Bose 901 II Manual

The Bose 901 Series II is a revolutionary direct/reflecting speaker system featuring nine full-range drivers (eight facing rearward, one forward), an active equalizer for frequency response correction, and a unique acoustic design for spacious, room-filling sound. This manual covers setup, operation, equalizer connection, placement guidelines, specifications, and troubleshooting for optimal performance.

Features at a Glance

Key design elements: Nine 4.5-inch full-range drivers per speaker, Active Equalizer for precise sound shaping, Direct/Reflecting technology for immersive soundstage.

Feature	Description
Driver Configuration	9 drivers (8 rear-facing, 1 front-facing) per speaker
Active Equalizer	Required for proper frequency response; connects between preamp and amp
Impedance	8 ohms nominal
Power Handling	Up to 150 watts RMS per channel
Frequency Response	35 Hz - 15 kHz (with equalizer)
Grille Design	Removable acoustically transparent cloth grille
Enclosure	Sealed, furniture-grade wood cabinet
Equalizer Bypass	Switch for comparing equalized/unequalized sound
Input/Output	RCA jacks for system connection
Finish Options	Walnut, Oak, or Black Ash veneer

System Components

Unpack and verify all items are present.

1. Two Bose 901 Series II speaker cabinets.
2. One Bose 901 Active Equalizer unit.
3. AC power cord for equalizer.
4. Two sets of speaker cables (recommended 16-gauge or heavier).
5. Two pairs of RCA interconnect cables.
6. This user manual and warranty information.

WARNING! Speakers are heavy; lift with care using two people. Inspect for shipping damage before setup.

Installation & Setup

Proper setup is critical for optimal Bose 901 performance.

1. Position speakers: Place on stands or shelves at ear level when seated. Follow placement guidelines in Section 7.
2. Connect equalizer: Power off all components. Connect equalizer between preamp output and power amp input using RCA cables.
3. Connect speakers: Run speaker wire from amplifier outputs to each 901 speaker (observe polarity: + to +, - to -).
4. Power up: Plug equalizer into AC outlet. Turn on system in sequence: source > preamp > power amp.
5. Calibrate: Use equalizer controls to match your room acoustics (see Section 6).

CAUTION! Never connect speakers without the active equalizer in circuit. This can damage speakers and produce poor sound quality.

Specifications

• System Type: Direct/Reflecting loudspeaker system with active equalization.
• Drivers: Nine 4.5-inch full-range drivers per enclosure.
• Crossover: None (full-range operation with equalizer correction).
• Impedance: 8 ohms nominal.
• Recommended Amplifier Power: 10-150 watts RMS per channel.
• Frequency Response: 35 Hz - 15 kHz (±3 dB with equalizer).
• Sensitivity: Not applicable (system gain set by equalizer).
• Dimensions (each): Approximately 25" H × 14" W × 12" D.
• Weight: Approximately 45 lbs (20 kg) each.
• Equalizer Power: 120V AC, 60Hz, 5 watts.

Equalizer Controls & Settings

The active equalizer is essential for proper 901 operation. Front panel controls:

Bypass Switch: Engages/disengages equalization for comparison.

Level Control: Adjusts overall system output to match other speakers in system.

Five-Band EQ: Slide controls for: 1) Low Bass (40 Hz), 2) Mid Bass (150 Hz), 3) Presence (1.5 kHz), 4) Treble (5 kHz), 5) High Treble (12 kHz).

Initial Setup: Set all sliders to center (0) position. Play familiar music and adjust to taste. Generally, reduce bands that sound overly prominent in your room.

Note: Equalizer settings are interactive; adjust one band at a time and listen.

Connecting to Your Stereo

Connection diagram: Source > Preamp > [Preamp Output] > Equalizer Input > Equalizer Output > Power Amp Input > [Amp Output] > Speakers.

1. Turn off and unplug all stereo components.
2. Connect RCA cables from preamp output to equalizer input.
3. Connect RCA cables from equalizer output to power amp input.
4. Connect speaker wires from amplifier outputs to 901 speakers.
5. Plug equalizer into AC outlet.
6. Power on components in correct sequence.

Tip: For tape monitor systems, connect equalizer through TAPE MONITOR loop.

Speaker Placement Guide

Optimal placement maximizes the direct/reflecting sound field.

1. Position speakers at least 2-3 feet from rear wall and 1-2 feet from side walls.
2. Angle speakers inward 15-30 degrees toward listening position.
3. Elevate speakers so front driver is at ear level when seated.
4. Ensure rear-facing drivers have clear path to reflect off wall behind speakers.
5. Symmetrical placement relative to room center yields best stereo imaging.
6. Experiment with toe-in angle to optimize center image and soundstage width.

WARNING! Do not place speakers in corners or directly against walls. This causes excessive bass and muddies sound.

Care & Maintenance

Unplug equalizer before cleaning. Dust speakers with soft, dry cloth only.

Grille removal: Carefully pull grille frame straight out from cabinet. Clean with soft brush or vacuum with brush attachment.

Cabinet: Use furniture polish appropriate for wood veneer. Avoid liquids near driver areas.

CAUTION! Never use solvents, abrasives, or water on speakers. Do not remove drivers. Keep equalizer away from heat and moisture.

Regulatory Information

FCC Part 15: Class B digital device (equalizer); complies with interference limits for residential use. Copyright © Bose Corporation. All trademarks owned by Bose Corporation. For technical support, contact Bose Customer Service at 1-800-999-2673 or visit www.bose.com.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No sound from speakers	Equalizer bypassed/off	Ensure equalizer is ON and bypass switch is OFF; check all connections.
Distorted sound	Overdriven amplifier	Reduce volume; ensure amp power is within 10-150 watt range.
Weak bass	Placement/EQ settings	Adjust speaker placement; increase low bass EQ slider.
Unequal left/right volume	Balance control/connections	Check receiver balance control; verify speaker wire connections are secure.
Hum or buzz	Ground loop/cable issues	Ensure all components plugged into same AC circuit; check RCA cables.

Reset: Set all equalizer sliders to center position and readjust.

Service: Do not attempt internal repairs. Contact Bose authorized service center: 1-800-999-2673.