Tag Archives: Bose

Bose 901 Series III Equalizer #181986 Repaired

Posted on April 8, 2015 by jwk

Cross-posted from the Rain City Audio Repair Blog: Bose 901 Series III Active Equalizers are uncommon compared with the other series, but I did have one through the shop just recently. The Series III design – while a great performer … Continue reading →

Posted in Audio, Bose, Projects, Vintage | Tagged , , | 6 Comments

Bose® 901 Series VI Active Equalizer #199732 Repaired

Posted on February 20, 2015 by jwk

Cross-posted from the Rain City Audio Repair Blog: A first for my shop, I recently worked on a Bose® 901 Series VI Active Equalizer! These are considerably newer than the Series I-IV that typically come through the shop, although they’re … Continue reading →

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

Bose® 901 Series I Active Equalizer #55382 Refurbished [Repair Blog]

Posted on February 17, 2015 by jwk

Cross-posted from the Rain City Audio Repair Blog: Another Bose® 901 Series I Active Equalizer came through the shop recently for a full rebuild. These are all nearly 50 years old and are definitely showing their age, and this one … Continue reading →

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

Bose® 901 Series I #38949 Repaired [Repair Blog]

Posted on February 13, 2015 by jwk

Cross-posted from the Rain City Audio Repair Blog: Another Bose® 901 Series I Active Equalizer came through the shop. These equalizers were manufactured between 1968 and 1973 and are really showing their age: most have degraded in one way or … Continue reading →

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

Bose® 901 Series IV Active Equalizer #116907 Overhaul

Posted on December 12, 2014 by jwk

Cross-posted from the Rain City Audio Repair Blog: Another Bose® 901 Series IV Active Equalizer came through the shop recently. It’s owner shipped it in without the wooden cover for security. This is a bad idea on the Series I/II, … Continue reading →

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

Bose® 901 Series I Active Equalizer #33133 Overhaul and Upgrade by Rain City Audio

Posted on December 8, 2014 by jwk

Cross-posted from the Rain City Audio Repair Blog: Another Bose® 901 Series I Active Equalizer was through the shop lately, serial #33133. It came in working well enough on its original components for an overhaul and upgrade to ensure it … Continue reading →

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

Boes 901 Series IV Active Equalizer #241792 Refurbishment

Posted on November 3, 2014 by jwk

Bose® 901 Series IV Active Equalizers are getting up there in years now, too, so more and more are coming up for repair. This one came in with a flickering power supply in need of an overhaul. Series IV was … Continue reading →

Posted in Audio, Bose, Hi-Fi, Projects, Stereo, Vintage | Tagged , , , , | 1 Comment

Esteemed Bose® Model 901 Active Equalizer – Serial #230 Repair

Posted on October 17, 2014 by jwk

Cross-posted from Rain City Audio: I had the distinct pleasure of working on one of the earliest  Bose® Model 901 Active Equalizers from Series I’s first production run. Serial #230, in fact! It’s made entirely by hand and shows traces … Continue reading →

Posted in Audio, Bose, Hi-Fi, Radios and Tubes, Stereo, Vintage | Tagged , , , , , , | 2 Comments

Bose 901 Series IV Equalizer #202245

Posted on August 29, 2014 by jwk

A bit different from the run of Series I and Series II that I usually see, I got to fix up this Bose 901 Series IV Active Equalizer which was sent to me from Austin, TX. The Series IV was sold from 1978-1983 and its construction reflects this.

The PCB on this model is single-ended, so can be completely removed from the chassis.

<img class="alignnone" src="https://lh4.googleusercontent.com/-yTJ3z3swIO4/U_wH-zjcj3I/AAAAAAAAkEA/YBDKfs9GTSs/s640/IMG_1459.JPG&quot; alt="" width="640" height="480 Continue reading →

Posted in Audio, Bose, Stereo, Vintage | Tagged , , , , , , , | 3 Comments

Bose 901 Series II Active Equalizer #67402 Repair

Posted on August 25, 2014 by jwk

This equalizer got a full overhaul with new 1% precision resistors, electrolytic capacitors, audiophile-grade output capacitors, transistors, gold-plated RCA jacks, 4% silver solder for all connections, a thorough switch cleaning, and computerized frequency response testing and a listening burn-in to verify proper operation. It sounds just fantastic with a very dynamic and life-like presence that really draws you into the experience of the source material, just like the Bose 901 should.

Read More


Check it out at Rain City Audio Continue reading →

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