Bose 901 Series 4 Manual

The Bose 901 Series IV is a high-performance direct/reflecting speaker system featuring nine full-range drivers (one front-facing, eight rear-facing), an active electronic equalizer, and a unique acoustic design that utilizes reflected sound for a spacious, lifelike audio experience. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: Two 901 Series IV speaker cabinets, Active Electronic Equalizer, Power cord, Speaker cables, Owner's manual.

Installation

Unpack and inspect contents. Place speakers on stable surfaces or optional floor stands.

1. Position speakers: Follow placement guidelines for optimal direct/reflecting performance.
2. Connect equalizer: Insert equalizer into tape monitor loop of receiver/amplifier.
3. Connect speakers: Run speaker wire from amplifier outputs to equalizer, then from equalizer to speakers.
4. Plug equalizer into AC power.

WARNING! Speakers are heavy; lift with care using two people. Ensure amplifier is turned off during connections.

First-Time Setup

Power on system; follow setup procedure.

1. Set receiver/amplifier: Select Tape Monitor or equivalent to activate equalizer circuit.
2. Verify connections: Ensure all cables are secure and polarity is correct (+ to +, - to -).
3. Adjust equalizer: Set controls to flat position initially; make adjustments after listening.
4. Test system: Play familiar music at moderate volume to verify operation.

CAUTION! Never operate speakers without the active equalizer connected and powered. This can damage speakers and produce poor sound quality.

Specifications

• System Type: Direct/Reflecting loudspeaker system with active equalization.
• Drivers: 9 x 4.5" (114 mm) full-range per enclosure.
• Crossover: Electronic via external equalizer.
• Recommended Amplifier Power: 10-250 watts per channel.
• Sensitivity: 86 dB SPL at 1 meter with 1 watt input (with equalizer).
• Equalizer Controls: Level, Contour, Presence, Brilliance adjustments.
• Equalizer Connections: Input/Output RCA jacks, AC power inlet.
• Power Requirements: 120V AC, 60Hz (equalizer).
• Weight: 48 lbs (21.8 kg) each speaker.

Controls and Settings

Active Equalizer Front Panel: POWER switch, LEVEL control, CONTOUR control, PRESENCE control, BRILLIANCE control, Status LED.

Equalizer Functions: LEVEL (overall system volume matching), CONTOUR (bass adjustment), PRESENCE (midrange adjustment), BRILLIANCE (treble adjustment).

Initial Settings: Set all controls to 12 o'clock (flat) position. Adjust based on room acoustics and personal preference. The equalizer compensates for the speaker's inherent response and provides tonal shaping.

Connecting to Audio Systems

Tape Monitor Method: Standard connection using receiver's tape monitor loop.

1. Turn off all components before connecting.
2. Connect equalizer INPUT to receiver TAPE OUT.
3. Connect equalizer OUTPUT to receiver TAPE IN.
4. Connect speaker wires from receiver speaker outputs to equalizer speaker inputs.
5. Connect speaker wires from equalizer speaker outputs to 901 speakers.
6. Activate Tape Monitor function on receiver.

Tip: For preamp/main amp systems, connect equalizer between preamp outputs and main amp inputs.

Equalizer Operation

The active equalizer is essential for proper system performance.

1. Power: Ensure equalizer is powered before turning on amplifier.
2. Level Matching: Adjust LEVEL control so volume matches other sources.
3. Contour Control: Adjusts low frequencies. Increase for more bass, decrease for less.
4. Presence Control: Adjusts midrange frequencies affecting vocal clarity and instrument definition.
5. Brilliance Control: Adjusts high frequencies for sparkle and air.
6. LED Indicator: Green when powered and functioning correctly.

WARNING! Do not bypass equalizer. This will result in poor sound quality and may damage speakers due to excessive high frequencies.

Speaker Placement Guide

Optimal placement is critical for the direct/reflecting design.

• Room Position: Place along the longer wall of rectangular rooms.
• Distance from Walls: 12-24 inches from rear wall, 24-48 inches from side walls.
• Angling: Angle speakers slightly inward toward listening position.
• Height: Ear level or slightly above when seated.
• Symmetry: Maintain symmetrical placement relative to listening position.
• Reflective Surfaces: Ensure rear walls have reflective surfaces (not heavily damped).

Experiment with placement to achieve best soundstage and imaging.

Care & Maintenance

Unplug equalizer before cleaning. Use dry, soft cloth for speaker cabinets. Vacuum grille fabric gently if needed.

CAUTION! Do not use liquids, solvents, or abrasive cleaners on cabinets or grilles. Keep speakers away from excessive heat, moisture, and direct sunlight.

Regulatory Information

FCC Part 15: Class B digital device; complies with interference limits for residential use. Copyright © Bose Corporation. All rights reserved. Bose and 901 are registered trademarks of Bose Corporation. For support, visit www.bose.com or contact Bose Customer Service.

Troubleshooting

Reset: Turn off all components, disconnect/reconnect cables, power on in sequence: Equalizer first, then amplifier.

Service: Contact authorized Bose service center. Do not attempt to repair speakers or equalizer yourself.