Bose® Active Equalizer Repairs

See some past successful repairs!


Rain City Audio’s Bose® Active Equalizer service offers a frictionless repair experience to bring your Bose® speaker system back to top performance. The first Bose® 901 speaker systems were introduced nearly 50 years ago, and the electronic components are reaching the end of their working lifetime and are due for a rebuild in the 901, 800 and many other active equalizers and system controllers. These worn-out parts are robbing your system of its full sound potential.


Most problems with Bose® Active Equalizers are age-related and display common symptoms: buzzing or humming in one or both channels, low volume in one or both channels, distortion, muddiness, flatness, flickering or burnt out lights, noisy switches, uneven output, and more. After so many years, nearly every Active Equalizer from Series I, Series II, Series III, Series IV and even some Series V and VI, along with Model 800 Active Equalizers and some 402 and 802 System Controllers can benefit from service. Rain City Audio’s Active Equalizer Service can fix nearly any problem your Active Equalizer could possibly encounter with one low flat rate. No surprises, no unexpected charges – just great sound!


Most of the issues with an Active Equalizer failing to perform its best are due to worn out capacitors; dirty switch contacts; broken jacks; and drifted resistors which are causing the equalizer to produce the wrong curves. Over time, electrolytic capacitors dry out or can leak and short causing damage. Some early film capacitors from the ’60s and very early ’70s used a less reliable manufacturing practice which can fail over time. Carbon resistors like those used in the Series I, Series II and Model 800 absorb moisture over the years and change wildly in value, making the equalizer apply an incorrect curve to the signal. Even transistors and op-amps can become tired with reduced gain, distortion or failure. These negative effects happen with the passage of time, whether the equalizer is in use or in storage, and there is relatively little you can do to stop it. Once it’s occurred, the fix is a rebuild to replace the worn out parts with new ones. Past Projects.


Rain City Audio’s Bose® Active Equalizer Service is the most thorough service available and restores performance as good as new – if not better! You pay a flat rate including all needed standard parts and labor, with free return shipping in the United States. All rebuilds feature Nichicon electrolytic capacitors, and precision metal-film resistors where needed. The components replaced vary by model and situation, but always includes electrolytic capacitors, and includes any other capacitors, resistors, transistors or op-amps, bass coils, diodes, power lamps, and voltage conversion depending on your model’s unique situation. One flat-rate price includes everything needed to get your equalizer playing good as new for most situations, with performance verified using the powerful Audio Precision System One computerized analysis system. A selection of optional upgrades are also available to customize your equalizer which are detailed on the service form.



Price List:


  • 901 Series I and II:  Regular $139.95
  • 901 Series III, IV and Up: Regular $119.95
  • 800 Active Equalizer: Regular $139.95 
  • 802 System Controller: Regular $159.95
  • 402 System Controller: Regular $114.95





If you have any questions about the service, Contact Us! Otherwise, move on to Getting Started to download the service form to send your equalizer in, or read some Testimonials from satisfied customers.


*Bose® is a registered trademark of the Bose Corporation; no endorsement is implied.