The Bose 901 Series VI Active Equalizer is a critical component designed specifically for use with the Bose 901 Series VI Direct/Reflecting® speaker system. It provides the precise equalization required to achieve the system's intended acoustic performance, compensating for the speakers' unique design to deliver flat amplitude response at the listening position. This manual covers setup, operation, connection guidelines, specifications, and troubleshooting for the equalizer.
The Bose 901 Series VI Active Equalizer is an integral, mandatory part of the 901 Series VI speaker system. It is not a conventional tone control but a sophisticated active filter network that applies a specific, fixed equalization curve. This curve corrects the acoustic output of the nine full-range drivers in each speaker cabinet, ensuring a balanced, spatially correct sound field as envisioned by Dr. Amar Bose's Direct/Reflecting® technology.
| Key Concept | Description |
|---|---|
| Active Equalization | Provides necessary frequency response correction that cannot be achieved passively within the speaker. |
| System Integration | The equalizer and speakers are engineered as a single system. Do not use 901 speakers without their specific series equalizer. |
| Signal Path | Plays a role in the overall system gain; includes a level control to balance with other speakers or sources. |
The front panel provides user-adjustable controls for system balance and monitoring.
NOTE: The equalization curve itself is not user-adjustable and is fixed internally.
Understanding the rear panel is crucial for correct installation into your audio system.
| Connection | Purpose |
|---|---|
| INPUT (L & R) | Receives the full-range line-level signal from your preamplifier, receiver's "Tape Out" or "Pre Out" jacks. |
| OUTPUT (L & R) | Sends the equalized, level-controlled signal to the power amplifier inputs that drive the 901 speakers. |
| RECORDER IN/OUT | A tape monitor loop. Connecting a tape deck here allows recording of the unequalized source and playback through the equalizer. |
| AC Power Cord | Standard 3-prong (grounded) power cord. Plug into a grounded outlet. |
WARNING! Always connect the equalizer between your preamplifier and power amplifier. Never place it in a speaker-level signal path.
Follow these steps for proper integration into your stereo system.
CAUTION! Incorrect wiring can damage equipment. Double-check all connections against your amplifier's manual.
The 901 speaker employs nine identical, small full-range drivers. Eight fire rearward and sideways to create reflected sound, while one fires forward for direct sound. This design results in a specific, non-flat raw acoustic output. The equalizer's fixed filter network applies precise boost and cut to this raw response so that the combined result—speaker plus equalizer—produces a flat amplitude response at the listener's ear in a reflective room. This process is essential for achieving the intended spacious, lifelike soundstage.
Speaker Compatibility: The Series VI Equalizer is designed only for use with the Bose 901 Series VI speakers. It is not compatible with earlier or later series of 901 speakers (Series I-V or VII, VIII), as each series has a unique equalization curve.
Amplifier Requirements: Because the equalizer provides significant boost in the bass and treble regions, it can demand substantial power from your amplifier. Ensure your amplifier is rated for adequate, clean power (Bose often recommended high-current amplifiers).
Unplug the unit from AC power before cleaning. Use a soft, dry cloth to wipe the exterior. Do not use liquid or aerosol cleaners. Ensure ventilation around the unit is not blocked. There are no user-serviceable parts inside.
CAUTION! Never open the chassis. Refer servicing to qualified Bose personnel.
Complies with FCC Part 15 for Class B digital devices. This equipment generates, uses, and can radiate radio frequency energy and may cause interference if not installed and used per instructions. Copyright and trademarks owned by Bose Corporation. The Bose 901 Series VI system incorporates patented Direct/Reflecting® technology.
For technical support or service, contact Bose Customer Service or visit www.bose.com.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| No sound from 901 speakers | Equalizer off, incorrect wiring, blown fuse | Turn equalizer POWER on. Verify all RCA connections are secure (Preamp -> EQ In, EQ Out -> Amp In). Check AC power and fuse. |
| Sound is thin, lacks bass/treble | Equalizer bypassed or not in signal path | Ensure signal is routed THROUGH the equalizer. Verify receiver/amp is set to use the "Main In" or correct input. |
| Distortion at moderate volume | Amplifier clipping, input overload | Reduce the LEVEL control on the equalizer. Ensure source material and preamp volume are not excessively high. |
| Hum or noise | Ground loop, poor connections | Ensure all components are plugged into the same AC circuit. Check RCA cables for damage. Try a different outlet. |
| One channel silent | Failed connection, balance control | Check RCA cable for that channel. Ensure BALANCE control is centered. Swap left/right cables at amp input to isolate problem. |
Service: Do not attempt internal repairs. Contact Bose Corporation authorized service center.