Tag Archives: vintage stereo

Everything to Know about Bose 901 Series I and Series II Active Equalizer Repair & Speaker Systems (and the 800, too!)

Posted on June 12, 2026 by retrovoltage

A deep dive into the history and repair of Bose 901 Series I and II, plus the Bose 800, sourced from direct experience repairing more than 500 Active Equalizers. Includes vintage ad copy, photos, tips and tricks, schematics, and parts lists. Continue reading →

Posted in Audio, Bose, Collections, Resources | Tagged , , , , , , , , , , , , , , | 5 Comments

Upcoming Projects for 2026

Posted on June 2, 2026 by retrovoltage

Having had a chance to unpack some of my shop from storage and settle in to the new space, I’ve got an idea of what projects I’ll be working on myself in between projects with my shop partner. Bose Active … Continue reading →

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1974 Sony STR-6200F Receiver Overhaul and Alignment

Posted on June 19, 2015 by retrovoltage

I recently got to work on a pretty big, fairly rare Sony receiver from 1973-74: the STR-6200F. It’s a powerful receiver featuring 60W per channel of power available, with quite a few inputs and outputs, and a strong FM tuner … Continue reading →

Posted in Audio, Electronics, Hi-Fi, Projects | Tagged , , , , , , , , | 4 Comments

Harman-Kardon Citation 17S Pre-Amplifier Refurbishing

Posted on January 2, 2015 by retrovoltage

I recently got to work on a Harman-Kardon Citation 17S pre-amplifier. Vintage HK gear is some of my favorite to work on: it’s robust, reliable, and built to be easy to service. The Citation 17 pre-amplifier is the companion for … Continue reading →

Posted in Audio, Projects, Stereo, Vintage | Tagged , , , , , , , , | 1 Comment

Harman/Kardon Control Amplifier A-401 Restoration

Posted on November 19, 2014 by retrovoltage

This little Harman/Kardon Control Amplifier, model A-401, just came through the shop for a full overhaul. It was in a pretty sorry state to begin with – one channel distorted, one barely gasping for air, and a world of scratchy … Continue reading →

Posted in Audio, Electronics, Hi-Fi, Projects, Stereo, Vintage | Tagged , , , , , , , , , , , , , | 8 Comments

Marantz 2245 Stereophonic Receiver Rebuild

Posted on September 19, 2014 by retrovoltage

An iconic piece of kit from the golden age of hi fi just came through my shop: the Marantz 2245 Stereophonic Receiver. This fantastic receiver is in pretty good cosmetic shape, but its owner reported that it started acting up – it’d take … Continue reading →

Posted in Audio, Electronics, Hi-Fi, Projects, Stereo, Vintage | Tagged , , , , , , , , , , , | 7 Comments