Installation: Powerbass PB Series Full Range Amplifier Owner Manual

Overview

The PB Series Full Range Amplifier is a vehicle audio power amplifier designed for flexible system building. Depending on the model and crossover settings, it can drive full-range speakers, component speakers, coaxial speakers, or subwoofers.

The series includes two-channel, four-channel, and five-channel configurations. Each amplifier uses a MOSFET power supply, adjustable gain, electronic crossover controls, and protection circuitry for common electrical, thermal, and speaker-related problems.

Installation requires knowledge of automotive electrical systems, speaker impedance, signal wiring, and vehicle safety. Professional installation is recommended if you are not familiar with amplifier wiring.

Specifications

• Models: PB-120.2, PB-90.4, PB-120.4, and PB-850.5.
• PB-120.2 output: 60 watts x 2 at 4 ohms, 120 watts x 2 at 2 ohms, or 240 watts x 1 bridged at 4 ohms.
• PB-90.4 output: 45 watts x 4 at 4 ohms, 90 watts x 4 at 2 ohms, or 180 watts x 2 bridged at 4 ohms.
• PB-120.4 output: 60 watts x 4 at 4 ohms, 120 watts x 4 at 2 ohms, or 240 watts x 2 bridged at 4 ohms.
• PB-850.5 output: 65 watts x 4 plus 300 watts x 1 at 4 ohms, 100 watts x 4 plus 450 watts x 1 at 2 ohms, or 200 watts x 2 plus 300 watts x 1 in the listed bridged configuration.
• Peak music power: 480 watts for the PB-120.2, 720 watts for the PB-90.4, 960 watts for the PB-120.4, and 1,700 watts for the PB-850.5.
• Frequency response: 10 Hz to 50 kHz.
• Signal-to-noise ratio: Greater than 100 dB.
• Total harmonic distortion: 0.3% at rated power.
• Input sensitivity: 0.25 to 6.0 volts.
• Crossover slope: 12 dB per octave.
• High-pass crossover range: 50 to 1,000 Hz on the PB-120.2, PB-90.4, and PB-120.4; 50 to 250 Hz on the PB-850.5.
• Low-pass crossover range: 35 to 250 Hz on the PB-120.2, PB-90.4, and PB-120.4; 50 to 250 Hz on the PB-850.5.
• Bass EQ: Selectable 0 dB or 12 dB boost centered at 45 Hz.
• PB-850.5 subsonic filter: Variable from 15 to 50 Hz at 12 dB per octave.
• Fuse ratings: PB-120.2, 25 A x 1; PB-90.4, 20 A x 2; PB-120.4, 25 A x 2; PB-850.5, 40 A x 2.
• Dimensions: 2.0 inches high x 7.1 inches wide. Length is 8.5 inches for the PB-120.2, 12.8 inches for the PB-90.4 and PB-850.5, and 14.8 inches for the PB-120.4.
• Electrical system: Designed for vehicles with 12-volt negative-ground systems and an operating range of approximately 9 to 16 volts DC.

Detailed Description

The amplifier receives audio from a source unit through RCA line-level inputs or, on supported models, through high-level speaker inputs. The PB-850.5 uses low-level RCA inputs only. High-level input wiring allows compatible models to connect directly to a factory radio without a separate line-output converter.

The GAIN control matches amplifier input sensitivity to the source unit. It is not a volume control. Correct adjustment helps the amplifier reach useful output without adding unnecessary distortion.

The X-OVER switch selects FULL, HPF, or LPF operation. FULL passes the complete signal range within the amplifier’s response. HPF removes lower frequencies so the amplifier can focus on midrange and high-frequency speakers. LPF sends a low-frequency signal to a subwoofer or other bass-focused speaker system.

The LPF/HPF control selects the crossover frequency used with the chosen filter mode. The PB-850.5 also provides a separate subsonic control for reducing very-low-frequency content that may consume power without producing useful audible output.

The BASS EQ switch provides either no boost or a 12 dB increase centered at 45 Hz. Because substantial bass boost increases demand on both the amplifier and speakers, use the boosted setting carefully.

The PB-850.5 includes an INPUT MODE switch for selecting two, four, or six input channels. It also has a port for the optional remote level control, allowing the secondary gain circuit to be adjusted from the listening position.

Power enters through the BATT+ terminal, while the GND terminal connects the amplifier to the vehicle chassis. The REM terminal receives a switched 12-volt turn-on signal from the source unit or another suitable switched supply. Speaker terminals use clamp-style connections and require correct polarity.

A blue POWER/STATUS indicator shows normal operation. A red indicator signals a protection condition. The internal protection system monitors for excessive load, speaker shorts, overheating, and DC output.

Safety

• High-powered car audio systems can produce sound levels capable of causing permanent hearing damage. Keep listening levels moderate.
• Excessive volume can prevent the driver from hearing horns, emergency vehicles, and other warning sounds.
• Disconnect the negative battery cable before beginning installation, and keep the battery disconnected until all wiring is complete.
• Install the main power fuse within 18 inches of the battery’s positive terminal. The fuse protects the vehicle’s power cable from a short circuit.
• Use the amplifier only in a 12-volt negative-ground vehicle electrical system.
• Wear protective eyewear when drilling, cutting, or working with vehicle wiring.
• Check for fuel lines, brake lines, oil lines, vacuum lines, and existing electrical cables before drilling or fastening hardware.
• Protect power wires passing through sheet metal with properly fitted grommets. Tubing through the grommet provides additional insulation.
• Keep at least 2 inches of clearance around the amplifier for ventilation and access. When installed under a seat, maintain at least 1 inch above the heatsink.
• Do not mount the amplifier upside down, in direct sunlight, or where it can be exposed to moisture.
• Avoid mounting the amplifier on a subwoofer enclosure because continuous vibration can cause malfunction.
• Do not allow wires to become pinched, sharply bent, or exposed to nearby objects that could damage their insulation.
• Hand-tighten terminal screws with a suitable screwdriver. Do not use a power drill, which can strip the terminals or crack the mounting feet.

Setup and Operation

Prepare the Installation

Before wiring, confirm that the vehicle charging system is suitable. With the ignition off, measure battery voltage using a volt-ohm meter; the manual specifies a reading of at least 12 volts. Have an automotive electrician inspect the system if the voltage is outside the expected range.

Gather suitable power and speaker cable, RCA interconnects when required, wire strippers, crimping tools, screwdrivers, heat-shrink tubing, a volt-ohm meter, and appropriate terminals. Use rosin-core electrical solder rather than acid-core solder when soldering is necessary.

Choose and Mount the Location

Suitable locations include the trunk floor, beneath a seat, or the back of a rear seat. Select a dry, ventilated area where cables can enter and leave the amplifier without sharp bends.

Use the amplifier’s mounting holes as a template, then set the amplifier aside before drilling. Confirm that no wiring or vehicle components are behind the mounting surface. Secure the unit by hand with appropriate fasteners; do not use a drill as a driver.

Connect Power and Ground

1. Disconnect the negative battery cable.
2. Run the correctly sized BATT+ cable from the battery to the amplifier, keeping it away from hot engine parts and heater components.
3. Install an inline fuse or circuit breaker no more than 18 inches from the battery’s positive terminal. Leave the fuse removed or the breaker switched off during the rest of the installation.
4. Prepare a short ground cable of the same gauge as the power cable.
5. Choose a strong chassis grounding point close to the amplifier and inspect behind it for vehicle lines and cables.
6. Remove paint and corrosion to expose clean bare metal.
7. Fasten the ground cable with a bolt, nut, and star washer. Seal the exposed area afterward to reduce corrosion and water intrusion.
8. Connect the ground cable to GND first, then connect the power cable to BATT+.

Connect the Remote Turn-On Wire

Connect the REM terminal to a switched 12-volt source. The preferred source is the remote output from the head unit. A power-antenna lead or switched accessory supply can be used when an appropriate remote lead is unavailable. An 18-gauge wire is sufficient for the remote connection.

Connect Audio Signals

Use shielded or twisted-pair RCA cables for low-level signals. Route RCA cables separately from the main power cable, and avoid running them alongside or across the power cable whenever possible. This reduces the chance of alternator whine, fan noise, and other interference.

For the PB-90.4 and PB-120.4 in four-channel mode, use all four RCA inputs. Do not connect high-level and low-level inputs at the same time. When using a high-level input connection, connect the designated black wire to ground as required for proper operation.

Connect Speakers

Use at least 16-gauge speaker wire and maintain the same positive and negative polarity throughout the system. Keep bare wire ends from touching one another or the vehicle chassis.

• The PB-120.2 is stable to 2 ohms in stereo and requires at least 4 ohms when bridged.
• The PB-90.4 and PB-120.4 are stable to 2 ohms per channel and require at least 4 ohms for bridged channels.
• The PB-850.5 channels 1 through 4 use the listed stereo and bridged limits, while channel 5 is stable to 2 ohms in mono.

Never connect a load below the specified minimum impedance. An undersized load can trigger protection and may damage the amplifier or speakers.

Set Input Gain

1. Turn the amplifier’s GAIN control completely counterclockwise to its minimum setting.
2. Turn on the source unit and set its volume to approximately two-thirds of maximum. Set source-unit bass and treble controls to zero.
3. Increase the amplifier gain until the sound begins to distort.
4. Reduce the gain slightly until the distortion disappears.

Do not use the GAIN control as a volume control. Excessive gain can cause clipping and may damage speakers or the amplifier.

Configure the Crossover

For coaxial or component speakers, select HPF and begin with a setting above approximately 65 Hz. For subwoofers, select LPF and adjust the low-pass frequency to suit the speaker system. Use FULL only when the connected speaker system is intended to receive the complete signal range.

On the PB-850.5, adjust the subsonic filter between 15 and 50 Hz when additional protection from inaudible bass is needed. Settings below approximately 33 Hz can reduce wasted amplifier power while preserving audible sub-bass.

Troubleshooting

Power LED Does Not Turn On

• Measure the BATT+ terminal with a volt-ohm meter. It should read approximately 12 to 16 volts DC.
• Measure the REM terminal and confirm that it receives approximately 12 to 16 volts DC when the source unit is on.
• Inspect the ground connection for clean bare metal, tight hardware, and continuity.
• Check the vehicle-side fuse and the amplifier fuses. Replace a fuse only with the same type and rating.

Blue LED Is On but There Is No Output

• Inspect the RCA connections and confirm that the source unit is producing a signal.
• Test the amplifier with a known-good speaker.
• Test with a known-good source unit when available.
• Use a volt-ohm meter in AC mode to check for signal on the RCA cable.
• Verify that the crossover switch, input mode, speaker wiring, and gain settings match the system configuration.

Red Protection LED Is On

• If the amplifier is very hot, allow it to cool and check that ventilation clearance is adequate.
• Confirm that the speaker load meets the minimum impedance requirements.
• Inspect speaker wires for contact with one another or with the vehicle chassis.
• Check that vehicle voltage remains within the amplifier’s operating range while the engine is running.
• Have the battery and charging system inspected if voltage protection occurs only when the vehicle is running.

If the red indicator remains on with no speakers connected and all power connections are correct, the amplifier may have an internal fault and should be evaluated by qualified service personnel.

Alternator Noise

• Inspect RCA cables for damage or poor shielding.
• Separate RCA cables from the main power cable and change their routing if necessary.
• Verify that the source unit has a proper ground.
• Reduce excessive amplifier gain.
• Check speakers and speaker wiring for an unintended chassis ground.

Weak Bass

Check speaker polarity. If multiple speakers are connected, reverse the connection of one speaker only as a test. A polarity error can cause cancellation and make bass appear unusually weak.

Warranty

PowerBass amplifiers are covered against defects in materials and workmanship for one year under the stated limited warranty terms. Coverage applies to the original purchaser of products sold through authorized dealers in the United States, and dated proof of purchase is required for service.

The warranty does not cover apparent rust or corrosion, liquid damage, excessive heat exposure, attempted repairs or alterations, or products that were not installed according to the owner’s manual. Removing or altering the serial number voids the warranty. Warranty remedies may include repair or replacement with an equivalent product at the manufacturer’s discretion.

Pros & Cons

• Pros: Multiple channel configurations support a wide range of vehicle audio layouts.
• Pros: Adjustable high-pass and low-pass filtering helps match the amplifier to speakers or subwoofers.
• Pros: High-level input support on applicable models simplifies integration with factory radios.
• Pros: The PB-850.5 adds a subsonic filter, multi-input selection, and remote level-control support.
• Pros: Thermal, overload, short-circuit, and DC-output protection help identify common installation problems.
• Cons: Correct wiring requires careful attention to impedance, polarity, fuse placement, and chassis grounding.
• Cons: The PB-850.5 differs from the other models in its input arrangement and control features, so its setup should not be treated as identical to the two- and four-channel amplifiers.
• Cons: Incorrect ventilation, undersized speaker loads, or excessive gain can activate protection or damage connected equipment.