Iso-Max SS-1SR User manual

ISO-MAX® PRO SERIES USER GUIDE
SPEAKER-LEVEL to LINE-LEVEL Interfaces
Models SC-2NR, SP-2SX, SS-1SR, SS-2RR, SS-2SX
Jensen ISO-MAX® Pro series audio interfaces are designed for use in the nest professional and audiophile sound systems.
They use the same industry-benchmark Jensen transformers that are installed in tens of thousands of the world’s best
recording studios, broadcast facilies, and sound reinforcement venues because of their sonic transparency, ultra-wide
bandwidth, and vanishingly low harmonic and phase distoron.
Model SP-2SX
SC-2NR
Full-range two channel “speaker” level to unbalanced “consumer” level converter and ground isolator
Terminal strip inputs, RCA outputs
SS-2RR
Low-frequency-only two channel “speaker” level to unbalanced “consumer” level converter and ground isolator
extended low-frequency response for extremely high-performance sub-woofers
Terminal strip inputs, RCA outputs
SS-1SR
Low-frequency-only single channel “speaker” level to unbalanced “consumer” level converter and ground isolator
extended low-frequency response for extremely high-performance sub-woofers
not shown here, but packaged in the same style case as the 2-channel versions
Terminal strip inputs, RCA output
SP-2SX
Full-range two channel “speaker” level to balanced “pro” level converter and ground isolator
Terminal strip and SpeakON inputs, RCA XLR outputs
SS-2SX
Low-frequency-only two-channel “speaker” level to balanced “pro” level converter and ground isolator
extended low-frequency response for extremely high-performance sub-woofers
Terminal strip and SpeakON inputs, RCA XLR outputs

All models are designed to accept, in four switch-selectable ranges, speaker drive voltages of 14 Vrms, 25 Vrms, 44 Vrms, or
77 Vrms. These voltages will be developed at full output of power ampliers rated at 24 W, 75 W, 240 W, or 750 W
respecvely into 8Ω loads or rated at 48 W, 150 W, 480 W, or 1,500 W respecvely into 4Ω loads. Input ranges also include
25 V and 70 V lines used in commercial sound systems covering large areas. Since the speaker inputs are ungrounded, they
are especially useful with power ampliers where both outputs are acvely driven and cannot be grounded (these are oen
referred to as “bridge-mode” or “oang” outputs). The speaker inputs represent a trivial addional load for the driving
power ampliers - maximum input power is 0.08 W, 0.4 W, 1.5 W, and 5.4 W respecvely in the four input ranges. In
addion, all models provide inherent low-pass ltering to remove ultra-sonic switching arfacts from the outputs of
“digital” or “class D” power ampliers. These arfacts can cause subtle distorons in downstream ampliers [Deane Jensen
and Gary Sokolich, “Spectral Contaminaon Measurement,” AES 85th Convenon Preprint 2725, 1988].
The SC-2NR, SS-1SR and SS-2NR output signals will reach 1.75 Vrms (+5 dBV) at maximum rated input - sucient to drive
any known power amplier with an unbalanced input to full output power. This level represents 15 dB of “headroom” in
consumer audio systems where the nominal or “reference level” signal is standardized at !10 dBV or 0.316 Vrms.
SP-2SX and SS-2SX outputs will reach 6.9 Vrms (+19 dBu), a level that represents 15 dB of “headroom” in professional audio
systems where the nominal or “reference level” signal is standardized at +4 dBu or 1.23 Vrms.
[not menoned in the specs, but while the SS models are intended for “extended low-frequency response for extremely
high-performance sub-woofers” only, the full-bandwidth models are also excellent for subwoofer applicaons, with only
decimals of a dB dierence at the low end.]
These ISO-MAX units are enrely passive and require no power supply.
FOR OPTIMUM PERFORMANCE, PLEASE REVIEW THE FOLLOWING PAGES!
General Applicaon Guidelines
Load Impedance Range (input impedance of device the unit drives) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 kÙ or more
Maximum Output Cable Length
SC-2NR, SS-2RR, and SS-2NR:
60 feet (18 m) of typical cable at 50 pF/ (160 pF/m) total capacive load < 3,000 pF
SP-2SX and SS-2SX:
3 feet (1 m) of typical cable at 50 pF/ (160 pF/m) total capacive load < 200 pF
Maximum Input Cable (amplier/speaker to ISO-MAX) Length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . unlimited
System Hookup
In choosing a physical locaon for the ISO-MAX unit, shorter output cables are preferred over shorter input (speaker feed)
cables. In general, the beer locaon will be near the amplier(s) to be driven. Inexpensive, small-gauge “zip cord” or
“speaker wire” is recommended for the speaker inputs to the unit. Its gauge is technically unimportant but 18, 20, or 22
gauge are generally easiest to strip and handle. It should be emphasized that the quality of this wire will have a negligible
eect on the quality of sound - normal technical concerns about speaker cables do not apply. The other ends of these input
cables can be connected to either the main-channel power amplier output terminals or the main-channel speaker
terminals, whichever is closer or more convenient. For 25 V or 70 V distribuon systems, make the “speaker” connecons
directly across the “constant voltage” distribuon line. Again, be sure to observe polarity and ghtly twist the strands of
wire at each end to avoid strands that “stray” beyond the clamp area of either the screw terminals or amplier/speaker
terminals.
For the SC-2NR, SS-1SR, or SS-2RR
Observing polarity, securely aach the speaker input cables to screw terminals 1 (+) and 2 (-), marked “CH 1 IN,” for one
channel and screw terminals 8 (+) and 9 (-), marked “CH 2 IN,” for the other channel. DOUBLE CHECK TO BE SURE THE
SPEAKER INPUT CABLES ARE CONNECTED TO THE CORRECT TERMINALS - OTHERWISE, THE UNIT MAY BE DAMAGED! Finally,

connect a standard, high-quality RCA male to RCA male cable between the ISO-MAX unit outputs and the inputs of the power
amplier(s) to be driven.
For the SP-2SX and SS-2SX:
Observing polarity, securely aach each speaker feed cable to terminals 1 (+) and 2 (-) of a Neutrik “SpeakON” model NL2FC
“2-pole” cable connector (not supplied). Please note that the mang Neutrik model NL2MP panel connector used on the ISO-
MAX unit will not accept 4-pole cable connectors. Alternavely, the screw terminals may be used for speaker input as
described below.
The Screw Terminal Strip (all models):
If desired, any or all connecons can be pre-wired to the detachable screw-terminal strip (included). These connecons
parallel any other connectors present. Terminals are numbered le-to-right when the screws face upward.
Terminal
Marking
Funcon
1
CH 2, OUT +
Channel 2, Line Output +
2
CH 2, OUT -
Channel 2, Line Output - (cable shield for unbalanced output models)
3
CH 2, OUT S
Channel 2, Output Shield (internally ed to unit housing/chassis)
4
CH 2, IN S
(no internal connecon)
5
CH 2, IN -
Channel 2, Speaker Input -
6
CH 2, IN +
Channel 2, Speaker Input +
7
(CHASSIS)
Unit housing, internally ed to Output Shields (see “Grounding” discussion below)
8
CH 1, OUT +
Channel 1, Line Output +
9
CH 1, OUT -
Channel 1, Line Output - (cable shield for unbalanced output models)
10
CH 1, OUT S
Channel 1, Output Shield (internally ed to unit housing/chassis)
11
CH 1, IN S
(no internal connecon)
12
CH 1, IN -
Channel 1, Speaker Input -
13
CH 1, IN +
Channel 1, Speaker Input +
Grounding
Although these units completely electrically isolate inputs from outputs, there are situaons where supplemental grounding
may be necessary. This generally happens only when equipment has a 2-prong AC power connecon (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 as a clipped-
o 3rd prong) to defeat safety grounding provided by its 3-prong power cord, we strongly urge you to remove it ... this is an
extremely dangerous pracce, promoted by the technically naive, that may result in re, severe shock or electrocuon.
For balanced output models (SP-2SX), grounding to the DESTINATION (equipment driven by the unit’s line outputs)
normally occurs through the XLR output cable shield connecons. However, for unbalanced output models (SC-2NR or
SS2NR), allowing ground current to ow in the output RCA cables would create hum or buzz. Therefore, an added
equipment ground is recommended. This can be most eecvely done by connecng an insulated wire (stranded #18 or
#20 AWG, green, length as required) between screw-strip terminal 7 and the chassis of the desnaon equipment.
Somemes there is a convenient “ground” terminal on the equipment for the purpose. If not, you can aach the wire under

an exisng screw somewhere on the equipment’s metal chassis. Somemes grounding can be done by simply mounng the
desnaon equipment in a properly-grounded equipment rack (taking care to remove paint that might prevent electrical
contact between equipment and rack rail). Another alternave is to have a reputable technician change the power cord on
the desnaon equipment from 2-prong to 3-prong, aaching the green wire of the new cord to the equipment chassis.
If the SOURCE equipment (ampliers that generate the s speaker input) is ungrounded, turn on switches S4 (Ch 1) and S5
(Ch 2), as shown below, to eliminate hum or buzz that might occur.
Seng the Switches
On the boom of the unit, you’ll nd a group of switches that select the rated
input, in terms of rated maximum amplier power output that will produce
the specied maximum output voltage (+5 dBV for the SC-2NR and SS-2NR or
+19 dBu for the SP-2SX). Use the 75/150 W seng for 25 V distribuon and
the 750/1,500 W seng for 70 V distribuon lines. Switches 1, 2, and 3 are
for Channel 1 and switches 6, 7, and 8 are for Channel 2:
Switch Sengs, Ch 1 / Ch
2
Amplier Power Rang (W)
S1 / S6
S2 / S7
S3 / S8
at 8 ohms
at 4 ohms
o
o
o
24
48
on
o
o
75
150
on
on
o
240
480
on
on
on
750
1,500
S4 and S5 are normally o. They are used to solve possible grounding issues (see “Grounding” above). While the unit can’t
be damaged by connuous input voltages up to 80 volts, regardless of switch sengs, severe distoron may result from
improper sengs.
ISO-MAX® is a registered trademark of Jensen Transformers, Inc.
Revised / Updated by Cable Soluons LLC
Richmond, TX USA
Copyright © 2024, Cable Soluons LLC, all rights reserved

ISO-MAX® PRODUCT WARRANTY
For a period of 1 YEAR aer purchase, Jensen Transformers, Inc. will, free of charge, repair or replace any part of an ISO-
MAX® product that fails due to defecve materials or workmanship. For a period of 20 YEARS aer purchase, Jensen
Transformers, Inc. will, free of charge, repair or replace any Jensen OEM transformer or any Jensen transformer contained
in an ISO-MAX® product that fails due to defecve materials or workmanship.
Both limited warranes are subject to the following limitaons:
1) Defects that are, in the sole judgement of Jensen, the result of accident, misuse, abuse, neglect, mishandling,
misapplicaon, faulty installaon, unauthorized repair, modicaon, or acts of God will not be covered by this warranty.
2) In the absence of proof of date of purchase, the date of manufacture (as determined from lot numbers of internal parts
and the records of Jensen Transformers, Inc.) shall be used in its place.
3) There are no express warranes except as listed above.
4) JENSEN TRANSFORMERS, INC. SHALL NOT BE LIABLE FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM
THE USE OF THIS PRODUCT OR ARISING OUT OF THE BREACH OF THIS WARRANTY. Duraon of implied warranes, if any,
is limited to 12 months. If a problem develops with this product during the warranty period, call or write us before
aempng any repair. We can help you idenfy specic problems, and possibly solve the problem, before the unit is
returned to us for repair or replacement. In any case, DO NOT RETURN THE UNIT WITHOUT AUTHORIZATION and
instrucons from us. Jensen cannot be responsible for damage due to shipping or improper packaging.
Limitaons of Liability
The informaon provided by Jensen about its products has been checked and is believed to be accurate; however, no
responsibility is assumed by Jensen for its use nor for any infringements of patents which may result from its use. No license
is granted by implicaon or otherwise under any patent or patent right of Jensen Transformers, Inc.
JENSEN PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS, OR IN ANY APPLICATION WHERE THEIR FAILURE COULD CAUSE INJURY OR
DEATH.
Jensen reserves the right to make changes without further noce to any of its products. Jensen makes no warranty,
representaon or guarantee regarding the suitability of any of its products for any parcular purpose, nor does Jensen
assume any liability arising out of the applicaon or use of any product or circuit, and specically disclaims any and all
liability, including without limitaon consequenal or incidental damages.
Jensen Transformers, Inc.