Technical Notes Volume 1, Number 12C

Polarity Conventions of JBL Professional Transducers and Systems

Introduction:
When Jim Lansing founded JBL in 1946, hebrought with him a number of traditions developed during his previous years at Lansing
Manufacturing Company and at Altec-Lansing
Corporation. One of these dealt with polarity
conventions different from those eventuallyadopted by the burgeoning loudspeaker manufacturing community. The majority of JBL transducers at that time exhibited inward motion ofthe cone when a positive-going signal wasapplied to the red input terminal, and this convention was, in many cases, carried over into
loudspeaker systems as well. As we can best
determine, the original polarity decision had
been made by Lansing on an arbitrary basis.
As industry standardization began during the1950s, JBL took note of the fact that the company already had a large base of users in thefield and that the productive “lifetime” of JBL'stransducers was indeed a long one. Any substantial change in product operating standards
for existing models would have caused chaosin the field.
The situation began to change when JBL first
introduced systems intended primarily formusical instrument (MI) applications. Since
these systems traditionally used 1/4" phoneplugs for signal input, there was no easy way
for the user to invert the input signal polarity.
However, there was a need for JBL's MI products to be consistent with the rest of the indus-try, since there has always been considerable mixing and matching of systems from different manufacturers in the field.
As time has gone on, there have been many pressures, both internal and external, for JBL to convert
to the “positive-to-red” standard. Such a prospect
has never been taken lightly, simply because nocompany has more transducers in active use in theprofessional field than JBL.
Beginning in the early 1990s, JBL began an orderlytransition to the positive-to-red standard in accordance with practices recommended by the AES,
EIA, IEC, and other standards organizations. This
process has been underway since that time, withchanges being applied to new transducer models
and loudspeaker systems. The firm decision wasmade that no “legacy” transducers in existence atthat time would be changed during their remaining
catalog lifetime. In most cases, JBL loudspeakersystems, even if they make use of negative polarity
transducers, have been internally wired so that they“behave” as positive systems. That is, a positive signal at the red or positive terminal of the system willcause the low frequency cone to move outward.
For the transition to be orderly, it is essential that allusers of JBL Professional products have access to acomplete listing of polarity conventions of current
and past products, and that all new and updated
specification sheets carry a clear indication of polarity. In addition, all new cone transducers, which willbe of positive polarity, will carry a small sticker

placed next to the terminals indicating the newconvention.
Bi- and triamplified systems are very commonplace today, and these have all been configured at the input connector to produce a positive low frequency output signal when a positive-going signal is presented at pin 2 of theXLR input or tip of a tip-ring-sleeve input connector. The assumption is made that all connections in the system have been locked inplace internally by JBL and that all pertinent
field assembly documents have been carefully
followed. A further assumption is that systems
using quarter-inch or Speakon connectors
have been wired according to industry polarity
standards.
This new version of Technical Notes Volume 1
Number 12 spells out the polarity conventionsof all current products, along with those of earlier products and product groups that havebeen discontinued but which may still be usedin the field and that are supported by repair
activities and spare parts. This new publication
is current as of the second quarter of 2005.
Terminology:
Positive systems: A system or transducer issaid to be positive if a positive-going voltage
applied to its red (or non-black) input terminal
causes a positive pressure at the acoustical
output of the device. For cone transducers, thecone will move outward and can be easily
seen. For compression drivers, a positivegoing pressure can be measured at the driver'sexit.
Many systems and transducers do not havecolor-coded input terminals, and in these cases
one terminal is usually labeled with a + sign.
Consistent with the positive standard, a positive-going signal at the positive terminal will
result in outward motion of the cone.
Negative systems: A system or transducer issaid to be negative if a positive-going voltage
applied to its red (non-black) terminal causes anegative pressure at the output of the device.
Polarity of JBL Professional systems andtransducers:
The following is a comprehensive listing of for-mer and current JBL Professional systems andtransducers by product category. Within eachcategory models are indicated as positive ornegative. The obsolete models included here
are those that are still supported by company
repair service and spare parts.
Musical instrument transducers:
The following models are negative:
E110-8E120-8, 16
E130-8E140-8
E155-4, 8
The following models are positive:
M121-8M151-8Control Monitors: all models are positive:
Control 1
Control 1 Plus
Control MicroControl 1AW/70
Control SB Micro Control 5
Control 10L, R
Control SB-1
Control SB-5
Control 12SR
Control Contractor SeriesStudio Monitors:
All 4300-Series models (except models 4311and 4312L, R) are negative
The following models are negative:
4406
4408L, R
4410L, R
4412L, R
4425L, R
4430L, R
4435L, R
The following models are positive:
4206
42084311
4312L, R
4408A-L, R
4410A-L, R
4412A-L, R
6208
DMS-1
LSR4300-Series
LSR-Series
LSR6300-SeriesCompression Drivers: the following models arenegative:
2402H
2404H
2405H
2426H, J
2427H, J
2446H, J
2447H, J
2450H, J
2451H, J

Cone Transducers: the following models arenegative:
LE8T-H
2118H, J
2202H
2220H, J
2235H
2241G, H

2105H
2123H, J
2206H
2226H, J
2240G, H
2245H

The following models are positive:
2012H
2020H
2242H
Coaxial transducers: the following models arepositive:
2142H
2152H
2155H
Cinema systems:
3000-Series systems; the following models
are positive:
3622N
3677
3678
3632
3632T
3678-LF
3639
4000-Series systems; the following models
are positive:
4622
4622N
4632
4632T
4000-Series systems; the following models
are negative:
4670D
4675C
4675C-4LF
4765C-8LF
5000-Series systems; the following models
are negative
5671
5672
5672Bi
5674
Cinema subwoofers; the following models
are negative:
4642
4645
Cinema subwoofers; the following models
are positive:
3635
4641
4642A
4642A-GS
4645B
4645C
Cinema surround systems: the following
models are negative:
8330
8333
8340

Cinema surround systems: the following
models are positive:
3310
8325
8330A*
8340A*(*Note change from previous model numbers)
Enclosed utility systems:
The following models are positive:
SLT-1
4612OK
8216A
8216AT
The following models are negative:
4660A
4671OK
4652
Application Engineered Series (Prefixes AM, AC,AL, ASB, SH): all models are positive
Architectural Series (Prefix AS): all models arepositive
Array Series (Models 4890A, 4892, 4893, 4894):
all models are positive
Cabaret Series (Models 4602, 4612, 4622,4623, 4625, 4627, 4680, 4690, 4695): all models
are positive
Concert Series (Models 4825, 4828, 4842, 4845,4847, 4850, 4851, 4852, 4853, 4860, 4861,4862, 4863, 3866, 4870, 4871, 4872, 4873): allmodels are positive
Control contractor Series: all models are
positive
EON Systems (Prefix EON): all models are
positive
HLA Series (Prefix HLA): all models are positive
JRX Series (Prefix JRX): all models are positive
MPro Series (Prefix MP): all models are positive
Marquis Series (Prefix MS): all models are
positive
MR Series (Prefix MR): all models are positive
Precision Directivity Series (Prefix PD): allmodels are positive
Soundfactor Series (Prefix SF): all models arepositive

Sound Power Series (Prefix SP): all models
are positive
SR Series (Prefix SR): all models are positive
SR Series X (Prefix SR): all models are
positive
SR Series II (Prefix SR): all models are
positive
SRX Series (Prefix SRX): all models are
positive
TR Series (Prefix TR): all models are positive
Venue Series (Prefix VS): all models are
positive
Vertec Series (Prefix VT): all models are positive
VRX Series (Prefix VRX): all models arepositive
General Note on Applications:
JBL Professional has always recommended
that absolute polarity standards be maintained
throughout an audio system, from microphone
input to loudspeaker output. Since most microphone and electronics manufacturers adhere to
the “pin-2 hot” convention, this ensures that apositive-going signal at the input of a microphone will produce a positive-going signal at
the non-ground output of a power amplifier atthe end of the chain. If JBL negative convention loudspeaker systems or transducers areused, the required polarity inversion should bemade at the system or transducer input terminals themselves. Note carefully: making thepolarity inversion anywhere else in the audio
chain is an invitation to confusion.

JBL Professional
8500 Balboa BoulevardNorthridge, California 91329 U.S.A.
A Harman International Company© Copyright 2004 JBL Professional

TN VOL 1 NO 12C
CRP
06/05