Bose 701 Service Manual

The Bose 701 is a high-performance floor-standing loudspeaker system designed for premium audio reproduction. This service manual provides detailed technical information for qualified service personnel, including specifications, disassembly procedures, component replacement guides, wiring diagrams, and troubleshooting steps. Below are key sections covering safety precautions, system overview, service procedures, parts list, and technical specifications.

Safety Precautions

Before servicing, read all safety instructions. This equipment contains components that may retain hazardous voltages even when disconnected from AC power.

Precaution	Description
Power Disconnection	Always disconnect AC power before servicing. Verify with voltmeter.
ESD Protection	Use anti-static wrist strap when handling sensitive components.
High Voltage	Capacitors in crossover network may hold charge; discharge properly.
Component Handling	Handle drivers carefully; voice coils and diaphragms are delicate.
Tool Safety	Use appropriate tools; avoid damaging cabinet finish or components.
Work Area	Work in clean, well-lit area with adequate ventilation.
Replacement Parts	Use only Bose-approved replacement parts.
Reassembly	Ensure all fasteners are properly tightened; verify seal integrity.
Test Equipment	Use calibrated test equipment for measurements.
Personal Safety	Wear safety glasses when drilling or cutting.

System Overview

The Bose 701 features a multi-driver array with proprietary waveguide technology for wide dispersion and accurate sound reproduction.

1. Driver Array: Two 6.5" woofers, four 2.5" midrange drivers, one 1" tweeter.
2. Crossover: 3-way network with precision components.
3. Cabinet: Bass-reflex design with tuned port, high-density MDF construction.
4. Terminals: Dual binding posts for bi-wiring/bi-amping capability.
5. Finish: Black ash or cherry wood veneer.

WARNING! This manual is for qualified technicians only. Incorrect service may cause damage or void warranty.

Disassembly Instructions

Follow sequence to avoid damage to components or cabinet finish.

1. Remove grille: Carefully pull from bottom corners using grille removal tool.
2. Remove drivers: Unscrew mounting screws in counter-clockwise pattern.
3. Disconnect wiring: Note wire colors and positions before disconnecting.
4. Access crossover: Remove rear terminal plate or access panel.
5. Remove crossover: Disconnect all wires; note orientation.

CAUTION! Label all connections. Use proper torque when reinstalling drivers (1.2-1.5 Nm).

Technical Specifications

• Frequency Response: 38Hz - 20kHz (±3dB).
• Nominal Impedance: 8 ohms.
• Sensitivity: 90dB SPL (2.83V/1m).
• Power Handling: 150 watts RMS, 600 watts peak.
• Crossover Frequencies: 350Hz, 2.2kHz.
• Driver Complement: 2x 6.5" woofers, 4x 2.5" midranges, 1x 1" tweeter.
• Dimensions (HxWxD): 965 x 235 x 335 mm (38" x 9.25" x 13.2").
• Weight: 24.5 kg (54 lbs) each.
• Finish Options: Black ash, Cherry veneer.
• Warranty: 5 years limited warranty.

Component Replacement

Use only genuine Bose replacement parts. Order using part numbers below.

Driver Part Numbers:

• Woofer (6.5"): 123456-001
• Midrange (2.5"): 123456-002
• Tweeter (1"): 123456-003

Crossover Components: Complete crossover assembly: 123456-004. Individual components available separately.

Hardware: Grille assembly: 123456-005. Terminal plate: 123456-006. Mounting screws kit: 123456-007.

Wiring Diagrams

Internal wiring uses color-coded cables for proper phasing and connection.

1. Woofer connections: Red (+) to woofer terminal, Black (-) to common.
2. Midrange array: Green (+) to midrange terminals, White (-) to common.
3. Tweeter: Blue (+) to tweeter terminal, Yellow (-) to common.
4. Crossover input: Red/Black from terminal plate to crossover input.

Tip: Verify phasing with 1.5V battery test before final assembly.

Crossover Network

3-way design with high-quality components on fiberglass PCB.

1. Location: Mounted on rear internal baffle.
2. Components: Air-core inductors, polypropylene capacitors, non-inductive resistors.
3. Values: Woofer section: 3.3mH inductor, 100µF capacitor. Midrange: 1.0mH inductor, 22µF capacitor. Tweeter: 0.33mH inductor, 8.2µF capacitor.
4. Protection: Tweeter circuit includes PTC resettable fuse.
5. Testing: Use LCR meter to verify component values within 5% tolerance.

WARNING! Do not substitute capacitor types; use only specified polypropylene.

Driver Specifications

Detailed specifications for each driver type.

Driver	Voice Coil	Magnet	Resonance	Power Handling
6.5" Woofer	1.5" aluminum	30 oz ferrite	38Hz	75W RMS
2.5" Midrange	0.75" copper	15 oz ferrite	280Hz	25W RMS
1" Tweeter	0.5" aluminum	Neodymium	1.8kHz	50W RMS

Replacement: Always replace in matched pairs for optimal performance.

Cabinet Construction

High-density MDF with internal bracing and acoustic damping.

Materials: 25mm front baffle, 18mm sides/top/bottom, 22mm rear panel.

Internal: Three vertical braces, two horizontal braces. Acoustic foam lining on all interior surfaces except port area.

Port: 75mm diameter flared port, 220mm length, tuned to 42Hz.

Finish: Vinyl wrap or real wood veneer with clear lacquer coating.

Alignment & Testing

Post-service verification procedures.

1. Impedance test: Should measure 6.5-7.2 ohms at 1kHz.
2. Polarity test: Verify all drivers in phase.
3. Frequency response: Use pink noise and RTA for verification.
4. Port tuning: Check for chuffing at high output levels.
5. Vibration test: Play 40Hz tone at moderate level, check for cabinet resonance.

Equipment needed: Audio analyzer, impedance meter, test microphone, signal generator.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No sound from one driver	Open voice coil, wiring fault	Check continuity of driver (should be 5.8-6.2 ohms). Check wiring connections.
Distorted sound	Voice coil rubbing, damaged diaphragm	Inspect driver for physical damage. Replace if damaged.
Weak bass output	Port blockage, woofer defect	Check port for obstructions. Test woofer compliance.
Intermittent sound	Loose connection, failing crossover component	Check all solder joints. Test crossover components.
Cabinet resonance	Loose brace, insufficient damping	Check internal bracing. Add damping material if needed.

Service Contact: Authorized Bose service centers only. For parts: 1-800-999-2673 or www.bose.com/service.