JBL GT series User manual

Thank you for purchasing a
new JBL GT Series subwoofer.
Subwoofer installation requires
woodworking skills and some
experience disassembiing and
reassembling automotive interiors.
If you lack the tools or necessary
skills, have your subwoofer installed
by an authorized JBL dea!er.
Warming: Playing loud music in
an automobile can permanently
damage your hearino as well as
hinder your ability to-hear traffic.
We recommend listening at low
levels while driving. J5L accepts no
liability for hearing loss, bodily injLiry
or property damage resulting from
use or misuse of this product.
GT Series subwoofers are optimized
io perform best in smali, seaied,
vented and prefabricated bandpass
enclosures. While infinite-baffle
mountina of GT Series subs is
possible,power handling will be
greatly compromised because
there’s no enclosed volume of arr
to prevent the speaker’s cone from
inovrng past its limit. For this reason?,
we do not recotnmend infinite-baffie
tnounting for GT Series subwoofers
You should choose ihe enclosure
you will use based on the type of
music you listen to, how Imuch
amplifier power you will use for the
subwoofer and how mucn space
inside the vehicle you can devote
to a subwoofer ernclcsure.
Because a sealed enclosure
provides the most control oVer the
woofer’s movement, a woofer
mounted in a sealed enclosure WI/~
handle more power than a woofer
mounted in anothe: enc!oszre type.
Sealed enclosures provide more
accurate sonic reproduction Can
other enclosure types, so Lhey are
weil suited to ail types oi music.
Sealed-enclosure constr&icn
is strarghtforward and there are
many prefabricated sealed
enclosures available. An optimum
sealed ernclostire is always smaller
than other types of enclcsures
optiniized for a particular speaker,
so they require the smallest amount
of space inside the vehicle.
Vented enclosures provide better
efiiciericy in the Sol+- 50112 range
but this efficiency comes at tlhe
expense of sound in the lowest
octave (below 403~) and at the
expense of some contra! and power
handling. If you are using a small
amplifier, a vented box will provide
more bass output from less power.
Vented enclosures are also well
suited to a variety of music types.
Because vented enclosures require
the ‘volume of the enclosure and
the size of the port to have a
specific relationship with the
characteristics of the woofer, the
enclosure must ce our/t exaci$ to
the specifications provided, Nhile
there are some prefabricated
vented boxes svailable, matching a
prefabricated box is a particu!a:
woofer is difficult. 3 you wish to use
a vented enciosure, we strong!y
recommend having your authorized
J5L dealer buiid it or verify that
your design is correct if you wish
to build it yourself. An optimum
vented enclosure is always larger
than the optimum sealed box for
the same woofer and will require
more space inside the vehicle.
Bandpass enclosures often
provide the most outptit available
from any amplifier and subwoofer
combination at the expense of
sonic accuracy. If sheer SPL
(sound-pressure level) is what you
desire most, choose a bandpass
enclosure. Bandpass-enclosure
design is very tricky and the aid
of a computer and enclosure
design software is necessary. If
you are an experienced installer
or have some woodworkino
experience, you may wish tb build
the enclosure described in the
enclosure design sheet included
with this woofer. Fortunately, there
are many prefabricated bandpass
boxes available and they are al!
optimized to extract tine most
output possible from any woofer.
Bandpass enc!osures can be quite
large and ;nay require a lot of space
InsIde your vehicie.

JBL GT Series subwoofers are
designed with single 4-ohm voice
coils. Multiple woofers may be
connected to an amplifier using
parallel wiring as long as the net
impedance is higher than the
lowest impedance tine amplifier
is designed to drive safely. This
will extract maximum power from
the amplifier without compromising
system reliability.
Total impedance of woofers In
parallel can be calculated using
the formula:
While it is possibie to connect
separate woofers in series, we
recommend tiiat you avoid doing
so. Because the amplifier-damping
factor (the amplifier’s ability to
control the motion of the woofer)
is expressed as a ratio of terminal
impedance (the sum of speaker
impedance, wire resistance and the
DC. resistance of any crossover
coil connected to the woofer) to
amplifier-output impedance, con-
necting separate woofers in series
reduces tne damprng factor of the
amplifier to a value of less than 1.
This will result in poor ‘transient
response.
Most ampiifiers deliver exactly the
same amount of power bridged into
a 4-ohm load as they do running a
2-ohm stereo ioad.
Tne diaarams below and at riaht Figum2.seriesconnection
”
7
show parallel and series speaxer
connections.

IO” Automotive
subwoofer
Tf20
72” Automotive
subwoofer
250 Wat%
1000 Watts
253 watts
1000 Watts
90dB 93dB
28Hz - 5OOHz
4 Ohms
23Hz - 450Hz
4 Ohms
5-3/4” (I 47mm) 6-l/4” (i59mm)
9- l/8” (232mmj i I -1/S” (283mm)
1 JBLGonsumarProducts* 250CroeswaysParkDwe.WnadbwyIY 11797
.-.--
Declaration of Conformliy

YourJBLwarrang protects the original owner and all subsequentowners for a
periodof one (I) year(parts and labor)for all loudspeakerand/orelectroniccom-
ponentsfrom anyfailure asa resultof ancriginal manufacturingdefer?solongas:
(1) your IBL product was originally purchasedwithin the fiiry UnitedStatesor by
military personnelfrom anauthorizedmilitary outlet, (2)the dealerfrom whom the
productwas purchasedwas authorizedbyiBL to se!1suchproductsat the time of
original purchaseand (3) the original, dated Bill of Saleis presentedwhenever
serviceis requiredduring the warrar@ period.Thiswarranty is only valid for serv-
ke within the UnitedStatesand doesnot applyto productspurchasedelsewhere;
other purchasersshould contact their local iBL distributor for warranty infcrma-
iiOn.
WHAT D5ES THE I% ~~~~~~~ COVER?
Exceptasspecifiedbelow,this warranty coversall defectsin original materialsand
workmanship.Thefclicwlng ar-enot covered:damagecausedbyaccident,misuse,
abuse,neglect,product mcd$ication;damageoccurringduring shipment;damage
causedby failure to fclicw instructicns in the owner’s guide,including failure to
perform recommendedperiodic or routine maintenance;damage resulting from
repairsby someonenot authorizedby JBL;units usedfor other than car use;units
not usedfor their intendedpurpose;ciaimsbaseduponanymisrepresentaticiisby
the seller: and any 161product on which tne serial number has been altered,
defacedor removed.
Duringthe periodci this warraniy,subjectto the aboiieconditions,iBFwiji pay all
of the labor andmateria! expensesto repaira warrantable defect.
NOW CAM WARW,NT’4 SERVICE BE OBTAWED?
in the even?that your-iBL product(s)should requiresenke, you should first ccn-
tact either the iBt deal?7from v$homthe productwaspurchasedor an authcrized
servke center. Fcr the name of a :EL serke center, visit cur Web site at
wwvv.jbl.ccn;,write us dire& at JBL(ATOM:CustomerSenicej, 250 Crossways
ParkDririe,~~&drou~~NVI I i’k. or calf(BOO)3364iP5,‘W ma)idirect you rc an
authorizedservicecenterfor JBLproductsor askyouPCsendthe producttc usfor
repair.Ineither case,you twillhaveto presentyour original Bill of Saleto establish
warranty coverage.DCnot sendyour productto us without prior authorization
from cur CustomerServiceDepartment.Youare responsiblefor transporting your
productto either iBL or an authorizedservicecenter and for payment of ail ship
ping charges;however,XL will paythe return shipping charges(in the eventyou
return the product to us) if the repairsare coveredby warranty. if you experience
difficulty in transpcrbng your product or are in needof paciting materials,piease
adviseus and we may be able to suggestalternative proceduresand/or provide
adequatepackingmaterials.
LIMITKWX4 5% WfPLlED ~~~~~~~~%$: All implied warranties, including
fitness for a particular purposeand merchantability,are limited in duration and
length to the warranty periodfor your product.
LBMITATION OF IWClDEfa4L OR CONSEQUENTIAL DAMAGES: if3 is
no?responsiblefor incidenta!cr consequentialdamageof any kind. Dur liabiiity is
limited to the repairor replacement, at our option, of a defectkveproduct
Somestatesdo not allow limitations on how long an imoliedwarranty lastsand/or
do not allow the exclusionof incidental or consequentialdamages,sc the above
!imitaticns or exckicns may not appiy to you. Thiswarranty gives gcu specific
iegalrights and you mayalsohaveother rights,which vary,from state to state.
MOTE: Inthe eventthat there isa differencebetweenthis warranty andthe pro-
visionsin anyadvertisements~productbrochureor packagingcartcns,the termsof
this warranty wi!i prevail.
j3L continuallystrivesto update and improveexisting products,aswell ascreate
new cmes.The specificationsand ccnstr~ricn detail in this and relayediB?
cubiicaticns are,therefore,subjecttc changewithout notice.