This Bose 901 Series II equalizer just came through the shop for an overhaul and upgrade. It’s in pretty good shape except for a small piece of delaminating contact paper on the side, but isn’t showing any signs of having been stored badly or abused.

The owner requested I upgrade the output capacitors to audiophile quality replacements, and add pigtail jacks to accommodate today’s thicker and more heavily shielded interconnect cables.

Inside the equalizer was all original except for the output capacitors, which had been replaced some years ago.

Component replacement and upgraded output capacitors installed next. It’s great seeing one of these cleaned up with fresh rows of components.

Finally, time to install the pigtail jacks. These are a great upgrade, and completely reversible back to the factory configuration if needed. The original ’70s RCA jacks just aren’t spaced far enough apart for most modern cables which have thicker plastic molding and thicker insulation and shielding. These OEM quality pigtails run through the center-pin holes on the RCA jacks, and provide the extra spacing to hook up your choice of cables.

Finally, time to clean the controls and move to test and pack it up! This equalizer sounded spectacular when tested out on my home system, it does the Bose 901 speaker system justice – at least as good as new, if not better. With high quality modern electrolytic filter capacitors, film output and coupling capacitors, and precision low-noise metal film resistors this equalizer will serve faithfully for many years to come.

Rain City Audio repairs Bose Active Equalizers