe jumpers.
-3dBrolloff point Jumpers
ChannelAf-3 =60kHzLK3CLOSED
ChannelBf-3 =60kHz LK2CLOSED
ChannelAf-3 =120kHz LK3OPEN
ChannelBf-3 =120kHz LK2OPEN
The figurebelowshowsthe V1638 and the location ofall the jumpersreferred toinSection 2.2-4.
Figure2.4.1
Jumperand Switchlocations
Front Panel
RearConnector
LK1
LK6
LK2
LK3
1234
SW4
ON

VISTEKV1638 analogue audio
distribution amplifier
HU-V1638 9
3. OPERATION
3.1 FrontPanel
3.2 LEDIndications
The green V+LEDislit wheneverpowerisapplied and the V1630’sinternalpowersupplyisoperating
correctly.
The yellow REM LEDflashesbrieflytoindicateaDARTbusaccess isinprogress.
Ared CLIP LEDisprovided foreachchannel. Theseindicatorshaveafast attack and 0.8sretriggerable
holdcharacteristic. The output signalismonitored and the LEDswill triggerat +28dBu, just beforethe
onset ofclipping. The LEDwill be on continuouslyofsustained clipping occurs.
Ayellow LOI/PLEDisprovided foreachchannel. Thesehaveaslowattack, 0.8s, and fast decay
characteristic. The input signalismonitored and the LEDswill triggerwhen the signallevelfallsbelow
approx-40dBuforlongerthan 0.8s. The LEDwill be on continuouslyifthereisno input orthe input has
very quiet passagesoflong duration.

VISTEKV1638 analogue audio
distribution amplifier
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3.3 GainAdjustment
The V1638 hastworotary panelswitchesforadjusting the gainofeachchannel. Thesepanelswitchesonly
haveeffect when the REM/LOCAL switchisinthe LOCAL position. The COARSE switchadjuststhe gainin8dB
stepsfrom-96dB(mute)to+24dB. The FINE switchadjuststhe gainin0.5dBstepsfromcoarsesetting dB
tocoarsesetting +7.5dB. The tablebelowshowsthe correspondencebetween the 16 switchpositions
and the gainsetting forbothcoarseand fine controls.
Coarse switch Fineswitch
Switch Gain value Switch Gain value
setting (dB) setting (dB)
0 -96 (mute) 0 0
1 -88 1 +0.5
2 -80 2 +1.0
3 -72 3 +1.5
4 -64 4 +2.0
5 -56 5 +2.5
6 -48 6 +3.0
7 -40 7 +3.5
8 -32 8 +4.0
9 -24 9 +4.5
A -16 A +5.0
B -8 B +5.5
C 0 C +6.0
D +8 D +6.5
E +16 E +7.0
F +24 F +7.5
It can be seen fromthe tablethatthe gainapplied isthe sumofthe settingsofthe COARSE switchand
the FINE switch.Careshouldbe taken when setting the gainsinan application toallowsufficient
headroomsothat the V1638 doesnot clipon peaks. Rememberthat the maximumoutput ofthe V1638
is+28dBu.The V1638 circuitry updatesthe gainsetting fromthe panelswitchesevery 50 ms.When
the rem/localswitchissettothe remposition,the gainseton the frontpanelswitchesisignored and
the gainissetfromthe DARTinterface.Onthe standardversion,gainresolution fromthe remote
interfaceis0.5dB, and on the high resolution version it is0.25dB.

VISTEKV1638 analogue audio
distribution amplifier
HU-V1638 11
3.4 MonitoringJack
The V1638 DAprovidesastandard3.5mm stereo headphone jack socket on the front panel, enabling
quick checkstobe made and monitoring done without having togo toajack field. The monitoring output
providesafixed signallevelapprox10dBlowerthan the direct coupled mainoutputs. Thusa+28dBu
signalon the V1638 baseversion output correspondstoa+18dBulevelon the monitoring output, whichis
designed tobe used withprofessionalqualityheadphonesof300-600 impedance, (eg Sennheiser
HD520).
3.5 DartInterface
The V1638 hasaserialEEPROMforreading and writing carddetailsthrough the DARTbusinthe same
mannerasotherV1600 range cards. Inaddition the unit hasseveralread and writeregisterswhichwill be
discussed. Detailsofthe DART interfacemaybe found indocument Scms1638.doc.
Small commercialheadphonesof32 impedance asusedin portableconsumer equipmentmay
alsobeusedbutthey may bedamagedatthehigh ofthesignallevelspossiblewith theV1638 DA
baseversion.