Cross-posted from the Rain City Audio Repair Blog:

This Bose® 901 Active Equalizer came through my shop recently for a full overhaul. After so many years, the electrolytic capacitors in these units leak and go open, and the resistors drift in value causing distortion, noise, and signal loss. Since the Active Equalizer is needed to get the most out of your Bose® 901 Direct/Reflecting speaker system, it’s important to keep them running! That’s where Rain City Audio comes in.

This one had seen some service before, possibly twice. The three main filter capacitors had been replaced with what look to be Siemens Brazil capacitors, and the output and feedback caps had been replaced at some point as well. No matter, though – all would come out and be replaced!

Brand new metal film resistors, mylar film capacitors, and Nichicon Fine Gold electrolytic capacitors will bring this one back to life, better than new.

Finally, this unit received some additional noise shielding, an upgrade to gold-plated RCA panel jacks for the main input/output connections, and top quality PulseX audiophile-grade film capacitors for bringing out the finest detail and best clarity possible from the music.

All rebuilt, this Active Equalizer is going to serve faithfully for many years to come.

Is your Bose® 901 Active Equalizer not working the way it should? Rain City Audio can help.