Iso-Max SC-2NR User manual

ISO-MAX® PRO SERIES USER GUIDE
SPEAKER-LEVEL to LINE-LEVEL Interfaces
Models SC-2NR, SS-2NR and SP-2SX
Jensen ISO-MAX8 Pro series audiointerfacesaredesignedforuse in thefinestprofessionalandaudiophilesoundsystems.
They usethe same industry-benchmark Jensen transformersthatareinstalledintensofthousandsoftheworld'sbest
recordingstudios,broadcastfacilities,andsoundreinforcement venues because oftheir sonic transparency,ultra-wide
bandwidth, an vanishinglylowharmonicand phase distortion.
Model SP-2SX
Models SC-2NR and SS-2NR aretwochannel "speaker" leveltounbalanced"consumer"levelconvertersandground
isolators - the SS-2NR havinganextendedlow-frequencyresponseforextremelyhigh-performancesub-woofers.The SP-2SX
(shownabove) is thefunctionalequivalent with balanced"pro"leveloutputs.Allaredesignedtoaccept,infourswitch-
selectableranges, speaker drivevoltages of 14Vrms, 25 Vrms,44Vrms, or 77Vrms. These voltages will be developedat full
output of poweramplifiersrated at 24W, 75 W,240W, or 750 W respectively into 8 Q loads or ratedat48W,150W,480
W, or 1,500 W respectively into 4 O loads.Input ranges also include 25V and70 V lines used in commercialsound systems
coveringlarge areas. Since the speaker inputsareungrounded,theyareespeciallyuseful with poweramplifierswhereboth
outputs areactivelydrivenandcannotbegrounded(theseareoftenreferredto as "bridge-mode" or "floating"outputs).
The speaker inputsrepresent a trivialadditionalloadforthedrivingpoweramplifiers - maximuminputpower is 0.08W, 0.4
W, 1.5 W,and 5.4W respectivelyinthefourinputranges. In addition,allmodelsprovideinherentlow-pass filtering to
removeultra-sonicswitchingartifactsfromtheoutputs of "digital" or "class D" poweramplifiers. These artifactscan cause
subtledistortionsindownstreamamplifiers[Deane Jensen and Gary Sokolich, "Spectral Contamination Measurement," AES
85th Convention Preprint 2725,1988}.
Thestandardversions have dual, or "stereo,"outputsthatcorrespondindependentlyto each ofthe speaker input signals.
The SC-2NR and SS-2NR output signals will reach1.75Vrms(+5dBV) at maximumratedinput - sufficienttodriveanyknown
power amplifier with an unbalancedinputto full outputpower. This levelrepresents 15dBof "headroom" in consumer
audio systems wherethenominal or "referencelevel" signal is standardized at- 10dBV or 0.316Vrms.Likewise,the SP-2SX
outputs will reach6.9Vrms(+19dBu), a levelthatrepresents 15dBof "headroom" in professionalaudio systems wherethe
nominal or "referencelevel" signal is standardizedat +4 dBu or 1.23Vrms.
"Mono" outputversions,denoted bya "-M" suffixinthemodelnumber, have a single outputthatrepresentsthesum of
the two speaker input signals. These would be used,forexample,whentheinputsareLeftand Right channelsandthe
output, L+ R, drives a single sub-woofer.
These ISO-MAX unitsareentirely passive andrequire no powersupply.
FOR OPTIMUM PERFORMANCE, PLEASE REVIEW THE FOLLOWING PAGES!

General Application Guidelines
Load Impedance Range (input impedance ofdevicetheunitdrives)10kOormore
Maximum Output Cable Length, SC-2NR and SS-2NR 60feet(18m)oftypical cable at50pF/ft(160pF/m)
total capacitiveload< 3,000 pF
SP-2SX 3 feet(1m)oftypical cable at50pF/ft(160pF/m)
total capacitiveload< 200pF
Maximum Input Cable (amplifier/speakerto ISO-MAX) Lengthunlimited
System Hookup
Inchoosinga physicallocationforthe ISO-MAX unit, shorteroutput cables arepreferredovershorterinput (speaker feed)
cables. Ingeneral,thebetterlocation will beneartheamplifier(s)tobedriven.Inexpensive, small-gauge "zipcord"or
"speaker wire" isrecommendedforthe speaker inputstothe unit. Its gauge istechnicallyunimportantbut18,20,or22
gauge aregenerally easiest tostripandhandle.Itshouldbeemphasizedthatthequalityofthiswirehasnegligibleeffecton
the qualityofsound- normaltechnicalconcernsabout speaker cables donotapply.Theother ends oftheseinput cables
canbeconnectedtoeitherthemain-channelpoweramplifieroutputterminalsorthemain-channel speaker terminals,
whicheveris closer ormoreconvenient.For25V or70V distributionsystems,makethe "speaker" connectionsdirectly
across the"constantvoltage"distributionline.Again,besuretoobservepolarityandtightlytwistthestrandsofwireat
each endtoavoidstrandsthat"stray"beyondtheclamp area ofeitherthescrewterminalsoramplifier/speakerterminals.
FortheSC-2NRor SS-2NR:
Observingpolarity,securelyattachthe speaker input cables toscrewterminals1 (+)and2 (-),marked"CH1 IN,"forone
channelandscrewterminals8 (+)and9 (-),marked"CH2 IN,"fortheotherchannel. DOUBLE CHECK TOBE SURE THE
SPEAKER INPUT CABLES ARE CONNECTED TOTHE CORRECT TERMINALS - OTHERWISE, THE UNIT MAYBE DAMAGED! Finally,
connecta standard,high-qualityRCAmaletoRCAmale cable betweenthe ISO-MAX unitoutputsandtheinputsofthe
power amplifier(s)tobedriven.
FortheSP-2SX:
Observingpolarity,securelyattach each speaker feed cable toterminals1 (+)and2 (-)ofa Neutrik "Speakon" model NL2FC
"2-pole" cable connector(notsupplied). Please notethatthematingNeutrikmodel NL2MP panelconnector used onthe
ISO-MAX unit will notaccept4-pole cable connectors.Alternatively,thescrewterminalsmaybe used for speaker inputas
describedbelow.
The Screw Terminal Strip (all models):
If desired,allinputandoutputconnectionscanbemadeviathedetachable13-polescrew-terminalstrip. These connections
paralleltheinputandoutputconnectors,ifpresent.Notethatterminalnumbers descend in left-to-right order.
Terminal
Marking Function
13 CH2,OUT+
Channel 2, Line Output+
12 CH2,OUT-
Channel 2, Line Output- (cableshieldforunbalancedoutputmodels)
11 CH2, OUTS
Channel 2,Output Shield (internallytiedtounit housing/chassis)
10 CH2,INS (nointernalconnection)
9 CH2,IN-
Channel 2, Speaker Input -
8 CH2,IN+
Channel 2, Speaker Input +
7 (CHASSIS)
Unit housing,internallytiedtoOutput Shields (see"Grounding" discussion below)
6 CH1,OUT+
Channel 1, Line Output+
5 CH1,OUT-
Channel 1, Line Output- (cableshieldforunbalancedoutputmodels)

4 CH 1, OUTS
Channel 1,Output Shield (internallytied to unit housing/chassis)
3 CH 1,IN S
(nointernalconnection)
2 CH 1,IN-
Channel 1, Speaker Input
1 CH 1, IN +
Channel 1, Speaker Input +
Grounding
Althoughtheseunitscompletelyelectricallyisolateinputsfromoutputs,there are situationswheresupplementalgrounding
may be necessary. This generally happens onlywhenequipment hasa 2-prong AC powerconnection(no third or grounding
prong). CAUTION: if any piece of equipment in your system uses a 3-to-2 prong "adapter" or other means (such asa clipped-
off3'd prong) to defeat safety grounding provided byits 3-prong power cord, we strongly urge you to remove it... this is an
extremely dangerous practice, promoted by the technically naive, that may result in fire, severe shock or electrocution.
Forbalancedoutputmodels (SP-2SX), groundingtothe DESTINATION (equipmentdriven by theunit'slineoutputs)
normally occurs throughthe XLR output cable shieldconnections.However,forunbalancedoutputmodels (SC-2NRorSS-
2NR),allowinggroundcurrenttoflow in theoutput RCA cables wouldcreatehum or buzz. Therefore, an addedequipment
ground is recommended. This can be mosteffectivelydone by connecting an insulatedwire(stranded#18or#20AWG,
green,length as required)betweenscrew-stripterminal 7 andthe chassis of thedestinationequipment.Sometimesthere
is a convenient"ground"terminal on theequipmentforthepurpose. If not,you can attachthewireunder an existing screw
somewhereontheequipment'smetal chassis. Sometimesgrounding canbe done by simplymountingthedestination
equipment ina properly-groundedequipment rack (taking care toremovepaintthatmightpreventelectricalcontact
betweenequipmentand rack rail).Anotheralternative is to have a reputabletechnician change thepowercord onthe
destinationequipmentfrom2-prongto3-prong,attachingthegreenwireofthenewcord to theequipment chassis.
If the SOURCE equipment(amplifiersthatgeneratethe s speaker input) is ungrounded, turn on switches S4(Ch1) and S5
(Ch2), as shownbelow,toeliminatehum or buzz thatmightoccur.
Setting the Switches
Onthebottom of the unit, you'llfind a group of switchesthat select therated
input, in terms of ratedmaximumamplifierpoweroutputthat will produce
the specifiedmaximumoutputvoltage (+5dBV forthe SC-2NR and SS-2NRor
+19dBuforthe SP-2SX).Use the75/150 W settingfor 25V distributionandthe
750/1,500 W settingfor 70V distributionlines. Switches 1, 2, and 3 arefor
Channel 1 andswitches 6, 7,and 8 arefor Channel 2:
H
JBBH1
o|
1 -
Switch Settings, Ch1/ Ch2
Amplifier Power Rating (W)
S1/S6
S2/S7
S3/S8
at 8 ohms at 4 ohms
off off off
24 48
on off off
75 150
on on off 240 480
on on on 750 1,500
S4and S5are normally off. They are used to solve possible grounding issues (see "Grounding"above).Whiletheunitcan't
be damaged by continuousinputvoltages up to80volts, regardless of switchsettings, severe distortionmayresultfrom
impropersettings.
All Jensen productsareproudlymade in theUnited States ofAmerica. If you have problems or questionsaboutthese
products,contact[email protected]m or call usat [phone],Mondaythrough Thursday, 9 AM to
5PM, Pacific time. For detailedspecifications, please see theproductdata sheets at www.iensen-transformers.com.
ISO-MAX® isa registeredtrademarkof Jensen Transformers, Inc.

ISO-MAX® PRODUCT WARRANTY
Fora periodof1 YEAR afterpurchase, Jensen Transformers,Inc. will, freeofcharge,repairorreplaceanypartofanISO-
MAX® productthatfailsduetodefectivematerialsorworkmanship.Fora periodof20 YEARS afterpurchase, Jensen
Transformers,Inc. will, freeofcharge,repairorreplaceany Jensen OEMtransformerorany Jensen transformercontained
in anISO-MAX® productthatfailsduetodefectivematerialsorworkmanship.
Bothlimitedwarrantiesaresubjecttothefollowinglimitations:
1) Defects thatare,inthe sole judgementof Jensen, theresultofaccident,misuse, abuse, neglect,mishandling,
misapplication,faultyinstallation,unauthorizedrepair,modification,or acts ofGod will notbecoveredbythiswarranty.
2)Inthe absence ofproofofdateofpurchase,thedateofmanufacture(asdeterminedfromlotnumbersofinternalparts
andtherecordsof Jensen Transformers,Inc.) shall be used initsplace.
3) There areno express warrantiesexceptaslistedabove.
4) JENSEN TRANSFORMERS, INC. SHALL NOTBE LIABLE FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM
THEUSEOF THIS PRODUCT OR ARISING OUTOFTHE BREACH OF THIS WARRANTY. Durationofimpliedwarranties,ifany,
islimitedto12months.Ifa problemdevelops with thisproductduringthewarrantyperiod, call orwriteusbefore
attempting anyrepair.Wecanhelpyouidentify specific problems,and possibly solve theproblem,beforetheunitis
returned tousforrepairorreplacement.Inany case, DONOT RETURN THE UNIT WITHOUT AUTHORIZATION and
instructionsfromus. Jensen cannotberesponsiblefor damage duetoshippingorimproper packaging.
Limitations of Liability
Theinformationprovidedby Jensen aboutitsproductsbeen checked andisbelievedtobeaccurate;however,no
responsibilityis assumed by Jensen foritsusenorforanyinfringementsofpatentswhichmayresultfromitsuse.No license
isgrantedbyimplicationorotherwiseunderanypatentorpatentrightof Jensen Transformers,Inc.
JENSEN PRODUCTS ARENOT AUTHORIZED FORUSEAS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS, ORINANY APPLICATION WHERE THEIR FAILURE COULD CAUSE INJURY OR
DEATH.
Jensen reserves therighttomake changes withoutfurthernoticetoanyofitsproducts. Jensen makes nowarranty,
representationorguaranteeregardingthesuitabilityofanyofitsproductsforanyparticularpurpose,nor does Jensen
assume anyliabilityarisingoutoftheapplicationoruseofanyproductorcircuit,andspecifically disclaims anyandall
liability, includingwithoutlimitationconsequentialorincidental damages.
Jensen Transformers,Inc.
9304Deering Avenue
Chatsworth,CA91311
United States ofAmerica
Tel:[phone]
Fax:[phone]
www.jensen-transformers.com
Version1.2,30Oct2013