GT5-12 - JBL

GT SERIES EnglishGT5-12car audio subwooferowner’s manualTHANK YOUfor purchasing a JBL ® GT Series subwoofer. Subwooferinstallation requires woodworking skills and some experiencein disassembling and reassembling automotive interiors. Ifyou lack the tools or necessary skills, have your subwooferinstalled by an authorized JBL dealer.

CHOOSING AN ENCLOSUREWarning: Playing loud music inan automobile can permanentlydamage your hearing, as well ashinder your ability to hear traffic.We recommend listening at lowlevels while driving. JBL accepts noliability for hearing loss, bodily injuryor property damage resulting fromuse or misuse of this product.GT Series subwoofers are optimizedto perform best in small, sealed,vented and prefabricated band-passenclosures. While infinite-bafflemounting of GT Series subs ispossible, power handling will begreatly compromised becausethere’s no enclosed volume of air toprevent the speaker’s cone frommoving past its limit. For this reason,we do not recommend infinite-bafflemounting for GT Series subwoofers.You should choose the enclosure youwill use based on the type of musicyou listen to, how much amplifierpower you will use for the subwooferand how much space inside thevehicle you can devote to asubwoofer enclosure.Because a sealed enclosureprovides the most control over thewoofer’s movement, a woofermounted in a sealed enclosure willhandle more power than a woofermounted in another enclosure type.Sealed enclosures provide moreaccuratesonic reproduction thanother enclosure types whenmounted inside a vehicle, so they arewell suited to all types of music.Sealed-enclosure construction isstraightforward, and there are manyprefabricated sealed enclosuresavailable. An optimum sealedenclosure is always smaller thanother types of enclosures optimizedfor a particular speaker, so theyrequire the smallest amount of spaceinside the vehicle.Vented enclosures provide betterefficiency in the 40Hz – 50Hz range,but this efficiency comes at theexpense of sound in the lowestoctave (below 40Hz) and at theexpense of some control and powerhandling at the lowest frequencies. Ifyou are using a small amplifier,a vented box will provide moreperceived bass output from lesspower. Vented enclosures are alsowell suited to a variety of musictypes. Because vented enclosuresrequire the volume of the enclosureand the size of the port to havea specific relationship with thecharacteristics of the woofer, theenclosure must be built exactly to thespecifications provided. While thereare some prefabricated vented boxesavailable, matching a prefabricatedbox to a particular woofer is difficult.If you wish to use a ventedenclosure, we strongly recommendhaving your authorized JBL dealerbuild it or verify that your design iscorrect if you wish to build it yourself.An optimum vented enclosure isalways larger than the optimumsealed box for the same woofer andwill require more space inside thevehicle.Band-pass enclosures often providethe most output available from anyamplifier and subwoofercombination, at the expense of sonicaccuracy.If sheer SPL (sound-pressure level)is what you desire most, choose aband-pass enclosure. Band-passenclosuredesign is very tricky, andthe aid of a computer and enclosuredesign software is necessary. If youare an experienced installer or havesome woodworking experience,you may wish to build the band-passenclosure described in the enclosuredesign sheet included with thiswoofer. Fortunately, there are manyprefabricated band-pass boxesavailable, and they are all optimizedto extract the most output possiblefrom any woofer. Band-passenclosures can be quite large andmay require a lot of space insideyour vehicle.2

CONNECTING YOUR SUBWOOFER TO YOUR AMPLIFIERThe GT5-12 subwoofer has a single4-ohm voice coil. Be sure to consideryour amplifier’s optimum load whendesigning a subwoofer system.Many bridgeable 2-channel amplifiersare optimized to drive a single4-ohm woofer in bridged mode. If youwill use multiple woofers, be sure toconfigure them to extract all thepower available from your amplifier.When designing a subwoofersystem, consider the following rules:1. Do not mix different subwoofers orenclosure types in the samesystem. Subwoofers being used inthe same enclosure or powered bythe same amplifier should beidentical models. Mismatchedwoofers and enclosures can resultin poor system performance.2. Most amplifiers deliver exactly thesame amount of power bridgedinto a 4-ohm load as they dodriving a 2-ohm stereo load.3. If you are designing a multiplewoofersystem, be sure toconfigure the woofers so that theyeach receive the same amount ofpower from the amplifier. Neverconnect two identical woofers inseries and then connect that pairto another woofer in parallel. Ifyour system will include an oddnumber of woofers, be sure toconnect all the woofers in eitherseries or parallel according to therules that follow, in order tomaximize the power available fromyour amplifier:a. The total system impedance ofvoice coils (or woofers) in seriescan be calculated using theformula:Impedance = w 1 + w 2 + w 3 ...b. The total system impedanceof woofers in parallel can becalculated using the formula:Impedance =11w 1+1w 2+1 ...w 3where w is the nominalimpedance of the woofer.The diagrams at right show seriesand parallel speaker connections.Figure 1. Connecting two woofersin series to the amplifier (8 ohms)RedPositiveTo AmpPositiveBlackNegativeFigure 2. Connecting two woofers inparallel to the amplifier (2 ohms)RedPositiveRedPositiveBlackNegativeBlackNegativeRedPositiveBlackNegativeTo AmpNegativeEnglishTo AmpPositiveTo AmpNegative3

SPECIFICATIONSGT5-1212" (300mm) Single 4-Ohm SubwooferPower Handling, RMS 275WPower Handling, Peak 1100WSensitivity (2.83V/1m) 93dBFrequency Response 23Hz – 450HzImpedance4 OhmsMounting Depth 164mm (6-7/16")Cutout Diameter 286mm (11-1/4")Overall Diameter 313mm (12-5/16")A valid serial number is required for warranty coverage.Features, specifications and appearance are subject to change without notice.These products are designed for mobile applications and are not intended for connection to the mains.Harman Consumer Group, Inc.250 Crossways Park Drive, Woodbury, NY 11797 USA2, route de Tours, 72500 Château du Loir, Francewww.jbl.com© 2007 Harman International Industries, Incorporated. All rights reserved.JBL is a trademark of Harman International Industries, Incorporated,registered in the United States and/or other countries. GT Series is atrademark of Harman International Industries, Incorporated.Part No. GT5-12OM4/07Declaration of ConformityWe, Harman Consumer Group, Inc.2, route de Tours72500 Château du LoirFrancedeclare in own responsibility that the product described in this owner’smanual is in compliance with technical standards:EN 61000-6-3:2001EN 61000-6-1:2001Klaus LebherzHarman Consumer Group, Inc.Château du Loir, France 4/07www.jbl.com