Bose 901 Series I Manual

The Bose 901 Series I is a revolutionary direct/reflecting speaker system introduced in 1968, featuring nine full-range drivers (eight facing rearward, one forward) with an active equalizer to achieve flat room response. This manual covers setup, operation, equalizer adjustment, placement guidelines, specifications, and maintenance for optimal performance of this iconic audio system.

1. Features at a Glance 2. Unpacking and Inspection 3. System Setup and Placement 4. Specifications 5. Controls and Connections 6. Connecting to Audio Equipment 7. Equalizer Operation and Adjustment 8. Listening Guidelines 9. Care & Maintenance 10. Warranty Information 11. Troubleshooting

Features at a Glance

Key components: Two 901 Series I speaker enclosures, Active Equalizer unit, Power cord, Grille cloths, Owner's manual.

Feature	Description
Driver Configuration	Nine 4.5-inch full-range drivers per enclosure (8 rear, 1 front)
Enclosure Type	Acoustic suspension (sealed)
Equalizer	Active 9-band equalizer required for proper frequency response
Impedance	8 ohms nominal
Power Handling	Up to 100 watts RMS per channel
Dimensions	Approximately 25" H × 13.5" W × 12.5" D
Finish	Walnut veneer (standard)
Grille	Removable acoustically transparent cloth
Equalizer Inputs	Tape monitor loop connection
Equalizer Controls	9 slide controls for frequency adjustment

Unpacking and Inspection

Carefully unpack all components and inspect for shipping damage.

Remove speakers from packaging: Handle by the cabinet, not the grille.
Inspect cabinets: Check for dents, scratches, or veneer damage.
Inspect equalizer: Ensure all controls move smoothly, no physical damage.
Check contents: Verify all cables and documentation are present.

WARNING! Speakers are heavy; lift with proper technique. Report any damage immediately to dealer.

System Setup and Placement

Proper placement is critical for optimal direct/reflecting sound.

Position speakers: Place on stands or shelves at ear level when seated.
Distance from walls: 12-18 inches from rear wall, 24-36 inches from side walls.
Angling: Point forward-facing driver toward listening position.
Symmetry: Ensure both speakers are equidistant from listening position.
Equalizer placement: Near amplifier/receiver in equipment rack.

CAUTION! Do not place near heat sources or in direct sunlight. Ensure stable surface.

Specifications

System Type: Direct/Reflecting® loudspeaker system
Drivers: Nine 4.5-inch full-range per enclosure
Frequency Response: 35Hz - 20kHz (with equalizer)
Sensitivity: 86dB SPL at 1 meter with 1 watt input
Recommended Amplifier Power: 10-100 watts RMS per channel
Crossover: None (full-range operation)
Equalizer: Active 9-band, required for operation
Dimensions: 25" H × 13.5" W × 12.5" D (each)
Weight: Approximately 45 lbs each
Finish: Walnut wood veneer

Controls and Connections

Equalizer front panel: POWER switch, 9 frequency band slide controls (32Hz, 64Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz). Rear panel: INPUT FROM AMP, OUTPUT TO AMP, AC power cord.

Speaker Connections: Use high-quality 16-gauge or thicker speaker wire. Connect positive (+) to red terminal, negative (-) to black terminal on both speaker and amplifier.

Equalizer Setup: Connect between amplifier/receiver tape monitor loop. Set amplifier to TAPE MONITOR or TAPE PLAY position when using equalizer.

Connecting to Audio Equipment

Equalizer must be connected through tape monitor loop of amplifier/receiver.

Turn off all equipment before connecting.
Connect equalizer INPUT to amplifier TAPE OUT/PLAY jacks.
Connect equalizer OUTPUT to amplifier TAPE IN/RECORD jacks.
Connect speakers to amplifier speaker outputs (not to equalizer).
Plug equalizer into AC outlet.

Tip: Ensure all connections are secure. Use high-quality interconnects for best performance.

Equalizer Operation and Adjustment

The equalizer compensates for the speakers' natural response to achieve flat room response.

Power on: Turn on equalizer before amplifier.
Initial settings: Set all slide controls to center (flat) position.
Select source: Play familiar music through system.
Adjust equalizer: Modify individual bands to achieve balanced sound.
Fine tuning: Make small adjustments, listen for several days before further changes.
Bypass comparison: Switch amplifier out of TAPE MONITOR to compare equalized/unequalized sound.

WARNING! Do not operate speakers without equalizer connected. This can damage speakers and produce poor sound quality.

Listening Guidelines

Direct/Reflecting design creates spacious, room-filling sound.

Break-in period: Allow 50-100 hours of play at moderate volume for drivers to reach optimal performance. Room acoustics: Different rooms require different equalizer settings. Experiment with placement and equalization. Volume: Do not exceed amplifier's power rating. Distortion indicates clipping which can damage speakers.

Care & Maintenance

Cabinet cleaning: Use soft, dry cloth. For stubborn marks, slightly dampen cloth with water only. Grille care: Remove grille by pulling from bottom. Vacuum gently if needed. Driver inspection: Check periodically for debris or damage. Do not touch driver cones.

CAUTION! Never use solvents, abrasives, or furniture polish on cabinets. Keep liquids away from speakers and equalizer.

Warranty Information

Bose 901 Series I speakers are covered by a limited warranty. Contact Bose Corporation for warranty service. Serial numbers located on rear of each speaker cabinet and equalizer. For service, contact authorized Bose service center. This product is covered by patents issued and pending.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No sound from speakers	Equalizer not powered/connected	Ensure equalizer is on; check tape monitor loop connections; verify amplifier set to TAPE MONITOR.
Distorted sound	Amplifier clipping	Reduce volume; check amplifier power rating; ensure proper equalizer settings.
Unequal sound between speakers	Wiring/placement issues	Check speaker wire connections; verify symmetrical placement; test each channel separately.
Lack of bass	Equalizer settings/placement	Adjust lower frequency bands on equalizer; move speakers closer to room corners.
Hum or noise	Ground loop/poor connections	Check all cable connections; try different AC outlet; ensure proper grounding.

Service: For technical support, contact Bose Corporation customer service. Do not attempt to repair speakers or equalizer yourself.