Tag Archives: Bose

Bose® 901 Series I Active Equalizer #7790 Repair

Posted on April 20, 2016 by jwk

From Rain City Audio: This rare early-production Bose® 901 Series I Active Equalizer, serial #7790, came through the shop recently for an upgrade. It’s original owner bought this new in 1969 and kept it in use until it began to … Continue reading →

Posted in Audio, Bose, Electronics, Projects, Stereo, Vintage | Tagged , , , , , | Leave a comment

Bose® 901 Series I Active Equalizer #28322 Repaired

Posted on April 18, 2016 by jwk

From Rain City Audio: This Bose® 901 Series I Active Equalizer #28322 came through the shop for an overhaul. The original series, these Series I Active Equalizers have the oldest electronic components which are nearly universally out of their service … Continue reading →

Posted in Audio, Bose, Electronics, Stereo, Vintage | Tagged , , , , | Leave a comment

Bose® 901 Series II Active Equalizer #81471 Repair

Posted on April 16, 2016 by jwk

From Rain City Audio: This Bose® 901 Active Equalizer, Series II #81471, just came through the shop for a repair. It’s owner sent this one all the way from Ontario, Canada for expert repair from Rain City Audio. This one … Continue reading →

Posted in Audio, Bose, Electronics, Projects, Stereo, Vintage | Tagged , , , , , | Leave a comment

Bose® Active Equalizer Test Platform

Posted on April 13, 2016 by jwk

This project is going to take a while since I’m slammed in the shop, but I’m in the process of converting a Bose® 901 Series I Active Equalizer to  a test platform. With sockets for the transistors, and clip connections … Continue reading →

Posted in Audio, Bose, DIY, Electronics, Stereo, Test Equipment | Tagged , , , , , | 3 Comments

Bose® 901 Series II Active Equalizer #46234 Repair

Posted on March 21, 2016 by jwk

This Bose® 901 Series II Active Equalizer, serial number 46234, came in for a repair just recently. As is happening with nearly all of these early ’70s equalizers by now, this one had developed poor sound quality and distortion and … Continue reading →

Posted in Audio, Bose, Electronics, Projects, Stereo | Tagged , , , | 3 Comments

The Speaker Spotter – March 3rd, 2016

Posted on March 3, 2016 by jwk

Some interesting stuff on Craigslist in this week’s The Speaker Spotter, a curated selection of Seattle’s local speakers for sale online. As always, Retrovoltage is not affiliated with any of these sellers and you should click through the link to the … Continue reading →

Posted in Audio, Collections, Speakers, Stereo | Tagged , , , , , , , , , | Leave a comment

Bose® 901 Series II Active Equalizer #68953 Repair

Posted on February 28, 2016 by jwk

This Bose® 901 Series II Active Equalizer was originally a European unit, designed for a 240V mains supply. Most if not all 240V equalizers with U.S. style plugs were sold on military bases in Germany and elsewhere, and returned with their … Continue reading →

Posted in Audio, Bose, Electronics, Projects | Tagged , , , | Leave a comment

Bose® 901 Series II Active Equalizer #64364 Overhaul

Posted on February 27, 2016 by jwk

This Series II Bose® Active Equalizer came through the shop. It had suffered age-related failures in its electrolytic capacitors, and the resistors had drifted with age and moisture to produce the wrong curves. Fortunately, it’s nothing some maintenance can’t solve! … Continue reading →

Posted in Audio, Bose, Electronics, Vintage | Tagged , , , , , , , | Leave a comment

Bose® 901 Series I Active Equalizer #6878 Repair

Posted on February 20, 2016 by jwk

This early-production Bose® 901 Active Equalizer came through the shop recently for a repair. These Early models were the very first production run, back in 1968, and have a pretty significantly different circuit design from the later models, and feature … Continue reading →

Posted in Audio, Bose, Electronics, Hi-Fi, Vintage | Tagged , , , , | Leave a comment

Bose® 901 Series IV Active Equalizer #253288 Overhaul

Posted on February 16, 2016 by jwk

This Bose® 901 Series IV Active Equalizer came through the shop for a full overhaul. Inevitably over the years, various parts wear out and degrade and can make the equalizer sound bad – or not work at all. Without the … Continue reading →

Posted in Audio, Bose, Electronics, Hi-Fi, Projects, Vintage | Tagged , , , | Leave a comment