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Active Subwoofers - Owners Manual

BTX250

Introduction / Installation JBL BASSTUBE BTX250
Thank you for choosing the JBL BTX250. BTX250 has been designed to provide the kind of high-performance low-frequency reproduction that used to require big, clumsy enclosures, large ampliers, and complex installation. To ensure maximum performance, we strongly recommend that installation be entrusted to a qualied professional. Although these instructions explain how to install the BTX250 in a general sense, they do not show the specic installation methods for your particular vehicle. If you feel you do not have the necessary tools or experience, do not attempt the installation yourself; rather, ask your authorized JBL car audio dealer about professional installation options. Remember to keep this manual and your sales receipt in a safe place for future reference. Your car and bass reproduction Depending on the interior volume of your vehicle and the dimensions of the passenger compartment and cargo area, reproduced frequencies below 80Hz may be boosted by nearly 12dB per octave as frequency decreases. This effect, known as the vehicles transfer function or cabin gain, plays an important part in shaping the overall in-car response of the BTX250. BTX250 is designed to reproduce frequencies below about 100Hz, but there may be other speakers in your vehicle that reproduce some of those same frequencies. It is important that all the speakers work together to reproduce frequencies they share. Depending on the orientation of the BTX250 and the distance from it to the other speakers, the BTX250 and the other speakers may be "in-phase" or "out-of-phase". The resulting conditions, known as constructive and destructive interference, also play a role in shaping the frequency response of your system. Fortunately, BTX250 has controls to optimize both of these conditions and their adjustment is explained later in the manual.

INSTALLATION

CHOOSING A MOUNTING LOCATION Choose a location that doesnt interfere with the loading or unloading of cargo, fold-down rear seats, or opening or closing of the trunk lid. The best location is likely to be the front or rear corner of the trunk or luggage compartment. These locations, in addition to being out of the way, will provide the best sonic reproduction in the 60Hz to 100Hz range because the woofer output will be corner loaded against the vehicles walls. In any case, BTX250 must not interfere with the safe operation of the vehicle. Once youve chosen a mounting location and made the necessary electrical connections, youre ready to mount BTX250 securely to the mounting surface (most likely the oor of the luggage compartment). Caution: Make sure mounting screws will not puncture wiring harnesses, brake or fuel lines, or the vehicles fuel tank. Some or all of these may be located behind or under the mounting surface. Horizontal Mounting: Lock the xing holders supplied (x2) on the metal bar of the BTX250 on each side. Then nd
the right place where the BTX250 will be installed and mark the exact position where the xing holders will be located (gure 1). Then remove the xing holders from BTX250. Screw the xing holders on the position marked initially (gure 2). Put back in place the BTX250 in the xing holders and press the lock to fasten the metal bar in position (gure 3).

Instructions BTX250

Hearing WARNING! Playing loud music in a vehicle can permanently damage your hearing, as well as hinder your ability to hear trafc. We recommend using low volume levels while driving. JBL accepts no liability for hearing loss, bodily injury or property damage resulting from the use or misuse of this product.

Figure 1

Figure 2

Figure 3

Connecting Your System JBL BASSTUBE BTX250

POWER-SUPPLY CONNECTIONS

Figure 4. BTX250 connections and terminals. B+: Connect a wire (at least 4mm2) between the vehicles + (positive) battery terminal and the "+BATT" terminal on BTX250. You must install a fuse holder with a 15A fuse within 50cm of the battery. Route the power wire through a grommet in the vehicles rewall. If there is no factory grommet available, you must install one. B: Connect a wire (at least 4mm2) Figure 4 between the "GND" terminal on BTX250 and a bare metal surface near the mounting location. You may need to scrape away some paint from the metal surface to insure a good connection. Use a screw and a lock (star) washer. Remote: Connect a wire between the remote terminal on BTX250 and the remote output wire on your head unit. This wire should provide between +5VDC and +12VDC when the head unit is on and no voltage when the unit is off.

INPUT CONNECTIONS

Note: BTX250 is equipped with two line-level (RCA) inputs and two speaker-level inputs.
Figure 5, Input connections
Head units with dedicated subwoofer outputs (line-level): Connect the subwoofer output from the head unit to the line-level inputs.
Head units with two line-level outputs and two (or four) speaker-level outputs: Connect the two line-level outputs from the head unit to the linelevel input on BTX250. Or connect two speaker-level outputs from the head unit to the Universal Interface inputs on BTX250, which correspond to the linelevel inputs. Note: The Universal Interface input wiring harness included with BTX250 is color coded to correspond with the speaker-level outputs of many aftermarket head units and adapters sold as accessories.

Figure 5

HIGH LEVEL INPUT

LINE INPUT

DC POWER INPUT

BASS BOOST.

CROSSOVER.

0 PHASE 180

+12V REM GND
L R. MIN. MAX. 0 dB. +6 dB. 40Hz. 120Hz

15A 15A

LF Speaker

RF Speaker

RCA Stereo Cables (not supplied)

Fuse 15 A

Splices (not supplied)

Source Unit

Universal Interface color code: White: front left + White/black: front left Gray: front right + Gray/black: front right

LR Speaker

RR Speaker
Tuning - Control and Functions - Adjustment

TUNING BTX250

BTX250 provides several controls that simplify sonic integration with virtually any vehicles unique acoustic properties. Please read the following section carefully to familiarize yourself with the function of each control. Figure 6. Locations of controls.

JBL BASSTUBE BTX250

ADJUSTMENT SEQUENCE
1. Start with gain control set to minimum and the crossover control and bass control rotated midway, to 12 oclock. 2. Choose program material with substantial bass content and turn the volume control on your head unit to threequarters of its total output (approximately 3 oclock on rotary controls). 3. Adjust the gain control clockwise until you start to hear some distortion coming out from the BTX250. Then slightly decrease the gain control counter clockwise. 4. Listen to your system, making a mental note of the amount of upper bass being reproduced. 5. Switch the phase control to 180 and listen again for upper bass content. There may be more upper bass, less upper bass, or no change at all. The position that provides the most upper bass is correct, but choose either setting according to your taste. 6. Adjust the crossover control clockwise or counterclockwise until you hear only low-frequency information. For example, you should NOT hear any vocals coming from BTX250 when seated in the normal listening position. 7. Adjust the bass-boost control clockwise or counterclockwise to suit your taste.

Note: In most cases, the above steps will provide satisfactory tuning. However, the actual process may require several readjustments of each control, since the settings will interact with each other. If necessary, consult your authorized JBL car audio dealer for help in tuning your system.
most upper bass is technically correct, you may choose the position that better suits your taste.

CONTROLS and FUNCTIONS

Gain Control: This control will adjust the input sensitivity of BTX250. Use this control to adjust the relative volume (loudness) of BTX250 with respect to the other speakers in the vehicle. Crossover: The crossover control adjusts the amount of high-frequency information present in BTX250s output. Bass Boost: BTX250s interaction with the acoustics of your vehicle may produce a peak or dip in BTX250s response. For the vast majority of vehicles, these peaks or dips occur at about 40-50Hz around the frequency of a low bass guitar note. Use this control to correct that peak or dip. Adjustment between 0dB and +6dB is possible. Although response without any sharp peaks or dips is technically correct, you may choose the position that best suits your taste. Power LED: The power LED will glow green to indicate that BTX250 is operational.
Phase Control: The phase control is a switch located on the panel with the electrical connections (see Fig. 6). This switch will reverse the phase of BTX250s output with respect to its input. When installing BTX250 with an existing factory or aftermarket system, depending on BTX250s location in the vehicle and the distance between it and the other speakers in the car, reversing the phase (by moving the phase switch) may produce a discernable increase or decrease in the amount of upper bass reproduced. Although the position that yields the

Specifications

TROUBLESHOOTING
1. Power LED not lit: fuse blown, head unit not functioning properly (no remote voltage), faulty power, ground or remote connection. 2. Power LED lit but no sound output: inputs not connected, head unit not functioning properly (no output), head-unit fader control set incorrectly. 3. Output from BTX250 sounds muddy or distorted: input gain set too high, bass boost set too high, head-unit output is distorted or blown. 4. No output from BTX250 when head-unit fader control set properly: input connections improperly wired. Amplier Power: Frequency Response: Fuse: Input Sensitivity: Crossover Frequency: Crossover Slope: Bass Boost: Phase Control: Dimensions (L x W x H):